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2014 Turbo YamaCat Viper?

T

Turbo11T

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Nov 26, 2007
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Lake Crystal, MN
Maybe your dobeck fuel controller CAN'T keep up!!!..... 240 on race..... Almost ALL your competitors run up to 270hp on 91oct fuel..... So I save 2k on the price of the kit BUT I spend 4k more over the life of my sled because I CAN'T run anything else but super expensive race fuel....

Quite obviously they are 240 on race without lowering the compression. mcx puts a head shim in. Impulse runs a head shim. Powderlites runs a head shim. Etc etc.

Install a head shim with the MPI kit and enjoy the same benefits.
 

YAMA S

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Quite obviously they are 240 on race without lowering the compression. mcx puts a head shim in. Impulse runs a head shim. Powderlites runs a head shim. Etc etc.

Install a head shim with the MPI kit and enjoy the same benefits.

In a momentary laps of memory "CRS".... The head shim got left out. I'm not sure why they don't push putting in a head shim. I makes way more sense to pay for a couple more hrs of shop time than super expensive fuel. It pays for itself in 5 full ride days just with fuel cost savings!!
 
T

Turbo11T

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Nov 26, 2007
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Lake Crystal, MN
In a momentary laps of memory "CRS".... The head shim got left out. I'm not sure why they don't push putting in a head shim. I makes way more sense to pay for a couple more hrs of shop time than super expensive fuel. It pays for itself in 5 full ride days just with fuel cost savings!!

I am sure that mpi is marketing it without because it appears the install is simple without the head shim install.

Either way I think guys will really like the nytro motor with a turbo on it in the cat chassis. The cat chassis handles light years ahead of the nytro.
 

yammi4ever

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I will let MPI defend their decision on why they don't recommend a head shim, but from memory when talking to them at haydays a couple years ago they were arguing performance, not ease of install.

Certainly a head shim is a settle of sorts, and kept me from buying from mpi when I did my nytro, but lots of others are fine with hauling fuel or running lower boost numbers. A decision that must be made by us all when building.
 

Matt@MPI

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I will let MPI defend their decision on why they don't recommend a head shim, but from memory when talking to them at haydays a couple years ago they were arguing performance, not ease of install.

Certainly a head shim is a settle of sorts, and kept me from buying from mpi when I did my nytro, but lots of others are fine with hauling fuel or running lower boost numbers. A decision that must be made by us all when building.

Good question. I think to answer this question we need to look at a few things:

1-We thought that opening up a top end on a high performance 4 stroke would be a turn off for some. Clearly its not as bad as we thought. <O:p</O:p
2-When running a head shim on a supercharged sled it seemed to have a ill effect on the bottom end performance. We didn't like the trade off between more boost and weak bottom end performance. That’s way you run a supercharger. I would rather have the snappy bottom end. But the turbo on the other hand is different. I don't think the head shim affects the bottom end performance (not much to screw up). I like the turbo and I think the trade off is worth it. <O:p</O:p
3-2 years ago we didn’t have the ability to re program the stock ECU. Now that we can its easy to pull some timing out without upsetting the bottom end performance but crank in more boost and still run pump. So the ECU is like doing a head shim without opening up the motor.<O:p</O:p
 

smwizzz

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Timing

I am going to ask the question for clarity: When doing the head shim would you not also do cam timing gears? ie: elongating the bolt holes and clocking the gears? I believe this is a normal procedure when the motor is getting worked on and installing a head shim.

I think that those considering a head shim should get the full answer. It is difficult for those who don't know to invent the question. Just a thought...

BTW, the gems may be ok for those riding the same locations all the time but for alot of us who use our sleds in the mountains and close to sea level coupled with extreme temperature variations it would be more convenient to utilize a better fuel management system. As in one thread, we are sick of being test pilots and wasting money on things that don't quite work. My experience with that particular controller is very negative and frustrating.

I am sure you have perfected it over the years, but for the guy who wants to ride and not learn how to read some code and hope they can guess at a fix to make things better, it stinks. When it works it works awesome, I'll give it that but the times it doesn't you just want to burn your sled and go back to a 2 stroker...

JMO

Cheers :face-icon-small-hap

Good question. I think to answer this question we need to look at a few things:

1-We thought that opening up a top end on a high performance 4 stroke would be a turn off for some. Clearly its not as bad as we thought. <o:p</o
2-When running a head shim on a supercharged sled it seemed to have a ill effect on the bottom end performance. We didn't like the trade off between more boost and weak bottom end performance. That’s way you run a supercharger. I would rather have the snappy bottom end. But the turbo on the other hand is different. I don't think the head shim affects the bottom end performance (not much to screw up). I like the turbo and I think the trade off is worth it. <o:p</o
3-2 years ago we didn’t have the ability to re program the stock ECU. Now that we can its easy to pull some timing out without upsetting the bottom end performance but crank in more boost and still run pump. So the ECU is like doing a head shim without opening up the motor.<o:p</o
 
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