OK I have hit a crossroads here and need some good advise.

As you might know, I have a 1991 Formula with 406, World Products Sportman II's and miniram. 700r4 trans by level 10 with 3000 stall Vigilante Convertor. Strange 12-bolt with 4.11 gears.

Last season it had a solid roller cam 242/250 with .657/.600 lift. A roller lifter went and took out the cam. The motor is ok because I had a large magnet on the filter and everything was stuck to the wall of the oil filter.

Anyway, here is the question. The heads I have are severely ported out. The have around a 230 cc intake runner and flow 300+ intake, 240ish exhaust. 2.08/1.625 valves. Should I keep these heads and change pistons to make 9.0:1 compression to run with an ATI D1-SC or should I go with off the shelf Air Flow Reseach 210's and leave the forge pistons I have now to make 9.0:1. I have -12cc dish pistons now with 64cc chambered heads. The AFR are 76cc chambers, JE pistons I am looking at are -28cc.

I have heard that cast iron heads are better for s/c applications because of the rigidity of the head/block mating surface.

Which one is better given the circumstances of sample compression ratio?

 

iron heads do seal well, but heads like the AFR have an extra thick deck surface over 1/2" in most cases. I recommend reading this as well for anyone contemplating heads. of particular interest to me is the fact that the vortec's up to .500-.550" outperform iron eagle 200 cc heads and many others http://www.chevyhiperformance.com/ed...=text&id=41598

 

That is a very good article for someone trying to choose heads. However, it did not answer the question of iron or aluminum for s/c applications. Besides the weight difference is there really one that is superior for this application given the same comp ratio and flow?

 

well procharger has kits for the l98 corvettes which have aluminum heads... thats all i really know

 

well aluminum can transfer heat easier.

 

The AFR 210 will work better with the supercharger. The reason is there will be less combustion chamber heat due to the rapid heat transfer of the aluminum head vs. cast iron. This will allow you to run more timing and in turn make more power.


My .02 is sell the Sportsmans and roll the money into a set of AFR's.

Hope this helps make your decision. Good luck.

 

Geeze, what a question. I’d love to see a really good answer to this. I have never seen a good back to back test with virtually identical iron vs. aluminum heads.

Seems that there are advantages and disadvantages to both. Aluminum of course saves you roughly 50# off the nose of the car and is easier to work (porting and repairing if they get damaged), but iron is more durable and from everything I’ve seen more efficient (the heat absorbed and carried away by aluminum heads is also heat that could be used to push the piston down. Yes, you can’t run as much timing and boost with the same iron setup, but that could be thought of similarly to a cam that results in a lot of dynamic compression and having the same results). Iron should have the added bonus of being easier to keep a good gasket seal since an iron head should expand and contract at the same rate as the block.

If the head that you’ve already got has the work done to it to really flow over 300cfm and has comparable exhaust ports (probably at least 240cfm for a blown/power adder engine), I’d have a hard time spending $$$ on something that will flow less. For that matter, seems like the lower compression pistons will probably run you 1/3 what the heads would, and you could take the opportunity to freshen up the bottom end (crank and rod bearings), which might be a good idea considering the history of your engine and the fact that it will add little to the cost (of course, you always run the chance of spending $$$ with the 'while I'm in here' syndrome).