I have an 86 with a supercharger, super ram, headers, exhaust. I want to go with a nice heads/cam combo. How big of a head do I need, and at what compression? Also what size cam for this type of setup. My supercharger is a P600B with intercooler.

 

Just my opinion here, and others will chime in with different ideas, but you have a fairly small blower in the P600B (can make a lot of boost, but you have to spin it fast).

On the cam, you need to watch the overlap so you don't end up bleeding boost. I'd look for something in the 215-220 duration range with an LSA of 114 or more. If you get one of the computer-friendly cams with a lower duration, the common 112 LSA will be fine.

Heads - I dunno, there are a lot of choices. I wouldn't get carried away by going too big. If your bottom-end is stock, I'd take this opportunity to drop the compression with a larger chamber volume.

By doing this, you WILL LOWER your boost, but should end up making more power in the end.

 

okay good stuff

 

Cam yes....heads not as important. Talk to the cam grinder of your choice (preferrably one that has ground a few for supercharged engines) and tell him about your setup and goals. Heads are kind of the icing on the cake. If you're not after every last HP, the money would be better spent on a beffier short block. The blower will cover up a set of heads that is less than great. You can "blow" your way to a whole lot of HP not available to the N/A crowd. Tune, cam, intake, and exhaust probably more important than the latest and greatest set of heads on anything but an all out engine.

 

Better heads will make more HP with less boost. To me, that's more than icing on the cake. I'd look into a set of AFR's if I were you.

 

My 2 cents

I would use AFR heads
here is a comparison link
http://www.airflowresearch.com/chp_test.php

The AFR 195's (I believe) are the largest smog legal head you can install.

Also, Your M.R. is a good intake that should flow about 265 CFM http://stealthram.com/flowcomparison.html

Your 113 heads will only flow 195-198 at .500 lift. http://temp.corvetteforum.net/c4/vader86/113heads.html

So right now, you MR can only flow up to 198 CFM as you head is an obvious restriction.

AFR 190's flow 260 CFM and would be a good match for you intake.

Cam choice is debatable and much of a personal preferance.
You should have about a 500 lift stock cam in it now. Your valve lift will open to .500 for only an instant. A .600 lift cam will have the valve over .500+" for a while and cylinder filling will improve.

I would go to 550"-560" as its only 1/16" more than what you have now. Lobe duration and seporation should such to avoid lobe seporation.
I would use a 110 Lobe seporation with a MR and a 112/114 with a TPI.

Get a blower/turbo grind form somone like Com., Crane, Crower..
Those guyes know more about cams than anybody here.

Adding chamber volume will not lower boost. It will lower static compression with a given cam. Lowering compression will let you run more timing and that, will make more power.

Improving air flow WILL lower boost. As boost is a result of resistance to air flow.

don't forget that you have to get all of the air flow out ; and through your tail pipe as well.

Improving flow potential is some areas while leaving restrictions in others will result in little to no power gain.

 

If we were talking about a roots type supercharger (fixed displacement) I would agree. With improved heads and cam you will get lower boost but air-flow would be about the same as before.

With a centrifugtal supercharger it is a different story. With improved heads and cam you will get about the same boost but air-flow into the engine would increase instead.

 

Answer a few questions.

Are you going to be upgrading the shortblock in the future?

Remember your intercooler will max out at 500hp, are you going further than that?

How much boost are you running?
How much do you want to run?
What type of belt setup to you have and how much boost will it allow you to run?


If you are not going to be running more boost then there isn't much of an advantage to lowering the compression ratio. If you are planning on bumping up the boost then I would say get a larger combustion chamber. It will make it easier to find proper pistons when you redo the bottom end. You'll want a compression ratio that will lower the compression to 8.5 or 9:1 or so. I'm not sure what the 85's came stock with so it might not call for a bigger chamber at all. If you can find some heads that will flow 160+cfm you will be happy with the increase and not have to fight the troubles of a "too large" head.

As for a cam you are going to want a 220/230 duration at .050 for a fairly mild cam. Supercharged engines need the extra exhaust duration to help get all the crammed air out. I would put it on a 114 LSA. This type of cam should also help you spin the engine to a higher rpm and take advantage of the super ram that you have on there.

Remember to take in to account all of your parts. Its about making the entire package work together and if one part doesn't fit it will not make the power that you are hoping for.

 

I suspect that your intercooler is a larger flow restriction than your heads. I'm not convinced better heads will help unless the supercharger/intercooler can support the additional flow without increasing the super charger work.

If you can pulley the blower for more flow that will of course help offset the intercooler flow restriction, but it will also help with your current heads.

How fast are you spinning the blower?

Of course, if you can increase the flow and reduce the supercharger work at the same time, it will make more power.

.

 

I will most likely not be upgrading the block, at least not anytime soon. I would like to get as much boost as I can get out of the supercharger. I have a 10 pulley right now.

 

How much is labor to do the heads and cam as well?

 

I believe you have the older cast iron heads that were the precursor for the 128 heads. These are inferior to the 113 heads.

Define the pulley size (crank and blower), and you should be able to define your MIS. At that point, there may be additional boost without changing the heads or cam.

Some of the eraly P600B packages were not supplied with the IC. Does your car have the singly large IC?

If you supply more data, you will get better recomendations.
Aaron