some good cutout information
Launching!
Joined: Dec 2001
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From: Bowling Green, Kentucky
Re: some good cutout information I have the 3" Factory SS Exhaust for 98 which is a single 3" inlet and one single 3" outlet going through a 40 series Flowmaster Muffler. Back when I only had SLP LT's and a stall I picked up 19RWHP with the cutout open and now with the Head/Cam setup I picked up almost 34RWHP with it open. Like you said though there Trevor you have the SLP Dual/Dual and I am sure if I had the same exhaust I would show simular results, but I run with the cutout open all the time and have always done it that way. Just sounds good to me and much more powerful. A lot more Torque as well, but I'll have to look up on my dyno sheet to see, I know with it open I pulled 406/419 and with it closed I put 373/??? down.
<img src="graemlins/camaro.gif" border="0" alt="[Chevrolet]" />
<img src="graemlins/camaro.gif" border="0" alt="[Chevrolet]" />
Thread Starter
Joined: Nov 2001
Posts: 4,399
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From: Lubbock, Texas
Re: some good cutout information Brian,
Yeah, the factory SS exhaust isn't much better than the stock unit that comes on the "regular" LS1 f-bodies. That's some good info, though!
Yeah, the factory SS exhaust isn't much better than the stock unit that comes on the "regular" LS1 f-bodies. That's some good info, though!
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Re: some good cutout information At our last dyno day a friend of mine with a 01 WS6 dynoed 326 with open cutout and 317 with it capped. Torque was also better with it open although I don't remember the #'s. I just don't have the heart to cut the B&B yet <img src="gr_grin.gif" border="0"> .
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From: Germantown, MD
Re: some good cutout information While your results are interesting I'm not sure if you can draw a solid conclusion from only two runs. So many factors could have contributed to a slower run the second time that would have nothing to do with the cutout. From my own experience I can tell you about my dyno results. I had removed my SLP Dual/Dual and replaced it with a Whisper aggressor and cutout combo. I picked up 4rwhp going from the Dual/Dual to the whisper(I forget how much torque was gained). I gained another 3 rwhp opening the cutout but lost 2 rwtq. Theoretically, with the lower torque/higher horsepower characteristics of the open cutout you should of had had an easier time hooking and a higher trap speed. But every car is different. Good luck with your tests.
Buschman
Buschman
Re: some good cutout information Yeah, I did the same test on both my cars... got a consistant 1mph increase in trap speeds. I hate comparing dynos.. but I saw a big increase there too TQ & HP.
11SECSS has run most of his 11.6 passes through a complete whisper cat back!
11SECSS has run most of his 11.6 passes through a complete whisper cat back!
Re: some good cutout information just dynoed my car today, got 350 hp with the cutout on , the took it out and BAM! got 381 hp!!!
i was using a crappy flowmaster muffler though....
now who was saying a cutout doesn't help? <img src="gr_images/icons/wink.gif" border="0">
i was using a crappy flowmaster muffler though....
now who was saying a cutout doesn't help? <img src="gr_images/icons/wink.gif" border="0">
Re: some good cutout information On back to back dyno runs, before I had headers, o/r Y, and 02 simms, I lost 2 rwhp by uncapping my cut-out. I know the computer needs to learn, but I wouldn't think it would lose power to start with...
At the track, with the cut-out closed, my car went 13.15 - and on a different night in similar weather it went no faster than 13.30's with it open. Both times mods were only Nittos and lid.
However - now, with headers and o/r Y, my car was such a dog with the cut-out closed - I just cut the whole cat-back off. I now have a cut-off.. <img src="gr_grin.gif" border="0">
At the track, with the cut-out closed, my car went 13.15 - and on a different night in similar weather it went no faster than 13.30's with it open. Both times mods were only Nittos and lid.
However - now, with headers and o/r Y, my car was such a dog with the cut-out closed - I just cut the whole cat-back off. I now have a cut-off.. <img src="gr_grin.gif" border="0">
Re: some good cutout information Trevor, my numbers are like yours...through a dual/dual...... cutout open... I went 114.7mph and 114.6mph....with it closed it went 114.4mph twice...I lost 0.30 mph without the cutout...not much. The dual/dual is a very efficient muffler.
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Staging Lane
Joined: Nov 2001
Posts: 73
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From: Ft Worth, Tx
Re: some good cutout information [quote]Originally posted by Trevor D:
<strong>I thought I'd post this since a LOT of guys install cutouts on their cars. I went out to Texas Motorplex this morning to TRY to get some runs in. I managed to get two in with no traction before it started raining, but those two runs showed some interesting stuff for open vs. closed cutouts.
I had an SLP dual/dual 3" catback installed, along with a cutout, this past Thursday to replace the loud 3.5" Mufflex. </strong><hr></blockquote>
Hey Trevor...I saw your car at Nick's on Wednesday when I was there getting my cutout done. Sweet ride! <img src="gr_stretch.gif" border="0">
[quote]Originally posted by Lane:
<strong>On back to back dyno runs, before I had headers, o/r Y, and 02 simms, I lost 2 rwhp by uncapping my cut-out. I know the computer needs to learn, but I wouldn't think it would lose power to start with...
</strong><hr></blockquote>
What's up Lane!! <img src="gr_stretch.gif" border="0">
<strong>I thought I'd post this since a LOT of guys install cutouts on their cars. I went out to Texas Motorplex this morning to TRY to get some runs in. I managed to get two in with no traction before it started raining, but those two runs showed some interesting stuff for open vs. closed cutouts.
I had an SLP dual/dual 3" catback installed, along with a cutout, this past Thursday to replace the loud 3.5" Mufflex. </strong><hr></blockquote>
Hey Trevor...I saw your car at Nick's on Wednesday when I was there getting my cutout done. Sweet ride! <img src="gr_stretch.gif" border="0">
[quote]Originally posted by Lane:
<strong>On back to back dyno runs, before I had headers, o/r Y, and 02 simms, I lost 2 rwhp by uncapping my cut-out. I know the computer needs to learn, but I wouldn't think it would lose power to start with...
</strong><hr></blockquote>
What's up Lane!! <img src="gr_stretch.gif" border="0">
Re: some good cutout information Kinda off the subject. But on back to back dyno pulls my car made more hp with open FLP headers than through no cats and a open borla. It even made more power down low, which is what everyone says you will lose. I will try and post a dyno chart with the 2 runs so you guys can check it out.
Thread Starter
Joined: Nov 2001
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From: Lubbock, Texas
Re: some good cutout information Hey Hank! Thanks for the compliment. <img src="gr_stretch.gif" border="0"> Nick is a BUSY man, but he's well worth the wait!
As for losing 2 RWHP, I think this is just a variance in dyno runs. It's virtually impossible to get the same #'s every run. There are WAY too many factors that could contribute to a very small gain or loss like this. How much torque did it kill? If it was the same amount, I would say that you're making the same power overall w/ open FLP's vs. an ORP and open Borla.
As for losing 2 RWHP, I think this is just a variance in dyno runs. It's virtually impossible to get the same #'s every run. There are WAY too many factors that could contribute to a very small gain or loss like this. How much torque did it kill? If it was the same amount, I would say that you're making the same power overall w/ open FLP's vs. an ORP and open Borla.
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From: Birmingham, AL
Re: some good cutout information Trevor-
Having identical short times on the two runs, if ANY other factor (like weather) played into the difference in your ET, wouldn't AutoTap have shown where it was? Just curious <img src="gr_stretch.gif" border="0">
Having identical short times on the two runs, if ANY other factor (like weather) played into the difference in your ET, wouldn't AutoTap have shown where it was? Just curious <img src="gr_stretch.gif" border="0">
Thread Starter
Joined: Nov 2001
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From: Lubbock, Texas
Re: some good cutout information [quote]Originally posted by Kristi:
<strong>Trevor-
Having identical short times on the two runs, if ANY other factor (like weather) played into the difference in your ET, wouldn't AutoTap have shown where it was? Just curious <img src="gr_stretch.gif" border="0"> </strong><hr></blockquote>
You're absolutely right. I was logging IAT, front O2's, KR, RPM's, blah blah blah, and it was all virtually identical on both runs. I make sure to have the engine temp right around the same (180) when I launch. I even had my electronic weather station at the track with me, and the two different runs showed a density altitude difference of 10'. I don't think that's enough to slow me down. <img src="gr_images/icons/wink.gif" border="0">
<strong>Trevor-
Having identical short times on the two runs, if ANY other factor (like weather) played into the difference in your ET, wouldn't AutoTap have shown where it was? Just curious <img src="gr_stretch.gif" border="0"> </strong><hr></blockquote>
You're absolutely right. I was logging IAT, front O2's, KR, RPM's, blah blah blah, and it was all virtually identical on both runs. I make sure to have the engine temp right around the same (180) when I launch. I even had my electronic weather station at the track with me, and the two different runs showed a density altitude difference of 10'. I don't think that's enough to slow me down. <img src="gr_images/icons/wink.gif" border="0">
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From: Tullahoma TN
Re: some good cutout information Trevor,
You can't exactly reduce exhaust system back pressure and run better times without a little AFR tuning help via MAF Trans unless you are already running way too rich. When I run my cutout open, I increase my WOT fuel by 2%. Without increasing the fuel, I won't see any gains. Your car was probably already running near optimum AFR or slightly lean with the cutout closed. Where did you mount your cutout?
I think you should retest your cutout while using a MAFT to increase your WOT fuel. You will see a gain. I usually see about .08 ET gain and at least .5 mph increase. I run a Dynomax UltraFlo Race Welded muffler, and if there is any better flowing muffler out there for our cars, I seriously doubt it.
You can't exactly reduce exhaust system back pressure and run better times without a little AFR tuning help via MAF Trans unless you are already running way too rich. When I run my cutout open, I increase my WOT fuel by 2%. Without increasing the fuel, I won't see any gains. Your car was probably already running near optimum AFR or slightly lean with the cutout closed. Where did you mount your cutout?
I think you should retest your cutout while using a MAFT to increase your WOT fuel. You will see a gain. I usually see about .08 ET gain and at least .5 mph increase. I run a Dynomax UltraFlo Race Welded muffler, and if there is any better flowing muffler out there for our cars, I seriously doubt it.
Thread Starter
Joined: Nov 2001
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From: Lubbock, Texas
Re: some good cutout information John - thanks for the info. I'll have to try it sometime. My O2's were pretty identical from run to run, FWIW. However, I know that they're not 100% accurate. My cutout is located at the back of the exhaust system, right before the pipe curves around to enter the muffler.
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Re: some good cutout information I've got a 3" catback with a Dynomax 17227 muffler (similar flow rates to the stock dual/dual).
On back-to-back runs, opening the cutout gained .6mph and a slight ET improvement. Since then, I have averaged about .7mph better, and maybe .03-.04 better. Previous best before the cutout was a 13.33@105.5. Best after was 13.29@106.28. I've run as fast as 106.67mph. Definitely helps (stock motor with a few bolt ons).
Dope
On back-to-back runs, opening the cutout gained .6mph and a slight ET improvement. Since then, I have averaged about .7mph better, and maybe .03-.04 better. Previous best before the cutout was a 13.33@105.5. Best after was 13.29@106.28. I've run as fast as 106.67mph. Definitely helps (stock motor with a few bolt ons).
Dope
TECH Junkie
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From: Chi-Town
Re: some good cutout information nittos, skinnies, cutout open= high 11s every pass
nittos, regular tires in front, gf, tools, and extra tires in car, cutout closed= 12.4. <img src="gr_stretch.gif" border="0">
thats all i have to compare.
nittos, regular tires in front, gf, tools, and extra tires in car, cutout closed= 12.4. <img src="gr_stretch.gif" border="0">
thats all i have to compare.
Thread Starter
Joined: Nov 2001
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From: Lubbock, Texas
Re: some good cutout information It's definitely different for every car. Just look at the mixed results we have posted. Keep in mind that I'm only making my claims on the SLP dual/dual vs. a cutout on a stock-internal LS1. It's a given that you'll see a gain with all of the bolt-ons and a cutout with the stock catback, and the same goes for any internal work.
I'll have dyno #'s and more track times sometime in January to show what's working best for my setup.
I'll have dyno #'s and more track times sometime in January to show what's working best for my setup.
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