Will Cut Outs Improve my E.T?
#994805
05/18/11 09:56 AM
05/18/11 09:56 AM
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Joined: May 2005
Posts: 128 usa
mrmopardan
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OP
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I make a occasional 1/4 Mi. pass down the track. I race with full 3 " TTI exhaust with their Dynomax mufflers. This exhaust seems to flow well but I'm wondering if there is even more performance to be had through exhaust modifications. would there be an improvement by adding "cut outs"? Anyone tried this and if so where is the ideal location to install and which brand. Thanks, Danny
68 GTX Full street trim, solid lifter cammed. Best 11.34 @ 121 mph. 1.72 60 ft. (yeah I know.. my 60 ft. sucks)
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Re: Will Cut Outs Improve my E.T?
[Re: mrmopardan]
#994808
05/18/11 10:34 AM
05/18/11 10:34 AM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
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Master
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Romeo MI
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I am planning a cut out system for my Rampage BUT I will have a header with about 16" long collector and I will come off the side of the collector to run to my exhaust, where most guys run straight off the back of the collector... you would need to jet differently without the exhaust... this is where guys dont see any change due to not jetting for the change... I plan on a split on the jetting... not perfect for either set up, unless it will see alot more street mileage, then I'll jet for the street and the exhaust
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Re: Will Cut Outs Improve my E.T?
[Re: DodgeCharger]
#994809
05/18/11 10:38 AM
05/18/11 10:38 AM
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Joined: Jan 2003
Posts: 1,142 Central New York
slippery440
Crybaby440
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Crybaby440
Joined: Jan 2003
Posts: 1,142
Central New York
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Same question almost a few days ago. Same answer. We found that if you drop the whole exhaust system off the car you will gain .1 to 1.5 in the 1/4. We guess some or most of that gain was for the lost of weight. You are just adding cut outs. Probly all your going to gain is to the noise pollution. Is it worth the hassel? If you have a totally junk exhaust yes if not no.
If the MODS did their job I would not be hitting the notify MOD button. LOL
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Re: Will Cut Outs Improve my E.T?
[Re: mrmopardan]
#994810
05/18/11 11:21 AM
05/18/11 11:21 AM
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Joined: Nov 2005
Posts: 690 New Hampshire, USA
oldiron
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mopar
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Posts: 690
New Hampshire, USA
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66 belvedere, 431/tti 1 7/8, 3 in (with tailpipes), dynomax, 4sp, cutouts saw no consistent measureable difference (best 11.07, consistent 11 2s to 3s. Would often run street stick class (closed) and quick stick (open) one after another. Liked the pipes open so I could hear engine revs on shifts (know if clutch slipped), plus I basically like the noise. If anything, slowed down slightly w/cutouts open, ran lean. If carb was jetted properly for open pipes probly would have picked up, but never tried cause I'm basically lazy.
66 Belvedere Vert, 4 Speed/Jerico, slowly, very slowly, getting faster - NA LD Wedge New New Best: 10.56 @129 68 B'cuda 4 gear Jerico - Another New Best of 9.86 & Trying to slow up https://www.youtube.com/watch?v=T4jDLKwd9Gs
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Re: Will Cut Outs Improve my E.T?
[Re: oldiron]
#994811
05/18/11 03:01 PM
05/18/11 03:01 PM
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Joined: May 2005
Posts: 128 usa
mrmopardan
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As I continue to research this subject.. I also have the oval GTX exhaust tips too. Are they restrictive??
68 GTX Full street trim, solid lifter cammed. Best 11.34 @ 121 mph. 1.72 60 ft. (yeah I know.. my 60 ft. sucks)
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Re: Will Cut Outs Improve my E.T?
[Re: MR_P_BODY]
#994812
05/18/11 03:23 PM
05/18/11 03:23 PM
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Joined: Sep 2004
Posts: 22,873 Chicken coop
dustergirl340
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Chicken Little
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Chicken coop
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Quote:
this is where guys dont see any change due to not jetting for the change...
amen to that! I've picked up 3-4 tenths with open exhaust AND jetting. I once forgot to re-jet when I uncapped and saw no gain, and ran very lean to boot.
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Re: Will Cut Outs Improve my E.T?
[Re: Jeff_383]
#994816
05/18/11 05:24 PM
05/18/11 05:24 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
68LAR went from a 11.60 to a 11.28 just with opening the exahust. No jetting change. He has a full 3" sysytem with dynomax ultraflows.
I think I was the winner of the "how much faster" contest on that one.
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Re: Will Cut Outs Improve my E.T?
[Re: mrmopardan]
#994818
05/18/11 08:18 PM
05/18/11 08:18 PM
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Joined: Jan 2003
Posts: 5,894 Florida
Locomotion
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Florida
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A lot depends on how the carb is jetted. Typically, ideal jetting for a closed exhaust will be lean for an open exhaust. Of course, the more cubes and rpm's you have, will also be a factor, so the results depend on how efficient the exhaust is compared to the amounbt of air/fuel you're putting through it.
I've been running TTI step headers on my 360 for years and had the carb tuned for it as best as I could. A few years ago I installed a 3" x-pipe and Dynomax Ultra Flo mufflers (oval) ending at the rear end housing. After some carb tuning which I believe included dropping the jet sizes 1-2 numbers and getting the weight back to what it was (system was +60 lbs), the car was about .5-.10 faster than open headers! I can only assume that the x-pipe affected the jetting, overall helped my particular combination and that the mufflers were not a restriction.
Last edited by Locomotion; 05/18/11 08:27 PM.
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Re: Will Cut Outs Improve my E.T?
[Re: DaveRS23]
#994822
05/19/11 02:04 AM
05/19/11 02:04 AM
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Joined: Jul 2006
Posts: 4,319 Puyallup, WA
StealthWedge67
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Puyallup, WA
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When I bought my car it had a fairly new exhaust sytem with Flowmasters on it, but it was 2-1/4" pipe. So I added about 18" of 3" pipe off the headers (to get past the subframe) leading to a set of 3" cutouts, then it steps down to 18" of 2-1/2, and then down to the existing 2-1/4" setup. I see a solid .25 when open, but my system is relatively restrictive compared to a full 3" system. To make it pay, you really need to rejet
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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