CVT Dyno

[rollupdetassa]

Hey guys,

Ok, I know that cars with the CVT cannot be tested on the dyno because of the dynamic gear ratio. But is it theoretically possible for us to do so? I have been doing some research ( gotta love google) about the Extroid CVT that’s in our cars http://auto.howstuffworks.com/cvt3.htmand noticed that the rollers are controlled electro-hydraulically ; meaning that electric motors control the pumps that push the fluid that causes the rollers to change position.

Now here is my theory. There is obviously some signal that goes to the motors which correlates all the factors telling the CVT how to perform. If we were to isolate this signal and make it so that we tell the rollers to stay axially aligned (http://wikicars.org/en/Continuously_Var ... ansmission see the section on roller based CVT) couldn’t we theoretically get the drivetrain to stay in the 1:1 ratio for a dyno run? Maybe tap in to the ECU or have some piggyback system which overrides the CVT controls? I'm not sure if that could happen but and I know that’s asking a lot but given the resources I believe it could happen.

Feel free to critique or prove me wrong. I’m just thinking out loud here.

[audtatious]

Alternatively you can yank the motor and dyno it out of the car

[rollupdetassa]

Alternatively you can yank the motor and dyno it out of the car

Lol, your absolutely right about that. But no way in yanking my motor out just to dyno. I rather plug something in, press a few keys on my laptop, then bam, dyno time lol. Do you think its a far fetched idea or a possibility?

[newbissan-tech]

what about dynoing in a certain gear? some cvts have the auto stick feature or paddle shifter by locking it in a certain gear could you then dyno it or is it still pointless?

[rollupdetassa]

what about dynoing in a certain gear? some cvts have the auto stick feature or paddle shifter by locking it in a certain gear could you then dyno it or is it still pointless?

I'm kind of doubtful about that but Ill look up and see If i can find some info about the ratios of those simulated gears. I have a feeling those are dynamic as well.

[ifuxwituz]

i heard from a very reliable source that if you pull the ABS relay you will be able to get accurate dyno numbers for a CVT at least thats how it works for the CVT maximas

[audtatious]

Taking the ABS fuse out seems to help from what I see but there is still no guarantee you are running a 1:1 ratio while testing.

[Ricko]

If you are worried about dyno numbers, buy a 6 speed.

[mattyfo0z]

I think the other guy on this forum who got his 3.5 CVT tuned had the tuner street tune it instead of on the dyno...

[funkee]

You can always do a crank dyno.

The problem with the CVT, is that even in manual mode - the gear ratio is not always fixed. Try accelerating hard in 6th gear in manual mode, going 20mph. You'll actually accelerate at a different gear ratio at first, until it puts you into a real 6th gear ratio.

The other issue is that you have to push the gas peddle past the click to go WOT, and this automatically downshifts unless downshifting causes you the car to redline.

So you could theoretically dyno the car at 95% throttle (before the click), but you'll still upshift when you redline. You could dyno it in 1st gear, but you won't have a 1:1 gear ratio. The automatic upshift can be a problem, so you may need to use UpRev to flash the ECU and stop that from happening.

If you're doing an upgrade, you can do a baseline run at WOT in either manual mode or CVT mode. Then another run at WOT after the bolt-on mods. You'll be able to find the gains that way.

This guy managed to dyno a CVT on a Rhino by openning the transmission, removing the primary sheave and weights and putting in a spacer. I don't think I'd want to do that to my transmission though.