Which Headers?

da vette guy said:

Just wondering, looking on the kenne bell website 3v tech tips they say there is no horse power gain in the exhaust up to 700 plus rear wheel horse power and they challenge any exhaust maker to prove a real gain on their dyno. except for sound is it worth it?

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Installing LT headers will definitely provide a power increase. There is a vid on youtube with JDM installing Kooks on a s/c mustang and it gained over 30rwhp. Now, having said all that, I don't feel the cost is worth the hp gains.

A set of Kooks, plus the 6 hours bay time for install, and I'm looking at probably close to $2,000 for a 30rwhp gain. That ratio of cost to power gains really sucks.

Consider this, a new smaller s/c pulley is only $100 shipped.

mustangdave said:

I suggest not going past 450 h.p. or so as the internal engine parts are reaching their limits at that point.

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That's not totally accurate.

It's more a question of how much boost psi and not the horsepower.

10 lbs of boost is considered the "safe" limit. So the safety for the engine is the same with a car at 10psi making 440rwhp or another at 10psi making 500rwhp.

1hOtStAnG said:

That's not totally accurate.

It's more a question of how much boost psi and not the horsepower.

10 lbs of boost is considered the "safe" limit. So the safety for the engine is the same with a car at 10psi making 440rwhp or another at 10psi making 500rwhp.

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I stand corrected; you are right, but I think ten p.s.i. is pushing it especially since their are blowers with 5 or 6 p.s.i. making over 450 h.p. on these engines now. Tuning and octane is critical the more boost you throw at it.

mustangdave said:

I stand corrected; you are right, but I think ten p.s.i. is pushing it especially since their are blowers with 5 or 6 p.s.i. making over 450 h.p. on these engines now.

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I've never seen or heard of anyone who actually makes 450rwhp with only 5-6 psi.

I think the only blower that even makes such a claim, and has yet to prove it, is that new Edlebrock blower. Remember, if you're going to use other peeps cars to validate the power claims you would need to consider all the mods on the car that would increase power. In otherwords, I believe a car running 5-6psi and reaching 450rwhp would also have any number of other mods that are helping to reach that power level.

mustangdave said:

Tuning and octane is critical the more boost you throw at it.

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Agree 100%

I beg to differ. 10 psi is "safe" and 12 psi is probably pushing it.

1hOtStAnG said:

I've never seen or heard of anyone who actually makes 450rwhp with only 5-6 psi.

I think the only blower that even makes such a claim, and has yet to prove it, is that new Edlebrock blower. Remember, if you're going to use other peeps cars to validate the power claims you would need to consider all the mods on the car that would increase power. In otherwords, I believe a car running 5-6psi and reaching 450rwhp would also have any number of other mods that are helping to reach that power level.

Agree 100%

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I didn't mean rear wheel h.p., just h.p. at the flywheel. Having driven cars with over 400 at the flywheel, I can honestly say that is all anyone needs on the street. If racing is your thing, then sure, more is always better.
The Edelbrock (due Feb.) claims 460 something at the flywheel with 5 or 6 psi and I think the new Roush is in that ballgame too.

Headers & o/r pipes will give you HP gains; my best guess is that is some kind of marketing tactic by KB.

While I have to agree that the factory manifolds on these cars are infinitely better than those on older Stangs, they are still manifolds and not headers; 'nuff said.

The problem with the off-road pipes is that they require a tune. When I put mine on, my car had a check engine light for a good 100 miles. Eventually, the computer "learned" to deal with it, and the light turned off.

However, when I got my custom tune that tuned my car for not having cats, I noticed a BIG difference!

Another thing I noticed when I did my h-pipe, is that the exhaust between 2,500-3,000 RPM made a trumpeting sound when you remove the cats. It made my whole car vibrate. Once I put in the headers, it smoothed out the exhaust note, and made the sound A LOT better!

That's a huge load. If you were making 700 hp with the factory exhaust my bet is you'd make 800 or more with LT headers and full 3" exhaust.

Off-road pipes I'm not real sure about, but long tube headers are a very real improvement over shorties. Granted, new shorties wouldn't be worth it, but long tubes are. Peak HP and torque gains may only be 10-15, but under the curve gains, especially at lower RPMs, will be very significant.

For the cost, I would leave it for last, but it is a good mod. I'd consider it a must for a heads/cams car.
Dan