open header slower?
 

so my car has long tubes to x pipe then thrush shorty mufflers, well i decided to pull it off and run it open headers to see if there was a difference, it actually felt slower...i thought was kinda weird everytime i have gone to the track almost every one is open headers

i think the computer needs to be tuned for the extra air flow.

Correct me if I'm wrong, but can't an absence of any backpressure cause a reduction in power?

What you're feeling is a loss in low end torque. You probably are making more power now than before (though based on your previous setup I'd say you might be making an extra 5 horses). The problem is that you shifted your torque band up higher. Instead of feeling, say, 250 rwtq by 2200 rpms, you're feeling 230 rwtq by 2200 rpms. But, you now are probably making an extra ten or so peak torque.

From what I've heard, unless it's just the LS1 and LT1 camaros, Back pressure is a myth.. the more free flowing the better. Then again.. that could be only for the newer camaros

I would love to have a discussion about how to manipulate that torque band and what techniques, modifications, and tools you would use...

i have heard that u loose bottom end but gain top but i didnt think it would feel that much of a difference, i have an ms4 cam so it sounds good but its so loud and vibrates so much it blurs my vision when i get on it lol

speaking of vibration open headers will also set your knock sensors into action.

Well, I it's not a myth but it does affect different motors in different ways. About the only thing I have seen with my own eyes as far as a problem is something tuned for a stock exhaust then goes to open exhaust might see a lean condition. Burnt valves are no fun. If you tune for it, your all set. It will, as mentioned above, raise the power band.

Phil

It's not about "back pressure"

It's about the velocity of the exhaust. The faster it flows, the more torque that can be applied in the lower end. When you reach maximum flow, it cuts down on your numbers when the engine is pushing out more air/fuel. This is why when you open up the exhaust, you lose a lot of low end torque but gain high end power. So a bigger pipe/no pipe will let more air flow, but at the lower RPMs, the exhaust is slower moving and doesn't scavenge as well. That make sense? Sorry I'm really tired, so what I'm saying may sound like french lol.

And you do not have to tune for open headers... RARELY will opening the exhaust as such create a lean condition the motor can't immediately counter. I've ran open headers on my race cars since I started when I was 14 (I'm 19 now) and I've never burnt a valve. That's usually something you only run into on a boosted car, not an N/A one.