Fünf Null Part XII: Post-Swap Engine Mount and Exhaust Upgrades –or- “It Never Ends”

If you’ve been following along with my build, you’ll know that this is where I talk a bunch and hock the rest of my build and make some jokes and something something something I’m feeling lazy. In this post I make a couple of upgrades.


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Fünf Null Part XI: Everything Needed to Install a 5.0 V8 in your E36 M3 –or- “Total Assimilation Part 2”

Stiff Upper Lip

Living with the car over the course of a few months and a few hundred miles revealed some weaknesses, the most notable of which was a rattling or knocking sound that would pop up during right turns or during hard acceleration. Because I used stock E30 rubber mounts to hold the engine in place, I was afraid that the engine was moving around too much and bumping the framerail, steering shaft, hood, subframe, or any of the other hard parts sitting within a quarter inch of some part of the engine.

So I ordered up some poly motor mounts from RevShift four about $60.

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I was able to lift the engine up high enough with the hoist to get the old mounts out and the new ones in, but just barely. There may have been some naughty words involved. I’m certain that blood was shed.

Installing the stiffer engine mounts didn’t solve the rattling/knocking problem, but it did increase vibration felt in the cabin. So I had that going for me.

I dove back into the front end to try and find a source of rubbing. This time I used my Jenga-With-Consequences blocks to put the car in the air with its suspension loaded. In that position, I found the front sway bar about a millimeter off of the front subframe.

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Of course, this wasn’t obvious with the front end in the air and the suspension at full droop, I had to get it at ride height to see the interference. The opposite side showed clearance of a couple inches meaning that the bar and worked itself too far in one direction, so I used a pry bar and mallet and centered the sway bar. This lasted about 5 miles until the sway bar made its way back to snap, crackle, and popping against the subframe, so I centered the sway bar again and used a hose clamp and some split rubber hose right up against the bushing to prevent the swaybar from walking away on me.

I’ve Always Been a Dog Person

When I originally did the exhaust for this car, I was afraid that having only the factory BMW cats and a little Borla catback between the exhaust manifolds and the outside world wouldn’t be enough to subdue the primeval roar from the V8. On the contrary, it ended up being much quieter than I expected, to the point that one could almost mistake this car for being factory stock. And what’s the point of  having a brash V8 in a sophisticated German car if things don’t get a little raucous every once in a while?

Knowing that I had some 2-1/4″ mandrel bends left over from doing the exhaust the first time, and knowing that the stock cats would be worth some money to a recycler, I realized that deleting the cats would actually net me a few bucks profit. More fun? More loud? And I’d get paid? Done.

I disconnected the catback at the v-band clamps I originally installed behind the chassis brace.

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I cut the v-bands and flex pipes off of the cat piping and reattached them to the pipes coming down from the headers for mockup. Then I lopped off the cats and factory resonators right before the flange connecting them to the stainless steel catback and welded a couple of slip-fit 2-1/4″ – to- 2″ reducers in place. Next I hung the remaining rear section of tubing and muffler back in place. Once again, I began the process of getting the delicious gasses and sounds from the front of the car to the back by slicing and piecing together bits of mandrel-bent tubing.

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The final result was two pipes with far fewer restrictions than before.
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Excellent. After installation, the exhaust was louder, but still certainly not obnoxious or to the point where you could consider me a bad neighbor.

Speaking of being a bad neighbor, check out the next installment:

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Fünf Null Part XIII: Stereo Upgrades –or- “I Knew You Were Trouble”

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