Technical question about Dyno test

[kifried]

Hi, I have a olds 350 in my 86 Regal. There is a 200r4 and the stock 2.56 gears that came with the regal. I'm in the process of figuring out exactly what rear I want as well as transmission components. Can someone please tell me, if I were to bring the engine to tested on a dyno, would the rear end have an affect on the results? For instance would the torque and power curves be a function of transmission and rear end? If they are dependent how can I use the results to help me spec out which rear and/or for instance valve body and governor would be right?

Also, anyone have any books they recommend on transmissions and rear ends? I'm not very familiar with the inner mechanics, and potential performance upgrades and I'd really like to learn..

Thanks, Ken

 

[Sleeper-6]

For the Trans I would definately pick up the book by Chris at CK Performance.

 

[Turbo6inKY]

Hi, I have a olds 350 in my 86 Regal. There is a 200r4 and the stock 2.56 gears that came with the regal. I'm in the process of figuring out exactly what rear I want as well as transmission components. Can someone please tell me, if I were to bring the engine to tested on a dyno, would the rear end have an affect on the results? For instance would the torque and power curves be a function of transmission and rear end? If they are dependent how can I use the results to help me spec out which rear and/or for instance valve body and governor would be right?

Also, anyone have any books they recommend on transmissions and rear ends? I'm not very familiar with the inner mechanics, and potential performance upgrades and I'd really like to learn..

Thanks, Ken

In short, no. A dynamometer measures a parameter called tractive effort. It then combines that measurement with an engine RPM reading and the tire RPM reading, does some math, and spits out calculated engine torque and horsepower numbers.

If you were to dyno the car, change the rear gear, and then dyno it again, you will get the exact same numbers, assuming the dyno operator knows what the hell he's doing.

I've personally had a really hard time finding a dyno operator than can deal with an automatic transmission and the implied torque convertor slippage properly. They just can't wrap their heads around the concept. Very frustrating.

 

[1 quik6]

I've personally had a really had time finding a dyno operator than can deal with an automatic transmission and the implied torque convertor slippage properly. They just can't wrap their heads around the concept. Very frustrating.

So what is a good way to tell if your dyno operator knows what he is doing? I wouldn't be sure if they know more than me or giving me a line of *hit.

I am planning on getting my car dynoed in spring also. Last year at the event each car got two pulls for $75. The operator gave the choice of owner in drivers seat or operator in drivers seat. A few guys tryed themselves pull one and operator on pull two. Each time the operator got more horsepower. Any idea why? Didn't seem to me like a hard concept on a street car - punch it!

Also, what should we know about disconnecting the kickdown so the car stays in high gear for the pull instead of shifting.

Thanks!

 

[Junior Samples]

So what is a good way to tell if your dyno operator knows what he is doing?

Check to see if he has a half pint of 5-Oclock vodka in his back pocket?

 

[Turbo6inKY]

So what is a good way to tell if your dyno operator knows what he is doing? I wouldn't be sure if they know more than me or giving me a line of *hit.

I am planning on getting my car dynoed in spring also. Last year at the event each car got two pulls for $75. The operator gave the choice of owner in drivers seat or operator in drivers seat. A few guys tryed themselves pull one and operator on pull two. Each time the operator got more horsepower. Any idea why? Didn't seem to me like a hard concept on a street car - punch it!

Also, what should we know about disconnecting the kickdown so the car stays in high gear for the pull instead of shifting.

Thanks!

If he tries to calibrate the the engine RPM reading on the dyno using roll speed, and you have an automatic transmission, leave. Your results will be garbage. The operator needs to know how to get some kind of direct RPM reading off the car, either through an inductive pickup on a plug wire, or an optical sensor attached to the crank pulley.

My local mustang dyno shop doesn't know how to do this. If you use the inductive pickup, the machine spits out negative horsepower numbers. They can't seem to wrap their heads around torque converter slip and how roll speed calibration with an automatic produces garbage numbers

I just disconnect the TV cable. Then you run it up past 3000 rpm in first and second to get into third, then back off until it gets to 2500rpm or so, hit the test start button, and floor it.