The explanation
So nobody can say what the difference is? Extra 135 bucks to zinc plate? Possibly the mnt fix kit grinds the spacer flat where the cheaper kit takes no time to make it flat? Would be interesting to know. Are the pistons the same?
Originally Posted by MTNTK
I appreciate the comments on our products, but there are a few things your not getting quite right. Polaris built this motor to be very compact and lighter than previously designed engines. This being said there were compromises made that they thought were "acceptable".
One of those were to shorten the piston as much as possible. This kit is not a rod ratio change nor does it fix a rod ratio. it does not use pistons with a higher rod location to allow a longer rod to change thrust loading. Nor has any of our research found that the polaris engine had improper thrust loading on the piston.
If the thrust loading problems were true, then you and i would have seen scoring and piston damage on the thrust side of the pistion/cyl. I have never had a problem with the thrust/intake side of the piston. It always looks good, but the exhaust side looks really bad. But it is interesting to look at the design of the polaris engine, because it looks like an engine that they were trying to eliminate rod thrust loading because the stock piston has a rod pin location that is high on the piston almost like they were trying to get the longest rod possible without getting any deck height increase.
What our kit does do is raise the cylinder up and allow us to put a taller piston in the cylinder. What we found is that the polaris engine has excessive piston to cylinder clearance. this allows the piston to rock in the bore effectively using the top and bottom edges of the piston instead of the entire bearing surface of the skirt.
I have a very reliable source that stated polaris had a severe piston heating problem in the prototyping of the engine and so they elected to go with increased clearance to prevent piston seizure. This heat problem was fixed with the ecu reflash. The clearance combined with the piston design causes the piston to scrape the cylinder wall on the compression stroke, especially the exhaust side.
This is why the piston looked like it ran out of oil on the exhaust side but not the intake. This is why the engine would never totally fail, just slowly start to run bad, not going into reverse and then hard to start and then put, put, put and barely back to the trailer. This is also why there was an interesting phenomenon that when using a turbo on this engine it would last longer than stock. Everyone thought it was a fuel issue, but it was not. It was a piston size problem. The turbo added heat and the piston grew taking up the clearance.
The taller piston benefit can be easily described by the analogy if you have a smart car(which is a very short car!) on a single lane highway it would be much easier to turn around without going off the road than it would be to turn a tractor trailer semi (a very long vehicle)around on the same road. The piston does the same thing. It can't move away from the cylinder wall nearly as easy if it is longer and has tighter clearance than the stock piston. This makes horsepower in more than one way.
The first way is because the piston is not leaned over it holds cylinder pressure longer and makes the power stroke longer. The second way is the piston is 40 grams lighter so there are not as much parasitic losses internally. Third and less known is the piston slap is reduced and excessive piston slap can set off the detonation sensor and back off timing. fourth is the previously stated crankcase volume increase, which has been proven in numerous sae studies with tuned pipes is almost always beneficial for engines designed for peak power.
On our dyno it made 4.9 hp more and that was on a totally stock 2010 engine, airbox, and fuel. I hope this sheds some light on the product and I hope you can have some faith in it that we don't just come up with some gimic or "widget" and sell you on it. We test, we prove, we cannot sell you something we do not believe in. I welcome any more questions. Shawn, Mountain Tek Performance.
