Dyno test?

[aldive]

I have been asked recently, since I am going up to Doug’s ( Bama Chips ) for some Dyno testing and tuning, to explain what actually goes on during a dyno. Well, the last time I was at a Dyno was many, many years ago and I don’t remember what went on then.

Doug, and others in the know, please answer the following questions about the Dyno:

How long does a “run” take?
What parameters are measured?
How is A/F determined?
Is there a person in the driver’s position working the throttle?
How many RPMs do you run the motor up to?
How is the rate of acceleration determined?
What information is available? eg, HP, torque, MPH, etc?
How long do you wait between runs?

Anything else you might add is welcomed.

Thanks in advance.

 

[spindlecone]

I have been asked recently, since I am going up to Doug’s ( Bama Chips ) for some Dyno testing and tuning, to explain what actually goes on during a dyno. Well, the last time I was at a Dyno was many, many years ago and I don’t remember what went on then.

Doug, and others in the know, please answer the following questions about the Dyno:

How long does a “run” take?
What parameters are measured?
How is A/F determined?
Is there a person in the driver’s position working the throttle?
How many RPMs do you run the motor up to?
How is the rate of acceleration determined?
What information is available? eg, HP, torque, MPH, etc?
How long do you wait between runs?

Anything else you might add is welcomed.

Thanks in advance.

#1, about a minute
#2H.P and TQ
#3 Lambda A/F computer
#4 Yes
#5 about 5250
#6 car is allowed to shift up to 4th Turn off the O.D. you want to measure with the tranny in a 1 to 1 ratio.
#7 H.P. and TQ
#8 untill the engine cools down, they will have fans to help out,also turn on your e-fan, moniter your IAT and try to be as close to ambiant as possible

 

[Doug904]

How long does a “run” take?

Like he says usually less then a minute depending on how long it takes your vehicle to get up to speed and such.


What parameters are measured?

On the dyno A/F ratio, MPH,and Torque. Then the Horsepower is calculated from this but it will show the Hp numbers first.


How is A/F determined?

Yup, wideband in the tailpipe.

Is there a person in the driver’s position working the throttle?

This can actually varry from dyno to dyno but at the one we'll be going to they will run the vehicle, as I feel safer with them doing it.

How many RPMs do you run the motor up to?

This is a question that is asked before you make the first run, normally what I say is I would like to start off with around 5200-5500 and then from there I'll read the dyno chart and if power is falling off after 5000 then I'll lower it.

How is the rate of acceleration determined?

The rate of speed that the wheels spin the rollers up at is the way the power is measured.

What they normally do is run it up to third gear slowly and then once they are in third, with the overdrive off, they floor the throttle until the desired RPM's are reached.

On some vehicles it will still shift into overrdrive no matter wether you have it in 3rd with the button deselected or not, mainly stock vehicles. This is because there is a value in the PCM that makes it shift to overdrive at a certain MPH no matter what the selector position is in, with my tuning I raise this value to it's max so this doesn't happen.

What information is available? eg, HP, torque, MPH, etc?

On the Dyno's computer HP, Torque, MPH, and RPM's. Using my datalogger all of the engine's sensors will be available to watch.

How long do you wait between runs?

There again it really varries, I've done back to back runs without shutting the vehicle off but I've also waited for more then 10 minutes trying to allow time for everything too cool down. It depends greatly on what you are trying to get from the dyno. If you're trying to squeeze every bit of HP out of it then wait but if you're trying to do comparison runs for a bolt on part and you did the first run hot then do the second run hot as well.


It's nothing and after you see if done one time then you'll be an old hand at it. I've got a folder I keep in my tool box that is as thick as most cities phone books so I've done this a few times .

EDIT** See ya that morning, I'll let you post the date if you'd like.

Thanks, Doug.

 

[spindlecone]

Have only been dynoed 5 times, but I was close

 

[aldive]

Thanks, Doug, you covered it all.