Have any of you guys had your quads dynoed on a car chasis dyno? Would the results be accurate? Im suppost to dyno mine on a dynojet car chasis dyno on friday! Let me no please if you have!
Later

 

I did almost all of my dyno work for the last two years on a car dyno. That's hundreds of runs. I can honestly say that it compaired very well to the ATV dyno's that the same bikes were run on. If it's run properly, it will be plenty acurate.

 

Thanks for the info, Im mainly doing this dyno run so i can order the right meetering rods to get the jetting spot on then ill take it back and dyno it again! The guy who owns the shop uses a exhaust sniffer so i can see where im lean and rich!

 

Does anyone know what fuel/air ratio I should shoot for for max power!

 

Are you running gas or alcohol?

Gas........Should be somewhere between 14.0 and 15.0 usally 14.7 is good.

Alcohol..6.1 to 7.1 usually 6.5 is good.

I know that others on here might have a different opinion. I am not saying that I am 100% accurate. But those numbers should get you in the right ball park.

DuneDevil

 

The standard ratio is 14.2-14.7:1 .

In my testing, I've found that this motor responds best when is is rich in low RPM's and lean up top. That will give you the broadest power band and highest peak power.

 

As Knutz stated car dynos work fine. Tune for power not for mixture. The problem I've run into with sniffers is air leaks in the exhaust flow, I have yet to find a pipe that makes power AND doesn't leak some air. ANY air will give you a false reading on a sniffer or wideband O2 sensor. Unless you weld a bung into the head pipe and install a wideband O2 sensor your readings will be subject to error from air leaks.

If you jet making repeated runs until it makes the most power at top end, then start adjusting the mid and low and recheck the top. If you use the sniffer, take a baseline run before changes, tune for power, then recheck the sniffer results. This will give you an inidication of the changes you made in mixture. When it is making the most power and you are happy with it, go up one main jet size for safety and you should be dead on.

One last note with regard to ratio. Although it is generally accepted that a 14.7:1 is the optimum burn ratio for a gas motor, it is not always the case. That ratio came into popular belief with the advent of pollution controlled vehicles, it is a lean (low hydrocarbon) producing mixture. It makes the EPA happy, but it doesn't make the most power in all motors.

Hope this helps.[img]i/expressions/face-icon-small-smile.gif[/img]

 

Thanks for the info guys. Well ill let you all know what it makes when im done with the dyno! My buddy just ran his banshee on there 2 nights ago and went from 36 to 43 horse just tuning! He wasnt very happy with those numbers, he was expecting much higher numbers which is usually the case on the dyno from what ive seen.