How much of a power gain with headers?

[Heisenberg]

Going from stock manifolds to headers, about how much horsepower is gained? I'm thinking that on a standard fuel injected small block V8, you can gain 20-30 hp. Does that sound about right, or am I way off?

 

[Evadman]

What kind of headers? ( short, long, 4 into 2 into 1, equal length, long tube, short tube, what size collector? )What HP/Torque do you make now? how may CI? How much CR?

 

[UltraQuiet]

What is the specific application? Some of the newer engines have very efficient exhaust manifolds and there is almost nothing to be gained with headers.

 

[Heisenberg]

It's on a 350 TPI motor. The motor has Vortec heads, a different lower intake manifold, Vette camshaft, slightly larger injectors, and a cat-back system. Right now it should be making around 305 horse.

Edit: The specific headers I'm looking at are Edelbrock's tubular exhaust system (I think that's what they call it).

 

[J0hnny]

Actually, Dave, there are new headers that are just coming into the market called "anti-reversion" headers. These headers have been around for a little bit, but not available to the average consumer. These new headers have a expansion on the pipe before the collector and it's supposed to help scavenge extra power (quite a bit actually).

Explanation Link

 

[Cyberian]

Originally posted by: J0hnny
Actually, Dave, there are new headers that are just coming into the market called "anti-reversion" headers. These headers have been around for a little bit, but not available to the average consumer. These new headers have a expansion on the pipe before the collector and it's supposed to help scavenge extra power (quite a bit actually).

Explanation Link

Great site, but my head hurts a little from reading that!

 

[toph99]

depending on how bad the stock manifolds were, anywhere from 5-20hp usually. it also depends on the design quality of the headers, and if they're tuned for the car properly. tuned exhaust can add quite a bit of power by scavenging the cylinders, instead of just reducing backpressure

 

[BillDKiller]

You'll really only have a power gain if your engine computer can compensate for the modifications. Installing slightly larger injectors was good, but make sure you also have the proper fuel pressure to run them. The stock pump (I think still in the tank on GM) will only handle slight increases in performance before it runs out of pressure.

Either way, your engine will run cooler, sound better, and have a flatter torque curve with headers.

Definitely think about changing the computer management chip, you will notice a huge difference.

 

[Keego]

maybe my '76 chevy pickup can use better headers