dyno day for the demon

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My current cam is int. .557/exh.551 running duration int 274/exh 299 112 lobe centers. Ran 12.40's with stock eddy heads. Car weighs 3645 calculator puts it at 410 hp at the wheel with stock exhaust manifolds. Your headers are worth a conservative 30 hp
 
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rumblefish360 said:
@northeastmopar

Being down 3 (?) quarts of trans fluid is super significant! Build thread link?

@justinp61

The 434 is with what crank and block?
360 x 4.***
Build threads & Dyno sheets to the engines above by chance?
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The 434 is 4.125" stroke and 4 .09" bore, R1 block. No build thread but do have dyno sheets at home. No build thread or dyno sheet for the 408.
 
furrystump said:
Carb might be on the small side, on my 408 I have run a BG 825 mighty demon which tend to flow bigger than other carbs of same cfm and am currently running 800 cfm eddy thunder. Not that you need it for you intended purpose, but it could be what is hurting you number.
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OK folks. Back to a different dyno shop today. They brought in a mechanic who likes to work on cars with carbs. First thing he noticed when he pulled a baseline run was the car was running too lean. This time the tranny is full. He then proceeded to check the timing. He pulled the number one plug and used the insert tool to bring the number one up on tdc and then checked my balancer to see if the balancer which had the timing marks scored into it from the factory. They were right on. He thought they may have been off because he checked the engine with a timing light and the previous dyno person had my total timing set at 50 degrees? So he reset the timing and did another pull and the torque went way up from 353 to 519. Then he opened both of the holley 750 carb metering blocks and up the front jetting from 70 to 72 and the rear from 80 to 82. Last pull was 353 HP and 523 torque. He also told me that his dyno is a Mustang Dynamometer and he said the readings are generally on the low side if you ask around. I am generally much happier than the first attempt to get this car dialed in. I told him I asked Mike from MRL to build me a nice street stroker and he told me that is exactly what I have. Idles real nice. Runs real smooth, and goes like hell in that 3-4K RPM range. Now I have to build a custom shroud to keep it from running warm on 90 degree days. He also told me if I wanted to up the HP that I should lose the Performer RPM manifold and install a single plane job? But I am really happy with this build as a nice cruiser.
 
northeastmopar said:
Pulled at 350 horsepower and 360 ftlbs of torque at about 5500 RPM. I am told the engine HP should be about 20% higher or somewhere in the 425HP range. I thought it would be a little more, but I am thrilled the way she rolls along. Plenty of power and a nice ride with great idle for a driveable street car. Engine is a 340 stroked to 416.
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Check all the way to the bottom. I went to another dyno shop today. much better results....
 
Each dyno has it's own corrections and therefore variables in output. I've heard some crazy numbers from Mustang dynos before, but the inertia dynos can spit oput the same stuff. It sounds like #2 found an issue with timing and then adusted the carb for it - so great! But the fact that torque changed by 31% but HP was flat tells me the calibration factors might have been a little off. HP is calculated off torque so one would expect if one got that much better the other would show more. Yet it didn't. Again - problems were uncovered and addressed so the tool did it's job. Now get it to NE Dragway!! lol
 
furrystump said:
My current cam is int. .557/exh.551 running duration int 274/exh 299 112 lobe centers. Ran 12.40's with stock eddy heads. Car weighs 3645 calculator puts it at 410 hp at the wheel with stock exhaust manifolds. Your headers are worth a conservative 30 hp
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Just wondering about your numbers here.....410hp rwhp w/stock manifolds? = approx 471fwhp@ only 15% loss, 471fwhp@3645lbs = 11.5's@116 with a car that hooks.......My old '71 340 Cuda 3550lbs w/me ran 12.4's all day @108 = 364fwhp.

Perhaps you made a typo and should've put 11.40's ?
 
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15% would be conservative for a 727-equipped car. It's more like 18% depending on the dyno/operator.
 
moper said:
HP is calculated off torque so one would expect if one got that much better the other would show more.
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Good point moper. The easy math shows 519 torque to be 375 horses... at 3800 rpm! Up that to 4000 which would be reasonable as torque peak and you are at 395hp... something doesn't add up here. Or is't a very "peaky" engine.
 
Weigh the car, take it to the track, post the MPH it runs in the 1/4, THAT will get closer to a true number than anything else...
 
replicaracer43 said:
Weigh the car, take it to the track, post the MPH it runs in the 1/4, THAT will get closer to a true number than anything else...
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Yup. I guess that's my next step. I am assuming that my torque went way up because of 2 factors. First was my total timing was set at 50 degrees which was way off. Second was that I made an aweful mistake of not filling the tranny and was down about 4 quarts of fluid. Lucky I did not damage anything. So that lack of tranny fluid I think is the main cause of the dyno bump in torque. As far as making horsepower is concerned. I chose a cam that was very steetable. I installed a Lunati 60404 duration 234 242 and lift 513 533. I also chose a performer rpm intake. I understand a single plane intake would also boost the HP way up. But I wanted to build a cruiser with a good amount of midrange HP and I think that is what I got??
 
I think you have what you wanted. The issue is the tools you're trying to use to tell you how good you did really can't do that. That's why I and others say weigh it and run it down the track. Even if the ET sucks because of wheelspin or whatever, the mph will give you a much more solid indication of how much power it's making. You can't really doubt data derived from basic variables rather than correction factors.
 
Hot Metal said:
Just wondering about your numbers here.....410hp rwhp w/stock manifolds? = approx 471fwhp@ only 15% loss, 471fwhp@3645lbs = 11.5's@116 with a car that hooks.......My old '71 340 Cuda 3550lbs w/me ran 12.4's all day @108 = 364fwhp.

Perhaps you made a typo and should've put 11.40's ?
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I run a f70-14 redline bias ply tire, 6" wide. 60's about 1.75.
 
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