What size exhaust are you turbo guys running?

[M. Holtmeier]

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."

[T_C_D]

Single 3" downpipe and exhaust = 500+rwhp

[M. Holtmeier]

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.

[T_C_D]

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.

[M. Holtmeier]

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?

[T_C_D]

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.

[M. Holtmeier]

Dual 2.5" also adds expense.

Duly noted. Thanks for your input, Todd.

[Nebraska_e28]

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!