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Snowmobile Suspension Tuning, and Turbo Idiosyncrasies


by Marc Cantin ,

Turbo: power to play with, but at what cost?
Like Pascal, I also felt turbo lag (The delay between opening the throttle and the arrival of all that power) on the 177 hp Turbo Sno Pro. Here's what happens.

The most powerful touring snowmobile on the market, will appeal to speed addicts.

In a turbo system, exhaust gases drive one side of the turbocharger, using the energy from expanding hot exhaust gases to pressurize air before it is pushed into the intake side of the cylinders. More gases and more fuel mean more power, which is the idea from the beginning.

Much like Hygrade franks (More people eat them 'cause they're fresher, and they are fresher 'cause more people eat them!), a turbo depends on exhaust gases to increase the volume of air going into the engine, which (you guessed it), increases the volume of exhaust gases driving the turbo. The system is all happy when the throttle is open and gases flow in great volumes.

But when the throttle is closed, such as to take a corner, the intake of fresh air going into the turbo is reduced and the volume of exhaust gases drops accordingly, forcing the turbo to slow down. When you open the throttle again, the turbo will only deliver a little pressure at first, giving the impression that the engine hesitates. After one or two seconds, exhaust gases increase and the turbo is able to pick up speed and shove more air into the engine. Output rises and everything is back to normal.

Advanced though complex and expensive techniques help manufacturers reduce turbo lag, but the cost is often too great for snowmobile enthusiasts. My advice is to learn to anticipate power needs and hit the throttle a second earlier. Be careful when modulating the throttle, however; too much speed too early in a corner will force you to slow down at the exit, re starting the bothersome turbo-lag circle again and killing your drive onto the straight.

In straight lines, the latter becomes orgasmic, almost like a sportbike with 150+ ponies on tap.

Photo Credit : Philippe Champoux, Matthieu Lambert
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