Coolant's Full Monty

I've got all of the Rocky Mountain Westy designed cooling loop in place, from the engine output all the way down to the heater wye hole in front of the torsion bar and back to the thermostat side of the Subaru EJ22. I've got busted knuckles and I'm grinning like a madman. Someone finally got it right, and damned if I'm not the beneficiary!

For those of you coming in during the Intermission, here's the quick recap: The bright lads at Rocky Mountain Westy produced a beautiful vehicle specific stainless steel coolant tubing kit similar to what they provide as replacement components for the Vanagon's oddball plastic coolant tubing that runs the length of the vehicle. Through some polite discussion with the owners of RMW, and a willingness to be the guinea-pig as they worked the kinks out of beta testing and making it ready for production, I got hold of a set of these lovely mandrel bent tubes, fittings and miscellany required to move coolant down to the heater wye area in front of the transmission nose-cone.

We're focusing on all of the stainless steel coolant tubing in the left third of the above diagram.

I have my own engineered solution for the radiator and cooling, but needed the components in the engine bay to be reliable. While I'll only briefly touch on my radiator solution in this post, I did want to show off the beautiful and clever work that RMW has performed. The idea that underlies their design differs from every other one I've seen: It's called "Nobody Move!"

What I mean by that is the worst, yet most common attribute of conversions is the use of generic/universal/cheap components, fitted one to another like tinker-toys, just enough to make a path to the radiator and back. A reasonable car buyer who looked under the hood of a new car and saw what is under the decklid of most engine conversions would scream like a sheep in that Superbowl Sprint commercial. (I won't insult your intelligence by linking it. If you want to hear it so bad, Google it.)

Instead, the RMW coolant tubing design is a delight of components rigidly aligned in the engine bay, and when their support transfers from the engine to the chassis, there is a flexible coupler interspersed to make both fore and aft sections rigid relative to the component that they're connected to: Engine supported at the rear, chassis supported at the front leading down to the heater wye.

So let me lead you on a tour of the system. For clarity, I'll be using the orientation definitions in the classic How to Keep Your Volkswagen Alive by John Muir: "Front is Front." When working on engines which face you when installed backwards in the vehicle...people get 'front' confused sometimes. My descriptions are based upon the alignment of the vehicle. Thus forward is toward the front, rear is to the back, and so on, use your imagination: behind, in front of, left side, right side, etc. I don't use the terms like driver's side, or passenger side or 'nearside' or 'offside': They are without a referent and are confusing. Everyone can do front, back, left and right. I DO use two nautical/aerospace terms for which there is no suitable substitute on a car: inboard (closer to the centerline axis of the vehicle) and outboard (closer to the exterior of the vehicle.) This way I can say that the vehicle speed sensor signal wheel is bolted to the inboard left constant-velocity joint. And you should know where that is, exactly.

Outlet from the coolant manifold at the top left of the engine, with hot
coolant passing through a coupler and into a 130° clockwise
rotation which sends the coolant forward down the left side of the
engine bay.

Looking left down the aluminum heat shield, we pass the first hard
mount to the engine. These "T-bolt" clamps put a threaded stud
perpendicular to the side of the tube. When tightened, they both clamp the
tube (placing compression equally around the circumference) but also
create a handy 1-1/2" long thread which may be used to secure
them and the tube to other objects.

Since this is experimentation time with the components that I was
sent by RMW, I felt a certain freedom to try different methods to
 secure the tubing. In this case, I chose to use the mounting tang
to attach to the heat shield. The shield doesn't really bear any weight,
it just restrains the tubing from moving.

Looking forward down the left side of the engine, the tubing transits 

inline with the engine and then jogs inboard , tucking somewhat in 

front of the engine to clear the body cavity of the engine compartment.

Looking forward, After the jog inboard, the hot coolant pipe straightens
out as it passes the transmission. When it reaches near the nose cone,
 there is a silicone coupler that separates the rear, engine mounted tubing
from the forward leg which is supported by the chassis. The flexible
coupler isolates vibrations from the engine from shaking the whole
tube, and vice versa: chassis movement is isolated from the engine.

Hot coolant tube and torsion tube viewed while facing forward, 

detail of previous picture. After passing the coupler, the forward left length 

of tubing passes over the torsion bar tube. This needs to be secured in 

such a way that the tubing doesn't press up against the body above, 

or the torsion bar below. It must pass through the area above the torsion bar 

with 1/4" (6.3mm) to spare above and below. The secret is in the bracketry

 which again ties on to the t-bar clamp so that the tubing stays where 

you put it. The tilt in the bracket allow the tubing to be pressed inboard, 

directly over the left rear trailing arm joint.

Without the bend in the bracket, this wouldn't be possible.

The brackets clamp around the torsion bar tube so that the forward section

 of the hot-side tubing is held rigidly in place. It's best to keep the fittings

 all a bit loose while connecting everything.

Here is where the hot side terminates, just behind the rear transverse support heater wye cutout. 

(Out of frame, to the right,) I found that by loosely putting all of the components in place and then tie-wrapping the outlet/inlet tubes together at the wye cutout, when everything is tightened down and the tie-wrap is removed, the tubes want to stay in place. Note that the hot pipe coming down (middle of the frame) is SUSPENDED between torsion tube and floor. Once all of the fittings are tightened down, it's not going anywhere. Try to give it a shake and you'll just injure yourself.

Now we've reached the transition where the VolksarU system takes over. For the purposes of this overview, we're going to assume that the tubing has transited into the central box area of the frame, passed through the radiator and exited back through the other tube, 

forward on the right hand (top of frame.)

The cold return tube (foreground) while looking to the left. Return coolant travels back to the engine, but first vaults over the torsion tube the same way the hot side did on its way to the radiator. There are two critical differences on the return: the coolant re-enters the engine at the bottom, and the pipes and brackets are shaped completely differently to accommodate that need.

 Facing to the rear, the front right tubing passes over the torsion bar and joins
the rear right tubing for its final external portion of the coolant run.
This happens just behind the torsion bar, to the right of the transmission nose cone.
Note that the bracket on the return side (right) is shaped differently and located
differently (inboard of the swing arm joint, instead of outboard.)

View facing the right rear. We're past the return coupler and are on our 

way to the thermostat. There's a lot of bob-and-weave, though: 

The final tube at the right rear comes up to clear the carrier bar 

(black, foreground), and then with another t-bar clamp and 

mounting tang, transfers it securement to the engine.

So there we go! That's as complete a circuit as I can make of the RMW coolant tubing kit. I can say that between the brackets, clamps, silicone hose couplers and the perfect fit only possible with CNC bent and beaded 16ga Stainless Steel tubing, the value (price I won't mention, since this isn't a production item yet) is phenomenal.

I still have the expansion tank to get hoses on, and then it will be time to mount the radiator which has already been dry-fitted and only waits for some fan electrical fittings and the time to perform the work. At the moment, I'm flat on my back and sick as a dog from having pushed myself too hard at work and some virus got me and gave me a smack down, which is the only reason this got written.

The Urge to Purge

About six years ago, I wrote an article on The Samba about rebuilding your M26 vapor recovery system for the Super Beetle. The article was very well received, mostly because it was the first time that anyone on that forum had taken the time to explain in small words and simple diagrams that the vapor recovery system was not some "power robbing emissions junk" (unlike the EGR or Air Pump) but rather a simple and convenient way to save fuel, not rupture your fuel tank or...well, catch fire.

The simplest version of the EVAP system ( as it is now known) is to capture fuel vapors coming off a warm tank full of fuel (which is trying hard to become a gas and escape) in a matrix of charcoal (absorption) and when you restarted the engine, purge the canister (adsorption) by pumping fresh air in one end and air + vapors out the other to the air filter, where they get sucked into the engine and burned. No fuel wasted, the cloud of gasoline vapor captured and safe from some bum flipping his burning butt under your Bus (FOOM!) and fewer Hydrocarbons for everyone to breathe. Everyone wins. Prior to 1970, all vehicles just dumped excess vapors to the atmosphere, which is why SoCal had smog that could just about kill on contact. A lot of good has come this simple change.

The Super Beetle User Manual's description of the M26 EEC system. It is hard to get it much simpler than this.

This is not a complicated system: three hoses (fresh air input from fan housing, evaporative tap from fuel tank, purge hose to the engine air filter) and one canister to hold the charcoal where the three hoses meet. Yet somehow over the years, M26 has developed a reputation as being more trouble than it is worth...until the driver wonders why they're constantly finding their garage or vehicle cab smelling like a refinery. At that point, the M26 system has usually be gutted and the parts thrown away.

Modern vehicles have improved methods of performing exactly the same job. The methods differ because now we have vehicle ECUs that are smarter than most drivers. The ECU consumes huge amounts of data to improve performance, reliability and reduce emissions, and here's where I run into a collision of cultures: A vehicle from the early days of emissions control, and a post 1996 On Board Diagnostics (OBD2) ECU standardized system, in this case by Subaru. OBD2 based systems are bristling with sensors and actuators that aren't on the vintage VW and can't be economically added. So again, we must make substitutions and do primary engineering to interface the two incompatible systems from different eras.

The VW has only a fuel level sensor wired directly to the gauge. In OBD2 vehicles, there is a level sensor, a fuel temperature sensor, a pressure sensor, and actuators as well. All data passes through the ECU, which is either great engineering or tin-foil hat scary depending on your temperament.

I started examining the OBD2 system and immediately got confused. The VW system is based on positive air pressure from the fan housing, pushing the vapors out of the canister and into the air filter where the air from the canister would be metered by the mechanical Air Flow Meter (AFM.) By contrast, the Subaru system is tapped to the intake manifold (downstream of both the throttle AND the MAF) drawing a vacuum through the carbon canister. So how do you keep from sucking unmetered air into the Subaru engine and running lean as a result? Would the earlier system be better, because the reclaimed fuel vapor was at least metered by the AFM?

After studying for several hours, my understanding of the OBD2 is improved enough that I have a plan for how to tackle it. To describe the adaptation though, I have to explain what an OBD2 compliant EVAP system is actually intended to do. Hint: It isn't just a blind system anymore. Self-tests have finally become the norm, admitting that any system will fail if it has no way to sanity-test its own safety systems. By contrast. the VW L-Jet ECU in the late Bay Bus is just barely smart enough to inject fuel.

Here's how EEC (Evaporative Emissions Control) worked in the early days:

1. The early 1971-1974 EEC forcibly pumped air into the carbon canister any time the engine was running. Any trapped vapors from the fuel tank were expelled to the air cleaner. 
1. Pro: Dumb as dirt and worked as well as legislation required at the time. 
2. Con: An uncontrolled dump of an unknown amount of hydrocarbon rich air mix on each start. No way to moderate or react to the purge of the canister; just stumble and gag until you had enough fresh air to smooth out. Not a good long term solution.
2. +75-(L-Jet EFI) Same as above, but with vacuum based EEC valve. Still a forced air system, but the air cleaner had a vacuum valve on it which required full ignition advance before it would click open the EEC purge valve and dump the HCs when the engine was already guzzling fuel and wouldn't notice the slight change in enrichment.
3. The common failing of both the early and late systems was that the pressurized air from the fan housing did not pass through a check valve. With the engine off, once the charcoal canister passed the saturation point, fuel vapor could find its way out-the-in-door of the fan housing fitting that provided the pressurized air.
4. Because there was no method to measure the efficiency of the vapor reclamation, VW's sole directive was to replace the carbon canister every 40,000 miles. As you can imagine, this maintenance was rarely performed, if ever.

While an improvement over dumping raw hydrocarbons overboard on a hot day, that's about as smart as VW's EEC system ever got in the Air Cooled era. Obviously, there was massive room for improvement.

15 years later and along comes OBD2. With the same intent as EEC, but with an ECU and processing capacity newer by 15 years and required to meet even more onerous emissions regulations. EEC is now referred to as EVAP and the EEC vacuum valve has been replaced with a Canister Purge Solenoid (CPS), a valve toggled by electrical signal rather than vacuum. Two big changes happened with the advent of OBD2: more parts, and more smarts.

There are now two controlled connections to the carbon canister: The CPS (Purge) and the CVS (Intake Vent.) The tank vapor recovery system still dumps there. So far, this just sounds like they put an extra valve on the carbon canister and switched from vacuum signaling to electrical signaling. If OBD2 were doing exactly the same job as EEC, that might be true. It isn't.

I mentioned that OBD2 included a fuel tank pressure sensor. I had assumed that if you had a pressure sensor, you would use a detected pressure to cue the CPS and CVS when there was excess pressure in the tank and to open the CPS to relieve the pressure. Wrong. SO wrong.

The fuel tank pressure sensor is not used at all in the regular maintenance of trapping and routing tank vapors for burning. In fact, the fuel tank pressure sensor is misleadingly named. Yes, it measures 'pressure,' but no-one said pressure has to be positive. The sensor is designed to measure vacuum. So let's ignore the fuel tank pressure sensor for a minute since it doesn't have anything to do with the EEC/EVAP management process that we are trying to graft together from incompatible 1970s and 1990s technologies. We'll come back to it.

The CPS (Purge) behavior is completely automatic and operates on a periodic cycle with the CVS (Vent), via a regular pulse sent to them by the ECU based on engine rpm. These two solenoids cycle open and closed together, momentarily admitting a very small amount of unmetered air mixed with fuel vapor straight into the manifold to be burned. (Question: Why not dump it into the air filter housing like the old EEC style system does? Answer: Because a MAF or MAP airflow meter doesn't respond well to being fogged with fuel vapor, especially hotwire MAFs! FOOM!)

So why the addition of the CVS (Vent) valve? When the car is off, you don't want the vapors escaping to the atmosphere from the canister by going out the fresh-air-in door. The VW EEC was exactly that kind of system, with the fresh air port wide open on the carbon canister without so much as a check valve. In an OBD2 compliant vehicle, when the power is off, the engine facing CPS and atmospheric facing CVS close, which means any vapor captured is really, truly trapped in the carbon canister. The system is sealed up tight, fore and aft.

So doesn't OBD2 just put a one-way valve on the fresh air inlet and when the draw stops, it closes? This is a simple solution, but the self-test systems that OBD2 brought to the party require more programmatic control that a check valve can offer. Similar to how the addition of an O2 sensor in the exhaust stream made ECUs enormously smarter because they could test how their changes actually altered the output at the tailpipe, a self test program of the EVAP system checks the status of the components by performing a clever and simple test.

My assumption that the addition of the tank pressure/vacuum sensor was to tell the system when to purge was a bad leap of logic. Instead, the tank pressure sensor is there to run sanity checks at regular intervals on the integrity of the whole fuel handling system. The regular pulse open/close of the CPS and CVS is the regular running program. But after a certain amount of engine run time, the ECU runs a diagnostic on the EVAP system.

Here's the EVAP self-test program in a nutshell:

1. The ECU commands the CVS to close. No more fresh air. The fuel system should be sealed.
2. The ECU commands the CPS to open. Now the engine intake is pulling about a 1/4 PSI of vacuum, and with the CPS open, it pulls that vacuum all the way through the whole fuel system: the hoses, the CPS, the charcoal canister, and even the fuel tank. The whole fuel storage and venting system is under vacuum.
3. After a set period of time pulling this vacuum, the ECU orders the CPS to close.
4. When the CPS is closed, the ECU takes a reading of the vacuum in the system.
5. It waits for a period of time, and then takes a second reading.
6. If the readings match, there are no leaks: The fuel system has passed the EVAP self test. The clock is reset for the next test, and the CPS and CVS go back to their regular opening and closing program, mixing captured fuel vapor with air from outside and then purging it into the engine for burning.
7. If the vacuum readings *don't* match, there's a problem. The ECU sets a pending fault code, but doesn't switch on the Check Engine Light (CEL or MIL, depending on how long you've been working on cars). It could be a fluke: A gas cap that didn't get tightened correctly, etc. But there is most certainly a leak.
8. If the ECU executes the fuel system sanity check a second time, and it fails again, then it lights up the CEL and throws a code.
9. If the sensor detected the same value both times, and it equals the same as the barometric pressure outside the vehicle, the test reports as failed: Not enough information to even guess.
10. If the sensor detects wide changes in values between the first and second reading, it throws the code for a LARGE EVAP leak.
11. If the sensor detects slight change in values between the first and second reading, it throws the code for a SMALL EVAP leak.

And that is what the tank pressure sensor does: It just gives the ECU a nerve ending to self-police its own design and cry for help if it is failing.

Unfortunately if the tank pressure sensor is missing, all of these tests fail and the OBD2 system will be dropping CEL codes like depth charges: your CEL will be on permanently, so you'd be likely to miss a code that you really care about. I have no tank pressure sensor to measure and no CVS (vent) to control to seal the system for the self test. To make the OBD2 ECU viable run to my engine, I'm going to have to lie to it, confining it to the sensors that I actually have, instead of the ones it wishes I had.

When adapting a Subaru into a vintage VW, folks like me use the Small Car Interface Board to provide faux-data that the ECU is expecting but is not available in the chassis being converted. The Interface Board pretends to be the fuel tank pressure sensor (and fuel level and temperature sensor) and responds with the same perfect vacuum value every time the ECU triggers an EVAP system test.

I still don't like the idea of an over-pressure tank being able to spill fuel vapor out of the fresh air inlet for the carbon canister when the engine is off just because the system has to be able to breathe IN when running. I can't put a stock Subaru carbon canister on my VW: the cost is astronomical, the wiring a headache, and the actual emissions win marginal. Instead, I'd prefer to use the stock VW carbon canister because despite its limitations and simple design, it has two things that beat the hell out of the Subaru canister:

1. The engine compartment already has brackets in place to mount it. If I use another solution, I have to cut those brackets out to make way for other components to be mounted there AND I have to fab a mounting system for the Subaru canister system in an engine compartment (or under the vehicle body.) The back of the vehicle is already becoming crowded with ancillary bits for this conversion.
2. The Subaru canister is a unitized replacement item and is expensive. The VW canister can be disconnected, opened without destroying it, and have new media loaded. New media is available, despite the difficulty in sourcing it.

Here's where I think there is an elegant compromise that allows the Late Model Bay Window owner to re-use a stock carbon canister and mounting bracket: Some modified fittings for the stock canister to the CPS valve, and a simple (VERY simple) petrol resistant nylon check valve available from McMaster-Carr: http://www.mcmaster.com/#standard-check-valves/=wxezc0

When the CPS (purge) opens, vacuum is created, which opens the check valve: Fresh air! Inhale the fresh air with the trapped vapors and into the manifold we go. When the CPS closes at the end of its pulse, no more vacuum, so the check valve closes, too. No way out for fumes. No fancy self test, but at least no dribbling fuel vapors trying to gas me in my own garage.

If you've wrenched or programmed or thought about these emissions systems and you can see a simpler way to get the same result, drop me a line. I'd love to hear about your solution. My goal is compliance with the spirit of the law. Yes, I have to lie to the ECU about the missing pressure sensor, but I can at least close the darned door on the carbon canister when we're done purging so that I'm doing better keeping my stink-hole shut than a Type4 or Type1 VW engine.

Top Gears

I'm getting all pumped up for my vacation in a week when all of the parts that have been specified have been delivered. I'll have mostly clear decks to go into the garage and work as hard and as fast as I can on this project that has gone through several retrenchments. Someone pointed out a nasty side effect of switch to Subaru power eight months ago and I've been looking at it since. It's called gearing.

While any number of adapter plates can put all sorts of engines into your VW, that doesn't mean that your VW transmission is going to appreciate 2-3 times the horsepower than it was designed for. Not only that, but you might not much like the experience either.

The VW transmissions were built with a basic idea about their power plant that goes all the way back to the Nazi era KdF-wagen: Top speed is cruising speed. In the KdF-wagen 100kph was as fast as the vehicle was expected to go, so everything about the engine's design was made to meet that goal and not a bit more. That means that the RPMs required are quite high by comparison, not for acceleration, or passing, but just for cruise: maintaining a mostly constant speed. So the engine is designed to produce its peak power and torque at the RPM needed to maintain cruise. At any RPM faster than max power and torque, both fall off rapidly: You can turn the engine faster, but not more productively.

So let's use an example to wrap our heads around this: The 1977 VW Bus has a designed top speed of 75MPH. With the right size tires on (185R14C which are a type of truck tire) the tire stands 25.7 inches tall. Every rotation carries you a certain number of feet forward. The taller the tire, the further forward you travel per rotation. So, pass the diameter of the tire, the engine RPM and the various gears in play in the transmission, and you can get a nice chart of what speed you'd be going in 4th gear for any given engine RPM. Confused? Relax. Here's what we've got, given a completely stock engine and transmission setup from the factory. (A 1 to .82 gear ratio in 4th, e.g. one rotation of the tire for 0.82 rotations of the engine.)

Speed (MPH) per RPM
2000	2500	3000	3200	3400	3600	3800	4000	4200	5000	5400	6000	6500	7000	7500	8000
38	47	56	60	64	68	71	75	79	94	101	113	122	131	141	150

So the top speed of 75MPH is achieved by turning the engine at 4000RPM in 4th gear. Coincidentally, maximum torque for the stock 2 litre Type4 engine is achieved at 3000RPM, and maximum power at 4200RPM. So 75MPH is a good spot for that engine: it can work at that RPM effectively and efficiently for a long time. It's designed that way. The maximum torque starts falling off after you've reached freeway speed at 3200RPM (60MPH) and then it's all about horsepower to keep things turning that fast or a little better.

As vehicles got heavier over the years, different gearing was installed in transmissions to match it to the peak efficiency of the engine, trying to stay in the sweet spot. The engines and their output kept changing too, as manufacturers struggled to comply with emissions regulations, usually resulting in engines that were less powerful: A constant dance between the weight of the vehicle, the power of the engine, and the transmission in between trying to mediate the constantly flexing relationships between the two.

So why the lesson in ratios? Because the EJ22 SOHC Subaru has a very different power and torque profile. It produces so much more power and torque than the poor old Type4 many people just assumed that it's a win to just swap the engine. What they don't count on is that the whole rest of the drivetrain, from the clutch all the way out to the tires, is expecting 4000RPM for cruising speed. This means that the EJ22 is capable of wailing away under the rear deck at 4000RPM and still have more power available. But it's LOUD. The RPM required to make the engine happy (where the EJ22 makes the best balance of torque and power) is much lower.

My EJ22 is from a 1997 Impreza Outback Sport which has an unladen weight of 2915 pounds, 127 pounds lighter than the 3042 pounds of a 1977 Deluxe Bus. So what RPM would the EJ22 cruise at if it was at home, coupled to its favorite Subaru 5MT transmission in a similarly weighted vehicle?

Speed (MPH) at RPM
2000	2500	2850	3000	3200	3500	3800	4000	4200	5000	5400	6000	6500	7000	7500	8000
43	54	62	65	69	76	82	86	91	108	117	130	140	151	162	173

Aiee! 4000RPM, while well below redline for the engine, is still flailing away making a lot of useless sound and fury for no good reason. To produce good cruise behavior, this engine only needs to be doing 3450RPM. Something has to give: either the engine needs to be completely redesigned or at least get new valve cams at a minimum, or the transmission in the Bus needs to be a closer match for the engine. Messing with the engine's behavior is expensive and a little ridiculous. Putting the Impreza 5MT transmission in the Bus is do-able, but very expensive. Having the 091 transmission in the Bus rebuilt with different gearing is not cheap, but it's less expensive than either of the other options. But there's a third option that has real merit...if you're willing to embrace some 'lifestyle changes.'

Remember I said that the tire diameter is part of the equation, moving forward a certain distance for each rotation? If you increase the diameter of the tire, you go further for the same number of rotations. That means, working backward from the tire, through the drivetrain and gearing to the engine...the engine turns more slowly. So it's only a matter of playing with the tire diameter until you find the (pun intended) golden ratio. Make the tire too big and it will have rubbing, grabbing and interference issues with the suspension and the body. So there's an upper limit. Thankfully, there's a tire that will fit, and produce an improved change of total ratio: instead of the 185R14C at 25.7 inches tall, we replace it with an Offroad/Onroad multi-purpose 27X8.5R14LT. (Yes, the sizing format changes to an older truck tire standard. It's roughly the same as a 215/70R14, a nick bigger at 26.8 inches tall.) 

So what do we get for running a big, scary off-road/on-road truck tire?

Speed (MPH) per RPM
2000	2500	3000	3200	3300	3600	3800	4000	4200	5000	5400	6000	6500	7000	7500	8000
39	49	59	63	65	71	75	79	82	98	106	118	128	137	147	157

Now we're getting somewhere! It isn't perfect, and 3800RPM is still much higher than it needs to be relative to the 3450RPM the Subaru 5MT gearbox would need for 75MPH. If you want to do better, you're going to need to regear: either a different transmission, or the same transmission worked over with different ratios of gears.

Fortunately for me, I don't have any desire to go 75MPH in my Bus! It is a 40 year old vehicle now, and has a reputation for far too much 'float' in the front end at high speed. I'm not in such a hurry to meet my Maker that I want to spend most of my time at that speed. So a John-Law approved 65MPH will put me at 3300RPM with gobs of headroom in torque and power if I need it. That's about the best I'm going to get without the $1700 for a rebuilt and custom re-geared 091 Bus transmission, or a rebuilt 5MT specially modified to join a VW Bus: $4150.)

I have to buy new tires anyway: the last time the tires on my Bus were healthy was when Clinton inagurated. They hold air...barely. So it's a bargain at $500 for four tires (General Tire - Grabber AT2 27X8.5R14LT / Load Range C) that will provide me many years of roadworthy travel and may lead me into adventuring in places that street tires might not take me. Everybody wins.

Decisions, decisions...

I've joined a few new forums recently to fan the flames for VolksarU. I don't want to do this solo; that's boring! But I am finding the number of people who have both experience *and* opinions to be thin on the ground. Opinions....you know what they're like. When it comes to the 'Conversion Perversion' crowd, the proportions change for the worse: 5 people in a room, 9 opinions.

I turned to the Vanagon crowd who have been doing conversions to their already liquid cooled vehicles for years. They've been very helpful, though all struggle with imagining the challenges of having to design the whole coolant system themselves. They're already plumbed for it. Burp the baby, and hit the road! A Bay window conversion? Not so much.

I've found a quite appropriate parallel to posting my solutions online only to have it shot at by those who've never worked on a Bay conversion in their lives: On the Discovery Channel, the program Mythbusters has a maddening fanbase. On the one hand, they're faithful to the idea of Confirmed, Plausible, or Busted. Where they differ is in the excruciating details of making a pop-science show that has to honor the scientific method on a modest budget while producing 42 minute episodes that entertain and educate. The pseudo-scientific second guessing (they're not taking drag into account! They've called it complete wrong!) got to be so bad that Discovery finally started producing an inexpensive 10 minute video blog to defuse the yelling. "Want to know why we did what we did, and didn't do what we didn't do? Log on..."

I'm inevitably in the same pickle. I can at least consider the opinion about my wiring from someone who has converted a Vanagon. But they're not qualified to comment on my radiator or coolant loop. You have to have tried a Bus conversion before I'll consider listening to comments about cooling. If you've actually succeeded, you have my attention. For everyone joining this blog in progress and who doesn't want to roll backward through two years of torturous decision making, here are the edited highlights.

But first, a word about international 'short-run' products: For the enthusiast in the USA ordering from the UK, the exchange rate and shipping usually winds up increasing the price of the component by at least a factor of three...or more. Add on your Federal, State and local taxes (all of which you are responsible for) and an 8 lb component from England can cost more in shipping than in the purchase price alone. Unless you are already shipping mounds of goods from abroad, you will get murdered on the shipping.

Therefore, most of my kit is from Rocky Mountain Westy in Fort Collins, Colorado, USA. They had two things going versus the UK conversion components: Their solutions required very little injury to the body of a vehicle being converted and they produce very high quality product at a reasonable price. They are a production shop, not a custom shop. If you ever want to standardize (one of VolksarU's chief goals) you have to have standardized interchangeable parts. I compared the quality of the following products that come from them with their competitors. They're also the only game in town in the Americas for production engine carriers.

So gaze adoringly at the T2B Bus EJ engine carrier, because its the only one on the American market. It's made of high quality materials, is mandrel bent for improved clearances and powder-coated for longevity. Sure, you can have your fabricator over and he'll weld up something that you can drill holes in the frame and bolt on. That's the solution everyone else offers for the Split and Bay bus. This makes every conversion an outhouse: put together with parts-on-hand to fulfill the bare minimum of utility. Parts from one aren't compatible with another. I've written elsewhere that this is the difference between an outhouse and an indoor bathroom. You're willing to read the newspaper in a standard bathroom, but an outhouse is 'minimal utility to do the job.' Not a place you want to linger.

So if you are doing a Late Bay Window as I am, the RMW hanger is the only design that locks the carrier into place in three degrees of rotation, and does so without requiring any cutting or welding on the body, re-using stock mounting points. In it's own way, it is the perfect demonstration of the VolksarU ideal: Installation is DIY friendly, no body mods needed and is compatible with two decades worth of Subaru EJ series engines. A lot of smart engineering, jig and fab work went into this carrier.

To my knowledge, only two other companies which offer carrier bars "cash and carry" rather than a custom fabrication each time. Both are both in the UK. (RJES & Fellows Speed Shop.) While good products and being weld-in compatible with many different models, this requires someone to do the welding, so they aren't as DIY friendly (unless you already weld.) Also, watch out for the international shipping killer costs if you aren't local to them.

My transmission adapter is made by Outfront Motorsports for Rocky Mountain Westy. Again, this is a CNC fabricated part, not a 'bespoke' one-off. Sure, Kennedy Engineering has been machining these adapters for years. Yet in my experience, they're also trapped in the technology dark ages, have a 20 year old web site, don't respond to email inquiries and often not to phone calls. They won't commit on delivery times or shipping. By contrast, there are several competitors who concentrate just on the Subaru to VW market and have taken the fit and finish to the next level. Why would I want to pay more for Kennedy's product when their quality and service has become demonstrably less? (This is my experience contacting them. Your Mileage May Vary.) It left a bad enough taste in my mouth that I decided to buy from someone else. Back to my friends at Rocky Mountain again.

I also needed a throttle valve reverser (TVR). While I can have this fabricated locally, why would I want to do that if I'm looking for standardization? RMW ships me one off of their shelf. When they run out, they fabricate new ones on their jig. Rinse and repeat. That jig can produce thousands of TVRs before it will need to be refreshed, and all of them will be as alike as pennies pouring out of a mint.

One area where some folks try to save some money is doing their own wiring harness. I took one look at that and while it is in my wheelhouse (My father taught me to do high conductivity electrical solder joints at the age of 7) I concluded that I wanted someone who had done a number of these and knew some of the pitfalls of the Subaru harness instead of finding them all myself...and ruining the harness in the process. So I put my ear to the ground and the name that kept coming up was Jeff Robenolt. Not just because he had done many Vanagons, but because he was willing to work with something unorthodox like a Bay bus and work WITH me. Jeff's contribution to the harness was invaluable.

So now I've got a backlog of product that I'm going to need: A Vehicle Speed Sensor (VSS), an OBD2 error suppressor, not to mention coolant tubing for the engine compartment and a complete exhaust system. When I went shopping for the VSS, I looked at the product quality offered by the vendors and shrank back with horror at some of them.

This vendor can look me straight in the eye and tell me that
I'm supposed to pay money for this ghettoo-rig engineering?

"To adjust the VSS distance to the trigger wheel, bend the bracket under the trigger wheel until you get a good signal."

Great slithering crow! I don't want that bracket to bend! I don't want it to even move! In any solution bolted to a vintage VW transmission, the VSS detects vehicle speed by watching a trigger wheel bolted to the Constant Velocity assembly on the outside of the transmission. On a Subaru, the VSS is inside the transmission where it's protected. Sticking a VSS on the outside of the transmission means it's implicitly more vulnerable, even if it is the only way to get a reading on a vintage transmission. Putting it under the CV, closest to the ground, is plain crazy. By contrast, the RMW unit is plasma cut from 10 gauge steel sheet, both the trigger wheel and the bracket. You don't bend the bracket to adjust it (you couldn't without tools: 10 gauge is stout.) The bracket bolts high on the transmission body to avoid debris that might remove it, and you adjust it using locking nuts on the VSS body.

Guess who's VSS I'm buying, even if I have to pay 30% more?

Right. Because I'm getting more than 30% more value.

Finally, I need an exhaust manifold that will fit a T2B Bay, and that won't crack on me. Why do they crack? Because often the chap whacking together his exhaust doesn't realize that for a structure this short, when one end is attached to the engine and the other end is attached the body (or just left hanging!) a crack is almost a guarantee. The engine vibrates and the body doesn't want to wiggle in time with it: crack.

A fully emissions compliant solution for both Vanagon and Bay,
and the components (muffler, CAT, sensors)
are all Commercial-Off-The-Shelf. (COTS)

The RMW solution connects both ends of the exhaust to the engine, so when it vibrates or rocks back and forth, so does the exhaust. It all moves together as a unit. No cracks.

Certainly, the RMW solution costs more than various fabit yerself solutions. It is built to last, not merely just to work until "It's Miller Time." Compared to what some 'write a check and walk away' vendors want for their solution, the RMW design is incredibly DIY friendly.

In the final analysis, I chose to source 80% of my solution from Rocky Mountain Westy because they were the only ones making solutions that were:

1. Engineered for Reliability
2. Cost Conscious (Not cheap, but not a price on the moon, either)
3. DIY Friendly
4. Cross-Compatible Solutions (More on this in a moment)

These attributes come so close to the ideal for VolksarU (Whenever possible, buy NEW specified parts. Fabricate from plans when necessary. Only fabricate without plans when otherwise unavoidable.) How could I not support their business and their willingness to support both T2B Bays and Vanagon?

I'll close with a riff on the cross-compatible solutions that I alluded to above. In my business (high performance computing) vendors are constantly pushing some amazing solutions. There's a dark side to it though: Instead of conforming to standards, where components from different vendors can be mixed and matched by the customer to scratch their special itch, you are sold a monolithic stack of products which all work together, but allow for no substitutions. It's called 'vendor lock in' and it's reprehensible when it is done only to cripple customer choice. Speaking as someone close to engineering, its also understandable. Getting everything to work together is enough of a challenge when you own all of the pieces, so it takes a manufacturer a lot of effort to go above and beyond to try to make their products compatible with some of their competitor's components, even when there are supposed to be standards everyone is conforming to.

While Rocky Mountain Westy isn't 100% compatible with Vanagon solutions from Kennedy or SmallCar, they take every opportunity to be compatible. For example, If you're unhappy with the exhaust you bought that cracked, you're not going to want to go back to the same vendor to buy another one, fully expecting it to crack again. RMW gives you the option to substitute in some of their parts for sub-standard parts from their competition. This is more than just smart business, this is a considerable engineering effort. They're so far out front with conversion products for the T2B bay Window, other vendors who want to get into the space will have to follow them. An arbitrary standard is often better than no standard at all. A well thought out standard (as RMW has managed) is a pearl of great price.

So don't assume that self fabrication is better because it's faster. Even when it is faster, it is what's referred to as a 'point' solution: A solution that is only good for one set of circumstances: one vehicle model configuration, one engine, one transmission. When you do the second one or someone else wants to follow in your footsteps, and any variable changes, another point solution has to be reworked from scratch.

That's why Modularity and re-usability is where its at. That's how you get Reliability, Cost-Conscious, DIY Friendly and Compatible Solutions. That's how many people collaborating can get usable solutions and keep the cost down at the same time. That's why I'm giving away my radiator design: Because anyone can buy that standard part, add some minor fab and have a working solution, a solution that others have time and experience with and can be vouched for by others in your community of enthusiasts.

So don't settle for 'it runs.'

Don't settle for 'It's Miller Time!'

Don't settle for anything less than 'reliably useful.' If that's your fundamental demand, it will guide your buying habits in ways you've never dreamed.

Long time coming

I have waited a long time for some parts. I've sweated and strained the grey mush in my skull to come up with a coolant layout that would work for my Bus and importantly, work for others as well. 

While scratching my own itch, I've been down two failed paths. The first (VolksarU-0.1) was placing scirocco style radiators in-bay only to discover that 'prior-art' examples were more the product of P.T. Barnum than Earnest the Engineer. The second failed path (-0.2) was a feasibility study on emulating the Fellows Speed Shop design, only to discover that FSS hang their coolant tubing even lower than their radiator! That one was abandoned without spending anything more than my time. (Which without money is all I have had much of this winter.) So much for the dead ends that VolksarU ran down so you don't have to.

The third shot (VolksarU-0.3) looks the most promising, and like most good work, it comes from a mashup of the best works of others, and lessons learned from all of those dead ends.

• The engine compartment coolant piping from the engine outlet / inlet to the heater wye hole in the rear transverse frame member is designed and fabricated by Rocky Mountain Westy.
• The low profile scoop and underbelly radiator concept from Fellows Speed Shop, redesigned with my own break-away scoop and the Champion Cooling EC281 radiator standing in for their custom radiator (at 1/8 the cost and made of the same materials.)
• My coolant piping design to bridge the gap between the connection to the engine bay via the heater wye hole to the radiator itself. The design's chief features are:


• Durable: Built from 304 Stainless Steel, the same material used in the replacement coolant tubing provided by companies like GoWesty, and Rocky Mountain Westy as replacement coolant tubing for the plastic factory tubing in the Vanagon. The Bus may rust down to a pile of brown goo, but this coolant tubing will still be there.
• Compact: Mashing Gates Greenstripe flex hose in the confines of the central box space of the frame is simply a no-go: They're not rigid enough, and they're so fat they won't fit down that narrow space between the radiator and the inside of the frame rail. You can't run them outside the frame rail without putting them at risk of road debris, and looking like an extra from Mad Max. Hose will want to follow its own internal desire to turn itself back into a straight line and puts stress on its end couplers because of it. In short, a hose with an ID of 1-1/2" (the size of the output and input of the EJ22 engine) will have an OD of about 2". Which is too pudgy to fit down that narrow corridor inside the frame rail. So you've got to go thin and rigid, both to fit in the space and to retain unlikely shapes without stressing the couplers, which can cause leaks.Ergo, tubing. Not hose.
• Thermally Conductive: As mentioned in a previous post, hose is an insulator. (It may not seem like it if you've ever grabbed a hot coolant hose, but compared to touching a metal radiator tank at running temperature...hose is an insulator.) Since our cooling ability is already compromised by the orientation of the radiator, best to be throwing off as much heat as possible as fast as possible before, during and after your coolant passes through the radiator. Also, any portion of coolant tubing in the engine compartment is also being cooled by the air scooped into the engine compartment from intakes at the rear corners of the Bus.
• Protected: All of the coolant tubing and radiator is above the frame of the vehicle. You would have to tear the scoop off and run aground first and the chances for your radiator and coolant tubing's survival are better than 50/50, even if you lost the scoop. Keeping all of the coolant tubing above the level of the frame leaves them especially well protected. Short of an in-bay solution, this combination should produce the best of all worlds without bankruptcy as a side-effect of success.

With my six pieces of mandrel bent SS from Columbia River Mandrel Bends in Saint Helens, Oregon, I'm ready to have the radiator modified to move the inlet / outlet, then have the tubing TIG stitched into three assemblies. 

Assembly #1 allows it to jog from the original heater wye hole into the left hand frame rail and forward to the front (previously top) of the radiator where a hose coupler attaches it to a U-bend (Assembly #2) and into the radiator via a hose coupler at the front left.

On the output side of the radiator, we exit at the right rear through a hose coupler and into Assembly #3 which is two 90° elbows cut and stitched into a jog that takes us back to the heater wye hole. 

That's the circuit for the most vulnerable part of the cooling system.

The final piece of fab is the scoop which will be fabricated of steel panels, two angle brackets and a reinforcing strap, any shop should be able to knock this out in under an hour. Between the TIG work for the tubing assemblies and the MIG work for the scoop the price should stay reasonable.

Remember the VolksarU policy on bespoke fabricated parts: Avoid when possible, but if necessary, work from plans. I'm hoping to lure someone with a CNC mandrel bender into fabricating all of the tubing assemblies from single lengths of tubing instead of doing TIG work to put them together.

A Ten Dollar Helmet

In the early 1970's when motorcycles were losing some of their outlaw image, Bell Helmets ran an ad that has become synonymous with risk analysis: "If you have a $10 head, buy a $10 helmet. If your head is worth more, buy a Bell." The helmets were expensive: About $640 in today's dollars, or 15% of the cost of a brand new 1970 Honda CB750, the first mass production 'superbike.' While the "Easy Rider" bad-boys were wearing defiant German Stahlhelm half-helmets, the Bell owners often lived to tell about a terrible crash and the Stahlhelm crowd...not so much.

Coincidental to this story, when I was young and dumb (and not too long ago) I was in a terrible rush to do some maintenance on my 1971 Super Beetle. I really, really wanted to 'git-r-done' and in my haste I finished on time, drove off and almost killed my dumb self.

Half of the problem was cheapness. The other half was laziness. The third half (!) was the internal stampede which causes teenagers to optimistically engineer according to appearance instead of heft. "I looks like it will hold. Let's go," has been the sad opening lines to many tragedies and near misses. The details of my personal idiocy are too mortifying to repeat: Suffice it to say, the fact that I didn't fetch up injured, dismembered, dead (or all three) was a miracle of Providence.

In my experience, some people outgrow this adolescent recklessness, and others make it a way of life.
The Vintage VW clan is infamous for its brand of tin-can patches and 'paint the dirt' solutions. Maybe it's the brand's reputation as an inexpensive novelty. Maybe it is because it attracts cheap dreamers. Unfortunately, there's a difference between frugality (don't waste your money on the bling; just wash it and wax it and keep it in good running repair) and cheapness. (Wherein every possible corner is cut to avoid paying for a correct product, yet still be able to to say 'it runs.')

Those of us who have been left holding the bag of someone else's half-assed work scream in frustration when these kinds of corner cuts bite us. The high ampere cable, spliced together with wire nuts and electrical tape that bear the weight of the hanging cable. The steering tie-rod ends with zip-ties standing in for cotter pins. Even fuel hose doing double duty as brake reservoir hose. They're all symptoms of what a former supervisor (and still close friend) refers to as the "It's Miller Time!" mentality: If it holds together until I'm out of sight, I'm home free.

While I've experienced all sorts of mechanics and tradesmen who produce rip-offs like this, doing this consciously to your own ride, or your own house is not just self defeating, it could qualify you for your own Darwin Award. Worse, you might wind up grieving and in the State Pen. for manslaughter when your daughter makes a left turn in that car you used the zip tie on...which suddenly heads uncontrolled into oncoming traffic when the steering tie-rod lets go...

What brought these terrible ideas to mind lately was listening to some very good people discussing (proudly!) some very bad engineering for vehicle conversion. Instead of selecting the right part for the job, they discuss the work in terms of "what I've got lyin' around." This isn't the same as the hoarder who has the entire McMaster-Carr back catalog in his shop. This is what my father (a mechanical engineer, welding inspector and specialist in nuclear safety systems) refers to as "kick into place at assembly, file sharp edges, and paint to match." It is placing a dubiously high value on having saved a nickel every time you have to replace that $20 part...because you have to replace it so often.

Living in the shadow of dear old dad caused me to develop this mantra for my Bus conversion:

"No part shall go on my ride that is of lesser quality than would be expected in modern automobile manufacturing."

This doesn't mean that a part needs to be made using the same methods: manual plug welding stands in fine for arc-spot welding. An anticipated 20 year life span is reasonable for any modern manufactured part. If a fastener is going to take a beating, use stainless instead of zinc coated fasteners. If you can't get stainless, prefer zinc plated over plain galvanized. Always uprate by one tier over what is require to merely 'make it work.'

There are times when a part must be fabricated to equal or better than factory standards. Obviously, most of us aren't skilled or tooled up to that. There are lots of fabricators out there who are, and if you plan to play in this hobby, it costs money to have their help.

I'll admit my own cut-corner temptations: I had originally thought to use pre-cut pieces of tubing and couplers for my coolant loop. I've had a 'Gates log' (36" length of straight hose) recommended to me to snake my way down to the radiator from my engine with lengths of hose unsupported and sagging like grandma's panty-hose. I was reminded by one of the other thermodynamic engineer wing-nuts I hang out with that 'Hose is a wonderful insulator. Are you trying to insulate the hot coolant to the radiator?' He suggested 16g Stainless Steel tube because, in addition to having a smaller OD and easier to route, it will be radiating heat for its entire length. You must take this into account when you're routing all of the other components, but you'll be throwing off heat efficiently all the way to the radiator and back.

The second half of this example is equally telling: All those pre-cut hoses and elbows and tubes...every time you transition, you have a potential site for a leak. You can't (and shouldn't) plumb the whole thing end to end with metal tubing even if you could, because you're going to have to take pieces out for maintenance so there must be some couplers in the loop. Just minimize them and you minimize the opportunities for leaks. For every part you put in, ask, "How many parts am I going to have to remove to replace this if it conks out?"

When Boeing (a former employer of mine) built the 777, it was the first plane that had been wholly designed (every panel and rivet) in a computer first, not only to make sure it would go together correctly, but also so that it could be engineered in advance for ease of assembly by humans (reach, component weight, arm turning radius) and also so it could be maintained without having to gut a whole section of the plane to get to a $100 part that had gone bad. That's why it is the most popular wide-body airliner in the world: It is easy to maintain and repair, which leads to more time in the sky, making money for its owner.

Therefore, the three cardinal rules for sane adaptation:


1. Use the right materials for the job: Nothing less than what you'll expect on a new car. If you have a part already, that doesn't mean its the right one for THIS job. Match the right part to the project, not the other way around.

2. Fabrication is part of the deal. Either ruin a few nice classics and become an expert yourself, or pay someone else to exercise their specialty on your behalf. DIY what you can, but know your limits. You'll be on the road that much sooner.

3. Pre-visualize assembly. Your clever idea will bite you if a $10 part requires a 200 mile tow and two days in a modern garage because you can't R&R it without removing the engine AND transmission.

Have you been a "Miller Time!" man? It's never to late to change your ways and start thinking like a mortal in a 50 year old VW, instead of approaching cruel reality with a "Ten Dollar Head."

Rubicon

    ru·bi·con

noun
A river in northern Italy

metaphor
The point of no return. Refers to Julius Caesar's march on Rome in 49 BC: It was considered treason to bring an army closer to Rome than the banks of the Rubicon River. If his campaign was successful, he would rule; if it failed he would be executed for insurrection. 

idiom "Crossing the Rubicon"

---

I have committed the unpardonable act of removing a component that can only be taken out in pieces. The rear main heater wye that routes hot air from the air-cooled engine heat exchangers, combines them into a single 4.75" tube that travels forward to a multi-way splitter and eventually produces a whisp of heat at the dash, or at vents on the floor. The whole affair never was very well insulated which is why the heat exchanger, producing an incredible 400°F, was under-appreciated: it never got a chance to do its job because of leaks, busted fittings, and incredibly poor airflow.

That wye pipe that joined the two exchangers on their way forward is a real stinker. It is welded into place before the decking is welded over top of it. Cutting it out with a Sawz-All (reciprocating saw) or an angle grinder is extremely nervous work since the tight quarters can cause you to cut something that you possibly don't want to.

Like the accelerator cable tube. The clutch cable tube. Nothing important. (Yikes!)

Obviously, this begs the question "Why did you take the heater wye out?" From those in the Bus biz (especially the über-purists) that phrase is essentially screamed because it means that for all intents and purposes, there no way back to an air-cooled engine. It is as one-way as losing your virginity.


The longer I've stared at the Fellows Speed Shop design, the less happy I've been with how low swingin' those coolant pipes are. One good shot and you're bleeding out coolant all over the road. The primary criticism of an underbelly radiator has been the proximity of the radiator to road debris. I had managed to get the radiator up and out of harm's way through a combination of skull sweat and smartly sourcing my components. Now I wanted to get the coolant tubing up above the level of the frame rails as well so all of the compromises for the conversion were removed.


The Fellows Speed Show design requires you to either drill through the side of the right hand frame rail like it was a bulkhead to return coolant to the engine, as well as drilling through the rear main transverse crossmember for the inlet side of the radiator from the engine. While both of these structural insults can be reinforced again...why are we drilling through rear and side of the frame again? To move coolant. The coolant travels through tubing 1.5" Outside Diameter (OD). That's not large....would it fit if ...? Remember what I said about that heater wye? The place where it already passes through the rear main crossmember is 4.5" wide and 3.75" tall. Remove the wye, and there's your way into the 'box' at the center of the frame where your radiator lives. Nothing hangs lower than the frame rail, and the whole run of coolant tubing (alternating with hose) is now very safe.


But if you're consuming the whole width between the frame rails with your radiator...how are you going to route coolant from the radiator outlet back to the engine? Won't you have to go outside of the frame rail and transverse crossmember box?


I spent serious time during the last two weeks freezing my tail-feathers off in that chilly garage staring up and visualizing how the hell I was going to run that coolant return without chopping holes in the frame.


First I noted that you could go OVER the frame rails. There is 1.6" of clearance between the top of the longitudinal frame rails and the decking. That's about an extra 3.5mm. That's close, but doable if I could route the coolant from the radiator tank up and over the frame rail. I ran into one of the major challenges everyone doing these kinds of conversions does: The reason the Bus is so big on the inside is that they really mashed everything together outside. The unfloor area I needed to navigate was as crowded as the bottom of a ladies purse.

Even assuming I could get over the rail, I would then have to run to the rear, and then jump BACK INSIDE the rail to catch the return fitting at the wye. That's too much jumping around, too many corners, too many fittings, and too many chances to spring a leak. No. I blew a week working that idea and concluded the only way it was better was that it didn't put a hole in my frame rail. Otherwise, just as bad.

But this failure did lead me in the right direction: I started thinking vertically and that turned out to be just the thing: I wondered about going over the top of the radiator. Nope: Fans there.

Maybe I could sneak around the edge of the fan? 1.5" isn't much. Nope. I'll be so occluded up there that I won't have a straight shot 1.5" in diameter to the rear.

Then it hit me like a pile of bricks: The radiator (with tanks at the front and back) is about 24.5" wide at the body. It has brackets TIG welded on which takes the total width to 28". The brackets hold the radiator to the bottom of the 'C' shaped frame rails. The bottom edges of the frame rails are 26" apart. The radiator shown below sits above the level of the frame rail and the long, serpentine coolant tubing snake *inside* the frame rail.(Not shown especially well by this overlay. Imagine the front to rear span above that frame rail.)

Ridiculous how I've had to composite together multiple pieces to show the layout accurately. The background is from a 1970 low-light Bus, but the principle is the same. The patch in at the rear generally shows the coolant tubing from the engine and how it all mates up at the rear crossbar. This is it: no drilling big holes through frame rails, or saggy coolant tubing running unprotected to the rear. Everything tucked up. Even the scoop (not shown) protrudes only 2-1/2 inches below the frame rails, higher than the lowest parts of the front suspension. 

So what's the distance, when the radiator is centered in the space, between the outside of the radiator body and the inside surface of the left frame rail? I tested it with the best object I had for the job:a piece of 1.5" diameter steel tube. Holy smokes. It fits, and with about that same 3.5mm 'expansion' space as was to be had by going over the frame rail.

There was some occlusion of the steel emergency brake cable conduit on the left hand side. So...close. I got my jack and carefully applying pressure with a rounded piece of wood in the cup of the jack, put a trivial new bend in that tube without kinking it. I checked the occlusion at the rear. Damme. This will work.

All we need now is a single piece of mandrel bent tubing to chase from the outlet at the front right, make a tight turn to the rear, into the space between radiator and frame rail, then emerge at the back and make another 90° turn to be facing right. The space is so tight that there's no way to do it with straight-pipes and elbows and hose fittings. It has to be done with one piece of 1.5"OD pipe.

And where am I going to get that for less than a king's ransom?

I found a fabricator. What you see shown above is the initial cut. Unfortunately, my draftsman (and consulting mechanical engineer with a lifetime of experience in high criticality cooing systems) is bugging out for the warmer climates of Florida for a month. I'm not going to lay around and wait for him to get back, but I'm going to have to put this on the back burner until he comes back and work other aspects of the design.