Thank You From MC-XPRESS USA


Well-known member
Nov 28, 2007
New Optional MCXpress Turbo Viper Race Parts

With the added Horsepower to the Viper,We increase cooling by adding a UCooler in the Tunnel.This Kit will also fit Non Turbo Vipers and the Radiator can now be removed .

We also make a Larger Intercooler that fits where the Radiator was removed.

We are also making a New Header that is lighter and more durable.

Our new Race Exhaust pipe is Lighter and has less restriction for more

For the Rider That like the Steep Mountains MCXpress USA has developed a oil bypass kit to keep more oil in the engine while at steep angles.This must be used with Race Exhaust Pipe

We also have New clutch Kits for your elevation (High or Low)



Well-known member
Premium Member
Jan 16, 2008
North of Sweden
U-cooler installed looks as it came that way from factory, really clean.
When radiator is removed a BIG intercooler can be installed = win / win.
Really psyked to try the race header this season, there's some obvious advantages with less volume and better flow = more power, better response, but also the Viper's exhaust "explosions" should decrease.
MCX never stop evolving their products, above is a proof of that, and it's not everything, there might come a couple more in a near future :D

Sent from my Sanwa M12


Well-known member
Nov 28, 2007
Black Friday MCXpress Nytro Turbo Special

NEW Nytro 190 Hp Turbo Kit 3295.00

This turbo kit is designed for the customer that would like to have some more reliable power in its Nytro. The compression ratio is stock. This makes the installation easier and faster. Pump gas can be used. The power maintains at any altitude thanks to our built in boost compensation system. This turbo sled is very nice to drive.



Well-known member
Premium Member
Dec 3, 2009
Reno, Nevada
Damm I wish i had the money to take advantage of this deal Maybe next year

NEW Nytro 190 Hp Turbo Kit 3295.00

This turbo kit is designed for the customer that would like to have some more reliable power in its Nytro. The compression ratio is stock. This makes the installation easier and faster. Pump gas can be used. The power maintains at any altitude thanks to our built in boost compensation system. This turbo sled is very nice to drive.



Well-known member
Nov 28, 2007
Mark's 2015 MCXpress Viper 270 Hp

Thank You Derek and Nan for traveling from Colorado to Montana to pickup my MCXpress 270 Hp Viper MTX . I'm Sure Derek's dad (Richard) will enjoy. I was also honored when you asked me to autograph the windshield . Thanks So Much.



Well-known member
Nov 28, 2007
Testing At MCXpress This Week

MCXpress testing a New EFI Box with ignition control this week.

Yamaha Viper 190 Turbo
Dyno test at different firing modes
The test is performed on a Viper engine, with ECU from in 2016.
Fuel: 98 octane commercial gasoline.
Effect given in horsepower.
70 degrees of cooling water temp.
Air intake temperature: -18 degrees
Turbo Charger: Mitsubishi 14T,
unplugged TCV

Preload WG: 1
mmSpeed ​​/ boost
Ignition Reduction
7000/26 kPa 8000/30 kPa 9000/33 kPa
0 degrees (= std) 132 163 185
5 degrees 127 159 184
8 degrees 127 156 178
12 degrees 120 148 170
15 degrees 116 137 167



Well-known member
Nov 28, 2007
New MCXpress 260 HP Turbo Kit for the Yamaha YXZ 1000

Yamaha YXZ 1000 turbo.

Yamahas 3 cylinder engine that is used in the YXZ 1000 is very suitable for turbo applications.
This engine was introduced back in 2005 in the snowmobile called RS, but then with 79 mm bore (973 cc)
The Yamaha YXZ has 80 mm bore (=998 cc), but the same stroke, 66,2 mm
We have great experience modifying this engine, both as natural aspirated and with turbo.
We got the confidence to build racing engines for team Yamaha Sweden 2006 and a few years forward for their snowcross snowmobiles.
It became very successful, and thanks to this, we got the honor to build a lot of natural aspirated snowcross engines for team Yamaha USA to 146 hp N/A RS engine prepared for Yamaha USA 2007.

But it is turbo we are most dedicated for.
Yamahas snowmobile Nytro and Viper also use this engine, but with 82 mm bore. (=1049 cc)
In January 2016 we sold over 3300 turbo kits to this kind of engine.
For us and for the UTV people that like speed and power it was great news when Yamaha decided to install this engine in the YXZ 1000.
We have made a lot of tests with turbo on the Can Am Maverick and Polaris RZR 1000.
These engines can handle up to about 180 hp with good reliability when using pump gas.
The Yamaha 3 cylinder engine can handle much more power and still be very reliable.
We have YXZ turbo kits ready for delivery.

The priority during the development of this turbo kit has been durability and performance.
What we found out very early when we made our durability tests was that the rods in the engine was to weak for turbo use.
We made tests on several engines. Already at 180 hp, the rods did break after a rather short period of time.
We did not test lower than that. If the rods can stand for instance 150 hp, the safety limit is not enough in our opinion.
That is the reason why we don’t offer any low performance kit to this model.
With new rods, the engine can stand extreme performance. That is why we include new rods with this turbo kit.
When we develop a turbo kit, we always consider how to install the parts. We spend a lot of time during the development making the installation as easy and simple as possible.
To get as high reliability as possible, we have only used high quality parts.
This is something we know is very important both for our customers, the mechanic that make the installation and for us.
We get happy customers and very few reclaims.
The turbo we have used is the high quality charger TD04HL19T.

We have not been able to find a turbocharger with higher performance to this engine when we are in the power range 250 to 300 hp.
And we have tested many turbos during the years!
The reliability of this turbo is outstanding.
Both the wastegate and the blow off valve are integrated in the turbo.

The configuration of the exhaust manifold is important for how the turbo system acts.
A long manifold will usually deliver high peak power, but the spool up time of the turbo can be slower.
If a long exhaust manifold is used, it is often better to us a slitghtly smaller turbo, but then the peak power will be less due to the increasing exhaust back pressure…
But the main problem with long primary exhaust tubes when using turbo is the gas volume that will fit inside the tubes.
When the engine hits the rpm limiter, it creates more or less exhaust bangs inside the exhaust.
This issue can hurt the exhaust valves, and the result may end up in a major engine failure.
A short header will rapidly reduce the risk of engine failure.
If the header is made extremely short, the turbo spool up time will be slower and the peak power will be less, so that is not an option either.
On many vehicles, it is not possible to choose the most perfect turbo location because there are no space, but on the YXZ turbo, is is plenty of space to put the turbo exactly in the best location. And that is what we have done.

Air Filter.
The air filter setup is very important for the life time of the engine.
We have chosen a large air filter that is easy and fast to replace.
The air intake to the turbo air filter is in the same location as the stock Yamaha air intake.
The clean air that has passed the filter is lead down to the turbo through a large silicone hose.
When driving i very dirty conditions, it is possible to place a pre-air filter before the actual air filter.

When the air pass the compressor of the turbo, it gets hot. A modern turbocharger has very high efficiency, but you can still expect that the temperature rises about 100 degree C at 100 kPa turbo pressure.
This temperature rise is not what you want. That is why an intercooler is used.
With an efficient intercooler, you can expect both higher performance and better reliability.
If it is possible to install, an air / air intercooler is normally the best choice for a normal vehicle.
But to get best possible efficiency of the cooler, it shall be placed in the air stream from the speed of the vehicle.
Our intercooler has very high efficiency thanks to the size and the location.

The development work with the turbo kit is very exciting. This is the best part of our job.
We spend a lot of time testing out all the components, so we are sure we offer the best possible setup.
To begin with we test the engine stock, so we know what we have to deal with.
The stock power on our YXZ 1000 was 109 hp. Yamaha claim 111 hp so this was what we expected.
The end cap in the end of the stock muffler is very restrictive.
We tested to install a much larger end cap, and then we got 113 hp!
After that we removed the complete muffler, but the power stayed the same.
The camshafts on the YXZ has much less lift and duration compared to the Viper -16 snowmobile cams.

We had to try the YXZ 1000 engine with the Viper intake + exhaust camshafts just to see the difference.

The power went up to almost 120 hp. We added some fuel to the stock injectors with our MCX EFI-box.
We also tested to drive with the Viper intake cam + the YXZ exhaust cam. The power then went down to 118,5 hp.
Turbo testing !
Now the fun started.
We installed a 2 mm cylinder spacer to avoid detonation, adjusted the cam setting to the stock lobe center (The cams rotate a few degrees when installing a cylinder spacer).
After testing different exhaust pipes, mufflers, and some different plenum sizes we started to get really good results!
Normally you can expect to double the power and torque at 100 kPa turbo pressure if the turbo kit is well designed.
When using the Mitsubishi 16T turbo, we usually gain sligthly more performance.
But in this case, we gained much more.
At just over 1 bar turbo pressure, we passed 260 hp!
This was better than expected!
The intercooler we use is very efficient. (Take a look at the dyno numbers beside the dyno graph below)
That is one reason. The big air filter is another. And we know from earlier that the Mitsubishi 16T turbo is a perfect choice for the engine. We also use extra injectors in the plenum. We have seen that this setup is very efficient.
Plenum on top of the throttle body.
The plenum size and how it is made is often very important for the performance of the engine.
We have been very surprised many times when we tested out different plenums.
The YXZ plenum size does not need to be very big we found out after testing some different ones.

Fuel injection system.
When installing a turbo, the engine will need much more fuel. The stock injectors are designed to handle just slightly more fuel than the stock machine needs. Either the stock injectors needs to be replaced by bigger ones, or extra injectors must be installed. We have tested this back and forward many times on different vehicles.
On the YXZ 1000, we find more benefits with installing 3 extra injectors in the plenum.
When driving slowly and on idle, the engine runs nicer with two normal size injectors / cylinder compared to one big.
And the vaporizing of the fuel is getting better at high rpm when the injector is far away from the intake valves.
MCX EFI-box generation 5.
We developed our first generation of EFI-box 1999.
The EFI-boxes has become more and more advanced during the years.
The last 4 years, we have used the 5:th generation of EFI- box.
This last version is very reliable and it can control a lot of interesting things.

The EFI-box is specially designed to be used on turbo engines with fuel injection.
It controls either the stock injectors or extra injectors. On the YXZ 1000, it controls extra injectors.
This EFI-box is easy to install
The MCX EFI-box also control the boost pressure through the TVC (Turbo Control Valve)
When climbing up in altitude, the MCX EFI-box automatically compensates for the thinner air, so the power maintain the same.
To get the best drivability possible, the turbo pressure depends on the rpm and throttle position.
Maximum boost at for instance 6000 rpm may sound like a nice idea, but the risk of detonation is much higher at low rpm, so we normally adjust down the pressure a little at lower rpm. At higher rpm, the detonation risk is less, so here we can turn up the turbo pressure. This make the torque curve very flat.
But before the engine reach the rpm limiter, we adjust down the turbo pressure so the power curve is turning down before it reach the limiter.
When driving fast at part throttle, the turbo pressure is normally rather high.
It is better with less pressure at this point for the fuel consumption and for the throttle feeling.


Well-known member
Nov 28, 2007
MCXpress Yamaha Sidewinder / AC ZR 9000 upgrade kits

Dyno Run on the New Yamaha Sidewinder At MCXpress
A impressive consistent 192 hp in stock form.

Sidewinder stock power
The new turbocharged snowmobile Yamaha Sidewinder / Arctic Cat ZX 9000 is the most powerful serial produced snowmobile ever build.
And it has great potential to be even stronger.
Yamaha claim the stock power to be about 180 hp.
The truth is even better.
When we test in our ASB calibrated and certified Superflow dyno, we measure 192 to 194 every run.
The stock turbo pressure at sea level is 65 kPa. (=This is 9,4 PSI).
Very impressive for a stock snowmobile.

MCXpress Yamaha Sidewinder / AC ZR 9000 upgrade kits

Boost compensation for altitude
One of the benefits with turbo is that it’s in these days possible to maintain the power at any altitude.
The ECU gets informed about the barometric pressure and controls a valve (=Turbo Control Valve) so the same total pressure enters the engine.
The baro pressure is about 100 kPa at sea level, and the turbo pressure 65. The total pressure will then be 165 kPa.
At 1000 meter elevation, the baro pressure is 90 kPa. The turbo pressure will then be 75 kPa, so the total pressure will still be 165 kPa.
At 2000 meter, the baro pressure is 80 kPa, and the turbo pressure 85 kPa ,total pressure 165.
Is it actually more relevant to talk about total pressure than turbo pressure, so we will do that in the rest of the text below.
To compare, a natural aspirated engine with 193 hp at sea level, has in best case 0,8 times the power at 2000 meter elevation (=154 hp).
MCX Stage 1 upgrade kit
The back pressure of the stock muffler is O.K, and still, the power increase by installing a less restrictive muffler is rather much.
Just by a switch to a racing muffler, the power at sea level goes up to 206-208 hp. The total pressure increase up to about 170 kPa due to that the wastegate hole in the turbine housing is a little to small for this setup.
At altitude, the total pressure will drop down to 165 kPa again, and the power will be just over 200 hp.
One problem with just installing a low restrictive racing muffler is that the air/fuel will be leaner.
The MCX Gen 5 EFI-box is specially developed for controlling the total pressure and the opening time of the injector.
The best lambda value on a turbo gasoline engine is between 0,80 to 0,85 at full throttle. We prefer to run rather rich to get as much safety limit as possible against detonation, so we aim for lambda 0,80.
If we run richer than 0,80 the power drops rather rapidly, and if we run as rich as 0,73, the engine starts to misfire.
(A natural aspirated engine is normally performing best at lambda 0,90)
The MCX stage one kit will include our EFI-box that controls the fuel and the boost, and a racing muffler that is less restrictive.
We have tested some different mufflers. All with low back pressure, but with different noise levels.
In many areas in the world, like in Scandinavia, Finland, Russia and the east of Canada and USA,

We have set the total pressure to just over 180 kPa. The engine delivers 225 hp at this point.
The stock ECU has a boost safety system that cut off the engine if the total pressure rise higher than about 185 kPa.
With our stage one kit, this safety system is still active. This makes it very safe.

Stage 2 upgrade kit
The turbo, fuel pump and injectors can handle more power.
And the engine show no sign of detonation with higer boost when using pump gas 98 octane RON.
So with just some more electronics to avoid the boost safety system, we can rise the pressure more.
At just over 200 kPa total pressure, (=15 PSI turbo pressure at sea level) the injectors are fully open at lambda 0,80.
The engine delivers 250 hp at this point

Stage 3 upgrade kit
At higher altitude, the turbo will have to work harder.
The compressor of the turbo will have to pump more the higher up you go if the power shall be the same.
So if you want more power than 250 hp at sea level, or if you want to keep 250 hp or more at high altitude, the stock turbo on the Sidewinder becomes to small.
We are now testing bigger turbos and a bigger intercooler for more power. And the fuel system also need an update to reach more power.
More information will follow soon…..
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Well-known member
Nov 28, 2007
Rocket Man Jake Shupe's MCX Sidewinder

Jake Shupe Ripping his MCXpress Stage 3 Sidewinder in the high country !

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