[5w20]

Here are two logs comparing "exhaust changes". I don't think there's much to gain, but I could be wrong. I'm sure there's maybe 2-5whp difference compared to my race setup or even a nice catback exhaust. I do it for the weight savings that can be had, which is roughly 45lbs. No software or hardware changes besides the exhaust itself.

F32 435i
N55 (stock turbo - ewg)
stock air box non mppk (not cut) w/drop in K&N
CTS inlet
MAD race intercooler
MAD charge pipe
VRSF catless downpipe
Dorch stg1 HPFP
Turbosmart Diverter/BOV
xHP stg3
BM3 stg 2+ E30 - MAP #1 on MuliMap stage 2+ v1.3
(50/50 blend of 93 and E85 - FF sensor on stand by because its too damn hot lol)





(07-02-2022)
The two below are with the completely stock exhaust after the downpipe.

https://www.bootmod3.net/log?id=64a2...90c6cc82292971

https://www.bootmod3.net/log?id=64a2...729bb107d7789a




(08-01-2022)
These next three are with the modified exhaust that I put together that is made to dump at the rear of the transmission. Full 3" piping and turndown.

https://www.bootmod3.net/log?id=64c9...90c63af3f5034f

https://www.bootmod3.net/log?id=64c9...729b9462c48a7b

https://www.bootmod3.net/log?id=64c9...729b9746393fd7

AmuroRay

[AmuroRay]

Originally Posted by 5w20

Here are two logs comparing "exhaust changes". I don't think there's much to gain, but I could be wrong. I'm sure there's maybe 2-5whp difference compared to my race setup or even a nice catback exhaust. I do it for the weight savings that can be had, which is roughly 45lbs. No software or hardware changes besides the exhaust itself.

F32 435i
N55 (stock turbo - ewg)
stock air box non mppk (not cut) w/drop in K&N
CTS inlet
MAD race intercooler
MAD charge pipe
VRSF catless downpipe
Dorch stg1 HPFP
Turbosmart Diverter/BOV
xHP stg3
BM3 stg 2+ E30 - MAP #1 on MuliMap stage 2+ v1.3
(50/50 blend of 93 and E85 - FF sensor on stand by because its too damn hot lol)





(07-02-2022)
The two below are with the completely stock exhaust after the downpipe.

https://www.bootmod3.net/log?id=64a2...90c6cc82292971

https://www.bootmod3.net/log?id=64a2...729bb107d7789a




(08-01-2022)
These next three are with the modified exhaust that I put together that is made to dump at the rear of the transmission. Full 3" piping and turndown.

https://www.bootmod3.net/log?id=64c9...90c63af3f5034f

https://www.bootmod3.net/log?id=64c9...729b9462c48a7b

https://www.bootmod3.net/log?id=64c9...729b9746393fd7

AmuroRay

According to the logs, you're making more power with the stock exhaust.

Look at the measured torque (Torque at clutch actual)

Pre log selected: https://www.bootmod3.net/log?id=64a2...90c6cc82292971
Post log selected: https://www.bootmod3.net/log?id=64c9...729b9462c48a7b

RPM| Measured Torque Pre | Measured Torque Post
5000| 555 |
5100| 544.9 | 528.7
5200| 539.5 |
5300| 532.7 | 511.2
5400| 527.2 | 502.6
5500| 524.2 |
5600| 520.1 | 498.2

Also, for the love of cars - please At least cut that airbox. Your WGDC is crazy high...
Edit:

Looked again, while you lost power, your WGDC went down as well.



RPM| Boost and WGDC Pre | Boost and WGDC Post
5000| 20.4/94%|
5100| 20.1/95% | 20.2/93%
5200| 20.1/95% |
5300| 19.9/97%| 19.8/95%
5400| 19.8/98% | 19.7/95%
5500| 20/98% |
5600| 20/96% | 19.5/97%






Try plugging it in to VD and seeing what it says?

[5w20]

Originally Posted by AmuroRay

According to the logs, you're making more power with the stock exhaust.

Look at the measured torque (Torque at clutch actual)

Pre log selected: https://www.bootmod3.net/log?id=64a2...90c6cc82292971
Post log selected: https://www.bootmod3.net/log?id=64c9...729b9462c48a7b

RPM| Measured Torque Pre | Measured Torque Post
5000| 555 |
5100| 544.9 | 528.7
5200| 539.5 |
5300| 532.7 | 511.2
5400| 527.2 | 502.6
5500| 524.2 |
5600| 520.1 | 498.2

Also, for the love of cars - please At least cut that airbox. Your WGDC is crazy high...
Edit:

Looked again, while you lost power, your WGDC went down as well.



RPM| Boost and WGDC Pre | Boost and WGDC Post
5000| 20.4/94%|
5100| 20.1/95% | 20.2/93%
5200| 20.1/95% |
5300| 19.9/97%| 19.8/95%
5400| 19.8/98% | 19.7/95%
5500| 20/98% |
5600| 20/96% | 19.5/97%






Try plugging it in to VD and seeing what it says?

One big factor to consider is the atmospheric conditions. It doesn’t clearly come up on the mobile app (which I’m replying from), but on the desktop it is legible.

Stock exhaust the car was effectively taking air in as if it was 2548ft above sea level, granted I’m about 150ft above sea level. With the exhaust dump, the conditions were so bad that it was effectively taking air in as it was 3557ft above sea level. Those 1000ft, make a huge difference. Coming from someone who has logged quite a bit of 1/4 mile logs and 60-130 on the dragy, the difference is easily noticeable.

I’ve never messed with a virtual dyno, and probably won’t ever, I’m more into timed data. Don’t get me wrong, I’ve thought about actually dynoing my cars, but at the end I always decide not to 😂.

[AmuroRay]

Originally Posted by 5w20

One big factor to consider is the atmospheric conditions. It doesn’t clearly come up on the mobile app (which I’m replying from), but on the desktop it is legible.

Stock exhaust the car was effectively taking air in as if it was 2548ft above sea level, granted I’m about 150ft above sea level. With the exhaust dump, the conditions were so bad that it was effectively taking air in as it was 3557ft above sea level. Those 1000ft, make a huge difference. Coming from someone who has logged quite a bit of 1/4 mile logs and 60-130 on the dragy, the difference is easily noticeable.

I’ve never messed with a virtual dyno, and probably won’t ever, I’m more into timed data. Don’t get me wrong, I’ve thought about actually dynoing my cars, but at the end I always decide not to 😂.

I noticed the difference in DA - maybe it’s better to test at night when it’s cooler.

[n55david]

Generally speaking you want a certain amount of exhaust pipe coming off the turbo and a certain size.. the problem is it varies depending on turbo size, spool times, levels of boost etc..

There is no right or wrong, it just depends on application and use.

I suspect that the n55 ewg turbo 3" is about good enough.. b58 or n55 stage 2 may like a 3.5". Torque will drop but hp will go up dramatically on the top end etc.. you won't have both because of exhaust scavenging and flow etc

[AmuroRay]

I did a virtual dyno for you - I used 335xi profile and gear ratio for both, so I'm sure it's not "accurate"

But you can see it's registering a gain between the two.

Pre log selected: https://www.bootmod3.net/log?id=64a2...90c6cc82292971
Post log selected: https://www.bootmod3.net/log?id=64c9...729b9462c48a7b

[5w20]

Originally Posted by AmuroRay

I did a virtual dyno for you - I used 335xi profile and gear ratio for both, so I'm sure it's not "accurate"

But you can see it's registering a gain between the two.

Pre log selected: https://www.bootmod3.net/log?id=64a2...90c6cc82292971
Post log selected: https://www.bootmod3.net/log?id=64c9...729b9462c48a7b

From what I've been seeing, I fully expect the power to be at or extremely close to the post log.

I've actually scaled the car and it is 3300lbs without me. I've removed quite a bit of weight. Rear tire is a 265/35/19 which equates to 26.3" according to the manufacturer.

I fully expect it to do a high 8 second 60-130 time and low 11 second @ 123 in the 1/4 mile when the DA is at or around sea level based on the current results. The 11.8@120 and 9.6 are currently outdated.

See below where it keeps up with a local 340i on a BM3 stg2+ E50 tune.

[AmuroRay]

Here is mine:

Pre and post same tune, but different days and temps (humidity levels) The Pre log about 8F hotter, and the post log was very high humidity.

There is a clear gain with exhaust work.

[5w20]

Originally Posted by AmuroRay

Here is mine:

Pre and post same tune, but different days and temps (humidity levels) The Pre log about 8F hotter, and the post log was very high humidity.

There is a clear gain with exhaust work.

Hopefully you can get more data. You're showing a measurable increase in power, I'd like to hope so. In my honest opinion I'm thinking it's minimal like 3-5whp, which essentially could vary from back to back pulls on the road or a dyno.

[thejeremyman9]

The best way to truly test this would be to install EGT and/or back pressure sensor(s)