mattipuh

Any experience on header pipe diameters for N/A? measured ours today - seems to be 54mm in the end of exhaust header after two header pipes connect, 2'' inside diameter.

Do you consider this to be limiting factor to go over 200hp? just read this article.. Header pipe sizing might be different than overall exhaust..
Our header is some aftermarket header but don't know exact type. it is 4-2-1 style, with longer primer pipes than what stock has.

http://www.exhaustvideos.com/faq/how...pipe-diameter/

V2Rocket

I'm 99% sure the 944S2/968 used the same pipe sizes as the 944 NA for the header primaries, the collector, and the system piping until after the cat.
So you should be OK until at least 236 hp

something im looking into for my car and power-testing is adding an abrupt step up in pipe diameter somewhere along the length.
idea is that at this step a negative pressure wave is created in the exhaust that shoots back towards the exhaust valves. depending on the length of the system before the step you can tune that to an RPM to help extra-scavenge the cylinder which makes for a small power boost.

i have to keep a catalyst installed so i dont know how the wave tuning would be affected by that but...it's something id like to try eventually.

mattipuh

Measured primers to be 39.5mm. One rule of thumb is to make collector area x2 primer area. With this optimal collector diameter would be 55.15mm. Were 3mm from that. Maybe this header gives good torque but it lacks abit top end. Increasing collector diameter would be quite easy as it could be done by small grind job and fitting new 2 1/4 bend before front muffler.

Per vers

In a few days, i will recive a header from Spencer.

If i can find the time, i will instal it next week. And make a dyno run.

Regards Per

V2Rocket

^LOOKING FORWARD TO THAT
it appears to be waiting in your customs btw, Per.

Per vers

Hello Spencer

Yes the packet is in customs. I will get it tomorrow.

Is it possible to install the header without remowing anything from the motor.

V2Rocket

I never installed the headers while I owned them.
But I think they should go in OK from the bottom/under the car.

mattipuh

It should fit there from below.

Noahs944

The Stahl Headers have the reputation for BEST in North America. They aren't cheap... but when the 330 hp n/a 4 cylinders are being built & tested by Michael Mount, these are the headers he uses. The other top 944 engine builder (Jon Milledge) endorses them. Worth the money YES. I bought mine here: http://www.mantissport.ca/Products/P...s/Default.aspx
Mine have a 3" collector & 1 3/4" primaries (external measurements). The gaskets fit PERFECT, no grinding needed.

mattipuh

did some bench stuff today. before after head work.




Say something about this photo

H.F.B.

211hp @ 6441 RPM, mission accomplished 200hp+
Congrats and thanks for sharing.

Nice to see what gains decent headwork can yield.

Per vers

Hello Mattipuh
Nice numbers.
I have installed the header, I bought from V2Rocket. Made a dyno run, but the numbers are a bit low. Need some adjustment.
Do you have a picture of your header.

mattipuh

Thnx. No pic of header, its simple 4-2-1 with 2inch collector

mattipuh

Was guessing to get 210-215, quite satisfied still with the figures. Torque curve is quite wide too.

mattipuh

We did not measure head but guy estimated the improvement to be in region 8-12%