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We have tried to make the best turbo kit possible for the RX1 snowmobile
and we are very satisfied with the result.
It´s probably not the cheapest turbokit you can buy, but our customers
demand something else.
The RX1 with MC Xpress turbo kit can take your snowmobile to another
level!
During the development work we have tested many turbos and different
locations of the turbo. Our 2004 model turbo kit has a rear mounted turbo.
During 2003 we built with front mounted turbo.
Benefits with rear turbo location are Lower exhaust back pressure
equaling higher performance and less exhaust temperatures.
- No extra heat under the hood.
- Faster and easier installation
- Less parts included with the turbo kit
- cheaper for the customer
- Stock fuel tank can be used
Benefits with front mounted turbo:
- Faster turbo response
- Simple oil lubrication system
- Low risk of snow coming in the air filter
- Stock exhaust muffler can be used
- low noise level.
During the summer 2003 we have worked a lot with solving the four main
problems with the rear mounting turbo version.
To get a fast throttle and turbo response has been achieved as follows:
The right tubing sizes on both intake and exhaust, perfect matching turbo
size and the most important thing, perfect carburetor air fuel mixture
during all kind of loads.
The intercooler and airplenum are developed so no rejetting of the carbs
are necessary what so ever.
The lubrication of the turbo is very important, if the turbo runs out
of oil pressure for just a couple of seconds during high load, it will
fail.
The oil that has lubricated the turbo will drain back in the engine case.
When the turbo is so far away from the engine, and especially when driving
in steep hills, the return oil will not drain back all the way to the
engine by itself.
The oil lubrication system can be made in two ways:
- a separate oil system for the turbo, driven by an electric oil pump
with a small oil tank, everything located around the turbo.
- or lubricated by the engine oil, pumped back to the engine by an electric
or mechanical oil pump.
A separate oil system has one advantage and some disadvantages. The
advantage is that it is rather simple to build and easy to install,
but an electric oil pump is never as reliable as the stock oil pump
of the engine. It´s difficult to control the oil temp.
Putting an electric oil pump in the rear of the snowmobile is not ideal
due to water, ice, snow, heat from the turbo and lack of space. And
it´s also better to avoid an electrical units. Yamaha only recommends
40 watts extra power output of the electrical system and this is about
what the electric fuel pump needs.
We made a small mechanic oil pump driven by the crankshaft, very easy
to install.
This type of oil pump has been used on some of our motorcycle turbo kits
since 1985, so we know they are reliable in the long run.
To avoid snow and water coming to the air filter we first of all made
some shields to cover the filter. A special snow proof K&N pre filter
is also installed above the air filter.
The last problem to solve was the noise level.
It´s not much space in the rear of the sled. To use all the space
possible, we made a bend muffler with conical baffle inside.
The flow resistant is very low and the noise reduction excellent.
To make it possible to get high performance from the RX1, we always recommend
to lower the compression ratio with the extra thick head gasket included
with the kit.
The power of our 2004 kit is 240 hp with pumpgas at 0,7 bar turbo pressure
(=10 psi)
If you want higher performance we have more to offer.
As an option, we can recommend Wiseco or JE low compression pistons.
At 1,2 bar pressure (=17,5 psi) and pumpgas, the power will be about
300 hp.
At 1,5 bar pressure (=22 psi) and 102 octane race gas, without muffler,
just a 3” exhaust bend, we tested 358 hp. (everything except the
pistons are stock parts in the engine)
Calibration weights for the clutch and new drive wheels are recommended,
but not included with the kit and has to be bought separately. |
