vespam5

So my intake manifold stacks on my car are cracked and although they are probably still ok I'd like to replace them.

Pelican sells them for $75 each but also sells the 993 versions for only $25 each. Anybody know if I can use 993 ones on my 964??

964 ($75):
http://www.pelicanparts.com/cgi-bin/...4%29%2C%20Each

993 ($24):
http://www.pelicanparts.com/cgi-bin/...8%29%2C%20Each

NineMeister

Yes you can ..... but the internal diameter of the 993 ones are fractionally larger to correspond with the larger ports in the 993 heads, hence you have to be careful to align them correctly with the 964 heads.

vespam5

Thanks I am going to give it a shot. I ordered one of the 993 versions for a mockup, I'll report back with pictures.

justin-in-athens

How did this turn out? I am looking to do the same thing.

Vandit

I put 993 intake manifolds (plus new seals) on my car late last year. Turned out great. My wallet was very pleased with the performance.

-nick

My originals had cracks around the bolt holes. I reused them, thinking that the cracks wouldn't cause a vacuum leak with the new seals.

I would have thought that the diameter change on the 993 version would be very bad for intake airflow. The lip on the head would act as a small a wall as the air flows in. Maybe in reality it doesn't make difference?

ClaytoVR

What about boring out the intakes on the cylinder head? Is there enough room(I'm looking at having a top end redone so I'm very interested)?

ThomasC2

Any new info about this? Is the difference so small that it doesn't matter? The price difference is still huge.

Steve Weiner-Rennsport Systems

It does make a small difference in power, especially above 5500 RPM.

ThomasC2

OK, then the given follow up question :-)

Is is a good idea to go for 993's and modify the top ends instead? or will the final cost be the same, or are there any other down sides taking this route?

justin-in-athens

I guess you could go that route, but frankly they don't need replacing that often, so I would just buy the original 964 part if you are that concerned about it.

I am a penny pincher, and my car is a street car, so I used the 993 part. As steve noted, it does create a hiccup in the airflow at high rpms, when the engine is really demanding a lot of air, but I don't think the average person would know the difference without a dyno.

ThomasC2

The question is for a friend who's doing a top en job right now. He tracks his car so a bad air flow is an issue. 3 mm is a difference. His mechanic also said that the position for the injector is also is different. Height or angle I don't know. We'll stick to 964 parts.

Thanks for your input!

greg1990964

Interesting topic. I have written here before about my cars stumble over 53-5500 rpm. Everyone says it is the resonance flap. But I hear mine click when turning the key. I always wondered if the cracks around where the stacks screw down could cause a air flow leak. I remember spraying starting fluid around there to see if it cause a rise in rpm but nothing. I wonder..

Vandit

The seals at the bottom also become dry, compressed, brittle and blow out of (or into) the intake.

https://rennlist.com/forums/964-foru...manifolds.html

JasonAndreas

Do you have an air compressor or a pressure bleeder? How about pressurizing the intake manifold to 7 PSI (0.5bar) and spraying it down with soapy water? If there is a leak it will bubble.