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How much are my small headers killing my performance #2148281
09/05/16 09:16 PM
09/05/16 09:16 PM
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Plymouth340 Offline OP
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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.
Re: How much are my small headers killing my performance [Re: Plymouth340] #2148297
09/05/16 09:26 PM
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hustlin hoosier Offline
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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.
Re: How much are my small headers killing my performance [Re: hustlin hoosier] #2148305
09/05/16 09:33 PM
09/05/16 09:33 PM
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[quote=hustlin hoosier]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. [/quote
I got some headers with the motor but will take a ton of work to get them to fit..but I may try this winter.. they are step headers..2inch 2 1/8 to 2 1/4....I'm shifting this thing at 8700 rpm and thought at that rpm small header is choking it

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148306
09/05/16 09:35 PM
09/05/16 09:35 PM
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camastomcat Offline
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What's the MPH?

Re: How much are my small headers killing my performance [Re: camastomcat] #2148325
09/05/16 09:56 PM
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Plymouth340 Offline OP
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Originally Posted By camastomcat
What's the MPH?
147-148

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148335
09/05/16 10:08 PM
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camastomcat Offline
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It's making HP then. Gears typically don't make a big difference. You might look at the stall on the trans brake, and decide if it's getting into the torque power band. Case in point, my dragster picked up from 7.80's to 7.50's and .60's because the one I was using stalled below the torque power band. It would make a lot more difference in a 3000 pound car.

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148338
09/05/16 10:11 PM
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camastomcat Offline
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By the way, header size, as already pointed out, won't hold you back much unless they are really wrong for the application. JMO

Re: How much are my small headers killing my performance [Re: camastomcat] #2148346
09/05/16 10:21 PM
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Plymouth340 Offline OP
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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.
Re: How much are my small headers killing my performance [Re: Plymouth340] #2148433
09/06/16 12:21 AM
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camastomcat Offline
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And peak Torque? I'm going to guess it's over 7000? I'm not a small block guy, so I could be wrong.

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148453
09/06/16 12:42 AM
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Plymouth340 Offline OP
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Peak torque 586@7200

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148459
09/06/16 12:46 AM
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camastomcat Offline
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Well, if you have actually checked the stall, and I assume you have, I would look at tune up and such. Again, I'm not a small block guy so someone here might have another idea. My max torque is at 6400. If the stall is under 6000 RPM, I'm 2 tenths slow.

Re: How much are my small headers killing my performance [Re: camastomcat] #2148482
09/06/16 12:56 AM
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7000 stall

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148764
09/06/16 01:27 PM
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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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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.


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Re: How much are my small headers killing my performance [Re: fast68plymouth] #2148841
09/06/16 02:50 PM
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Plymouth340 Offline OP
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Step headers...2inch 2 1/8-2 1/4. I have the other headers just need to do a lot of modifications to make them fit

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148916
09/06/16 04:25 PM
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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.


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Re: How much are my small headers killing my performance [Re: Plymouth340] #2148954
09/06/16 05:21 PM
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Plymouth340 Offline OP
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I need to talk to someone about it that knows more than me that's why I'm asking.

Re: How much are my small headers killing my performance [Re: Plymouth340] #2148987
09/06/16 05:51 PM
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camastomcat Offline
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Isn't Dwayne Porter a small block guy?

Re: How much are my small headers killing my performance [Re: camastomcat] #2149020
09/06/16 06:44 PM
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Originally Posted By camastomcat
Isn't Dwayne Porter a small block guy?



Mmmmmmmm, not particularly.

Never even laid my eyes on a W7 head in person.


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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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Originally Posted By Plymouth340
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.


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