O.K., at the risk of "honking someone off" I'll give you my two cents. Does Polaris make a sport quad? Yes. Do they make a high performance machine? No.

I seperate the machines into two different catagories. The line between high performance machines and sport machines just keeps getting blurrier and blurrier. I used to consider electric start and reverse as standard equipment in the sport class, never to be used in the high performance class. But when it comes to kicking over a big (400 cc +) four stroke single, I'll take electric start any day.

Still, there is a way to distinguish between the two. Horsepower to weight ratio is the one that comes to mind. Sure the 400EX and the 500 Scrambler make about the same rear wheel horsepower, but the Polaris weighs more than 150 lbs more (depending on the model). The DS650 and the Polaris 400 Scrambler 2x4 weigh about the same, but the DS has way more horsepower. Is any one starting to get the drift here?

We could probably have endless discussions on the difference between rear wheel horsepower versus crankshaft horsepower, especially when it comes to CVT machines. But the problem is that most people want to compare the RWHP on a manual clutched machine to one on a CVT equipped machine. Dynos (most specifically chasis dynos) aren't set up to take CVT machines. More than likely, they'll actually give a lower number than the same motor on a manual clutched machine. An interesting compairison would be the Sportman 400 vs the manual shift Xpedition. Both use the same basic motor, but one employs a manual transmission and the other uses a CVT. In theory, both should make the same crank shaft horsepower, but the RWHP would be different. It would also be interesting to see the drag race results on the two machines (assuming both weighed the same).

In answer to the question originally posed:

500 H.O.- 38 crankshaft horsepower

Regular 500- 32 crankshaft horsepower

400- 36 crankshaft horsepower

250- 22 crankshaft horsepower

 

Mike --

I agree with one exception. There are several dynos out today that can accurately measure the hp on a cvt equipped atv. That was not the case a few years ago, but there are quite a few of them today. They are costly and many of the atv speed merchants making Polaris stuff don't have them because of the cost. How these guys get these numbers is anyone's "guess". Many of the speed merchants are still using this as an excuse. The pro shops don't use excuses and will tell you their nubmers.

With more and more cvt equipped "utility" atv's it was only a natural progression to have the proper equipment to get these numbers right and do comparisons as they can today. The days of the backwoods shops with seat of the pants stuff is coming to an end. With the resources the large shops have today, the little guy's days are unfortunately numbered.

I personally never believe anything but rear wheel horsepower numbers. The rest is for the record books and advertising hype. I recently had my Duramax diesel on a dyno to get a baseline as to where were are at before we start making some changes to performance exhaust system, airbox modifications and computer module adjustments. I know where we are starting and will know what we have "at the rear wheels" when we finish each stage. EGT's are another good reading to pay attention to when making performance changes and doing dyno pulls to check things out. Some changes are not worth it if the EGT's can't be controlled to tolerable levels. Many one race missiles are created without proper readings.

If you can't get it to the ground, it's just like it's not there.

(Mike - how did the sprocket chnage affect the top end for you?)

Best regards,

 

polaris has a sport quad????

 

Jack,

You're right about the dynos. The problem is that most people who compare their machines, compare them like apples and oranges. They compare them on machines not equipped to properly test CVT machines (modquad's machine test in ATV Sport comes to mind), then test manually clutched machines right behind them.

I kind of figured that you might have a new project when you talked about getting more performance out of your truck. Wow, that's one tall order! I'm glad it's you and not me. Other than a diesel's basic operating principles, I'm lost when it come to squeasing performance out of them. I can figure out how to get more performance out of a gas engine (if speed is a question of money, I can't afford to go fast, LOL).

The 30 tooth sprocket gives VERY good acceleration all the way to the top end. It seems a lot faster now, but my guess is that it's only about 5 mph give or take. Still it's scaryfast. Fast enough that I really don't want to open it up without all my gear on. Believe it or not, it didn't affect the low end that much. Wheel spin is down and wheelies are easier. It's still not like it was before I put the 3"+ swing arm on it, the machine will not wheelie at speed, it just accelerates hard.

jon 1,

Yes, they do. See the reasoning above in my first post. Check out paragraphs two and three.

 

Hey Mike -

I'm finding that it's a lot easier to get hp from these diesels than from a gas engine. We did some baseline dyno pulls to check where we are at now so I can compare the differences each step might make. The interesting thing is that diesels don't get much hp improvement with exhaust help, it only lowers the egt's and allows the turbo to spool quicker. It does take 1 sec. off 0-60 runs. They have adjustable black boxes to change the fuel injection timing and pressures to enhance performance. Fuel Pressures on these diesels are 22,000+ psi.

The computer boxes will give you 30 - 70 - 100+ hp and 100 - 150 - 250 ft.lb. torque increases. You can basically have a highway hauler with 320 rear wheel hp and 650 ft. lb. of torque on the middle setting. Quite impressive. And boy, you can really feel it, it's for real. This thing goes up to 100 so quick, we have to find a way to disable GM's speed limiter in the near future. I'm having a little fun with the truck instead of the wheelers right now.

It's amazing how fanatical some of the diesel guys are. They have "dyno run weekends" and burnout constests, to measure hp and have some fun. They are dead serious on performance enhancements which I like. It ain't cheap, but the gains/rewards are great compared to gasoline engines.

Stay tuned . . .

 

Personally, I think the results on my runs would've been greatly increased had it not been for some "slightly" misaligned titanium rear wheel studs. Even after using an alignment dowl setup, the thing still shook like a Yugo. This has since been corrected, and yes they are still titanium. Also HPD has provided a different compound helix for the roller clutch. The main comment was that (I'm not bragging, just complementing HPD's HP) the motor was simply over-powering the clutch. I'd really like to get out and run it up again.

If you guys want diesel HP and MONSTER TORQUE visit the Desiel Register...I think it's even a .com with some nutty pics of 500hp with 1000ft/lbs of torque. An incredible engine that can still provide great gas mileage to boot. Tree stumps anyone??

Ken Thompson