What size headers ?
 

I am going to a racing exhaust on my 88 911 and was wondering what size headers I should be getting and why ? It is a stock 3.2 engine. Any insight would be appreciated.

3" all the way back so you have 6 3" pipes coming out the rear... :D

What are you running Gary ?

http://forums.pelicanparts.com/uploa...1265387663.jpg

But mine is a 3.0L, I believe your needs are different.. Where you want the power dictates the collector lengths and diameter AFAIK.

1.5" at the head up to 1.625" around 10" back in to a merge collector for each bank which should be around 1.875 then back up to 2.5 out, per bank. Most folks run waay to big a diameter which kills the scavenging on these engines.

James

How do mine look? :D

find out what streak is running and then go bigger FTW!

Are there sets off the shelf with this set up or is this purely a custom set up ?

I guess it's not as simple as getting 1 5/8 or 1 3/4 ?



Gary, you know you're suppose to put oil in your car right ? ;)

or look here:

Welcome to Rennsport Systems, Porsche Performance Products for the 21st Century

Keeping it small will give you a little more on the low end and the inverse holds true, larger better in the high rpm range.

I would opt for 1½" but that's my opinion.

My 3.8 has 1¾" headers.

Stock 3.2 engines run very well with 1 5/8" headers, however muffler systems play a big role and the wrong one will kill the powerband.

I drain it for the pictures....

If you want some dyno data from my old car it can be seen on Steve Wong's website. This was with 1.5" primaries but a stepped primary like I mentioned above will give you a bit more at the top if your application requires that but at much greater expense, ie custom header fabrication.

911Chips - Porsche Dyno Runs

Scroll down to see my results under James Achard's 1987 911



Cheers, James

FWIW I ran 1-5/8 European Racing headers with an M&K 911R muffler on my 3.2 for the past two years. Engine made power to almost 6800 then started dropping off. But with stock rods, that's into no-mans land anyway. But I made great torque from 3800-5300 too.

All validated on a chassis dyno. Don't have all the numbers in front of me but the car made 201.5 rwhp at 6300 and still held 190 rwhp at 6550. That's 230 engine hp at 6300, with nothing but headers and muffler, and software of course. Completely stock engine with 190K miles on it.
It also made peak torque of 178 wheel torque at 4900 (204 lb-ft at the crank), but also made 165 lb-ft (190 crank) from 4000-6200.

Are there other headers out there that'll make more HP? Sure. But at what price. This wasn't an expensive setup and it made good power and torque in the rpm ranges I needed for the track.

If you don't need heat or a muffler the step headers discussed here are a good choice

1 5/8 for a 3.2. 1 3/4 is too big (better for a 3.6), and 1 1/2 too small.

I just ordered a set of 1 5/8 from Steve last week for my 84 3.2.

1.5 is actually perfect if you have a stock engine. See my dyno graphs on Steve Wong's website. I was getting 221hp at the wheels. plus it moves the power band down a bit which worked well for me with my gearing at the tracks I run.

Cheers, James