MyE28.com

I'm curious to see what size pipe you are able to stuff under an e28 and what kind of power you made with it.

I was planning 3.5" down pipe into dual 2.5."

Single 3" downpipe and exhaust = 500+rwhp

I want a system good to 600whp, realistically in the 550whp range- if things go my way. Single 3" is only calculated to 525 or so hp. I don't want to the exhaust to be the bottle neck.

M. Holtmeier wrote:I want a system good to 600whp, realistically in the 550whp range- if things go my way. Single 3" is only calculated to 525 or so hp. I don't want to the exhaust to be the bottle neck.

3" single supports 600rwhp easily. 3.5" on a 600rwhp engine is good for another 5-10rwhp max. Turbine wheel and exh housing are the choke point. Just size those appropriately.

I need to dig back through the dyno data base.

The turbo is Borg s300 .91 twin scroll, 73mm turbine wheel.

You're saying I'm good to 600 on a 3" downpipe? I won't see better spool with a larger DP?

M. Holtmeier wrote:
You're saying I'm good to 600 on a 3" downpipe? I won't see better spool with a larger DP?

I am saying a 3.5" pipe is better if you have the room but has minimal benefits at your desired HP level. Dual 2.5" just adds unnecessary weight.

Dual 2.5" also adds expense.

Duly noted. Thanks for your input, Todd.

T_C_D wrote:

M. Holtmeier wrote:
You're saying I'm good to 600 on a 3" downpipe? I won't see better spool with a larger DP?

I am saying a 3.5" pipe is better if you have the room but has minimal benefits at your desired HP level. Dual 2.5" just adds unnecessary weight.

Noted, thanks!