Cam for my 396 small block
Race Director
Joined: Apr 2000
Posts: 17,676
Likes: 201
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
DD put me a few ponies short of 600HP. Everythiing I tried to do building this motor has turned out right on the money for a change 
I am thinking of taking the motor to a engine dyno near me this winter to find out exactly what it puts out
I am thinking of taking the motor to a engine dyno near me this winter to find out exactly what it puts out
Race Director
Joined: Nov 2000
Posts: 11,872
Likes: 12
From: Waterloo ontario Canada
And what do you mean alloy heads effectively lower compression? What kind of alloy? For the moment I'll assume that you're talking about aluminum in which case I don't agree. I've heard that aluminum heads can effectively lower CPR at most half a point with advantages that far outweigh this, but a full point?! Sounds like someone has aluminum head envy.
If you have 2 identical shaped heads, one from cast iron and one from aluminum they will have the same compression ratio but the iron head will produce more horsepower because it retains heat. To equal the horsepower of the cast iron head the aluminum head needs to be run one point in compression higher to make up for the lost horsepower.
If you have 2 identical shaped heads, one from cast iron and one from aluminum they will have the same compression ratio but the iron head will produce more horsepower because it retains heat. To equal the horsepower of the cast iron head the aluminum head needs to be run one point in compression higher to make up for the lost horsepower.
Burning Brakes
Joined: Feb 2005
Posts: 894
Likes: 91
Originally Posted by norvalwilhelm
And what do you mean alloy heads effectively lower compression? What kind of alloy? For the moment I'll assume that you're talking about aluminum in which case I don't agree. I've heard that aluminum heads can effectively lower CPR at most half a point with advantages that far outweigh this, but a full point?! Sounds like someone has aluminum head envy.
If you have 2 identical shaped heads, one from cast iron and one from aluminum they will have the same compression ratio but the iron head will produce more horsepower because it retains heat. To equal the horsepower of the cast iron head the aluminum head needs to be run one point in compression higher to make up for the lost horsepower.
If you have 2 identical shaped heads, one from cast iron and one from aluminum they will have the same compression ratio but the iron head will produce more horsepower because it retains heat. To equal the horsepower of the cast iron head the aluminum head needs to be run one point in compression higher to make up for the lost horsepower.
P.S. Many years ago, my friend Bill Mitchell (World Products) started the "original" Dart program with cast iron heads. We would sit and talk and we all realized in an "apples-to-apples" situation iron heads always made more power. This was his reason for going the iron route at the time. I just posted on another site a recent test where we took all the components out of a 400" SB (G.M. casting) and placed them in a Dart SB casting. Due to the density of the Dart block, at least this is what we believe, we picked up 18 HP. It's exactly opposite with alloy blocks, we've also tested this, they are able to "consume" up to 40 HP on a race unit. This is all facts. Thanks again, Gary.
Melting Slicks
Joined: Sep 2004
Posts: 2,412
Likes: 3
Well I'm sure, but with aluminum heads (alloy only means two different metals combined not necessarily aluminum) you can run higher compression and much more timing without detonation. It mooore than makes up for any losses. Why do you think all of the best engines you see today have aluminum heads?
Last edited by enkeivette; Nov 12, 2005 at 07:02 AM.
Thread Starter
Safety Car
Joined: Jan 2001
Posts: 3,637
Likes: 27
From: Norwalk Ct
Just as an FYI, recieved the kit today and the KB (or silvo-lite) pistons are actually flat tops with notches for the valves, there not domed)
I also went with a custom small base circle, solid roller from Comp cams.
Nick
I also went with a custom small base circle, solid roller from Comp cams.
Nick
