Project: L-body headers

[IsaacHayes]

I'm sure on a 3400 you'll see 20+ hp especially if it's tuned for them. You'll see even more if you have other mods as the manifolds are a huge bottle neck.

[19Cutlass94]

Id love a set of headers, but until I get it tuned, Im not sure if I should bolt a pair on.

[slinky]

I'm sure on a 3400 you'll see 20+ hp especially if it's tuned for them. You'll see even more if you have other mods as the manifolds are a huge bottle neck.

I know your word is good isaac, but forgive me if im going to be paying $600 for a set i would like to see dyno/flow results

[3400-95-Modified]

I know your word is good isaac, but forgive me if im going to be paying $600 for a set i would like to see dyno/flow results

Then your going to have to wait till he has time to do this.

Headers area a PROVEN, time and time again in every application, mod for a car, ESPECIALLY ours with our restrictive exhaust systems.

If you wish to wait then so be it... I spent $550 to cut up a set not even knowing if I could get them to fit.

[slinky]

I have all the time in the world to wait for the results,
And thats cool i once started a fire with $550

[IsaacHayes]

IIRC the S&S 3400 Grand Am headers dynoed at 28 HP to the WHEELS without a tune. So that right there gives you an idea. The SDI headers differ in that they are equal length (or damn close to it) and that the rear bank is more equal in length to the front as well. That's only going to help. The closer you can get every cylinder to the same air flow, the more accurate the AFR for ALL of the cylinders is going to be and thus more power.

Think of it this way, if you had a cylinder that was not pulling in a lot of air compared to the others, it would make the exhaust stream richer and the O2 sensor would be read rich and the PCM will pull back fuel. Now you have a lean condition in the other cylinders, and the one is still rich. So they never become all in balance, and it throws everything off to where few or none of the cylinders get the best AFR. An extreme example of this would be a missfiring cylinder, which would cause fuel to be pulled, then once pulled, the O2 would read lean, so then it richens it up, and it bounces back and forth. If you had every cylinder flowing the same amount of air, then the O2 would read "right" and every cylinder would run dead on at your desired AFR.

That's just the benefit of equal length. (one reason why the gen2 lower intake manifold sucks, not equal length runners). Then you got the benefit of headers themselves...

[19Cutlass94]

Now heres a question of importance that I have. Since Im not swapped to OBDII yet, how will these affect my car when I put them on? If these do happen to fit a W-body, sign me up though.

[bob442]

better flow? cooler engine temps? economy and fuel consumtion gains?

[19Cutlass94]

How will it be affected tuning wise?

[robertisaar]

better flow? cooler engine temps? economy and fuel consumtion gains?

definite yes on flow.

cooler engine temps: only if the stockers were REALLY shitty...

fuel consumption: if you keep EGR, you will probably see an increase, if you get rid of it, you will definitely see a decrease.

How will it be affected tuning wise?

wouldn't be very tough to make the necessary changes...

[SappySE107]

The EGR has never done anything for MPG in my cars. Not sure why headers would hurt gas milage unless you change how you drive.

[onefastV6]

I got the best gas mileage when I had headers on my car. 33.2 mpg on the highway with headers, 3500 heads & intakes, and 65mm tb.

[robertisaar]

The EGR has never done anything for MPG in my cars. Not sure why headers would hurt gas milage unless you change how you drive.

really? because i've been tuning the GP's EGR table, and when 8% of the airflow is EGR, the ECM reduces the fuel injected by 18.3%...

[SappySE107]

I turn the EGR off and no mpg loss to stock. If you are adding egr, then possibly, but that goes against my goals of efficiency.

[onefastV6]

Agreed, I have not noticed any difference in my Mileage with the EGR removed. I did notice when I took my headers off that my mileage sucks. A well designed header should increase fuel economy, which is a plus if your car is a street strip car.