DavidNJ

If you read this forum, head comparisons are made on flow numbers. In the adjoining dyno forum, it is based on rear wheel horsepower. And in the drag race forums they actually compare times and trap speed.

In this forum, the aftermarket castings--ET, AFR, Dart, etc.--dominate. In the other forum, Cartek and TEA are up there also. Maybe even a little ahead. It seems every Cartek car is in the 10s or faster.

It looks like the aftermarket heads all have better chambers than the LS1/2/6 heads. Presumably they would have better ports also. So why does it seem we are more likely to see a Cartek or TEA posting top numbers on the dyno or even more so at the track?

Is it, especially in the case of Cartek, also a function of engine assembly? Things like quench and cam timing.

jermzz

iTrader: (18)

In the end all that really matters is tap and MPH if you're talking about racing, but there's so much more to having a fast car then just having good heads. They do play a major role though!

I think the mistake most people make when looking at dyno numbers is that the number you see, whether it be 390, or 500+ is only the horsepower at 100 rpm, and its usually redline. But your car is only at redline for a split second before you shift and go back to 3 - 4K. Where is that number now?

People say ohh, he has 500 RWHP and he only has 450 RWHP so hes gonna lose! Not always true! This is why stroker motors are great, they produce great power at the lower RPM where smaller motors produce less. You want your dyno graph to look more like a hill, rather then a mountian. HP and torque starting earlier and staying longer rather then a qucik jump up and fall down.

You can see this when you look at flow sheets on a set of heads, what they flow at different lifts. Some companies work on getting the flow throughout the powerband, some work mostly for that "peak" number while others do both. I think this is why you will see different heads being praised in different forums, because they like the head that best suits their need.

cam plays a big part too obviously, you need your setup to fall together its not going to give you the power you want. This is just a small example but say you have a set of heads that flow really well at .600 but hen drop substanially from .400 to .500 then you have a cam with only .550 or less lift. What good does it do you to have good flow where your cam doesnt even get too?

this is the way ive always understood it anyway!!