How much are my small headers killing my performance
#2148281
09/05/16 09:16 PM
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Plymouth340
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I have a 900 horsepower W7 small block with 1 7/8 headers on it. I put more gear in the rear end. (4.88 to 5.38) and more converter doesn't seem to make much difference on the performance. I'm thinking the headers are holding this thing back big time..runs 9.20s in 3000 da air @ 2800 lbs ???????????
Last edited by Plymouth340; 09/05/16 09:16 PM.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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09/05/16 09:26 PM
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hustlin hoosier
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We have tried about everything possible with headers and never found over a few hundredths going from what we thought was a great set of headers to what we thought was the worst set of headers. I hope you have better luck chasing et with we exhaust than we did.
Last edited by hustlin hoosier; 09/05/16 09:26 PM.
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Re: How much are my small headers killing my performance
[Re: camastomcat]
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that's just it. I think they are considering the step headers that were on it when the previous owner was running it.. Converter is 7000 stall and motor makes peak hp at 9000
Last edited by Plymouth340; 09/05/16 10:23 PM.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2148764
09/06/16 01:27 PM
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polyspheric
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Tried shortening the collector?
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2148813
09/06/16 02:32 PM
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fast68plymouth
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It's "900hp", what headers were on it when it made 900hp?
2800 lbs, 148mph shows 700hp on the moroso chart. Figuring 10% loss for air quality, parasitic losses, etc, you're still off over 100hp. I don't know if the headers would be worth that kind of power.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2148916
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At seasons end...... Might be worth a trip to the dyno and see just how much difference in power there is between the headers......before going through the effort of fitting them to the car.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: camastomcat]
#2149020
09/06/16 06:44 PM
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fast68plymouth
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Isn't Dwayne Porter a small block guy? Mmmmmmmm, not particularly. Never even laid my eyes on a W7 head in person.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2149023
09/06/16 06:48 PM
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I need to talk to someone about it that knows more than me that's why I'm asking. Unless someone has tested a motor combo that's very close to yours with both sizes of headers you're talking about, and they're willing to share that info, you might have to test if for yourself to find out exactly what the answer is....... On your motor. 100+ hp seems like a stretch for a header swap to me....... But that's what the dyno is for. To provide answers to those questions.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2149027
09/06/16 06:58 PM
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If max hp is at 9000rpm why are you shifting at 8700?
I don't know a thing about W7 engines but 900hp sounds a little optomistic.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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09/06/16 11:55 PM
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My guess is the super stock guy probably wasn't using those headers unless they made more power than anything else he has tried. I would try and make them work and report back.
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Re: How much are my small headers killing my performance
[Re: B3422W5]
#2149287
09/07/16 12:05 AM
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My guess is the super stock guy probably wasn't using those headers unless they made more power than anything else he has tried. I would try and make them work and report back. I think that's going to be the plan for now
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2149301
09/07/16 12:32 AM
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Several years back Brian( IMM engines) who posts on here ran two different sets of headers on I believe a stroker W2 motor. Headmans and TTI headers as memory serves me. There was a 30 or 40 horse difference between them
Last edited by B3422W5; 09/07/16 12:33 AM.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight 418 BPE factory replacement headed stroker, 565 lift solid cam Best so far, 10.40 @127 1/4 1.41 best 60 foot 6.60 at 103.90 1/8
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Re: How much are my small headers killing my performance
[Re: B3422W5]
#2149315
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Several years back Brian( IMM engines) who posts on here ran two different sets of headers on I believe a stroker W2 motor. Headmans and TTI headers as memory serves me. There was a 30 or 40 horse difference between them I wonder if there was a difference in diameter or length or what?
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Re: How much are my small headers killing my performance
[Re: B3422W5]
#2149317
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From everything I've read and heard about this engine combo I would lean towards the converter not being the right stall. That seems to be the biggest issues
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2149585
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fast68plymouth
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To be running w7 heads in a super stock car, it would have to be one of the modified classes. The whole car was likely set up around that engine package, and I'm sure part of what the op is seeing is that a class car is often a better, more sophisticated overall "package" than a typical bracket car.
Take a stock eliminator motor out of a good running stocker package and stick it in a similar bracket car and I doubt the ET's would even be close.
Another question I would have is, how close to 900hp was the performance of the car the motor came out of? Did the ET/mph/weight show it to be 900hp?
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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09/08/16 09:36 AM
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Another thought; an SS racer will kill for .02 ET. If he was running the headers that came were in the car he raced, They are probably as good as it gets, but might not show a lot of improvement. The best answer is try it and see. Be ready to tune for them, and find out EXACTLY what stall you have. I was fooled for years because I went by a tach. I am no small block guy, but hear they are sensitive to converters.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: How much are my small headers killing my performance
[Re: gregsdart]
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Another thought; an SS racer will kill for .02 ET. If he was running the headers that came were in the car he raced, They are probably as good as it gets, but might not show a lot of improvement. The best answer is try it and see. Be ready to tune for them, and find out EXACTLY what stall you have. I was fooled for years because I went by a tach. I am no small block guy, but hear they are sensitive to converters. Yes one thing at a time I will put these headers on and see what happens. I had my converter stall raised from 6500 to 7000 that was all they could get out of my 8 inch converter. 60 footed a couple hundreds better but the ET remain the same
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Re: How much are my small headers killing my performance
[Re: fast68plymouth]
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To be running w7 heads in a super stock car, it would have to be one of the modified classes. The whole car was likely set up around that engine package, and I'm sure part of what the op is seeing is that a class car is often a better, more sophisticated overall "package" than a typical bracket car.
Take a stock eliminator motor out of a good running stocker package and stick it in a similar bracket car and I doubt the ET's would even be close.
Another question I would have is, how close to 900hp was the performance of the car the motor came out of? Did the ET/mph/weight show it to be 900hp? Yes his car was probably a whole lot better than mine being a super stock car. But what I really want to know is are my headers killing my motor a tremendous amount I'm going to find out over the winter
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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What did the car the motor came out of weigh, and what was the speed?
IMO not a converter builder, but it seems to me that in order for an 8" converter to be loosened up enough to stall 7000rpm behind a motor with less than 600ft/lbs, it would lose some effeciency in the process.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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I'll throw this out there, not sure if it means much. Read about a test some engine builder did on a small block Chevy, on the dyno, with the results of dinging headers, if it lost power. They went so far as to almost flatten them completely and saw no power loss, maybe 4 or 5 hp tops, they where dumbfounded? You might see a change in a poorly designed set over a top of the line set, but not the gains you're looking for, IMO
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Re: How much are my small headers killing my performance
[Re: cudaman1969]
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I'll throw this out there, not sure if it means much. Read about a test some engine builder did on a small block Chevy, on the dyno, with the results of dinging headers, if it lost power. They went so far as to almost flatten them completely and saw no power loss, maybe 4 or 5 hp tops, they where dumbfounded? You might see a change in a poorly designed set over a top of the line set, but not the gains you're looking for, IMO That could be true. But what was the horsepower level of that motor? I would think this 900 horsepower motor turning 8,700 rpm it would make a bit of difference.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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I'll throw this out there, not sure if it means much. Read about a test some engine builder did on a small block Chevy, on the dyno, with the results of dinging headers, if it lost power. They went so far as to almost flatten them completely and saw no power loss, maybe 4 or 5 hp tops, they where dumbfounded? You might see a change in a poorly designed set over a top of the line set, but not the gains you're looking for, IMO That could be true. But what was the horsepower level of that motor? I would think this 900 horsepower motor turning 8,700 rpm it would make a bit of difference. I would be skeptical of it being 900 hp unless I was there when they dynoed it. Did he say what mph the other car was going? The header banging was a u-tube video. I dought they could fake it.
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Re: How much are my small headers killing my performance
[Re: cudaman1969]
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I'll throw this out there, not sure if it means much. Read about a test some engine builder did on a small block Chevy, on the dyno, with the results of dinging headers, if it lost power. They went so far as to almost flatten them completely and saw no power loss, maybe 4 or 5 hp tops, they where dumbfounded? You might see a change in a poorly designed set over a top of the line set, but not the gains you're looking for, IMO That could be true. But what was the horsepower level of that motor? I would think this 900 horsepower motor turning 8,700 rpm it would make a bit of difference. I would be skeptical of it being 900 hp unless I was there when they dynoed it. Did he say what mph the other car was going? The header banging was a u-tube video. I dought they could fake it. 153 mph @ 3280lbs this motor is legit it has the best of everything on it
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Re: How much are my small headers killing my performance
[Re: slantzilla]
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Are you runing the same converter, trans gearing, and rear gear he did? no,no,no all I'm wondering is if these 1 7/8 headers I'm using are killing my performance and if it would be worth the work to make the larger step headers work !!!
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2150868
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It would, at least be worth the effort to try them. That much power, with the rpm needed, might be cause for concern with a 1 7/8" tube. The longer the tube, the more the restriction. Works just like resistance in wiring. Smaller tubes, in general, give more torque. Bigger tubes are for mid to high rpm use. You have to watch your fuel curve through mid range with big tubes.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2150966
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153 mph @ 3280lbs this motor is legit it has the best of everything on it The moroso chart shows that to be pretty much right on 900hp.
68 Satellite, 383 with stock 906’s, 3550lbs, 11.18@123 Dealer for Comp Cams/Indy Heads
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Re: How much are my small headers killing my performance
[Re: sgcuda]
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It would, at least be worth the effort to try them. That much power, with the rpm needed, might be cause for concern with a 1 7/8" tube. The longer the tube, the more the restriction. Works just like resistance in wiring. Smaller tubes, in general, give more torque. Bigger tubes are for mid to high rpm use. You have to watch your fuel curve through mid range with big tubes. Yes I think it will be worth the effort. I've never built headers before but to make these fit shouldn't be that bad I have a tube chassis car there's lots of room. And my time is free
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Re: How much are my small headers killing my performance
[Re: fast68plymouth]
#2151086
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153 mph @ 3280lbs this motor is legit it has the best of everything on it The moroso chart shows that to be pretty much right on 900hp. Yes the power is there. Just seems like something's holding this motor back. I've tried a lot of things and nothing really seems to make much difference so this is my next step
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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It will be interesting to see if your headers are killing 150 horse.
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Re: How much are my small headers killing my performance
[Re: Alchemi]
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All that header beat up test did was prove that the wrong headers were on the motor to start with.... You need to watch the follow up video. TL/DR answer, no they were the best size.
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Re: How much are my small headers killing my performance
[Re: fast68plymouth]
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At seasons end...... Might be worth a trip to the dyno and see just how much difference in power there is between the headers......before going through the effort of fitting them to the car. x2 Not only would you find out what the other headers are worth, it could provide more data to help with converter setup.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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I did a header test on my 470 engine between 2" dyno headers and 1 3/4 stepped to 1 7/8 dyno headers. At 6800 rpm the 2" headers were 10 ft-lbs better.
Last edited by AndyF; 09/11/16 03:05 PM.
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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Damn, I'm not so upset with having 1.75 TTI's on my 420 G3 anymore.
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Re: How much are my small headers killing my performance
[Re: pittsburghracer]
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From everything I've read and heard about this engine combo I would lean towards the converter not being the right stall. That seems to be the biggest issues Well I finally put in a 7 inch converter and it picked up all most 2 tenths..9.07 @ 149 in 4000 da air..that was the ticket and I haven't tried leaving at higher rpm yet or a little more jet
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Re: How much are my small headers killing my performance
[Re: justinp61]
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Your not gonna see a 100hp difference from the set you have on the car to the ones that were on it.. I was running a W-9 with step headers (1 7/8-2-2 1/8.. if your conv stalls at 7000 it is real close I stalled at 5600 and it was a bit low.. I shifted at 8200 rpm.. it didnt make any more power when shifted at higher rpms.. I went up to 9400 and dint do a damn thing
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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From everything I've read and heard about this engine combo I would lean towards the converter not being the right stall. That seems to be the biggest issues Well I finally put in a 7 inch converter and it picked up all most 2 tenths..9.07 @ 149 in 4000 da air..that was the ticket and I haven't tried leaving at higher rpm yet or a little more jet What carb(s) are you running............
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
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Las Vegas
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FWIW the smallblock in the heads up car made over 1000 with a set of 1 7/8" 20 long primary headers on the dyno. Headers on the car are 1 7/8 to 2 to 2 /18". Car ran 8.0's last year at 2800.
"I am not ashamed to confess I am ignorant of what I do not know."
"It's never wrong to do the right thing"
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2543019
08/29/18 01:59 PM
08/29/18 01:59 PM
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Joined: Feb 2005
Posts: 20,161 PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,161
PA.
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From everything I've read and heard about this engine combo I would lean towards the converter not being the right stall. That seems to be the biggest issues Well I finally put in a 7 inch converter and it picked up all most 2 tenths..9.07 @ 149 in 4000 da air..that was the ticket and I haven't tried leaving at higher rpm yet or a little more jet Very nice!!!!!!!
1970 Duster Edelbrock headed 408 5.984@112.52 422 Indy headed small block 5.982@112.56 mph 9.42@138.27
Livin and lovin life one day at a time
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Re: How much are my small headers killing my performance
[Re: Al_Alguire]
#2543060
08/29/18 03:03 PM
08/29/18 03:03 PM
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Joined: Feb 2006
Posts: 501 CEDAR RAPIDS
Plymouth340
OP
mopar
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OP
mopar
Joined: Feb 2006
Posts: 501
CEDAR RAPIDS
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FWIW the smallblock in the heads up car made over 1000 with a set of 1 7/8" 20 long primary headers on the dyno. Headers on the car are 1 7/8 to 2 to 2 /18". Car ran 8.0's last year at 2800. had some headers built...1 7/8-2 1/8-2 1/4..didnt see much performance diff..converter made all the diff
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Re: How much are my small headers killing my performance
[Re: Thumperdart]
#2543062
08/29/18 03:04 PM
08/29/18 03:04 PM
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Joined: Feb 2006
Posts: 501 CEDAR RAPIDS
Plymouth340
OP
mopar
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OP
mopar
Joined: Feb 2006
Posts: 501
CEDAR RAPIDS
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From everything I've read and heard about this engine combo I would lean towards the converter not being the right stall. That seems to be the biggest issues Well I finally put in a 7 inch converter and it picked up all most 2 tenths..9.07 @ 149 in 4000 da air..that was the ticket and I haven't tried leaving at higher rpm yet or a little more jet What carb(s) are you running............ one 1200 cfm
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Re: How much are my small headers killing my performance
[Re: Plymouth340]
#2543394
08/30/18 12:27 PM
08/30/18 12:27 PM
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Joined: Jan 2003
Posts: 9,986 Frostbitefalls MN (Rocky&Bullw...
gregsdart
master
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master
Joined: Jan 2003
Posts: 9,986
Frostbitefalls MN (Rocky&Bullw...
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I agree on the horsepower being in the 700 range with current setup,given a decent chassis. First off, you say peak power is 9,000 and you shift at 8700? Peak torque is 7200 and stall is 7,000? My deal makes peak power at 6900, and shift at 7450 and 2/3 at 7300, stall is 6200, but peak torque is 5,000! I dynoed the motor and it said 847 hp, car weighs 3065, i use 2078 Goodyear slicks that weigh 41 lbs each, and the car went 8.900 at 2100 da. The point of all this info is if ypur tq and hp peaks are what you say, the stall and shift points may be a big part of the problem. Too low. Its dyno time! Get the real dope on the motor and go from there.
Last edited by gregsdart; 08/30/18 12:32 PM.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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