Header options advice needed

[rfuerst911sc]

Originally Posted by BYprodriver

Generally speaking installing most catless headers will decrease low RPM torque which is what gets the car moving & the headers increase power at high rpm. That's why I sold my headers & bought Fabspeed sport cat manifolds for my 3.6 litre.

I tend to agree there is a trade off with exhaust , I wonder if smaller tube straight headers ( no cats ) help with torque vs. larger diameter ? I made 252 lb ft of torque recently with mine and I have cheap Chinese headers , no cats , cat delete pipes and a stock muffler with PSE style bypass pipes . I also made over 282 hp at the wheels which would suggest my setup flows pretty well . Common sense tells me going with a larger diameter exhaust will yield more HP but " may " give up too much torque . It is a fine line . Have you dyno'd your setup ?

[BYprodriver]

Originally Posted by rfuerst911sc

I tend to agree there is a trade off with exhaust , I wonder if smaller tube straight headers ( no cats ) help with torque vs. larger diameter ? I made 252 lb ft of torque recently with mine and I have cheap Chinese headers , no cats , cat delete pipes and a stock muffler with PSE style bypass pipes . I also made over 282 hp at the wheels which would suggest my setup flows pretty well . Common sense tells me going with a larger diameter exhaust will yield more HP but " may " give up too much torque . It is a fine line . Have you dyno'd your setup ?

It's all about what rpm you want max efficientcy & then optimize pipe diameter for that rpm. For street driving I shoot for 3000rpm. Your engine is so unique I would ask JR what you should use. I try to have everything ceramic coated to keep the heat inside also.

[Terryg]

Originally Posted by BYprodriver

It's all about what rpm you want max efficientcy & then optimize pipe diameter for that rpm. For street driving I shoot for 3000rpm. Your engine is so unique I would ask JR what you should use. I try to have everything ceramic coated to keep the heat inside also.

Is the 3000 rpm a typo or is there something I am missing?

[Starter986]

Originally Posted by Terryg

Is the 3000 rpm a typo or is there something I am missing?

I believe what BYP is suggesting is that for normal street driving you want to be maintaining at least 3,000 RPMs. That's what I try to practice when I'm local. I believe he's suggesting that you want to consider what should be the pipe diameter based upon that 3,000 RPM... not just some random eBay pipe.

BYP, correct me if I'm wrong.

[Terryg]

Originally Posted by Starter986

I believe what BYP is suggesting is that for normal street driving you want to be maintaining at least 3,000 RPMs. That's what I try to practice when I'm local. I believe he's suggesting that you want to consider what should be the pipe diameter based upon that 3,000 RPM... not just some random eBay pipe.

BYP, correct me if I'm wrong.

So why would you tune your Porsche to drive it at 3000 rpm? I don't get it.

[BYprodriver]

Originally Posted by Terryg

So why would you tune your Porsche to drive it at 3000 rpm? I don't get it.

For a 986 "S" that is around the most efficent engine RPM & if you are installing headers you want the pipe size to be ideal for the intended rpm range. If you normally drive on public streets RPM range is 1,000-6000 so the best overall compromise is headers that give best exhaust velocity @ 3.000 rpm.

[Terryg]

Originally Posted by BYprodriver

For a 986 "S" that is around the most efficent engine RPM & if you are installing headers you want the pipe size to be ideal for the intended rpm range. If you normally drive on public streets RPM range is 1,000-6000 so the best overall compromise is headers that give best exhaust velocity @ 3.000 rpm.

Ok we must have very different cars and driving styles