3in exhaust questions..

[myke354]

whats up everyone .. im new to the bmw world so i have a few questions...

i am looking at getting a 3in catless DP and as there are alot of exhausts out there i was thinking of just doing my own..

now here is the question.. is a 3in piping from the DP back to much for such small turbos?? i see alot of exhaust are 2.5in and go in a 3in near the rear axle .. why is this??

any info would help alot..
thanks
myke

[CMSS2000]

I think you need to clarify if you plan on running a single 3'' or dual 3'' (which could have clearance issues) before anybody can help answer your questions.

[myke354]

Originally Posted by CMSS2000

I think you need to clarify if you plan on running a single 3'' or dual 3'' (which could have clearance issues) before anybody can help answer your questions.

im sorry your right ..

ok i was planing on a 3in single exhaust piping into a single muffler ...

[SlicktopTTZ]

Originally Posted by myke354

im sorry your right ..

ok i was planing on a 3in single exhaust piping into a single muffler ...

AMS style?

If it is enough depends on your horsepower goals.

[myke354]

Originally Posted by SlicktopTTZ

AMS style?

If it is enough depends on your horsepower goals.

kind of just not that kind of muffler... im sure i will get killed for this but i was thinking of more of a import style muffler like the hks carbon... i feel it will have a great sound and save some weight.... i do not have a whp goal as of yet more of just a picture in my head of how i want the car

[CMSS2000]

Originally Posted by myke354

now here is the question.. is a 3in piping from the DP back to much for such small turbos?? i see alot of exhaust are 2.5in and go in a 3in near the rear axle .. why is this??

myke

Single 3'' piping is definitely not too much for a 135i....many four cylinder turbo cars run 3'' or more with no problem.
Most exhausts for this car have dual 2.5'' mid-pipes because they allow more ground clearance and flow as good or better than 3'' so it is not a bottle-neck.
None that I know of are single 2.5''...that would be pointless. The dual 2.5'' go back to 3'' in the rear because at this point ground clearance is no longer an issue and the single 3'' is narrower and probably a little easier to route around the rear axle.

If you don't mind losing a little ground clearance, a single 3" all the way back would probably be fine (except for a tight fit) and would most likely weigh less and be less costly to build. I have no idea if or how it would affect the sound.

[myke354]

[QUOTE=CMSS2000;8036940]Single 3'' piping is definitely not too much for a 135i....many four cylinder turbo cars run 3'' or more with no problem.
Most exhausts for this car have dual 2.5'' mid-pipes because they allow more ground clearance and flow as good or better than 3'' so it is not a bottle-neck.
None that I know of are single 2.5''...that would be pointless. The dual 2.5'' go back to 3'' in the rear because at this point ground clearance is no longer an issue and the single 3'' is narrower and probably a little easier to route around the rear axle.

If you don't mind losing a little ground clearance, a single 3" all the way back would probably be fine (except for a tight fit) and would most likely weigh less and be less costly to build. I have no idea if or how it would affect the sound.[/QUOTE

yea i seen that but wouldnt 3in downpipes into a 2.5in piping cause a bottle neck ?? im not worried about ground clearance ...

but ok i guess i will have to play with it some to find something that will work...

[CMSS2000]

Originally Posted by myke354

yea, i seen that but wouldnt 3in downpipes into a 2.5in piping cause a bottle neck ?? im not worried about ground clearance ...

Yes if you only used single 2.5'' midpipe, no if you used dual 2.5 inch mid-pipes.

If you are planning on big HP, just run dual 3 inch all the way back from the turbos. :>)