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Gains from un-corked exhaust?
#720226
06/10/10 01:02 AM
06/10/10 01:02 AM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
OP
super gas
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OP
super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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I'm thinking of dropping down my pipes (at the collectors) this Friday at the track, i'll make a baseline run with it 1st. before trying it, is there much to be gained with a mild 360, I got rid of the solid 7 blade fan & installed a clutch style, it already feels better above 2500, so this should give it something, just wondering if dropping down the pipes will help  , the exhaust is 2.1/4" with summit turbos. My last outing the DA was around 2500, it ran an 8.13 on a 1.82, the DA should be around 28-3000 this Friday night, i'm really wanting that 7.99 slip, i know the only real answer is "trying it", but just wanting your opinion 
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Re: Gains from un-corked exhaust?
[Re: joedust451]
#720227
06/10/10 01:59 AM
06/10/10 01:59 AM
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Joined: Aug 2003
Posts: 43,309
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,309
Bend,OR USA
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joe, every combination is different so keep that on mind while reading about one of my old cars that I disconnected the exhaust and the results. The car was a 1969 Dart with a bracket type motor 440 in it, Hooker 2 inch fenderwell headers, 2.5 exhaust pipse to a set of 2.5 corvair style "turbo muffs and then 2.5 inch pipes to the front of the wheel wells like side pipes. I ran the car with closed exhaust, it went 12.23 at 109.5 MPH, I removed the muffs and pipes and the car ran 11:39 at 117.67 MPH  I didn't belive that time slip so I ran it again thirty five minutes later in the other lane and the car ran 11:42 at 117.75 MPH  I hope you get simialr results  My Duster only picks up .04 ET and .22 MPH in the i/8 mile by removing the three inch system from it
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: Gains from un-corked exhaust?
[Re: joedust451]
#720228
06/10/10 07:10 AM
06/10/10 07:10 AM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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One thing most people dont do is re-jet to peak performance also most off the shelf headers come with SHORT collectors so in that condition the exhaust MIGHT help some... but with a race style engine or there abouts I have never made more power with the exhaust on it... but I also build the headers with the correct collector length 
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Re: Gains from un-corked exhaust?
[Re: Cab_Burge]
#720229
06/10/10 10:12 AM
06/10/10 10:12 AM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
OP
super gas
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OP
super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
joe, every combination is different so keep that on mind while reading about one of my old cars that I disconnected the exhaust and the results. The car was a 1969 Dart with a bracket type motor 440 in it, Hooker 2 inch fenderwell headers, 2.5 exhaust pipse to a set of 2.5 corvair style "turbo muffs and then 2.5 inch pipes to the front of the wheel wells like side pipes. I ran the car with closed exhaust, it went 12.23 at 109.5 MPH, I removed the muffs and pipes and the car ran 11:39 at 117.67 MPH I didn't belive that time slip so I ran it again thirty five minutes later in the other lane and the car ran 11:42 at 117.75 MPH I hope you get simialr results My Duster only picks up .04 ET and .22 MPH in the i/8 mile by removing the three inch system from it
Cab, you must have had "corn cobbs" shoved up that exhaust to restrict it that much 
Mr Pbody, i know on another SB car i had, i ended up advancing the timing a good bit, this was at 3700ft. though, & abviously it was running pretty rich, I do have this 650dp jetted 70/76, but its not overwhelming with fumes, i'll un-cork it today & see how it sounds/responds, i still have the total timing at 30*, i'm told it'll like 34*, but i just don't feel it in the seat when i advanced it .
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Re: Gains from un-corked exhaust?
[Re: tjmarcus1]
#720232
06/10/10 08:59 PM
06/10/10 08:59 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
ok joe, here's my  any engine that doesn't make more power with open headers probably isn't tuned right.
Exactly..... 
I had a bone stock, cheap rebuild 440 Six Pack in a '69 Superbee.........Had repro cam.....exhaust manifolds......stock converter......factory replacement exhaust from Year One with Hemi mufflers........Car ran 14.20's @ 95 and 13.20's @ 105 after I cut the exhaust pipe right by the bellhousing..... I put 2 1/2" Flowmasters on it and it run 13.40's @ 103..........
Every car I've ever had that's run 10.50 or slower has picked up at least 2 tenths and 2 MPH by opening the exhaust..... 
Wayne
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383man
[Re: tjmarcus1]
#720235
06/10/10 09:13 PM
06/10/10 09:13 PM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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Quote:
ok joe, here's my any engine that doesn't make more power with open headers probably isn't tuned right.
It could also tell you how restrictive your exh system is. Ron
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Re: 383man
[Re: 383man]
#720236
06/10/10 09:37 PM
06/10/10 09:37 PM
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Joined: May 2009
Posts: 511
Temperance, MI
68 HEMI GTS
mopar
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mopar
Joined: May 2009
Posts: 511
Temperance, MI
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i have 4" exhaust on my Dart with 2 chamber flows and no tail pipes. car usually picks up a tenth and a half uncorked with just collector extensions.
every other car i've ever had usually picks up at least a few tenths uncorked.
Last edited by 68 HEMI GTS; 06/10/10 09:39 PM.
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Re: 383man
[Re: 383man]
#720238
06/10/10 11:04 PM
06/10/10 11:04 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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Quote:
I have never uncapped mine but I have 3" pipes with the Dyno-Max Ultra-Flow mufflers that are straight thru so I really dont think uncapping my 63 would help much at all. Ron
I guess it's the thought that counts??? 
Wayne
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Re: 383man
[Re: Ari440]
#720241
06/10/10 11:49 PM
06/10/10 11:49 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
OP
super gas
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OP
super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
0pen pipes collecter extentions 18 inch long and jet up 4 jet sizes up
I won't have extentions, i drive it to the track, I'm going to try & tighten the pipes so there about 20% or so restricting the collectors, now do i jet up 4 F&R, so 74/80??
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Re: 383man
[Re: Cab_Burge]
#720243
06/11/10 07:31 AM
06/11/10 07:31 AM
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Joined: Mar 2008
Posts: 5,746
Ontario, Canada
Dodgem
master
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master
Joined: Mar 2008
Posts: 5,746
Ontario, Canada
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Quote:
Run it the way it is first, rejet it richer and leaner, if needed at the track
Yea don't go all crazy on jets you are already up from stock rich will slow it down. Next move might be something in the 850 CFM area. with that small exhaust I would look at 4 to 5 tenths in the 1/8
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Re: 383man
[Re: 383man]
#720245
06/11/10 08:27 AM
06/11/10 08:27 AM
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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:
I have never uncapped mine but I have 3" pipes with the Dyno-Max Ultra-Flow mufflers that are straight thru so I really dont think uncapping my 63 would help much at all. Ron
try it Ron... you'll love the sound.
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I don't own anything that's fast enough to justify being that loud, too.
