Flowed Carrera 3.2 Intake

[WydRyd]

I was just browsing the RennSport WEB page and came across this section/table:-

Airflow comparisons from 3.2 Carrera Stock vs Flowed Intake Manifolds

Cylinder Stock Airflow cfm Flowed Airflow cfm
#1 277 351
#2 280 349
#3 280 351
#4 295 351
#5 286 349
#6 289 352

(DAMN! Excuse the formatting!)

It seems that there can be substantial gains from having the Intake Manifold flowed properly, especially for a forced induction setup coupled with Pressure Sensing.

Has anybody perfomed such a mod and if so, how much does it typically cost to have the intake manifold flowed?

[juan ruiz]

Extrune Hone $600USD, Home made Ported FREE

[WydRyd]

Is that what you did Juan? "Hand-ported" at home?

Were your heads match-ported also?

[juan ruiz]

Yes thats what we did Ported the Intake Manifold by hand at the shop and Ported the Heads by hand also, but we ported both the Intake & Exhaust

[A Quiet Boom]

Just a few comments, those numbers would amount to a substantial increase in HP, on a V8 that much flow would be good to well over 650 NA and a lot more with force induction assumming the cam gets up into that lift range long enough. Note: My Mustang heads flow somewhere around 310 or so with about 650hp on tap. What where the specifics of the test? was it done at industry standard 28" water? As far as home porting goes, it's not for the uninformed or faint of heart you can actually make LESS HP with incorrectly ported heads. Do some research on porting race car heads before attempting this. You could just polish them up a bit without doing to much harm, just leave a slightly rough surface on the intake side.

[WydRyd]

AQB - I agree, those numbers would equate to some serious HP capability, providing everything else is matched accordingly.

I can't really give you specifics, but here's the URL if you are interested. I will query RennSport about these figures and test setup.

http://www.rennsportsystems.com/~porsche/engines%202.7-3.2.html

If I were to perform such a mod, I wouldn't dare attempt it myself. I'd have the manifold and heads sent away to be matched ported, flowed and polished by a suitably qualified shop.

At a guess, I'd say that you'd also require a larger throttle body to match the increased flow rate?

[A Quiet Boom]

Originally posted by WydRyd
At a guess, I'd say that you'd also require a larger throttle body to match the increased flow rate?

Yep, only as good as the smallest restriction as they say. Throttle-bodys can be sized according to HP level desired. I'll have to dig up a Mustang page to give you an idea. It's something like 1mm per 5hp if I remember right, just rule of thumb though.

[Steve W]

I would think for forced induction setups, flow balancing the intake manifold would not have much of an effect on hp, cuz you already forcing as much air as the motor can take with the turbo. I had my manifolds ExtrudeHoned years ago, I think it cost me $600 buxs, but my car is n/a. The insides of the manifolds sure are smooth as silk. Smoothing out the intakes effectively makes the runners larger at hi flow, because with the stock cast surface, eddie currents are generated along the surface at high flow, which reduce the effective diameter of the runners. Bruce Anderson and Jerry Woods dynoed a 7 hp gain on a 3.2 with the ExtHoned manifolds from something like 4700 up.

[A Quiet Boom]

Actually flow balancing between cylinders is more critical on boosted engines to keep detonation at bay. Besides porting will make the turbo more efficient on both sides and most likely spool up faster.

[beepbeep]

One question to you 3.2 guys: Are there any spacers between 3.2 intake and heads? Or is it only gasket? Also, what's the diameter of intake on 3.2?

I'm still thinking about smacking one of those on 930 togheter with EFI, don't have money for time being tough.

[ChrisBennet]

Originally posted by beepbeep
One question to you 3.2 guys: Are there any spacers between 3.2 intake and heads? Or is it only gasket? Also, what's the diameter of intake on 3.2?

I'm still thinking about smacking one of those on 930 togheter with EFI, don't have money for time being tough.

Yes , there is a 10mm (?) plastic spacer between the heads and the intake with gaskets on both sides.
-Chris