dual exhaust or headers
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St. Jude Donor '10-'11
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I ran few quarters and got an average time. Took off my exhaust system from the collectors back and left them in the car and did some runs. Nothing changed that I could say "Ah HA!" Right now, I have Borla cat back stingers with a good cat, Could I get a system that flows more? Maybe. Would it help? I haven't seen it. Maybe if all I was doing was WOT runs and was running way more than what I am getting (410 RWHP), it might make a difference. Thing is, it doesn't matter how much it will flow once you get past a certain point.
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St. Jude Donor '10-'11
I ran few quarters and got an average time. Took off my exhaust system from the collectors back and left them in the car and did some runs. Nothing changed that I could say "Ah HA!" Right now, I have Borla cat back stingers with a good cat, Could I get a system that flows more? Maybe. Would it help? I haven't seen it. Maybe if all I was doing was WOT runs and was running way more than what I am getting (410 RWHP), it might make a difference. Thing is, it doesn't matter how much it will flow once you get past a certain point.
Last edited by M.J.L.; Feb 28, 2009 at 01:14 PM. Reason: Grammar
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That isn't going to take much since the stock system is a mess of pipes. The question is whether you will lose some scavenging effect.
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St. Jude Donor '10-'11
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If you put an X or H pipe, maybe not but straight dual back out the rear, I would think might be hurt because of the exhaust pulse charge of one side not being able to pull the charge out from the other side.
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No I didn't, the gap in the middle pipe is so gas can try to get out the one working outlet pipe.
I noticed that the dummy outlet did have a slight amount of flow and always wondered why. That dummy pipe isn't sealed tight and pressure seems to force some gas into the closed off chamber, allowing a bit to flow out. Just in case anyone was curious about that.
I noticed that the dummy outlet did have a slight amount of flow and always wondered why. That dummy pipe isn't sealed tight and pressure seems to force some gas into the closed off chamber, allowing a bit to flow out. Just in case anyone was curious about that.
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I went with long tube headers and duals on my '85, no cats. I noticed a big increase in power but a slight loss at rpms below 1500. I was told its because of a lack of backpressure. Oh well it sounds cool 
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St. Jude Donor '10-'11
on the sound!
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But was that because of the LT headers or what? I think you lose responsiveness below 1500 because of the scavenging
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Old wive's tale.
The header collectors provide all the "tuning" necessary so that open headers will provide as much power as any fancy pseudo-tuning thereafter.
Plus the "D" ports of the #113 heads tend to minimize reversion that can occur when the exhaust valve is closing and the intake is opening.
The bottom line with exhaust sizing, as illustrated by David Vizard in his book on SBCs, is that it needs to flow around 2.1cfm/chp. So, even at 300chp no single cat will flow enough; at 400chp even a single 3" pipe will not flow enough.