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#41
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If we are going to throw out HP numbers how about MPH and weight to go with them. That kind of helps even out if a stingy or a happy dyno. and numbers can be changed by a different correction factor easily also.
My IA runs closer to the uncorrected numbers(132.5mph 3595 lbs) which is less than the 695 corrected. probably because most track days are warm and humid like the dyno day was! The 455 in my TA at 3750 ran 124 mph and only dynoed 525 corrected! Wallace calculator and Moroso slide 550 hp.Different dynos.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
The Following User Says Thank You to Skip Fix For This Useful Post: | ||
#42
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#43
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https://youtu.be/iry0QhiuulM
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#44
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I understand what you are saying and why maybe the IA is less based on mph running an exhaust. But dynos like flow benches can be all over the place on the same engine, especially when you start using correction factors. I still think knowing taking some off for accessories and some for a full exhaust would get us closer to comparing using mph. ET yes more traction/60ft bottom end issues(chasing that on the IA Camaro).
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#45
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Body style and wind conditions will play large factors as well….a low slung car with low frontal area and a tail wind will obviously mph higher … Not an exact science by any stretch!
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71 GTO, 463, KRE 295 cfm heads ported by SD Performance, RPM intake, Qjet, Dougs Headers, Comp cams HR 246/252 ...11 to 1 , 3.55 cogs, 3985lbs.....day three- 11.04 at 120mph ....1.53 60', 6.98 1/8 mile |
#46
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That video is great! I’m hoping for some results like that with my efi….especially with the carb that was used being so small |
#47
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I think you will. Being crab was only 750. How much who knows. But hey down road you can always make a cam change, that will definitely get you there.
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#48
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Pontiacs take more carb for a horsepower number than a comparable Chevy does. Its always been that way.
Has something to do with our long strokes for a given cid and crappy heads. Still better than a puke Chevy. |
#49
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If your going to compare track numbers you're in the same boat with dynos. You still need correction factors. Cars out here at elevation and desert heat won't run as quick as someone in Florida or Maine.
In fact all my stuff ran quicker in Ohio than it does here in Arizona. Figure in DA and it starts making sense. |
#50
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Yeah Pontiacs never have been big HP makers anyway when talking about using conventional heads. So they always make great torque curves and that's what carries them down track. BBC has a far superior head much easier to make HP with that doesn't need a monstrous cam to get there, but they don't have the torque curve a Pontiac does.
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#51
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+2
A big block Chevy build can get there with a much smaller cam for sure. Less stroke/piston speed, not nearly the mass of spinning and reciprocating parts, smaller bearing diameter, better bore to stroke ratio, and you can drop a tennis ball thru the intake ports on most of the heads they are using to get the big numbers we see on dyno runs, etc. As far as the 750cfm carb being used here. About 20 years ago I did a carb CFM test back to back on they dyno an repeated the testing at the track. The carbs tested were 750cfm, 825cfm, and 850cfm. On a 500hp engine the 750cfm carb cost 13hp with no other changes. The 827cfm carb and 849cfm carb were near mirror images of each other on the dyno. At the track remarkably the entire spead of ET was less than .05 seconds between all the carbs tested. The 825cfm actually ran the highest MPH for all runs made that day by .30 mph. The quickest ET was using the 850cfm carb. I wasn't really all that surprised because on the dyno ALL the carbs were dead nuts even to 4500rpm's and they shift points were 5500rpms. The engine simply spent very little time in the RPM range where the larger carbs were using more power plus at the 500hp mark the engine didn't act like it needed much more than 800cfm. So there is no doubt you are giving up some power at high RPM with the smaller carburetor but it's not going to be anywhere near 100hp.......IMHO........
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If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
The Following User Says Thank You to Cliff R For This Useful Post: | ||
#52
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Torque curves however are a different story. My 454 only makes 589 where as a similar sized Pontiac will generally make well over 600 and be nice and flat. But that's to be expected when building a 455 Pontiac that has SBC sized intake ports. Last edited by Formulajones; 11-25-2022 at 10:21 AM. |
#53
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My now retired machinist had on old dial dyno, engines "ran the numbers". A shop down the road with a Superflow the same identical combination engine would always be 50HP more. He eventually took over that shop(owner died in a racing crash) and it took him quite a while to calibrate that dyno correctly to read correctly.
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Skip Fix 1978 Trans Am original owner 10.99 @ 124 pump gas 455 E heads, NO Bird ever! 1981 Black SE Trans Am stockish 6X 400ci, turbo 301 on a stand 1965 GTO 4 barrel 3 speed project 2004 GTO Pulse Red stock motor computer tune 13.43@103.4 1964 Impala SS 409/470ci 600 HP stroker project 1979 Camaro IAII Edelbrock head 500" 695 HP 10.33@132 3595lbs |
#54
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That's dam good. I wonder if the Road paver at 246/252 would have you gaining anything.?
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68 Firebird. IA2 block, 505 cu in, E-head, Solid roller 3650 weight. Reid TH400 4:11 gear. 29" slick. Best so far 10.12@133 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
#55
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My engine is capable of more rpm for sure.
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466 Mike Voycey shortblock, 310cfm SD KRE heads, SD "OF 2.0 cam", torker 2 373 gears 3200 Continental Convertor best et 10.679/127.5/1.533 60ft 308 gears best et 10.76/125.64/1.5471 |
#56
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What RPM are you going through the traps at now? I forgot what your rear gearing is and 60 ft times.
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68 Firebird. IA2 block, 505 cu in, E-head, Solid roller 3650 weight. Reid TH400 4:11 gear. 29" slick. Best so far 10.12@133 mph. 1.43 60 ft. 76 Trans am, TKX .81 o/d, 3.73 Moser rearend, 468 with KRE D-ports, Doug headers, 3" Exh. |
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