I was wondering if anyone has really messed with the iron heads for performance. Reason being is i have flowed the iron head just like it came off my spare motor and it flowed 263 CFM. Well we have a stock set of aluminum heads that my boss put 2.02, 1.60 valves in and ported and they flowed 295 CFM. But just looking at the chamber designs from head to head the iron vortecs look far superior. The valves are alot less shrouded in the chambers and it looks like the spark plug is a bit more in the center. I think with some bigger valves and some massaging these things will pick up more than 32CFM. I may be wrong and proly am but i was wondering if anybody has run these things in the past.

 

maybe on the B body forums.

 

not really trying to be a jerk or anything, but i think your bench needs calibration if thats the numbers you're getting from non worked LT1 heads.

 

Well they were flowed back in the winter. If the air is right it will give u a pretty impressive set of numbers. Those same head might not flow but 240 if i flowed it today. But if u ask me i dont doubt that they flowed it at all when u take a gander at how they are designed. They come with a decent 3 angle valve job and 30 degree backcuts on the valves.It looks like GM did every thing they could to gets some good numbers outta these things. But the flow numbers above for the aluminum heads is after some extensive reworking. I havent had a chance to flow them in stock form.

 

The stock iron heads on my bench flow right about 220-226 on the intake any season. The aluminum heads flow the same. I've never seen a set of anyone's ported stock lt castings flow more than 285 on my bench. That was a set of heads Brian Tooley ported for a guy about 3 years ago. Really nice stuff and I told him I couldn't help him anymore on the intake - but I did manage to get his exhaust from 189 up to 201 (no pipe).

Everyone's flow bench is different so if the bench you flowed those on is consistantly measuring those same numbers then that is ok. You just have to keep in mind that that particular bench is a little loose. My bench is pretty tight. On a set of AFR 227's we just did on my bench (SF600) they flowed 301 and on my friends SF1020 they flowed 323. Likewise a set of LE2 heads that flow 285 on his bench flow 272 on mine. Nothing wrong and both benches were calibrated, sometime internal leakage can cause flow reading differences and just the setup of the head on the fixture has a major influence on how it reads.

 

The popular LT1 head flow comparo indicates that the iron heads flow about 9% better than the aluminum ones (225CFM for the iron vs. 206CFM for the aluminum).

http://www.malcams.com/legacy/misc/headflow.htm

Check for posts by "96capricemgr". He's done great using the iron heads.

 

I musta had a brain fart an left the spark plug out or somthing. It was almost a year ago when i flowed them. But i looked up the flow sheet on the aluminum heads from before and they flowed 278 after the port work. So that was my screw up. What happened is i got the baseline of a set of RHS heads mixed up with the aluminum LT1s.

 

Flow numbers are not the only source of power from heads. Aluminum transfers heat better than iron, so you can run more compression/boost/nitrous without detonation. Theres also a weight difference.

-Pete-