Short story:
I purchased a new ECU reflashed by RVS Performance. The tune adds 13RWHP to the Ranger 900, for a new total of 86HP at the engine (provided the stock drivetrain loss percentages). Stock, Polaris rates the 2015 Ranger 900 at 68 horsepower.
Long story:
Polaris uses the current 875cc ProStar motor in at least three different vehicles: the 2013+ Ranger 900, the 2015+ RZR 900, and the 2016 ACE 900. While each of these vehicles are different and intended for different uses, the 900 motor is identical between all three. The engines are identical except for one thing, the tuning.
Via the ECU that's about the size of a deck of cards, Polaris makes and markets multiple levels of power. For example, when the Ranger 900 was released late summer of 2012 as a 2013 model, Polaris proudly advertised the new ProStar 900 with 60HP and 54lb-ft of torque. This engine had a different crank, different pistons, combustion chamber, and different intake than their hottest rocket, the RZR XP 900 which had 88HP. The Ranger 900 motor wasn't simply just a de-tuned RZR 900 XP motor.
In 2015 Polaris revamped their SxS lineup. The Ranger 900 got a sizeable bump in horsepower, a bump up to 68HP. To do this, they moved the rev limiter up 600RPM, clutched it a bit higher, added a little timing advance, and opened the throttle body 3% more. Interesting. For this model year, Polaris also released the all new RZR-S with the 900 ProStar motor. Using the same engine out of the Ranger 900 series, Polaris rated their new RZR at 75HP. Then in 2016, Polaris dropped the inline twin cylinder 900 motor in the single seat ACE chassis. In this vehicle, Polaris rated the ACE at, you guessed it, 60HP.
By using the ECU to retard engine timing and by limiting the throttle body's maximum open position, Polaris was able to tune this engine to meet marketing and perfomance demands.
Since I know the Ranger 900 platform the best, I know that my 2015 model only opens the throttle body to a maximum of about 70%. Furthermore, Polaris varies this based on what drive range is selected and vehicle speed. Nail the throttle in Low Range, and you will get a burst of tire-spinning power, but the ECU will back off the throttle in what Polaris calls "shaft saver" programming. It smooths the power. This creates a little bit of a numb feeling in the pedal, especially when you are trail riding.
The ECU flash flashes the OEM computer to give 100% throttle in all gears, it removes the shaft saver programming, and it lowers the engine fan on temperature down from 204F to 184F. It also removes the vehicle speed limiter that is programmed at 60MPH. You do have to use 91+ octane fuel with the new tuning. The company who tuned my Ranger promised 60HP to the rear wheels, up from the stock 47HP of my 2015 model Ranger 900.
I installed the ECU in my Ranger, and I immediately noticed how much more responsive the engine felt. I'm used to stepping on the throttle to engage the belt and then backing off. Now if I do the same technique, I spin my tires. I spin my tires a lot. In fact, my Ranger will spin the rear tires on asphalt from a dead stop. If I unlock the rear differential and floor it while turning right, it'll boil the right rear tire.
I need to adjust my clutching a bit to take full advantage of the new power. I need to remove a couple of grams from my adjustable flyweights to get my RPM up a bit more. Overall, this is a huge jump in performance, to be sure, but it is also a major increase in fun factor to drive. It's like driving a RZR with a bed and a bench seat. I hope I don't slide out! LoL
Is there any clutching available to smooth out the clutch engagement? I drove a 900 Ranger awhile ago and it was jumpy in slow technical situations. I'm sure with the added snap from the ECU reprogram this becomes more evident.
I have a DDP clutch which includes a new secondary. My clutch is as smooth as a wet clutch machine. It'll still burn a belt if you don't pay attention, but it's buttery smooth. The stock secondary is where all the clunky jerky starts come from on these machines
thats awesome. glad it stepped up the power and performance that much! can't wait to hear how it is after you get the clutching dialed in.
also.........
did you ever give the duraclutch a thought on your ranger before you went DDP? I've been thinking that clutching is going to be the first upgrade to the ranger besides accessories, and the DDP was top of my list, until i stumbled across the duraclutch. a dry clutch with killer engine braking and guaranteed to not smoke a belt. been doing a little research on them and was wondering if you had as well?
I jumped back and forth between the DDP and the DuraClutch, trying to decide what was best for my use. I liked the concept behind the DuraClutch as one coming from machines that used centrifugal clutches.
The main reasons I chose the DDP over the DuraClutch were adjustability, performance, and price. The DuraClutch simply cannot be "tuned" to different tire sizes like the clutches utilizing more standard flyweights. Imagine if the only weights you could get in a Rhino were either 20gram or 17gram. You couldn't tune the CVT with much precision. The DuraClutch currently ships with their standard flyweight or their "high altitude" flyweight. I'm not aware of any other options at this time. This means performance is not going to be quite the same as when you can really match the shiftout RPM to the engine powerband. Finally, the higher cost of the DuraClutch makes it even tougher on the wallet.
Probably the worst thing about the DuraClutch is that you have to buy it from Hunterworks... YUCK! LoL!!!
With all that said, I do like the DuraClutch. It seems to be working fantastic in both utility and recreational applications. I think they are really starting to get popular. There are already way more of them floating around than there were six months ago. If they can ever get the price below $1000, they'll sell even more.
I had the opportunity to adjust my clutch flyweights a bit to better match the new ECU tune and power band. I lightened the weights a bit to increase my RPM during shiftout. RVS, the company who does the tuning, suggests aiming for 7400-7600RPM. I'm in the neighborhood, but still need a bit of fine tuning. I think I need to lighten the tips of the weights, and I may need to possibly lighten the middle slot as well.
This sure isn't a Yamaha!
Here is a pic of my flyweight as it come from Dirty Dawg Performance. This was perfect for the stock engine tune and my 27" Bighorns.
Here is a pic of the weight after a few adjustments.
Here is a quick video of my acceleration.
My speedometer is a tiny bit slow due to the taller tires. I'm sure the glass front and rear windshields slow me down a little bit. Overall, this Ranger runs pretty good for a utility. I'm going to see if I can't milk a little more spunk out of her through the clutch. I think there's a little more to be had...
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