Revup lower plenum on non revup FI car???
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Revup lower plenum on non revup FI car???
I've searched and searched on the forum for someone that has used a revup lower plenum on a FI non revup car and can't seem to find any mention of it. I'm wondering because if you sit a revup and a non revup lower plenum next to each other its obvious that due to the shorter runner length that the revup plenum will have more volume than the non revup (correct me if i'm wrong), it would seem to me that a FI setup on a non revup would possibly show some gains with the use of a revup plenum. you would maybe lose some tq but with greater volume and shorter runners i would think you would gain more power overall and have more power usable at the top end. I'd really like to know if anyone has tried this or has any def answers on what would happen and any input from anyone is always welcome, tell me what you think
thanks
thanks
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Runner length is much less important during boost (as positive pressure is driving flow) compared to a NA engine. I think that swap may help top end flow a bit, but you will lose low end torque before the turbo spools - as you predict. In essence you will narrow the powerband, favoring the right half. My prediction would be you would lose more low end (pre-boost) than you would gain at the top, which you can always up the boost for...
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I just switched to the revup lower plenum on my 04. I have a Greddy TT setup. You can check my mods below on my cardomain page. A loss of torque down low in the RMP will be a good thing. It's the massive torque that's causing traction loss in first and second gears. Off WOT driving around town you won't notice any difference. I have not tuned the car yet so I don't know how it's going to work.
Westpak has the rev-up lower plenum on his non rev-up car. He is making power higher up than what I would consider normal for a non rev up motor.
Here is Westpak's dyno graph showing power til 6850 RPM. He is running the Greddy TT as well.
JET
Westpak has the rev-up lower plenum on his non rev-up car. He is making power higher up than what I would consider normal for a non rev up motor.
Here is Westpak's dyno graph showing power til 6850 RPM. He is running the Greddy TT as well.
JET
Last edited by JETPILOT; 01-26-2008 at 06:03 PM.
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But it's the torque after boost hits that's hard to utilize, not the NA torque (pre-boost), which you still want to maximize. Hard to say if the top end gain will outweigh the loss down low. I notice the OP is an automatic with a fully built tranny (and I presume a high stall TC). In that case, you will be in boost practically always so a revup plenum may have no negative impact on you.
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Originally Posted by rcdash
Runner length is much less important during boost (as positive pressure is driving flow) compared to a NA engine. I think that swap may help top end flow a bit, but you will lose low end torque before the turbo spools - as you predict. In essence you will narrow the powerband, favoring the right half. My prediction would be you would lose more low end (pre-boost) than you would gain at the top, which you can always up the boost for...
Raising ther boost does not move the powerband to the right. It may actually make the powerband move to the left if there is a restriction in the exhast flow.
JET
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Originally Posted by rcdash
But it's the torque after boost hits that's hard to utilize, not the NA torque (pre-boost), which you still want to maximize. Hard to say if the top end gain will outweigh the loss down low. I notice the OP is an automatic with a fully built tranny (and I presume a high stall TC). In that case, you will be in boost practically always so a revup plenum may have no negative impact on you.
i'd also like to thank everyone for their input so far
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Originally Posted by JETPILOT
I am always in boost. It may only be 2-4 psi driving around town, but your never really not in boost unless you drive like my grandma.
JET
JET
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Originally Posted by rcdash
^ sounds like all-around good mod in that case. On a separate note, that's the most linear power band i've seen for a greddy tt. Not sure what to make of it... Do you know if boost is being held steady or increasing?
I also have a plenum spacer and open dumps
it is probably in the tune as well, I did it conservative and don't start off with a lot of timing down low
Last edited by westpak; 01-27-2008 at 10:36 AM.
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