Dyno vs. Dragstrip Tuning

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Depending on who and where it is dyno tuned by it can be spot on or way off.
Some shops have dyno setups that don't have an adjustable acceleration rate and that doesn't help as much. I adjust the acceleration rate on mine to match the expectations of the car it is going in
My customers are normally as good on the tune up as they can get. Typically they find 0 gains by changing things
Keith

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Some dynos on the market let the engine accelerate at whatever speed it wants to and the computer converts the information into an estimated value of what the engine should put out at a certain acceleration rate.
Those aren't very accurate and from the couple of engine builds I helped guys tune at the track that came from them, they liked a couple of degrees more timing and a couple of jet sizes more fun we like at the track.
Keith

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That`s what I`ve seen............

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Depending on who and where it is dyno tuned by it can be spot on or way off.
Some shops have dyno setups that don't have an adjustable acceleration rate and that doesn't help as much. I adjust the acceleration rate on mine to match the expectations of the car it is going in
My customers are normally as good on the tune up as they can get. Typically they find 0 gains by changing things
Keith

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I ended up opening the dyno room doors, turned off the pusher fans and left the exhaut fans on and redid the pulls to see how much differences I found.




So Cab.......did you see any difference in HP #s?

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To be real truthful I don't remember exactly how much less it made, that was one of the first pump gas engines I built and dyno tested a long time ago(1991-93 or so). It was a pump gas 426 C.I. M.W. with stock cross ram and carbs. with a true 9.46 to 1 compression ratio. I got a best of 499.6 HP at 5600 RPM and a little more torque than HP IHTHs

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Make sure the tune up is safe and then take it to the track, look at the time slips and spark plugs and go from there Some of the dyno I have used have big pusher and puller fans feeding them(the dyno room) fresh air. If your dyno had postitve pressure in the dyno room during the testing your motor had some artificial boost Been there, done that I ended up opening the dyno room doors, turned off the pusher fans and left the exhaut fans on and redid the pulls to see how much differences I found. Test, test and test some more Another thing to keep in mind is not only the weather on the day of the dyno tuning but the altitude as well as the density altitude at the dyno and race tracks Sometimes more power spins the tires worst also

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I always try and use the headers that are going in the chassis and weld in the EGT bungs and O2 bung. After tuning for best timing, A/F ratio, spacers and whatnot I'll put the airflow meter on to see what the engine is actually using. Also try the aircleaner assembly they want to use, fan and alt. I've opened a few eyes by showing how bad or good some of their stuff is.
My 605 LOST 117hp bolting up my 3-1/2" dual exhaust with X-pipe and 3-1/2 Ultra-Flows over open headers and collectors. A friends resto 440 mag lost 22hp using a factory dual snorkel aircleaner assembly over an open style element.Dave

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There is nothing out there for exhaust on a engine
of that size unless you start looking at diesel exhaust
(a pair of them).. even with dyno testing I have
always had to tweak it in on the track for each day
if the weather is way different... the dyno tweaks
it in for that day

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I always try and use the headers that are going in the chassis and weld in the EGT bungs and O2 bung. After tuning for best timing, A/F ratio, spacers and whatnot I'll put the airflow meter on to see what the engine is actually using. Also try the aircleaner assembly they want to use, fan and alt. I've opened a few eyes by showing how bad or good some of their stuff is.
My 605 LOST 117hp bolting up my 3-1/2" dual exhaust with X-pipe and 3-1/2 Ultra-Flows over open headers and collectors. A friends resto 440 mag lost 22hp using a factory dual snorkel aircleaner assembly over an open style element.Dave

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There is nothing out there for exhaust on a engine
of that size unless you start looking at diesel exhaust
(a pair of them).. even with dyno testing I have
always had to tweak it in on the track for each day
if the weather is way different... the dyno tweaks
it in for that day

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Fair enough Mike, my dyno does have a weather station that corrects the numbers to the standard, that's about all a person can do. What most people fail to recognize is it's a tuning tool. For instance, first pull makes 400hp, after tweaking the timing, carb, intake, fuel, whatever... you might finish at 450-500hp. Doing the same testing at the strip might take a whole season or a full day or two of private testing. I made 18 dyno pulls just dialing in the thermoquads on my tunnelram. Most people can't do it but in my case I made the sacrifices and spent the money so I could.Dave