Cold Turbo for Polaris Indy

A new product for old F/C Indys

Polaris Cold Turbo sketch
There is a basic problem with my drawing. The fan spins clockwise, so I will reverse the snail in the actual product.

The Big Indy Trail problem

Indy Trails from 1986 with Fuji fan-cooled 433s and 488s had overheating problems. On warmer days and slow speed snowmobile operation several events occurred and occur to this day... power diminishes noticeably, the sled will stop and when cooled down will restart. Some engines just seized. Not at all what owners expected from stone reliable Polaris engines and for the “wife’s” sled.

Running around the barn

I read with some mirth the many cures owners used to try and stop the problem... rejetting, oil pump recalibration, carb overhauls, plug changes. The problem had a very simple cause. The fan on Fuji engines pulled intake air directly from the hot exhaust only inches away. Of course the engine turns into a dog. The fuel/air mix ratio was disturbed. Heat robs power.

The factory I’m sure knew about the problem but never supplied a remedy. They did sort of. When they made the 550 engine after 2009 they restyled the recoil cover to draw air through the hood deck. That cover could be retrofitted to the 433 and 488 but the owner had to cut a hole in the hood. My guess from all the on-line complaints is that the cause and any formal fix still lie beyond the common grasp until now.

My new Cold Turbo© is a simple system that draws fresh cold air from the pan’s right side. All Trails had little pop-in louvers well rear of the engine. I don’t know what the intended purpose for them was but I’m using it. My kit has four basic parts:

  • NACA-shaped intake duct which fits on the outside of the pan and uses the four louver holes. The NACA shape is designed to compact and speed air flow
  • A hose fitting on the inside mates to the outside duct
  • A 3” aluminum flexible hose runs under the exhaust and connects to a hose fitting on the...
  • Snail-shaped cover bolts to the recoil cover. Snail loops grow ever smaller further speeding the air speed.

The benefits

Air flow will be greatly enhanced. The fan still pulls at the same rate but my kit parts compresses and speeds air flow. I suspect Fuji over heating will go away. And no I don’t think the exhaust will heat the air in the flex tube-it will be moving too fast.

Cold Turbo fits these sleds if you are having over heating problems:

  • All Fuji 433 Fans
  • All Fuji 488 Fans
  • 550 Fans before 2009

How to get one

You can’t now because I’m building it as we speak. I can’t even guess the price.

Action now

If this product looks as though it will cure some of your problems I want you to email me and tell me to put you on the followers list. As I make advances I will send out mass mailings so you can see the product take life. If you have friend with 433 and 488 Fujis, have them write too.

Product report 12/5/16

cold turbo 1Here you see the base plate which mounts to the six 6mm holes in the recoil cover. That disc on top is suspended about ¾” above the cover.

cold turbo 2Here are struts that establish the external cover with the base plate. I’m using cut pieces of 3/16” fiberglass as a frame for what follows.

cold turbo 3With flexible sheet of fiberglass woving I am closing in the structure. This took one and a half days.

  • [Site updated May 27]