does anyone have any dyno proof that tq is lost with too little back presure?
02-09-2004, 05:58 AM
#21
My original opinion was to agree w/ Ryan. Thats why I put the cutouts on in the first place. But, since I'd only be using the cutouts at the track, I haven't tuned for them. More than likely, I'll go ahead and change mufflers, and remove the cutouts and tune for a better flowing, single exhaust system.
GMC5.3L - look at the truck list for my mods. I have a cam and basically most bolt ons.
pariish8 - Yeah, after you posted up about TM closing your TB, I realized mine must be doing the same thing. I need to at least get a shift kit and servos installed to firm up the shifts. Those shifts were wayyyy too long.
Flyer - Bottle was full. I had an issue with my WOT switch mounted to the petal - it worked fine until my adrenaline was flowing, then I would stomp it so hard, then the switch would rotate some and turn off. I was spraying through the shifts. I had shifts set at about 6250 and on that nitrous run, it took so long to shift, my autotap caught a 6600 rpm.
GMC5.3L - look at the truck list for my mods. I have a cam and basically most bolt ons.
pariish8 - Yeah, after you posted up about TM closing your TB, I realized mine must be doing the same thing. I need to at least get a shift kit and servos installed to firm up the shifts. Those shifts were wayyyy too long.
Flyer - Bottle was full. I had an issue with my WOT switch mounted to the petal - it worked fine until my adrenaline was flowing, then I would stomp it so hard, then the switch would rotate some and turn off. I was spraying through the shifts. I had shifts set at about 6250 and on that nitrous run, it took so long to shift, my autotap caught a 6600 rpm.
02-09-2004, 09:44 AM
#22
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Thanks Tex! (sorry Parish, didn't mean to change the subject on you).
I've heard the less backpressure - less lowend power thing a lot, but the couple of old-school hot-rod books that I've got, don't agree. They say you will always make more power with a free-flowing exhaust.
I guess they're not saying the exact same thing, so maybe they're both rigth?
You'll loose lowend power with an open exhaust, but the gains up top will more than make up for that?
I've heard the less backpressure - less lowend power thing a lot, but the couple of old-school hot-rod books that I've got, don't agree. They say you will always make more power with a free-flowing exhaust.
I guess they're not saying the exact same thing, so maybe they're both rigth?
You'll loose lowend power with an open exhaust, but the gains up top will more than make up for that?
02-09-2004, 12:16 PM
#23
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I'm gonna agree with Ryan too on this one .. I know it feels like it's dragging when I nail it with the headers uncorked. I did have the o2's unhooked too so that they wouldn't make it run pig rich like they did last time. Even before though, when I had cutouts open with the blower on, it still didn't feel as strong, even being FI.
Closing the TB during the shift must only be a 6.0 thing cause mine doesn't and didn't. It would pull timing back to -10, prolly more but that was the most EFILive would show it pulling.
Closing the TB during the shift must only be a 6.0 thing cause mine doesn't and didn't. It would pull timing back to -10, prolly more but that was the most EFILive would show it pulling.
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