Dyno's..... A tuning tool or a misleading print out???

Couldn't help but notice how many times hp numbers have come up in this drag racing forum...Some of us find a dyno as nothing more than a tuning tool used to find the perfect A/F ratio...I myself found the dyno alittle humbling this past weekend if I was to strictly look at the peak rwhp and torque ....But it showed a very clean, smooth power curve...So having said that,there are many variables that will deem rwhp a fraction of what makes up a successful engine/bike package....LOL...even if mine put out 240 plus....I'm not experienced enough to utilize it anyways...:(

So what numbers did you put down?

Would that be CORRECTED your looking for or UNCORRECTED????? Another area involving hp #'s a HUGE majority of readers don't fully understand!

I don't think most people look at HP numbers as some kind of absolute thing. At least any knowledgeable person. Unless you're bench-racing..

I didn't even know dynos measured hp. Thought they just measured torque and the hp was calculated.

great tool to tune for gas mileage

great tool to use for BEFORE AND AFTER mods

great tool to troubleshoot problems

now,when comparing modded engines etc,to toher dynos,not so great in my mind

what scale being used? STD? SAE? corrected? uncorrected?

so many variables using different dynos.. even the make,superflow,vs dynojet etc will read different..

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Originally Posted by casacrow

I didn't even know dynos measured hp. Thought they just measured torque and the hp was calculated.

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Don't think anyone claimed they measured HP..although it's obviously just semantics..

Every dyno gives out different numbers and those numbers change on given days, even after correction. An example: my car put out 502whp at 3650lbs with me in it and ran a 129mph trap speed in the 1320... beating a "650hp" big single turbo Eagle Talon by a car length... does not compute. I think more than anything they're an excellent tuning tool that can help you find modifications that actually work.

I'm with Mike on this. Dyno charts are best used to get a baseline so you can track your changes. It is fun to compare numbers though. In the end there are too many other variables. The skill and setup mean alot more than raw torque.

Bingo!!"!""""""

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Originally Posted by casacrow

i didn't even know dynos measured hp. Thought they just measured torque and the hp was calculated.

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Originally Posted by Shaman

An example: my car put out 502whp at 3650lbs with me in it and ran a 129mph trap speed in the 1320... beating a "650hp" big single turbo Eagle Talon by a car length... does not compute.

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Not to derail the thread, but you could have been the better driver that day...

But agreed with the concepts being discussed here - essential tuning tools for those of us throwing on engine mods (my 'Stang went to the dyno several times when they were tuning my supercharger to insure everything was okay as they played with the PSI; guys were impressed the first question out of my mouth wasn't along the lines of "OMG OMG OMG IS IT FAST????").

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Originally Posted by Shaman

Every dyno gives out different numbers and those numbers change on given days, even after correction. An example: my car put out 502whp at 3650lbs with me in it and ran a 129mph trap speed in the 1320... beating a "650hp" big single turbo Eagle Talon by a car length... does not compute. I think more than anything they're an excellent tuning tool that can help you find modifications that actually work.

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Let me relay how a low-powered econobox can beat a "650 hp" monster. This is based on actual observation at a test-and-tune at Cayuga.

Stock looking Mazda 3 lined up beside an older and obviously hot-rodded and turbocharged VW.

Off the line, the Mazda silently took off in a normal-stock-Mazda sort of way. The hot-rodded VW made tons of noise but bogged down and slowly crawled away until the engine got some revs up and then the front tires instantly went up in smoke to the sound of the engine bouncing off the rev limiter.

Second gear. Same thing. Bog, NOTHING, slowly creeping along (the Mazda was long gone at this point) then BOOM, tire smoke and rev limiter. Third gear ... same thing! Only after shifting to fourth did the drop in revs let the engine stay somewhere near its powerband.

650 hp at 6499 rpm does no good whatsoever if the rev limiter is at 6500 rpm and it only makes 3 hp at 6498 rpm.

I've no idea what was under the hood but my guess is too much turbo, too much cam.

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Originally Posted by Brian P

I've no idea what was under the hood but my guess is too much turbo, too much cam.

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I see that happen all the time, mostly in the import car world. Everyone wants the biggest baddest turbo. A friend of mine got talked into putting a GT35R on a 1.8 litre audi a4 by the shop he went to. It didnt make enough power to puree a tomato under 5000 rpm, then you got about 750 rpm worth of "powerband" right at redline. It was a terrible car to drive on the street and never put down the track numbers the peak hp figures would have suggested.

I use dyno's as a tuning tool only. My cars and bikes have never put out super impressive numbers but as long as the curves are smooth and they deliver the goods on the track Im happy.

To answer the OP's question, it's both.

If you don't know what you're doing (or, if you DO know what you're doing), you can get a dyno to show numbers much different than actual horsepower capability of your engine/vehicle. If you understand the test, you can exploit the limitations of that test. SAE changed the engine HP measurement standard a few years back and engines tested using the old standard AND the new standard showed different numbers.

If done right, dyno numbers (torque curve, not just peak HP) are a useful tool when tuning an engine.

I ran a 129mph trap with the nose of his car just behind my rear bumper. He beats just about everyone around here and has for years... Pavel can drive some... I just brought a (very slightly) bigger gun, although if I could get the 60' he's capable of with AWD it would have been a hurting...