cutouts. worth it?
01-21-2004, 09:47 PM
#21
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Originally Posted by Colonel
"first pull was with all closed
2nd pull was with just the back one open
3rd pull was with all 3 open."
I hope you take this in the helpful manner in which it's intended but here's a suggestion so that you get a more accurate understanding of what really happened.
1. Get the engine and drivetrain (drivetrain takes longer) up to normal driving temperature. This means driving it for a good half hour I would think.
2. Dyno 4 pulls with the single cuttout open. Take the highest reading.
3. Allow the engine to cool back to the starting temp of the first pull.
4. Dyno 4 pulls with all three cuttouts open. Take the highest reading.
Be sure to use a diagnostic scanner to monitor timing advance and O2 readings. Better yet, use a wideband. Keep the fuel/air mixture between 13:1 and 13.3:1.
I think you'll see that there is little to no difference in power between 1 and 3 cuttouts UNLESS you have a restriction between the 2 cuttouts and the single, such as a restrictive sized I-pipe.
2nd pull was with just the back one open
3rd pull was with all 3 open."
I hope you take this in the helpful manner in which it's intended but here's a suggestion so that you get a more accurate understanding of what really happened.
1. Get the engine and drivetrain (drivetrain takes longer) up to normal driving temperature. This means driving it for a good half hour I would think.
2. Dyno 4 pulls with the single cuttout open. Take the highest reading.
3. Allow the engine to cool back to the starting temp of the first pull.
4. Dyno 4 pulls with all three cuttouts open. Take the highest reading.
Be sure to use a diagnostic scanner to monitor timing advance and O2 readings. Better yet, use a wideband. Keep the fuel/air mixture between 13:1 and 13.3:1.
I think you'll see that there is little to no difference in power between 1 and 3 cuttouts UNLESS you have a restriction between the 2 cuttouts and the single, such as a restrictive sized I-pipe.
i have a custom y-pipe made with no cats and with a cutout on each side of the y-pipe and then the cutout on the i-pipe and stock muffler. ive always gained about 15 rwhp with just the cutout on the i-pipe and this is my first dyno since having the 2 on the y-pipe. my a/f ratio was around 12.5 on all pulls. the car was fully warmed up. i always make sure espcially with the white one because of the cam and heads it has and the electric water pump.
thanks for the input
01-22-2004, 11:29 AM
#22
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It is worth it, cheap hp mod! I didn't dyno with it capped, but I'd say probably 10 rwhp on a stock car. I made 302 rw w/ a lid & cut out on a '98 Z A4. Car definately has more top end pull with it uncapped.
01-22-2004, 03:15 PM
#23
Originally Posted by pdd
i decided not to get them. emissions seems like a problem up here in mass
Dope
01-22-2004, 03:43 PM
#24
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I only picked up a tenth (.10) and half a mph at the track over the stock exhaust. Don't even use it anymore. Don't know what the dyno#'s were.
Last edited by highgear; 01-22-2004 at 03:44 PM. Reason: spelling
