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Stuffed: Sno Pro Part I


(8/13/2009)

For two years we’ve watched the purpose-built Arctic Cat Sno Pro 600 race sled succeed in cross-country and snocross competition.

Accustomed to seeing race sled technology transition into consumer sleds (think 1990 EXT Special, the entire ZR series, and the Firecat), we expected that the latest race sled would get trail-friendly 600 and 800 engines and be available at our local dealer in full-production quantities.

So when Arctic Cat unveiled the 2010 model line and we saw the consumer-available Sno Pro 500, the reaction was, “Cool. Now where’s the big iron?”

“Won’t fit,” said company officials.

 

600 Race engine in the chassis

The 600 Race Engine inside the Sno Pro Chassis. Note how close the relatively-short tract flatslide carburetors are to the belly pan, as well as the mounting area on the front of the case. These two areas are where the 600D and 800 H.O. engines are too large to fit.

 

600 Race Engine Cylinder Head Clearance

See too how close the cylinder head is to the bulkhead. This is the area where the 800 H.O. exceeds chassis capacity.

Assuming this was a simple ruse and that we’d see a special autumn announcement (perhaps at Hay Days, where there is a history of such pronouncements) of a 800 Sno Pro, we looked for a wink or nudge that supported our hope.

Nothing.

My own off-the-record conversations with Cat engineers produced the same answers:

The 800 doesn’t fit in the chassis, and neither does the oil-injected 600.”

Still skeptical, it wasn’t until I spent some time with Cat engineers Troy Halvorson and Greg Spaulding that I truly believed the company line.

500, both 600s and the 800 H.O.

Spaulding was kind enough to line up what they call the “500AA” (the 500 EFI twin used in the F5 and the new Sno Pro 500), the “600 Race” (the pre-mix-only, carbureted 600 twin that comes in the Sno Pro 600), the “600D” (the oil-injected, 120-hp 600 EFI twin used in the F6) and the new 800 H.O.

Only the 600 Race and 500AA engines are capable of fitting into the tight confines of the Sno Pro chassis, according to Cat.

Comparing the engines side-by-side, it’s very evident the dimensional differences between the engines. Similarly, with the body panels off of Sno Pro it’s evident just how little space is available for the engine, intake, exhaust and muffler.

Compared to the 600 Race engine that the chassis was designed around, the 500AA is clearly smaller, although getting the injectors to fit without hitting the steering post required a new intake tract.

 

600 Race Engine Left, 800 H.O. Right

With a larger bore, the 800 H.O. is wider and deeper than the 600 Race, which means that the top of the cylinder head would hit the bulkhead. And its injectors are significantly longer than the short-tract flatslide carbs/boots used on the Race engine, and would bottom out on the bellypan. Just as challenging, according to Spaulding, would be achieving the regulated sound level with such a small space allocated to the muffler.

Given the similarities between the 600D and 600 Race engines, I expected the 600D to be close enough to fit into the chassis. There are two critical problems.

The first is the oil pump, which exists on the 600D but not the Race mill, and which directly interferes with the engine mounting location and the bottom of the bulkhead.

The second is added length of the EFI injectors, which interfere with the steering post from a width standpoint, and whose added length would bottom out on the bellypan.

I’m convinced that the current Sno Pro chassis doesn’t accept the 600D or 800 H.O. engines. Yes, I expect that one or two highly-skilled garage mechanics will stuff a larger, carb-fed engine into a Sno Pro chassis, but that’s a different challenge than efficiently and economically building 5,000 production examples.

Now check out Part II, where I discuss why the Sno Pro chassis wasn’t designed to accept a larger engine, as well as speculating the reasons why Cat isn’t willing to retool the chassis.



Comments (12):

John says:
9/13/2009 3:46:00 PM

Hmm... i think its funny how a few people have already put the 04/05 800 mod motor in the 08/09 sno pro. There is a guy in my area that has put a f1000 with a DandD 1200 big bore in one. i think its more a money thing that a "It wont fit thing"

Richard Buresh says:
9/13/2009 7:01:00 PM

Excellent article , This is the type of information that is always hard to find , but very enjoyable to read . Great pictures too . The only think that would be better is having more of it to read . Thank for a great story .
John Sandberg says:
9/14/2009 6:00:00 PM

More information to come later this week. Agree that it's interesting when people mod the big stuff (especially before they've even ridden it). However, there is something intoxicating about pure power. I've had the fortune to ride the Sno Pro 500 and I can tell you this: in rough conditions or on most trails, there are VERY FEW sleds that will keep up. Especially if you're riding through most of a tank of gas and not stopping.
Jeremy Schoeder says:
9/22/2009 10:05:00 PM

Great read! A bit of a "reality bites", but insightful none the less. Love the site and I look forward to more.
John Sandberg says:
9/23/2009 9:57:00 AM

More is coming. Are you the same Jeremy that I rode with on the Cat's Pride tour in the Black Hills, 1996? If yes...HELLO! Give the family my best.
flintstone says:
10/4/2009 3:29:00 PM

I think I see just enough room for a little turbo to liven up the 500!!!
dan flint says:
10/9/2009 8:44:00 AM

your and idiot who wrote this article there is no bulk head on the chassis, its an all tubular frame, and yes a bigger motor will fit in there because the mod motor for these sleds is bigger than a oil injected 600.
John Sandberg says:
10/9/2009 10:17:00 PM

Dan, I'm the guy who wrote the article. No need for name-calling here...doesn't serve any purpose. I want conversation, but not flaming. FYI: "bulkhead" is a general term used for the part of the chassis that the engine mounts to. The dimensions of the oil-injected 600 don't allow it to fit. I've seen the motors in front of me, you can look at the oil pump as well as the throttle bodies in relation to the...bulkhead...and the steering post. Read Part II of the story to learn some of the nuance to this story.
Brad Reardon says:
11/13/2009 5:57:00 PM

We Need that 800 motor in that new chassis Johnny Boy..... It would be great. I have the 2010 Crossfire 800 Sno Pro LE and already had it for a few short runs and this motor kicks ass.... I think it seems to have more power then my 07 Crossfire 1000 Sno Pro...... Cmon Cat.......Stick that 800 in!!!!lol
josh greenwood says:
5/7/2010 1:06:00 AM

I have a 2010 600 race sled and i talk to thearctic cat race director mike K he said that the 2006 mod 800 motor has the same lay down as the 08-10 race sleds and should fit in the pipes will have to be fabed up diffrent to fit. In the chassis
Samson says:
1/14/2015 1:10:00 AM

- No clue! I'm a bad mom, we've never taken the kids sledding other than we get snow. They spent last wkeeend mud/snow sledding on a cardboard box while we were in St Louis there was only about 2 of snow at any given time It was lovely. Lol Sounds like a nice little get out of Salem trip tho! And atleast she got to wear the clothes once February 13, 2010 7:28 am
Daniel says:
1/14/2015 10:25:00 PM

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