Thinking of switching to aluminum heads

I already have a very good set of ported iron heads on the car that flow 285 intake and 202 exhaust at .550. I ran 11.18 at 121 when I had a stage 2 scoop, glass front bumper, electric water pump and fans. For now, I'm back to the steel front bumper, steel GS hood, regular water pump and clutch fan. With this I ran 11.32 at 119 this past fall, through the 3", x-piped full exhaust on ET Streets just as I drove it to the track. I leave it in drive and it shifts just under 6000 rpms. My brother wants to sell me his Gessler Level 2 ported Edelbrock heads and 1.6 full roller rockers for a great deal. I know they flow about 305 on the intake at .600 but he doesn't remember what the exhaust flow is. Any one know about what the exhaust flow is on the Level 2 heads? I know they can be ported more down the road if I choose but does any one have an idea as to how much power they might add the way they are? I also run an old set of Poston 1-7/8" headers, would it be worth going to 2" headers? I have a ported older SP1 on the car now, is there any advantage going to the SPX. I'd love to see some high 10's.

Thanks,
Ken

 

I noticed a difference when I switched.

At speed the iron heads had a knocking (detation)

I do not have a "before" and "after", but it has to be better as the weight alone will help.

Each iron buick head was 63 pounds where the pair of aluminum heads are 75 pounds. That is complete units (valves and springs).

 

I am guessing your brother lost the flow sheet for the eddy heads? What are the spec's on the cam you want to use. Peak flow #s really don't mean anything, really you need the flow sheets for both sets of heads.

 

I agree with this. But to help with your question regardless, my Gessler level 2 eddys flowed 314 int 201 exh.

 

I believe the general "rule of thumb" when going from iron to iluminum is you'll shave .3 to .4 off of your ET's. Good luck hunting for the 10's.

 

I agree. I just built a 10/1 BBC (iron 1973 781 ovals) peak flow was only 299@.500". End result 623hp@5800 91 octane.
Cam is an old crane 255/265/110 Solid FT. Good low-mid lift#s however. 164@.200", 230@.300, 275@.400, 293@600".
Ray

 

He is still looking for the flow sheet. I do have the flow sheets for my iron heads. The cam I'm using now is a Straightline Performance 276/282F12 solid. With the 1.6 rockers, it is .600 lift intake, .594 exhaust, intake duration 276, exhaust duration 282. I really like this cam. The motor has 11 to 1 compression also. I plan to keep the cam for now.

---------- Post added at 05:22 PM ---------- Previous post was at 05:16 PM ----------

Thanks. I did some searching online and could not find that info. Hopefully, he will find the sheet for the heads soon.

 

Ken, if the flow sheet can't be found, it wouldn't hurt for you or your brother to contact Greg Gessler to see if he still has it filed under your brother's name...it wouldn't surprise me if he still has the info.

Ray, those BBC numbers fit well with what I'd expect, plus you got a bit more. Nicely done!

Devon

 

What about the headers and intake? If I get the Edelbrock's (which I probably will) would stepping up to the 2" headers and the SPX intake show any noticeable power gains? I assume the 2" headers would help some at the top end of the track but have no idea if the SPX would help me at all since I shift at just about 6000 rpms.

Thanks,
Ken

 

Larry, do you have any head to head testing/data you can link us to in support that you have to up the compression 1 point when using a aluminum head to match the HP and TQ made for a identical head made of cast iron?

 

My iron heads are 66cc.
LIFT INTAKE EXHAUST
100 75 57
200 137 116
300 193 146
400 262 166
500 281 195
550 285 202

That will be great not needing to bump up the compression after switching to aluminum. Right now I drive the car on the street with 93 octane with no problems and just put some 100 octane in from the local Sunoco when I race it. The plugs always look great. I used to put a little 110 in it at the track but it didn't slow the car down or cause any issues going to the 100. I'm thinking the aluminum heads will give me a little extra protection from detonation.

Thanks
Ken

 

Ken, who ported your iron heads? Can you take the Eddy heads to the same flow bench that your iron heads were flow tested on? I wouldn't spend the money until you can get some solid flows #. It sure would take a lot of the guess work out of things if you can repeat the flow bench, bore size, etc that was used on your iron heads to test these eddys. I wonder what kind of a bench your iron's were tested on? Your iron heads have been resurfaced abit to get 66 cc's, if the Eddy's pan out I would check valve to piston which should be fine but always get a base line. If the Eddy's have been unshrouded out to the bore size then I would knock some off the head surface to get down to 66 cc's. With that cam as long as you have good quench you should have no problem racing on 93.

 

The heads were done by Jim Burek of PAE in 2000 or 2001 before all the problems started there. I don't have any info on what kind of flow bench was used. The Edelbrock heads were done for my brothers 430 and he said they were not unshrouded to the 455 bore size. Hopefully, he will find his flow sheets soon. I'm hoping they will make some more power and the weight savings is a plus too. Thanks for your help.

Ken

 

I now have the flow numbers for the Edelbrocks. There was a note on the sheet saying that they were done without header flow tube. I don't know how that effects the numbers but here is what we have.

LIFT INTAKE EXHAUST
100 68 66
200 142 116
300 210 155
400 260 176
500 294 187
600 305 193

I'm starting to think I should just keep saving $ and get a set of mildly ported stage 2's but I would still like to hear your opinions on the Edelbrocks vs my ported iron heads. If I'm going to spend that kind of money I'd like more than just weight savings.

Thanks,
Ken

 

IFT INTAKE EXHAUST
100 68 66 100 75 57
200 137 116 200 142 116
300 193 146 300 210 155
400 262 166 400 260 176
500 281 195 500 294 187
550 285 202 600 305 193


That is a tough call, I am guess only here but I would lean towards the iron head #s being a little high and Greg's being more on the mark. There is really only one thing to do if you want to know for sure. Take both sets of heads to the same bench, apples to apples test. Money well spent. Any pic's of the combustion chambers on the eddy heads, this might be an area to make gains.

 

Right now the heads are still on the 430. You are probably right about the numbers, I think I'll just wait and try to get a set of stage 2's for it this year. By the time I spend the money on them to get me where I want to be I'd probably be better off getting the T/A heads in the long run. Thanks for taking your time to answer my questions.

Ken

 

While I don't have time to make a long drawn out post on this, I will say that I have experience that indicates that if you can get a set of E heads with that Level 2 Gessler port from your Brother, go ahead and do it.

At your performance level, you will not pick up significant power with "better heads".

The heads are not the limiting factor, the camshaft is. 300 cfm flow is plenty for what your asking the engine to do.

While heads that flow better numbers will make more power, we are talking 10-15 HP here, and you have to ask yourself, is that worth the extra $$.. could be a lot of money-- maybe several thousand, depending on what kind of deal you can get from your bro.

You have done a good job optimizing your combo, considering your times. I ran the same times back years ago, in a 4100lbs GS with iron heads, but that was more of a race car. I suspect good cecil air had something to do with 11 teens with your build, but none the less, it is impressive. But at your level, 10-15 HP might be a couple hundredths.

Were it me, I would put those E heads on, especially since your running a solid cam. The knock on E heads is not that they don't work, it's that it's difficult, if not impossible, to get a quiet hydraulic valve train with them.

I would not fuss with the headers and intake... I have tested so many headers that didn't have a dime's worth of difference between them, it would take all day to tell those stories.

The intake depends on how well it's ported.. judging by your times, I would say it's working fine. My testing in the past indicates that the SPX trades 10 ft lbs at peak torque, for 10 HP at peak HP.

JW