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Thread: Electric Cutout Discussion

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Posts: 21-27 of 27
2012-04-03 03:03:40
#21
Wrong! I have dyno data showing massive torque gains with a cutout on my bolt on NA sr20. matter of fact I saw a gain of 10wtq at 3500rpm with open cut vs closed. My setup was gen 6 header with 3" high flow cat and catback with the cutout right before the muffler. I had a 2000 maxima muffler so the car would be quiet when it was closed.

http://www.sr20forum.com/general-sr20/134869-new-dyno-results.html

Originally Posted by classicaddict
Exhaust has nothing to do with back pressure and everything to do with velocity. On a turbo engine everything after the turbo is some what of a moot point. But on NA the exhaust size and length has everything to do with cyl scavenging and proper flow rates. A cut out on an NA engine will do nothing but hurt performance. Case closed.
Last edited by Nismo87SE on 2012-04-03 at 03-19-23. Reason: Adding proof
2012-04-03 03:08:17
#22
Originally Posted by classicaddict
Exhaust has nothing to do with back pressure and everything to do with velocity. On a turbo engine everything after the turbo is some what of a moot point. But on NA the exhaust size and length has everything to do with cyl scavenging and proper flow rates. A cut out on an NA engine will do nothing but hurt performance. Case closed.


you are compeletly wrong.

look at any 1/4 n/a car, they run open header, megaphone with reverse cone and thats it.

stratton.
2012-04-03 04:37:20
#23
Originally Posted by Nismo87SE
Wrong! I have dyno data showing massive torque gains with a cutout on my bolt on NA sr20. matter of fact I saw a gain of 10wtq at 3500rpm with open cut vs closed. My setup was gen 6 header with 3" high flow cat and catback with the cutout right before the muffler. I had a 2000 maxima muffler so the car would be quiet when it was closed.

New dyno results - SR20 Forum


Interesting, but I won't be installing my cutout before the muffler. Mine will ideally go just before the catalytic converter since I intend to keep the stock exhaust for daily driving. I'm wondering if this setup would net something different from yours.

I'm seeing a lot of mixed results so far.
2012-04-03 04:59:38
#24
Originally Posted by Superluminal
Did you have 2.5" exhaust on both cars, or just on the G20?


Just the G20. On the B13 I have a ecutout and a HKS catback.
2012-04-03 06:30:40
#25
Would having a cutout in the system promote back pressure at all when it isn't open considering it pretty much is a blocked pipe attached to the main?
2012-04-03 11:59:48
#26
BACKPRESSURE IS FUCKING BAD FOR ENGINE OUTPUT. Get it through your thick skulls.
2012-04-03 13:50:10
#27
Originally Posted by BenFenner
BACKPRESSURE IS FUCKING BAD FOR ENGINE OUTPUT. Get it through your thick skulls.


Developers! Developers! Developers!

Oops wrong crowd I mean.... Velocity! Velocity! Velocity!

Another thing to add on, if you go with piping that is too big, you start loosing exhaust velocity. The exhaust starts expanding to fill the space and cooling, which causes it to slow down. This colder slower moving exhaust gas starts acting as back pressure then. This generally doesn't apply to turbo cars though.
Last edited by Vadim on 2012-04-03 at 14-28-03.
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