MPI Turbo
I wrapped up my install this last week and took the sled out to do some initial testing/tuning in the Black Hills of S.D.
I have personally been riding 800 etecs with aerocharger's since 2011 and have been very happy with this combination. Over the last 5 years the clutching has been tweaked and small adjustments have been made to the aerocharger kit to make them run extremely well.
I rode 2 days in the black hills with the first day at 5500' at 45-50 degrees F and the second day up to 7500' at 30 degrees F. The snow was marginal so It was difficult to really load the sled on top. My impressions of the MPI kit and the Gen 4 boosted are as follows:
1. The MPI Kit is a work of art. The machining, welding, and fit and finish are top notch. The MTA turbo is also a very nice piece.
2. Install: This is not a 2-3 hr install. I would plan on 6 - 8 hrs minmum. The install is not necessarily difficult by my standards but there are many steps! There is a lot of dis-assembly which requires re-assembly, clutching changes, etc. I think many people might want to consider paging through the install guide on MPI's website before they tackle this themselves.
2. Fueling: I was initially under the impression that the gems box was going to be locked. This is not the case. The gems box is completely tunable, although I do think that most people will find that it will be tucked away with the recommended settings and wont be touched. The ambient temps were extremely high and I was not able to make the sled bobble as a result of fueling.
3. Octane: I am running the stage 1 kit with the High elevation waste gate. I was going to be riding below 6000' on day one so I put in 4 gallons of race gas. I wanted to error on the safe side as the high elevation waste gate is intended for above 6k. This was likely way to much octane but did this on a routine basis on the 800 etecs with no penalty. The boosted 850 does not like to much octane. It made the bottom end extremely lazy. On Day 2 I pulled all the fuel out and went to straight 91. This was definitely noticeable were as on the 800 etec I would not have noticed any "seat of the pants" difference.
4. Clutching: Everything I learned about clutching my turboed 800 etecs with the TRA primary was absolutely useless with the pdrive on the 850. I started out clutching this sled with the same mindset I would have on my turboed 800 etecs and it literally felt as if it didn't have a turbo on it. John and I butted heads on this for weeks prior to my maiden voyage....I will admit that I was wrong and he was right:face-icon-small-blu I was blown away at how very minor changes with the pdrive had very large impacts on the power delivery to the track. After tweaking with John's recommendations I found the clutching to be good, considering the limited clutching components for the p-drive at this point. I do think there is a ton of potential for improvement with custom ramp profiles, adjustable weighted ramps and primary springs.
5. Electronic Boost Control: I don't have much to say other than it seemed to work as advertised.
My overall impression of this package is very good. Once the clutching was good you couldn't make the sled bobble and it would braap off whoops and yank the skis in the air. I think there will be some little tweaks that can be done to this kit that will make it that much better.
A few short vids from day 1( too much octane and 50 degrees F) at 5 lbs of boost. Keep in mind low snow, so no tree riding or climbing in the hills.
https://www.youtube.com/watch?v=5lcFcF_dJX8
https://www.youtube.com/watch?v=fph_-r7ZfvA