porsche2fst4you

OK gentleman...so far your a wealth of information and I thank you. So to pick your brains once again...I am looking for intake manifolds that will work with my CIS that are going to flow better than my originals on an 88 930. I actually like the CIS since this is my third car with the setup and about 60 or 70,000 miles with no fueling problems..I really want to keep the CIS. This summer I am putting in 964 cams and doing a bottom end rebuild. Already have the exhaust (B&B headers to a dump pipe, love that sound), 64mm garrett, and big intercooler. I am not putting a spring in the waste gate either. Just want as much pep as I can get and keep it living with plenty of reliability since I love to drive it. Any help?

Sameer

If you do upgrade to the 964 or SC intake manifolds, you'd have to go EFI. With the CIS intake manifold, you can have it extrude honed.

Kevin

Right now with his 64mm Garrett he has maxed out his CIS fuel system.. If he stuck it on a dyno your most likely running lean.. You can't swap manifolds unless you upgrade to a EFI system.. Making a switch to a different manifold will force you into increasing the size of your intake ports on your heads... Right now they are sitting at 32mm...

jhunt@huntinter

You can have the intake manifold extrude honed and use tapered injector blocks to channel the airflow to the heads. First thing is to dyno the car as-is with an A/F meter hooked up. CIS is reliable, but it was also designed with a slide rule. So each one is a bit different. Some can deliver enough fuel for a bit more hp then others. Once you work out fuel, then looks to other things for hp.

porsche2fst4you

Yes my CIS is maxed. What is Extrude Honed and who can do it?

Kevin

This has been a problem for many years.. As turbocharger's have been made more efficient and better header designs have been made.. basically you are stuck.. You either have to buy another turbo (smaller) or upgrade to a EFI system.. Check the "Billet Pulley" thread.. If you Extrude Hone your intake you will create more problems.. because you will be adding more air into your engine, without the ability of adding more fuel.. Some people will tell you to activate your cold start injector for more fueling, but with the 64mm turbo that you have, it won't work... Been there done that...

Extrude Hone is a process where the company uses abrasive putty or clay to polish the intake manifold ports, or enlarge the ports...

porsche2fst4you

Has anyone hears of adding an injector ?

BrianKeithSmith

EFI man. Do it and never look back. You'll be glad you did.

Brian

Kevin

The CIS manifold is designed as a dry manifold.. If you add the 7th injector it's not going to evenly fuel each cylinder.. Typically you will lean out #2 & 5.. or more.. It only take one hole in your piston to ruin your day... You can find the odd person who will tell you it will work... to give you peace of mind, but in the end at 64 mm and .8-1.0 bars you have no safe reserve with your fuel system and you will run lean..

Sameer

Firstly have you had your car on the dyno to see if your running lean anywhere? The CIS with a good fuel enrichment is good upto 47-480fwhp MAX. Are you producing that kind of power? What are the mods done to your ride?

Brent 930

If you really want to stay CIS and run big power you would have to set up and AIC. Not worth it IMO.

porsche2fst4you

All thats been done so far is the exhaust with a dump pipe and the turbo, ah yes, Tom put in a different set of injectors to help with the fueling problem...it has 78K on it so is due a rebuild. I figured I would see what I liked since its due to get torn out soon anyway. I am very pleased with the punch from the new turbo and the exhaust not to mention the fact that its getting to full boost at about 27 or 2800 rpm now with the free flow exhaust. Sometimes its a battle just to keep it straight!
It has not been dyno'ed as yet...in May I am having 964 cams and new rings /bearings put in it a long with what ever else it needs to stay healthy and still out run vette's. I cannot stand the thought of one of those things geting away from me! Keep the hints and info coming gentleman...I appreciate it a lot.

JBH

Listen to Kevin...his advice is solid.

Eventually you will not be able to keep up with those vettes (like this year) with you current configuration. Andial Fuel Enrichment will not get you there either. If adding injectors or changing the manifold was the way to get more hp, we all would have done that.

Now it is time to look at your budget, set you objectives, and decide how to spend. My advice is to set the foundation for improvements that, made over time, will get you to your hp goals. Having said that, remember there are a number of other expenses that come with these upgrades - transmission, suspension, and brakes.

I had a similar situation and decided to spend money on the tranny and suspension. Once I learn to drive the car with its current hp/torque (375 rwhp), I'll start thinking about serious engine mods. Right now, the car is maxed out in terms of handling, braking, and transmission - that's my foundation.