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2004 grand prix gtp headers

Basically, your two options are to increase octane or increase cooling.

You can either switch to a high octane race fuel, or cool the intake charge with an intercooler or e85.
 


Cylinder temperatures increase when it can't flow the already exhausted gas out of the cylinder hence how headers DO reduce kr the extra flow helps the gas get out faster which keeps the cylinders cooler. There are still people fighting knock with headers but usually simply because there trying to run a 3.4 with headers being there only mods. Im topswapped with headers, rockers, and e85. I can only run a 3.5 with 18*.

Like mentioned above headers are a supporting mod. You could go straight to e85 or an intercooler but once you start getting to smaller pulleys your going to be getting knock because your not going to be able to flow all that air out that your putting in and at that point it doesn't matter if your air is going through an intercooler or not.

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Yeah I'm not modding it too much, probably not even enough to touch the pully honestly. I replaced the tranny after 300 miles of owning it (I got burned on this baby $5000 before that) and essentially I need to drive it until i'm like 45 to get my monies worth. I just thought headers would look cool while providing some small advantages and for $200 would be worth it.
 
Well if your not planning to run a smaller pulley then you might as well just keep everything stock maybe just get a downpipe to help with the degree or two of kr most of them have from the factory and call it a day.

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You can see where the restriction is. The heavy black carbon is restriction in the stock manifold where it does not mate up with the heads properly. (in case the other thread wasn't enough. LOL)



 
Can someone explain exactly what it is and why it's bad? I know it's knock retard and done by the computer but if it's done by the computer why fix it?
 


suitercrew said:
Cylinder temperatures increase when it can't flow the already exhausted gas out of the cylinder hence how headers DO reduce kr the extra flow helps the gas get out faster which keeps the cylinders cooler. There are still people fighting knock with headers but usually simply because there trying to run a 3.4 with headers being there only mods. Im topswapped with headers, rockers, and e85. I can only run a 3.5 with 18*.

Like mentioned above headers are a supporting mod. You could go straight to e85 or an intercooler but once you start getting to smaller pulleys your going to be getting knock because your not going to be able to flow all that air out that your putting in and at that point it doesn't matter if your air is going through an intercooler or not.

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Click to expand...

But you have no experience with how it actually works.

I ran a 2.7 pulley with a cam and e85. No ic, and no kr.

If the stock manifolds were a restriction, you'd see gain from swapping them out.
 
rickisrad said:
You can see where the restriction is. The heavy black carbon is restriction in the stock manifold where it does not mate up with the heads properly. (in case the other thread wasn't enough. LOL)
Click to expand...

Yeah, it doesn't mate up with the head...the port on the head is smaller.
 
I dropped the car off today and was told there was a massive vacuum leak in the EGR so that will fix the headers getting red hot somehow.
 
Just delete the EGR.

Just another thing that'll cause a vacuum leak with the crappy pot metal stove pipe that's used.
 


About 5 years back I finally bought some ebay headers for $99 (different car). Figured they would be junk for that money. The main problem was the flange mating plane-how flat to mate to the exhaust ports on the head. Using a mechanics straight edge ( accurate to .001") and a table saw surface I found a gap of .020" across the surface. Rule says shoot for .004" max. Cranking down on torque or extra gasket probably will not solve this problem. Leaks.

The fix: machine shop mill set up- expensive. Access to a 36" belt sander and patience-good. I used a Sears bastard file. These are not cheap, about 18" long. Use a blue marker pen and alcohol and start working across all header flanges. Do a diagonal rotation . Keep wiping off the blue with a clean rage and reapplying. This is time consuming, but works.

Besides this the ports were slightly mismatched. The welds and chrome have held up way better than expected. There was one "step" mismatch in the down pipe which could not be fixed, but minor. Another problem was insufficient room on several flanges for the nuts to center on the holes, requiring a little flattening of weld bead. Finally, I opened all bolt holes up so I could move the header slightly (.020") in all directions when placed on the studs without nuts. IMO this avoids snapped fasteners. A flaming bargain, but they need some work.
 
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