Scotty G wrote:
here's my 2 cents on it....
I picked up an engine with a set of 'D' heads that were ported by a very well known engine builder here in Ohio - Gellner Engineering.
Knew nothing about the motor, so off to BTR I go with it and we put it on the
BTR dyno which, for those who do not know, is a conservative dyno that spits out numbers that match track ETs.
Motor was 13:1 with a big mechanical roller, stock rods and N crank, Torker and an 850 and it made 502 horsepower.
We decided to pull it apart to make sure everything was in good shape and found the bearings eating themselves up.
Looked at the porting job and I would say that Bill was impressed with it, basically a full tilt ported set of iron heads done correctly without getting too close to the water jackets. Bill can comment further, but they're a bad ass set of iron heads.
We decided to put the thing back together with the same pistons, tossed the stock rods and put a set of CAT H-beams in it. I had a factory 455 forged crank that I had been saving for 'who knows what' that we decided to use instead of the N crank and we put a BTR girdle on it since we were there.
No other changes were made to the motor. Heads were good so Bill honed the block with his deck plates, new rings and coated bearings, lapped the valves, same cam, same pistons, no other internal changes to the motor.
We decided to toss the Torker and installed an out of the box Victor dominator intake and I had an old dominator on the shelf that we used.
Motor made 565 horsepower on Bill's dyno and that would have probably been well over 600 on some of the dynos I've been on in the past.
There was something in the intake and carb and there was probably more in proper clearancing and assembly.
The point is, you can make respectable horsepower with iron heads. Could you have made 565 with as-cast Edelbrocks ( I'll use Ebrocks as an example because they are the least expensive aluminum cylinder head available for the Olds) on this same motor instead of the bad-ass iron heads? My guess is you'd get close but maybe not quite.
But if you threw the money at stock Edelbrocks that it cost to port the iron heads, especially if you went to the BTR-Brocks it would blow the iron heads away.
Seems like it boils down to the cost of the aluminum heads and what theme you're going for on the build.
It's also pretty time consuming and expensive to have iron heads ported and it takes some experience or a really good mentor before you can do it right yourself.
If money is not an issue, aluminum is the way to go for power, but this all iron 455 is one bad-ass piece (we also put a fogger on it).
Don't overlook that there is a bunch of power in good engineering (component selection), machining, tolerancing, assembly and component matching - you could spend a bunch of money on a set of ported aluminum heads & intake and lose power in these areas.
Not bad for that builder in Ohio. I get the cost point and how much one can do themselves and with Pro-Comp entry level heads it looks like AL heads are there. I agree that the combo is critical and mild builds may suit iron heads. I think Pro-Comp will continue to improve the castings and that should force Ebrock to make a better (Victor) version. Unlike ROP, were everyone automatically shots new parts down, I want to discuus this with folks who know first hand so others can make informed decisions.
Also, I doubt Bill didn't talk shit about Gellner Engineering's work. Just a hunch