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Discussion Starter #1 (Edited)
I didn’t buy my Gator with the intention of making it compete with the likes of a Commander or Razor, but hey, can’t everything stand a little more power?

We started by establishing a baseline (in stock form) of the HP, Torque, and top speed on a Dynojet Automotive 224-based chassis dyno. OK, this is probably the first time that anyone has seen a John Deere on a chassis dyno, so their reaction was more like, “are you serious”, as opposed to “oh my god, what a cool project. The look on everyone’s face was priceless when the Gator came to life and spun the rollers nonetheless J











Did ya notice the plow on the front? Like I said, I didn’t buy it to go set any records on the dunes.

OK, so the engineering group at Dynojet spent the better part of a day acquiring / measuring various signals in order to adapt a Power Commander V (PC5) to my John Deere Gator 825i XUV. After whipping up a harness for the PC5 to plug directly into my OEM harness, it was time for more dyno testing and fuel tuning.

The stock fuel curve was at or near stoich from idle to redline, and yeah, stoich is good for maximum MPG’s, but I like to reserve that AFR for idle and light load conditions, not when my foot is on the floor! For reference, the stoich point of “real gas” is 14.64, while E10 (10% ethanol) from the pumps in most regions is right around 14.13. My Gator was literally 14.20 AFR from idle to redline and everywhere in between. OK, so normally a guy would shoot for 12.8 – 13.2 AFR for best power on naturally aspirated engines, but for whatever reason we settled for 12.0 until I can further refine the mapping.

Here’s graph of stock power / torque vs. speed with and without the Power Commander. We picked up about 2 wheel HP and 2 ft-lbs or torque.



Now that’s not a huge pickup in power, but remember these are “wheel HP” figures, not engine HP figures. Also, the power that’s soaked up in a CVT transmission and turning some big, aggressive tread, low pressure tires is NOT insignificant.

The engineers then added an ignition module that allows the addition of, or subtraction of timing (spark advance) at any operating condition (it’s fully mappable). We didn’t get a lot of time to test with this module, but with the addition of 4 degrees of spark, there were NOT huge gains. Also, to be fair, the AFR was also changed during this run, so the results are not really apples-to-apples on this particular run. Stock vs. Power Commander vs Power Commander w/ Ignition Module:




This is also telling, I chose to take the dyno runs and graph them in ways that traditionally I wouldn’t (I’m more of a “car guy” / EFI tuner guy, not a UTV w/ CVT expert). As some have reported on this forum, the 825i seems to peter out at 44 mph, and they’re right. The graphs clearly show that, but what’s telling is that the clutches are “shifted out” at about 38 Mph:



But here’s what’s cool, in stock form, my Gator would cover about 300 ft in 8 seconds on the dyno. With the Power Commander it would cover 318 ft in the same time, and finally, with the Power Commander with Ignition Module it covers 325 ft !! Not too shabby.



Another interesting thing to look at was the speeed / time relationship. In stock form, my Gator would reach 34.5 MPH in 5.8 seconds……OK, not exactly a rocket ship, I know….then with the Power Commander it would hit 36.5 MPH in the same time, and finally, with the Power Commander with Ignition Module it tickled 36.3 MPH:




Video of a power sweep:

http://youtu.be/UaEplMmJ9B8

So, back to reality, my day of tinkering tuning and dyno testing left me with a better understanding of what the Gator 825i likes, and dislikes. It’s now back home doing regular stuff like moving dirt, carting the kids around, and otherwise living the life of a normal Gator. Hope you enjoyed my “short story”J
 

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Great post...I enjoyed reading that....that was really cool for sure...

Thanx for posting the story of your testing...I am very interested in the same thing...I am looking at clutch mods now also...

Larry in MD :D
 

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Really cool! I like the info you can see on a dyno. No need to compete with RZRs in my neighborhood (only Gators, Mules and RTVs within 10 miles of my farm ;)) but I always have an itch for more power too.

- Steve from CO but in MT today (without the Gator :()
 
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