header diameter?

[delinquent543]

What diameter header does everyone use? 3/4..7/8 etc.. What are the benifits on either? Im thinking of getting headers, then eventually a cam. Should i go for the bigger diameter if im going to cam my car?

[Hi-Po]

Just remember that the size of the pipes inside diameter is MOST importnt. Usually longer headers improve low speed torque. Picking the right headers is actually something to think about. Primary pipe diameter is far more important to ultimate engine power than pipe length. Smaller header pipes incrase gas speed at low rpm which effectivly evacuate the chanber at low speeds, improved low spped torque. But resriction at high speeds. But as you said you do the occasional little race so that would be best choice. Large diameter pipes tend to lazy at lower engine speeds . lower exaust speeds allows portion of exaust gases to remain in chamber.-- Cant burn it twice so it contaminates incoming a/f charge.Match this with a short duration cam and a dual plane intake and you have a responive torquey, fun drive. Ron

[hammertime]

Match this with a short duration cam and a dual plane intake and you have a responive torquey, fun drive. Ron

Where does one find a dual plane intake for an LS1?

True for a carbureted car, but not fuel injected.

As for Pipe size, take into consideration your intended use. Just because you'll be doing heads and cam down the road, do you want to lose any of your low end to a too large pipe for the limeted amount of time you'll be at WOT? If you want best all around, consider staying with 1 5/8 - 1 3/4.

Just my $.02

Hammer

[Hi-Po]

No Hammer i think i didnt explain my self correctly, i believe one should go with a smaller diameter LT header not a larger one agreeing with you on losing low speed torque- Thats not acceptable if your driving a DD. And the ? about finding a dual plane intake for LS1 i dont know. Im by no means an expert at LS1 engines, Actually not expert on any engine, i just graduated from NADC (nashville auto diesel college) took a High- Performance class there and completely blueprinted a 350 fastburner engine and got priviledge to run on engine dyno and try my best to blow it up. ( didnt happen(:---) But what i learned there was pretty much all carbed engines where dual plane intake. But i dint have the chance to screw with any fuel injected engines. Your probaly right about fuel injection.

Ron

[hammertime]

Hi-Po

I think you can get a carb'ed intake for an ls1, but they are generally for guys making major power and without the patience to tune a computer, so they are usually single plane manifolds.

You are 100% correct about the short duration cam and a dual plane for a carburetor setup. I ran a comp 268H with a quadrajet and a factory dual-plane aluminum intake from a 305 in an otherwise stock 350 with headers and duals. That was in a 3400 lb '81 Chevy Malibu, and it turned 14.7's at 96 mph with the stock 2.41 rear gears. Really a great street motor!

[Hi-Po]

Sounds like a fun drive. did you say you put 305 heads on your 350? scratch that. re-read your post.

Ron