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open headers vs. full exhaust ? UPDATED new best
#803319
09/16/10 07:55 PM
09/16/10 07:55 PM
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Joined: Oct 2003
Posts: 4,008
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,008
South Park, Pa.
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For the first time in about 15-20 years, I plan on running this Saturday at the PID reunion at Pittsburgh Raceway with no exhaust system, just headers. The only reason that I'm doing this is for my brother. He has always wanted to see me run with open headers and I don't get to see him much. This weekend he is coming in from out of town to watch me race. I'm thinking that the performance won't change much, just the noise level. What do you guys think?
Last edited by 68LAR; 09/21/10 12:37 PM.
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: open headers vs. full exhaust ?
[Re: 68LAR]
#803320
09/16/10 07:58 PM
09/16/10 07:58 PM
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Joined: Feb 2007
Posts: 6,295
U.S.
moparniac
master
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master
Joined: Feb 2007
Posts: 6,295
U.S.
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whats the whole exhaust setup right now...
Mopar Performance
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Re: open headers vs. full exhaust ?
[Re: 68LAR]
#803323
09/16/10 08:36 PM
09/16/10 08:36 PM
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Joined: Jan 2003
Posts: 302
Casa Grande,Arizona
DennisJ
super street
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super street
Joined: Jan 2003
Posts: 302
Casa Grande,Arizona
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If you don't jet your carb a couple of steps richer,you will probably be a couple of 10ths slower.
Dennis Jokela
I started out with nothing,and I still have most of it.
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Re: open headers vs. full exhaust ?
[Re: Mr.Yuck]
#803324
09/16/10 08:37 PM
09/16/10 08:37 PM
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Joined: Jan 2003
Posts: 4,247
Newfoundland
codfish
master
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master
Joined: Jan 2003
Posts: 4,247
Newfoundland
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Quote:
you'll pick up 3-4 tenths
You're kidding right? 
codfish
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Re: open headers vs. full exhaust ?
[Re: codfish]
#803327
09/16/10 10:38 PM
09/16/10 10:38 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:
Quote:
you'll pick up 3-4 tenths
You're kidding right?
codfish
nope. Over a stockish exhaust 3 tenths easy. My old 440 coronet w/ headers and 2.5 exhaust would pick up 3-4 tenths. There's a reason most drag cars don't have exhaust. If you jet it up 2 you can pick up et. You are NOT going to lose any. I've never seen that happen. flow = HP.
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Re: open headers vs. full exhaust ?
[Re: DJVCuda]
#803329
09/16/10 10:57 PM
09/16/10 10:57 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 run 4" exhaust on my car with no tail pipes, it still picks up a tenth and a 1/2 uncorked. i think every car i've ever had picks up atleast a tenth if not more.
68 Dart GTS "HEMI" 10.30 @ 131 pump gas street car 3780#
69 Roadrunner 511 six pack 10.92 drive to track street car
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Re: open headers vs. full exhaust ?
[Re: 68 HEMI GTS]
#803330
09/17/10 01:52 AM
09/17/10 01:52 AM
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Joined: Oct 2003
Posts: 4,008
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,008
South Park, Pa.
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So, jet up primary or secondary or both?????
4 speed street legal. Best time 10.99 @ 124 mph on 93 octane pump gas @ 3926# total weight
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Re: open headers vs. full exhaust ?
[Re: 68LAR]
#803331
09/17/10 02:15 AM
09/17/10 02:15 AM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
So, jet up primary or secondary or both?????
Both, but remember, if you don't run "extentions" you'll more then likely (most definitly) loose 60ft. times, there goes your whole purpose of any gain  , sure un-corked exhaust = HP, but you also need some back-pressure, otherwize you push the torque curve way up & there goes your 60ft., so run at least 18" extentions or install cutouts (dumps as i call them) 
Start off with the jets you have now, make a pass, then jet up 2&2.
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Re: open headers vs. full exhaust ?
[Re: 68LAR]
#803333
09/17/10 03:41 AM
09/17/10 03:41 AM
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Joined: Aug 2003
Posts: 43,127
Bend,OR USA
Cab_Burge
I Win
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I Win
Joined: Aug 2003
Posts: 43,127
Bend,OR USA
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I had one car(1969 Dart 440, 727, 3.91 and slicks) with Hooker 2 inch fenderwell headers to 2.5 turbo muffs and side pipes exiting in front of the rear wheels. It ran 12.23 ET at 109.7 MPH corked up, I remove the muffs and pipes (9 or 12 lbs each side maybe (no other changes) and the car ran 11.39 at 117.8 MPH  My Duster has a full three inch exhaust to the 3 inch x 14 long Magnaflows mounted at the rear bumper, that car pick up .04 ET and .3 MPH in the 1/8 mile by removing the exhaust Those wiegh around 25 lbs per side I think I have never ran the car with the exhaust off at a 1/4 mile track, maybe some day Jet for MPH, run it the way it is on the first run(put in one or two new plugs just before that run) and then look at the new plugs at the end of the run, shut it off at the finish line if you can to get a valid read on them. make a jet change the way you think it needs to go and run it again to see if you went the right way on the jetting  Go the other way if it slows down on the first jet change, I try to use two Holley jet size changes at first and then go to one size per change whenm I think I'm close Good luck,have fun and let us know your results
Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
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Re: open headers vs. full exhaust ?
[Re: Mr.Yuck]
#803334
09/17/10 07:17 AM
09/17/10 07:17 AM
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Joined: Jan 2003
Posts: 4,247
Newfoundland
codfish
master
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master
Joined: Jan 2003
Posts: 4,247
Newfoundland
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Quote:
Quote:
Quote:
you'll pick up 3-4 tenths
You're kidding right?
codfish
nope. Over a stockish exhaust 3 tenths easy. My old 440 coronet w/ headers and 2.5 exhaust would pick up 3-4 tenths. There's a reason most drag cars don't have exhaust. If you jet it up 2 you can pick up et. You are NOT going to lose any. I've never seen that happen. flow = HP.
Maybe I'll see a 10 second pass yet lol.
codfish
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Re: open headers vs. full exhaust ?
[Re: codfish]
#803335
09/17/10 07:37 AM
09/17/10 07:37 AM
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Joined: May 2004
Posts: 853
Brisbane Australia
572B1
super stock
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super stock
Joined: May 2004
Posts: 853
Brisbane Australia
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Quote:
Quote:
Quote:
Quote:
you'll pick up 3-4 tenths
You're kidding right?
codfish
nope. Over a stockish exhaust 3 tenths easy. My old 440 coronet w/ headers and 2.5 exhaust would pick up 3-4 tenths. There's a reason most drag cars don't have exhaust. If you jet it up 2 you can pick up et. You are NOT going to lose any. I've never seen that happen. flow = HP.
Maybe I'll see a 10 second pass yet lol.
codfish
Hey codfish, what type pipes are you using, 4 into 1 or tri-y's.
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Re: open headers vs. full exhaust ?
[Re: codfish]
#803337
09/17/10 09:59 AM
09/17/10 09:59 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:
Quote:
Quote:
Quote:
you'll pick up 3-4 tenths
You're kidding right?
codfish
nope. Over a stockish exhaust 3 tenths easy. My old 440 coronet w/ headers and 2.5 exhaust would pick up 3-4 tenths. There's a reason most drag cars don't have exhaust. If you jet it up 2 you can pick up et. You are NOT going to lose any. I've never seen that happen. flow = HP.
Maybe I'll see a 10 second pass yet lol.
codfish
give a whirl. It only takes a few minutes a side.
as for upping both sides of the carb, I'd think the secondary is the one you want to go up on.
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Re: open headers vs. full exhaust ?
[Re: codfish]
#803339
09/17/10 10:05 AM
09/17/10 10:05 AM
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Joined: May 2004
Posts: 853
Brisbane Australia
572B1
super stock
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super stock
Joined: May 2004
Posts: 853
Brisbane Australia
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Quote:
TTI under chassis 2" headers with 3.5" collectors, 3" X-pipe kit and 3" Ultra Flows.
codfish
My brother has 2'' tri-y's with a 3'' x pipe and 3'' straight through mufflers. He has run 10.7 @ 125.5 on pump fuel with a std stroke 440 @ 3650-3700lbs. His car runs like a pig with the pipes disconected. I also have another friend with a 440 with tri-y's and its the same.
I had a 440 with 4 into 1 pipes and it responded well to open pipes.  Rob.
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Re: open headers vs. full exhaust ?
[Re: codfish]
#803340
09/17/10 10:08 AM
09/17/10 10:08 AM
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Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Quote:
TTI under chassis 2" headers with 3.5" collectors, 3" X-pipe kit and 3" Ultra Flows.
That's what I have on my Challenger, too. I don't see that particular system holding back the car's performance much, if at all.
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Re: open headers vs. full exhaust ?
[Re: joedust451]
#803341
09/17/10 10:44 AM
09/17/10 10:44 AM
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Joined: Feb 2007
Posts: 2,578
sweden
1Fast340
master
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master
Joined: Feb 2007
Posts: 2,578
sweden
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Quote:
Quote:
So, but you also need some back-pressure, otherwize you push the torque curve way up & there goes your 60ft., so run at least 18" extentions or install cutouts (dumps as i call them)
cant this myth about backpreasure being good for a 4stroke engine just die?
you are right about adding lenght to the collectors to make a correct collector length but thats not for backpreasure that is to be able to take advantage of the pulses in the collectors to get all 4 pulses from the same bank tuned and work togheter, thats as good as i can explain it since my english is fairly crappy..
i dont think the threadstarter will gain much from open headers, maybe a tenth or so from the lost weight unless the exhaust has some problems (reduction in diameter in the bends or some other restriction) built into it in the first place
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Re: open headers vs. full exhaust ?
[Re: 1Fast340]
#803342
09/17/10 11:22 AM
09/17/10 11:22 AM
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Joined: Jan 2003
Posts: 3,616
Riverside, Ca
G_bob
master
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master
Joined: Jan 2003
Posts: 3,616
Riverside, Ca
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I have a 3" system with H-pipe and spintech mufflers. I have cutouts in sort of a max wedge style, so the flow when they're capped isn't optimal. Every time I've done back to back tests, I've picked up 2-3 tenths, simply removing the plates. Now, I haven't changed the jetting since the motor was dyno'd, and it was dyno'd at sea level, 70 degrees and open exhaust. Fontana, where I usually run is 1100 ft, and DA is always 2000+, so I'm sure it's running fat anyway. I haven't worried to much about jetting as I'm not legal for 9's and short-shift it to stay in the 10.0's anyway. Best DA I've ever experienced was new year's day this year, 1700 ft. Went 9.92  Your results may vary...  
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Re: open headers vs. full exhaust ?
[Re: codfish]
#803344
09/17/10 01:52 PM
09/17/10 01:52 PM
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Joined: Jan 2003
Posts: 354
Mid-Michigan
GOREO
enthusiast
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enthusiast
Joined: Jan 2003
Posts: 354
Mid-Michigan
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Quote:
TTI under chassis 2" headers with 3.5" collectors, 3" X-pipe kit and 3" Ultra Flows.
codfish
Exact same setup I have also,TTI 2" headers,3" TTI x pipe and Ultra Flo's.will be making a few runs soon with the exhaust off,has run 10.95/121 with the exhaust earlier this month at Milan.
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Re: open headers vs. full exhaust ?
[Re: Mr.Yuck]
#803345
09/17/10 01:52 PM
09/17/10 01:52 PM
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Joined: Jan 2003
Posts: 74,978
U.S.S.A.
JohnRR
I Win
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I Win
Joined: Jan 2003
Posts: 74,978
U.S.S.A.
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Quote:
Quote:
Quote:
you'll pick up 3-4 tenths
You're kidding right?
codfish
nope. Over a stockish exhaust 3 tenths easy. My old 440 coronet w/ headers and 2.5 exhaust would pick up 3-4 tenths. There's a reason most drag cars don't have exhaust. If you jet it up 2 you can pick up et. You are NOT going to lose any. I've never seen that happen. flow = HP.
He didn't say what exhaust he had on it before you made that prediction but a 3" pipes and ultraflo's is not even remotely stockish.
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Re: open headers vs. full exhaust ?
[Re: 68LAR]
#803348
09/17/10 10:48 PM
09/17/10 10:48 PM
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Joined: Aug 2003
Posts: 11,179
Atco NJ
DJVCuda
I Live Here
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I Live Here
Joined: Aug 2003
Posts: 11,179
Atco NJ
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Quote:
My game plan is to make the first time trial with no changes. I will make a change ONLY if my time slows. Seriously, I don't think I will see much of a gain in performance, just noise level. Thanks for all the suggestions, I'll update later as to the results.
pull a plug - it will be leaner then with full exhaust - so i would not be surprised if there was no gain with no jet change.
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Re: open headers vs. full exhaust ?
[Re: 68LAR]
#803353
09/19/10 12:35 AM
09/19/10 12:35 AM
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Joined: Oct 2004
Posts: 5,618
long island NY
Ari440
master
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master
Joined: Oct 2004
Posts: 5,618
long island NY
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my 18 inch collecter extentions used on a 65 454 chevelle where over 2 tenths
11.00 to 10.76
1.39 9.85 - 137 mph
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Re: open headers vs. full exhaust ? UPDATE
[Re: 68LAR]
#803354
09/19/10 02:15 AM
09/19/10 02:15 AM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Quote:
How much gain was that, you changed the old best on your sig. picture and my memory is horrible
Old new best was set at the Mopar Nat's this year. 11.57 @ 118 and change. 3 tenths and 1 1/2 mph improvement. I never would have thought....
Why do you say 1 1/2 mph, 118 too 121 is 3 mph
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Re: open headers vs. full exhaust ?
[Re: 68 HEMI GTS]
#803357
09/19/10 09:59 AM
09/19/10 09:59 AM
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Joined: Jan 2003
Posts: 16,923
NC
440Jim
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,923
NC
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Quote:
i run 4" exhaust on my car with no tail pipes, it still picks up a tenth and a 1/2 uncorked. i think every car i've ever had picks up atleast a tenth if not more.
My car (511 CID) has 4" header collectors. I did testing with open headers, 4" collector extensions, and 4" bullet mufflers. No difference from open headers to extensions with turnouts, and only 0.02 slower with the "mufflers" with turnouts. So it depends on the exhaust system, converter/torque peak, etc. etc.
Congrats to 68LAR on his new best, uncorked!
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Re: open headers vs. full exhaust ? UPDATE
[Re: 68LAR]
#803358
09/19/10 10:34 AM
09/19/10 10:34 AM
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Joined: Feb 2005
Posts: 4,311
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,311
Prospect, PA
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congrats. Did you do back to back runs with and without the exhaust system? FWIW, the weather difference between the Nats and PRP yesterday is worth about 0.20 sec.
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Re: open headers vs. full exhaust ? UPDATE
[Re: 68LAR]
#803359
09/19/10 10:39 AM
09/19/10 10:39 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:
And the winnner is........wait for it.... wait for it..... Mr. Yuck
My car now has a new best in both ET and mph.
How's 11.28 @ 121.23 sound? The way the car ran shocked the heck out of me. I would have never thought it... By the way, I never opened the hood. The only adjustments were to tire pressure and shock settings. 
 told ya so...lol good job. I can't wait to get mine to the track. I'd love to see thse kinds of numbers.
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Re: open headers vs. full exhaust ? UPDATE
[Re: BSB67]
#803363
09/19/10 12:54 PM
09/19/10 12:54 PM
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Joined: Oct 2003
Posts: 4,008
South Park, Pa.
68LAR
OP
master
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OP
master
Joined: Oct 2003
Posts: 4,008
South Park, Pa.
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Quote:
Did you do back to back runs with and without the exhaust system?
FWIW, the weather difference between the Nats and PRP yesterday is worth about 0.20 sec.
No, My previous best was at the Nat's @ the 11.57 on a 95* day.
Quote:
Congrats on the new best Larry! What were the weather conditions like compared to your previous best at the Mopar Nats? I know the weather at the Nats was brutal, so I wouldn't be suprised if your gain was more to due to better weather conditions than the open headers. IMO your exhaust system sounds perfect and really shouldn't hold you back much if any.
Btw, did you do some engine changes since last year?? Seems like you picked up a lot...Or are you just getting better at bangin the gears
Weather conditions were very different. Nat's it was 95* hot and humid as you know. But, as stated, I ran my best with the 11.57 @ 118 almost 119 mph. Saturday at PRP, the weather was comfortable at around 73-75*, seemed like no or little humidity.
Over the past winter I installed 1.6 rockers and an aluminum flywheel. I didn't pick up much using my old "launch and shifting" procedures. It wasn't until the UMTR race the week before the Nat's, that some stick shift racers made some suggestions to me with the launch and shift points. I started using those suggestions at the Nat's and the performance level has jumped. I can't thank all the guys with UMTR enough. Great bunch. As far a getting better at bangin' gears,.... maybe.
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Re: open headers vs. full exhaust ? UPDATE
[Re: 68LAR]
#803364
09/19/10 05:08 PM
09/19/10 05:08 PM
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Joined: Nov 2005
Posts: 690
New Hampshire, USA
oldiron
mopar
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mopar
Joined: Nov 2005
Posts: 690
New Hampshire, USA
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Way to go Larry  Get .15 out of the 60' & 10s street car FWIW - pulled pipes & muffs - no change to 1/4/mph but did have a best ever 60' at PRP (but really wasn't much pipe & muffler) But I like noise - can't really tell if its loud any more though, I wonder why
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: open headers vs. full exhaust ? UPDATED
[Re: fishy340]
#803368
09/20/10 10:13 AM
09/20/10 10:13 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:
with x pipe 3 and 4" exhaust they have today,other then sounding like a top fuel car there is no advantage i believe..plus u have to re jet ur carb for open headers..look @ the turbo and pro charge cars w exhaust..
most of those "exhuast" systems are nothing more than a way for people to say "yeah it has exhaust" They consist of big pipes and mufflers that do anything but muffle the sound and end in dumps in front of the rear wheels. Some of those things are as loud as open exhaust. A 3" complete system, including tail pipes and mufflers (that muffle) will restrict exhaust flow.
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Ron
How much gain was that, you changed the old best on your sig. picture and my memory is horrible 
You are correct going off of my posted mph, but my fastest was a 120 with a 11.60et last year, so I just rounded off the difference between the two. My best ET and MPH aren't on the same pass. Kind of confusing, but that's the story of my life... 
Mine picks up 2-3 tenths with open headers. It likes to run lean though, so we have to fatten it up.
