Exhaust Size

[sjhenry1075]

Does anyone know what the optimal exhaust diameter size is for a 1.7? I realize different manufacturers use different sizes; some use 1 5/8, some use 2 1/4. What is the ideal size? The header I purchased is 2 1/4. Am I robbing my engine of power due to the pipe being too large?

Thanks in advance!

[Dmitry at Pelican Parts]

Give us a call at 310-626-8765 and ask to chat with a Porsche rep - they'll be able to help you out with the diameter.

[Dave at Pelican Parts]

Engine size is only part of the equation. Rev range, cam choice, exhaust length (primary/secondary/total), induction, and so on all figure into what the optimum is.

If your engine is a highly-tuned race motor, your builder should have suggestions on what size exhaust is appropriate. I would follow those suggestions.

If your engine is a street motor, I wouldn't worry about it. Use what you've got and drive the car.

--DD

[Mark Henry]

Are you sure it's 2-1/4" ?
I think you're measuring the collector or exhaust tip, not the primary pipes. common sizes are 1-1/2" to 1-7/8" OD.

Are you sure it's a header?
Stock and SSI heat exchangers are not headers.