HOW TO GET POWER OUT OF A 4-TEC

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Everyone is buzzing about the potential for naturally aspirated 4-stroke power in snowmobiles.

The point is, there are several really good, durable 4-stroke engines out there in the industry that make excellent power in the 130-hp range.

Yamaha’s 1049 triple is one of the most attractive 4-strokes to ever grace a snowmobile chassis and there’s a big-time love affair going on with Ski-Doo’s 1170cc 4-TEC triple.

A question we’re frequently asked is, “What do we think Ski-Doo is going to do with that engine?” Our best guess is the Valcourt engineers are working on something to bring that mill up into the 150-plus horsepower range.

Some of our readers and viewers tell us this engine’s CPU can simply be re-chipped to get it into this range. We believe this is true but here’s what happens and it may be why Ski-Doo has not amped-up the power with this motor yet.

After speaking with a couple of engineers we learned that the 1170 is fully capable of producing more power – but there’s a caveat.

The engine currently makes its power on a very flat, broad curve and has a full shift RPM somewhere around 8,400 RPM. It generates excellent torque numbers at its current max-rev level and has proven to be dead reliable.

By messing with the cam timing, the computer and even the exhaust and intake, the engine would produce power in the range everyone is hoping – however – it would need to rev up close to the 10,000 RPM range.

Frankly, this changes everything. It would likely result in the necessity for a gear reduction system like Yamaha uses with the Apex so the clutches could handle the extra RPM reliably. Hmm. We all know how much Ski-Doo hates adding weight.

If the product people at Ski-Doo don’t want to do this it leaves a couple of alternatives: One, add a turbo to the 1170 (more weight) or two, punch the engine out to over 1300ccs.

Increasing the displacement this much would likely result in the engineers starting over with a clean sheet of paper – a completely new engine.

We don’t know where it will go with Ski-Doo’s 4-strokes but we’re sure Rotax is working on it.

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