Exhausting Work

It has been three weeks since I got any appreciable work done on the Bus, and it is irritating the life out of me. Not that there is much I can do about it: The latter half of my vacation week was taken up with family duties surrounding Easter, and when I walked back into work the next Monday morning, all hell had broken loose in my absence. I'm not sure this vacation thing really works for me: If I take a week off, I don't have a week's worth of work waiting for me when I return, I have five weeks worth of work, so it has been 14 hour days for more than a month, such that I return home wrung out like a damp rag. This doesn't seem like a fair trade-off. So five weeks later, I'm finally starting to see the waves above me and hope to break the surface soon.

That said, I had a pretty un-memorable time working on the Bus' retrofit by way of Rocky Mountain Westy products. This isn't a dig at RMW, it's compliment! Most memorable experiences I have when wrenching are BAD memories. So 'unmemorable' is the highest compliment I can give.

Most of the RMW solutions are straight up bolt-on. During the week when I could work, I got a lot finished: and even more mocked up. Instead of just telling what I did, I decided the best use of this blog would be to show and comment, rather than describe to death. In this installment, we'll review the Rocky Mountain Westy Stainless Steel Exhaust system.

First installed are stand-offs that the heat-shield / muffler support mounts to. They replace the cam belt cover bolts. If you can't manage this part, you should probably not be working on your own car yourself. Also, you should probably get someone else to brush your teeth. (Tech Tip: Juice up the old cam cover bolts the night before with PB Blaster so you don't round off the bolt heads. Don't use an adjustable wrench or even an open end wrench: use a socket. This is not a component that you want to get stuck.)

The standoffs come with letters stamped on their bodies and a diagram for which cam cover bolts each one is to replace. This is paint-by-numbers, made easy for the DIY installer.

Heat shield mounted on standoffs. Note un-used vertical holes to the right (for muffler bracket and strap) and to the left (for EJ25 engines which have additional points which may accept standoffs.) One part that works for both engine applications.

The standoffs hold the heat shield away from the plastic timing belt cover just enough to protect the cover and provide a finger-width distance from the crank pulley. It is a safe clearance, but replacing a belt would be cramped, and replacing the crank pulley itself would require dismantling the entire exhaust system. Still, that isn't a part that you're likely to replace on a whim. If you just MUST get your bling on with a new crank pulley, install it before you add the exhaust components.

Having bolted down the exhaust heat shield to the standoffs, I added the powder coated steel bracket for the 6" round Magnaflow muffler. Whenever possible, I flip the fasteners around so that the bolt head represent either the least ground clearance or hide the nuts and threads for aesthetic purposes. In this case, only the bolt heads are visible because they're facing to the rear where you look in at the engine: the threads and nuts are still accesible from above where you can't see them unless you climb into the engine compartment. Suffice it to say, the bracket hardware remains accessible while not flashing the less lovely bits to the public.

Powder coated 12ga. steel bracket bolted to .080 Corrugated Aluminum heat shield. This bracket is specifically designed to support the 6" diameter Magnaflow mufflers, though there is scarcely room in the cavity for anything else. The Subaru design expected to put the exhaust UNDER the engine, 

The T304 exhaust manifold for the right hand side exhaust port.
RMW provides exhaust for both single and dual port EJ engines.

Having installed all of the support materials, I started on the exhaust manifold proper. Also T304 Stainless Steel, all of the RMW manufactured mandrel bent tubing (coolant and exhaust) came with their ends capped to keep debris out of them. Excellent attention to detail and beautiful TIG welded joints and fittings.

The secret sauce for assembly is that the whole system is modular. Some folks have expressed nerves about slip-fit exhaust. If the whole thing were just held in place 'slip-fit' I'd agree. Instead, it uses Stainless Steel Torque-tite band clamps and the slip-fit joints are two inches deep (except for one, which I'll get to.)

The exhaust manifold prior to the CAT is a serpentine thing that each leg joins, then exits to the left, then swings back toward the right side via a 180° elbow to bend the exhaust flow up into the engine bay. The 180° elbow has a bung in it that the up-stream O2 sensor can be mounted in. In my case, I'm interested in the delta between the O2 values pre-CAT and post-CAT since my ECU has the capacity to measure both. (Recording the delta between the two lets you see what the efficiency of your CAT is and when it begins to fail. Some folks go without the upstream and just record the downstream values, tricking the ECU into thinking that the emissions are cleaner than they really are.)

You can assemble the lower portion of the exhaust manifold, and then work the whole thing up (according to packaging instructions) with muffler cement. Goop up the inside of the larger ID slip fit, then assemble and loosely add the torq-tite clamp.

(Note: Before you go cranking bolts down on the exhaust studs, make sure that you can get a properly fitting exhaust nut all the way up and down the stud; used studs are often pretty rusty or corroded. Running this simple exercise BEFORE you try to mount the manifold might make your life a lot easier just in the confidence of knowing that you can add new exhaust nuts to the existing studs and know that they'll come off again without snapping off the stud. Plenty of PB Blaster and some quality time running the new nut up and down the stud is worth a world of confidence when it comes to the final fit-up.)

Get the assembly under the car and bolt up to the exhaust ports, remembering to sandwich the gasket in between the manifold and the port. Tighten down your exhaust stud nuts to finger tight, such that the whole shebang wants to stay in place. Once both sides are done, wiggle until both sides are aligned, then add the torque-tite and tighten down on it until it wants to hang on. Torque-tite bolts are 14mm.

Run the same procedure for the 180° elbow. (It should still be able to pivot at both ends when finished, as you'll need to pivot around both the top and bottom portions of tubing and components as you rotate the assembly into final position.) This moves us to the top of the stack: The CAT and the muffler. Predictably, this is where it get interesting.

The muffler is the reversible Magnaflow 16450, a 6" round 18" long body with 3" long input / ouput pipes which are both offset from center on opposite sides. That CAT is also a Magnaflow unit.

This picture is a wealth of information: All of the slip-fit portions are dry fitted together and you can see some of the modifications that had to be made: 1) The left rear bumper bracket had to be clearanced, 2) The sequence of slip fit components means that each component added should have an input larger than the output. 3) the upstream O2 sensor visible behind the tubing elbow is screwed into place, 4) The muffler is BIG when lifted high into the space, necessitating the heat shield. All components are T304 Stainless Steel.

This is sort of the Achilles heel of the installation for people who want to run and gun. The components require modification for use in a Bay-Window Bus, the kit having been originally designed for the much wider Vanagon. There just isn't the same amount of space to fit the whole stack of the elbow, CAT and muffler into the narrower space available without some modification. It isn't short by much, but it's enough to cause problems that will stop the project dead in its tracks: The muffler is too long to fit in the space comfortably. The body occludes the muffler at the right rear when the muffler clamped into the support we saw earlier. The only way that this 'almost, not quite' solution works is by some judicious trimming in the right places. The following are the steps that I took to deal with it, steps that anyone with a $15 grinder and a nearby muffler shop can cope with.

First, we'll bob the inlet of the CAT, a Magnaflow 53034 recommended for this installation:

Take your die grinder and remove 15mm of the inlet end, e.g. the end opposite of the O2 bung. When you fit the CAT into the flared end of the 180° elbow, it will now shift 15mm to the left.

Take your muffler to a reputable muffler shop and have them stretch out either end (but not both) to accept the CAT's 2" OD outlet. Since one now fits inside the other, you just bought 25mm of width back. Best to take the CAT with you for a test fit. it should be as close a fit as you can manage.

Here you can see the outlet of the CAT (left, with O2 sensor above) INSIDE the stretched inlet of the muffler (right). Fitting one inside the other  buys back another 25mm, again shifting the muffler to the left. But now you must clamp these two together to make a seal: you can't 'unstretch' the muffler inlet pipe. Welding (since it is Stainless Steel) would be with TIG: Expensive. Instead, we'll make our own ersatz fitting.

Using the cutting wheel again on the inlet, cut 5 parallel relief cuts 20mm long equidistant

around the pipe, just short of where the pipe flares out to its largest diameter.

(If you pass that line where the pipe flares out, you'll never get it to seal. So don't botch it.)

Now you finally have the option of getting a clamp around this stinker and crimping down on it. As before, I used muffler cement liberally since this is the most likely spot (due to the relief cuts) for there to be leak. So I gooped up the inside of the muffler inlet and then inserted the outlet of the CAT all the way inside. Then I added the clamps shown below.

I used a basic set of 1-5/16in" to 2-1/4" dia adjustable  Stainless Steel clamps sourced from my local Lowes. (PN 48536.) The mating area is thoroughly gooped up with muffler cement, and the clamps worked down tight. Between the friction fit, the clamping effect of the adjustable clamps and the pressure of tubing which can collapse and seal the better for the presence of the relief cuts, this should be a well sealed connection.

So judicious trimming bought back enough space to be able to slip-fit all of the parts together and pull the right end in considerably. Total up all of the trims, and the muffler moved more than 1-1/2" to the left. But we're not quite through yet: We're going to shift the 180° elbow to the left, too, which will move the whole upper stack to the left by enough to allow the muffler to clear comfortably.

To shift the upper stack to the left, a compromise must be made at the bottom slipfit joint of the elbow. The elbow permits about a 2.25" overlap of the slipfit which is then covered by the 2" long Torqtite band clamp. To shift the whole upper stack to the left, I overlap the exhaust manifold by only 1.25" and then put the 2" bandclamp in place. 

This solution does not thrill me, since the elbow now hangs out to the left and forces me to clearance the left rear bumper bracket. Short of a re-engineered exhaust manifold, it is the only way to move the upper stack (CAT & muffler) the last full inch for a total of a 2.5" shift to the left for the muffler. This is just enough to allow the muffler to clear the body and still have a finger width of clearance.

The details of the trivial trim. No plasma cutter required, just an obnoxious
swipe with a sharpie to follow, and some  sacrificial cut-off wheels for my grinder.

The clearanced bumper bracket. I'll be candid: this did not make me happy. Not because I think that the extra bit of steel is going to be the difference between life and death, but because the clearance is so close, it might interfere with plans I have for an eventual tow bar installed in those bracket positions. I don't see how that will be possible with this setup without having to cleverly wade back in with the grinder.

The CAT dry-fitted to the elbow, showing the amount of clearance required.

The exhaust adaptation is by far one of the more headachy challenges that relies on some commodity products (Muffler, CAT) as well as niche production products from RMW, and neither of the solutions are ideal. It is an intensely tight fit. It works; let there be no misunderstandings. But it is awkward and needs to have a better way to crunch space to make a Bay Window fit as elegantly as it does on a Vanagon. The great news is that once you've gone to the trouble of fitting it, removing and replacing components is dead simple. The Stainless Steel exhaust manifold is extremely well made, and if there ever was a reason to replace a component, the ability to unbolt components from each other without having to revert to the sawzall is great.

There may be other designs out there which will connect to a repurposed EJ22 or EJ25, but none that are built to be emissions compliant from the word go, and none that are built to this level of fit and finish. (Fit for the engine, not necessarily this engine bay.) If you have to deal with a State which is likely to hassle you on your emissions compliance, being able to open the decklid and immediately point at the upstream O2 sensor as well as the down stream O2 sensor threaded into the CAT, this is your solution. I expect to raise quite a few eyebrows with this for everyone who still harbors the 'speed freak' assumption about engine swappers, or the 'dirty hippy' view of VW Buses in general. As solutions go, it allows you to back up to your independent Subaru repair shop and they will know where all of the important engine parts are.