help me understand the dyno...

[Foxfan88]

When you dyno your supposed to have in like 3rd right, a 1:1 ratio gear right?
How would and auto get dynoed then??

Also can someone explain dyno tuning, do you just dyno and have a pro tune it for you? Like the efi will whack out with cams and more airflow so he wil burn a chip for your computer and it will run better for your setup??

Can someone go into detail??

 

[Asha'man]

1:1 is 4th gear in most 5-speeds.

Brian

 

[cjman15]

Also interested... bumppp

 

[Scorcher2005]

i always wondered bout dynoing an auto car since you cant just put it in 3rd gear (AOD gear for 1:1). Also, i dont see why the 1:1 gear ratio matters as the rear gears come into play. Meaning if a car got dynoed w/ 3.55 gears and then had them changed to 4.10s, would he see different results in the dyno? The only thing i can really see making a difference in the auto car is if the converter locks up or not.

For tuning, its mostly getting your a/f ratio set right, usually somewhere in the 12s-13s. This is done w/ an adjustable fuel pressure regulator and a chip also usually helps a bit.

 

[cobradvm]

For 5 speeds the dyno pull is done in 4th gear since that is a 1:1 gear in the transmission - this means there is less drive train losses than if it were done in a different gear.
Dyno tuning is simply adjusting different settings on the car, and seeing how they affect hp and torque. If you have an engine management setup like FAST, then alot more parameters can be adjusted, for your particular set up. If you don't, then you are limited to adjusting timing and fuel pressure (assuming you have an AFPR). The engine management setups will extract more power from the engine, and can help control detonation etc at different rpms and allow better A/F control.

HTH

 

[Speeds8erM-1]

For 5 speeds the dyno pull is done in 4th gear since that is a 1:1 gear in the transmission - this means there is less drive train losses than if it were done in a different gear.
Dyno tuning is simply adjusting different settings on the car, and seeing how they affect hp and torque. If you have an engine management setup like FAST, then alot more parameters can be adjusted, for your particular set up. If you don't, then you are limited to adjusting timing and fuel pressure (assuming you have an AFPR). The engine management setups will extract more power from the engine, and can help control detonation etc at different rpms and allow better A/F control.

HTH

You can tune with a tweecer, pms or have a chip done by anybody that tunes with Autologic, SCT or Diablo. You dont have to have FAST.

 

[90Notch]

"Meaning if a car got dynoed w/ 3.55 gears and then had them changed to 4.10s, would he see different results in the dyno?"

Yes, assuming we're talking about a Dynojet dyno it measures the rate that you accelerate the drum (HP) throughout the rpms then it calculates the torque. You typically use a 1:1 ratio because of this as well as it's closer to what the motor is actually making. All gears have drivetrain loss associated with them, I fail to see why another would have less...if this was case why not dyno in fifth gear?

 

[propellerhead]

I had my auto on a dyno recently. They locked out OD and punched it in 3rd. They bring it up to like 4000 RPM before flooring it and measuring it. I guess so it doesn't downshift into 2nd.

 

[Speeds8erM-1]

Rearend gears do have an effect on it, unless the newest software corrects for it. I know not long ago that changing the gear would affect power at the wheels. The LS1 guys tested this a bunch. Im gonna ask James at RWTD if the newest software corrects for it since he has a brand new dynojet with the latest software.