Introduction and 128i build

[sprp85]

So the stock muffler replaced with PE + resonator delete (or SS section 2, I believe?) can net some good gains?

How about secondary-cat delete with ss section 1?

[Ryan13]

According to Viral at AA, the exhaust is brand new. I'll have it in a few days, will take some pictures and post.

We'll see if the throttle hang is evident. I believe you that it is in the stock program, but I haven't stressed the car yet to find any limits. Soon as it is buttoned up, I'll give it a test in a parking lot.

[Taskmaster]

Originally Posted by sprp85

So the stock muffler replaced with PE + resonator delete (or SS section 2, I believe?) can net some good gains?

How about secondary-cat delete with ss section 1?

The PE barely flows better than the stock exhaust, but replacing the secondaries with something like a SS section 2 will provide gains.

[chris82]

Originally Posted by TheAxiom

The PE barely flows better than the stock exhaust, but replacing the secondaries with something like a SS section 2 will provide gains.

How does it only flow "barely" better than the stock exhaust?

[Taskmaster]

Originally Posted by chris82

How does it only flow "barely" better than the stock exhaust?

BMW's marketing material states it gains up to 5hp

"Enter the BMW Performance Exhaust System. This solution produces an outflow of exhaust gases that is so free (though still under control) that it markedly reduces back pressure. The flow is free enough, in fact, to actually pull more air into the engine. So while it's saving power at one end, it's increasing power at the other. RPM performance is heightened and engine performance is increased by up to 5hp and 3 ft-lbs of torque at 6600 RPM."

I'm pretty sure the one dyno I did find on that was about 3whp, compared to approx 5 - 7whp gained from just lopping off the muffler itself. My own black car vs white car (same mileage) the white car made 2whp more peak, and about 1wtq, but it did have more low end grunt.

Either way, it's only a handful of hp, and the PE sounds awesome.

[Suprgnat]

Originally Posted by TheAxiom

BMW's marketing material states it gains up to 5hp

"Enter the BMW Performance Exhaust System. This solution produces an outflow of exhaust gases that is so free (though still under control) that it markedly reduces back pressure. The flow is free enough, in fact, to actually pull more air into the engine. So while it's saving power at one end, it's increasing power at the other. RPM performance is heightened and engine performance is increased by up to 5hp and 3 ft-lbs of torque at 6600 RPM."

I'm pretty sure the one dyno I did find on that was about 3whp, compared to approx 5 - 7whp gained from just lopping off the muffler itself. My own black car vs white car (same mileage) the white car made 2whp more peak, and about 1wtq, but it did have more low end grunt.

Either way, it's only a handful of hp, and the PE sounds awesome.

My money is on the accuracy and repeatability of BMW's dyno.

[RyanDavies]

This is one thing I'll absolutely agree with Axiom on. Both the stock muffler and BMW PE are very, very restrictive. Cut open a stock muffler if you have one around. It couldn't be worse for flow. A muffler delete alone (if you like annoying everyone around you) is near double digit power numbers, plus *25*lbs, just for the muffler section itself (cut at entry point to muffler). Remove the piping post-resonator and it is well over 30. Substantial performance difference.

I don't get the appeal, given that for what it costs, you can fab up an entire post-header section, that will be just as DD-friendly, but make substantially more power. And it isn't a bolt-on affair, so you've got to hit a welder anyways.

[Ryan13]

Took a little over a month, but the car is finished. Ran into a couple of hurdles, but somehow figured out how to cross them.

Quick recap of everything that went into it...

ST-XTA suspension. Set it up with -2.2 front and rear. Had the car corner balanced.

M3 rear subframe bushings.

Diffsonline 4 disc 30/60 ramps with 3.64 gear.

Stainless steel brake lines

3-stage intake manifold

AA headers

AA exhaust

AA tune

Gaskets on Valve cover, OFHG, and oil pan

Stayed with stock 256 wheels...added Bridgestone sport comp2

Had to make a decision on the sway bars. Had the subframe out, put it back in, then realized the rear sway mounts on top. Took subframe back out. While installing control arms, snapped off the bolt...probably should have run a die through the rusted hole. In any case, I gave up on the rear bar for now. Will see if it really matters on the track. Since we didn't add the rear bar, I left the stock front bar in place.

Had a little issue with the tune from AA, but it was fixed pretty quickly. Just throwing a code from the O2 sensors, no performance problem.

Car feels great. AA Exhaust is a little loud, there is definitely a drone between 2k-3k rpms...I'm going to give it time to break in and see if any changes. Lots of burbles on decel, sounds F1 like in the higher rpms.

Will post some pictures tonight...everything is on my phone. Happy with the build. My wife drove it at summit point main this past weekend, both days in rain with standing water on the track. Not ideal for her first outing, but she kept it between the lines.

[chris82]

Originally Posted by Ryan13

Took a little over a month, but the car is finished. Ran into a couple of hurdles, but somehow figured out how to cross them.

Quick recap of everything that went into it...

ST-XTA suspension. Set it up with -2.2 front and rear. Had the car corner balanced.

M3 rear subframe bushings.

Diffsonline 4 disc 30/60 ramps with 3.64 gear.

Stainless steel brake lines

3-stage intake manifold

AA headers

AA exhaust

AA tune

Gaskets on Valve cover, OFHG, and oil pan

Stayed with stock 256 wheels...added Bridgestone sport comp2

Had to make a decision on the sway bars. Had the subframe out, put it back in, then realized the rear sway mounts on top. Took subframe back out. While installing control arms, snapped off the bolt...probably should have run a die through the rusted hole. In any case, I gave up on the rear bar for now. Will see if it really matters on the track. Since we didn't add the rear bar, I left the stock front bar in place.

Had a little issue with the tune from AA, but it was fixed pretty quickly. Just throwing a code from the O2 sensors, no performance problem.

Car feels great. AA Exhaust is a little loud, there is definitely a drone between 2k-3k rpms...I'm going to give it time to break in and see if any changes. Lots of burbles on decel, sounds F1 like in the higher rpms.

Will post some pictures tonight...everything is on my phone. Happy with the build. My wife drove it at summit point main this past weekend, both days in rain with standing water on the track. Not ideal for her first outing, but she kept it between the lines.

Nice build. If you're getting drone from exhaust, try stuffing a sweatshirt or blanket in the trunk in the compartment that's next to the battery, I did that when my exhaust was first breaking in

[Taskmaster]

Originally Posted by chris82

Nice build. If you're getting drone from exhaust, try stuffing a sweatshirt or blanket in the trunk in the compartment that's next to the battery, I did that when my exhaust was first breaking in

Get a dyno so I can have the numbers for a database

[Ryan13]

Thought I would check in and say Hi. Still have the car, still tracking it quite a bit. Wife blew the clutch, really it was the flywheel that disintegrated, on the track mid 2018 while she was learning to heel-toe at VIR...so I upgraded with a single mass and little better clutch.

She couldn’t make to the last event of the season at VIR, so I decided to borrow it for the weekend. Video below from perspective of a P-car, but you can catch the headlights in the review mirror coming out of Oaktree at 1:10 or so in. The guy has some other videos of the weekend if you want to see more. There was a stripped 135 I think the person races in another video...I could stay with him on the turns, but he just pulled away on the straights.

It was my first time taking her car on the track outside of Summit once with her in passenger seat, but I was averaging 2:17 - 2:18 around VIR on the clean laps with Bridgestone RE71s square 235s.

She is upgrading to a E46 M3 this year that will double as my club racing car, but we are keeping the 128 as a back up track car...everyone needs a back up just in case you know.

[Ryan13]

Around 2:30 you’ll catch the 135. He lost me coming into turn 1 since I had to take the inside, but definitely a quick car and a really good driver.