In the January 2000 Dirt Wheels, they have an article on a totally modified Hot Seat Sport 400. In the article, they put the quad on the dynojet dyno and, hmmm, it only puts out 45 hp. Since this is a chassis dyno, it shows how much power is actually reaching the rear wheels.

In the same issue, they dyno a bone stock 2000 Banshee at 39.8 hp. Interesting.

So this begs the question - Why do I keep hearing that a modified 400L will "smoke" a Banshee? It doesn't make any sense, unless we are talking about a completely modded 400L racing a stock Banshee. Then it might have a chance. Just put pipes on the Banshee and its hp rises to over 46, and it weighs a lot less. By the numbers, it sounds like a Polaris can't get all of its power to the rear wheels due to the automatic tranny. I'm sure that crankshaft hp is a lot higher on this motor (60 hp???), but that's not a real number since the crankshaft doesn't connect directly to the ground.

I'm not trying to start an arguement. I just want to hear what other people have to say.

 

I don't know what the deal is. I think they have their wires crossed or something. The way I remember a stock Banshee was like 37 or 38HP. And a stock 400L was like 37HP. At the crank on both. With just my mods my Scrambler should be about 46HP. Jerry & Jacks 400's are like 60-65HP. I don't think a stock Banshee puts out 38HP on a chassis dyno. I think they must have forgot to mention that or something.
They main reason a stock Banshee is faster isn't the power, it's the weight difference.

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Andrew Thomas

'99 Scrambler 400 & '99 Trailblazer, both with RCR mods.

 

The 39.8 hp was on a dynojet chassis dyno. Every other dyno sheet I have lists the stock Banshee at 38 - 39 hp, so this one is not out of line. Maybe the test was run under better conditions than the others I have seen.

Crankshaft hp doesn't mean much if there are tremendous losses in the driveline and transmission.

I'm not discounting the 60 - 65 hp at the crank numbers you mention for the 400L. It's just that I didn't realize (if the Dirt Wheels numbers are correct, I'm assuming they are), that the losses in the PVT were possibly so high. I would bet that companies that do Polaris engine work would have a better feel for how much of the power actually reaches the rear wheels, that is if they have done dyno testing.

I realize there is a weight difference, but it's only about 70 lbs., right?? That wouldn't offset the difference in hp if the 400 actually put 60 hp on the ground and the Banshee put down 39. See what I mean? It just doesn't make sense. I'm just trying to make heads or tales of this issue since it's the first time I've seen dyno information published on a Polaris. It's very intriguing to me.

 

Andrew- It's not the HP? Yes the Banshee is lighter, and will always smoke a 400L. The crazy thing about it is. The Banshee is 100 cc's smaller. Now hows that for HP.

 

Big Cat,
The 400L is only 378cc, compared to a 350cc Banshee.
I don't know maybe that's why I don't like DW magazine because they are goofs. It's just hard to believe that the Banshee is 38HP, & then on a chassis dyno they are 38.5 HP or so??? It gains on the chassis dyno? no way!
I'm not putting the Banshee down, my friend has 2 of them. So I know that they are not "unbeatable". I've only got $300 worth of mods and my Scrambler (4WD) "only" loses by 3 quad lengths. Not bad for a 519lb machine against an all out racer. A loss of 20hp through the drivetrtain is hard to believe, when the Banshee stay the same. That drivetrain must be coated with Teflon!
I don't know what the problem was... You can do a few hundred dollars of mods to a 400L and beat Banshee and still have less in it than the cost of a stock Banshee. I don't know about those numbers, all I know is what I've seen. If Yamaha rates the Banshee at 38-39HP at the motor, it can't possibly carry it through the wheels with no loss.

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Andrew Thomas

'99 Scrambler 400 & '99 Trailblazer, both with RCR mods.

 

Big Cat I'm sorry the Banshee is "only" 347cc, compared to 378cc. Not the 100cc difference you stated.
Sandman, I looked at that article. One dyno is a Powerjet, the other is a Dynojet. Maybe that has something to do with it??? I don't know what the differnce is. Do you have any idea?
c-ya,

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Andrew Thomas

'99 Scrambler 400 & '99 Trailblazer, both with RCR mods.

 

Excuse me Andrew I didn't mean to say one hundred. I was thinking Warrior for some reason. I don't go by dw either. I do like the Banshee. Never ridden one but I have ridden a 400L Dang fast bike. It's a little loud though. Sorry guys I'm gonna have to go with the LT quadzilla 500 on everything.

 

Sandman; you are correct in stating that the Polaris clutches do not get the power to the wheels efficiently. However in defense of the CVT, when tuned properly it is more efficeint that a convential transmission.

Olav Aaen, of Aaen performance has over 30 years experience with the CVT. With a Masters Degree in Engineering he has single handily lead the evolution of the CVT to what is is today (referring to it's use in ATV's and sleds).

As a convential tranny shifts the RPM's of the motor are continualy changing. Meaning you rev out to say 9000RPM's in first, shift, RPM's then drop to say 4000, rev it back out to 9000, shift, they drop again to 6000, shift, rev out to 9000 and so on untill your wide open in 5/6th gear. Through this process little time is spent at 9000RPM's, where the motor is making it's peak HP.

With a CVT you can set the engagement of your clutch to various RPM's. Let's assume the average is set to 3000RPM's. On a motor that revs out at 9000, your already 1/3 of the way there when you start moving. This leaves only 6000RPM's for the motor to bulid before it's running at it's peak HP. And, with your CVT tuned for a "straight shiftout" the tranny will hit 9000 and hold the engine RPM's on the power curve while it continually changes ratios. Thats efficientcy.

The inherent problem with the Polaris ATV motors is that they will only rev the 7000RPM's reliably (stock is like 5600). And when you package them in a frame built out of lead it only adds to the equasion.

Aaen Performance sponsers a SCCA race car that uses a sled motor, with a CVT and reliably delivers 200HP, at th erear wheel. There are so many different factors involved in tuning a CVT, compared to just buying new plates and a basket for a convential. This is very time consuming, requires many tools and can become rather expensive, which are a few of the reasons I believe it really has'nt taken off. Weight is probably the biggest factor to overcome for high performance ATV applications.

I hope this helps a bit, as I still am learning even the basics of it myself. The Hot Seat 400 used for the article was only making 46HP at 6300RPM's (according to DW). Hot Seat has a few good products, but if DW wanted to do a real article on a modded 400, they should've contacted HPD whose motors are built to peak at the 6900-7000RPM mark producing nearly 72+HP, as DW stated "the Hot Seat motor will rev up to 7000, the HP drops off considerably". Assuming a 15% (worst case) loss of power through the use of the CVT this makes for 60HP at the crank with the HPD motor, impressive!

The clutch components/tuning used on the test ATV was average at best. The use of ball bearing driven clutches, Kelvar belts, and an infinate amount of spring and weight combinations will dramatically improve the efficientcy of the CVT to less than a 10% loss of power.

So on an ATV that cost $4900, spend $1200 on motor work (using the printed prices from the atricle for the Hot Seat work) you now have a quad making 46HP, at the crank, for $6100, as opposed to the $6000 Banshee making 40HP. Now this is where I have to difuse the situation to aviod an all out argument here. At this point it is up to the individual buyer to make PERSONAL choices about which ATV they prefere.

By the way, in '93 a Polaris ATV was the FIRST ATV to cover the 3500 mile long Paris to Dakar Rally, after convental tranny ATV's, including Honda's, had been trying for over a decade!


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Jerry Goodman '99 400L, '98 TBlazer



[This message has been edited by A400L (edited 12-15-1999).]

 

I've been reading the ongoing conversations (above) and one question I can't get out of my mind is does anywone dyno the engine at both the crank and chasis to guage tranny efficency? I'd think that would put the question to rest about tranny efficiency?

I'm struggling with which machine to buy? I Really like the scrambler set up but, am afraid of the PVT tranny. Can it really be as efficent as a conventional tranny?

 

Nice post Jerry, but there are some holes in it. Auto trannies slip the clutches in order to maintain engine rpm, that's a given. The same thing happens in an automotive auto tranny. Were you aware that in a typical aumotive tranny, that they are only about 70 - 75% efficient? That's a fact. With a manual tranny, efficiency climbs to roughly 85 - 90%. Where am I getting these numbers? Well, being a mechanical engineer, I've run into these issues over the years. If I had to, I could find documentation on them, but these numbers have stuck with me since they are of interest. I have no idea how you could say that "worst case" losses on the PVT are 15%. That doesn't make sense. I think we're in agreement that a manual tranny is much more efficient. Using your 15% loss, if they measured 46 hp at the rear wheels, then the crank hp would be 46 / .85 = 54 hp. Using a more realistic loss percentage of 25%, the crank hp would be 46 / .75 = 61 hp, which falls right into your original 60 - 65 hp range.

What about the Banshee? First off, Yamaha doesn't list a hp number, only a torque value of 33 ft-lbs at 7000 rpm. Using the standard formula of hp = torque x rpm / 5252 we get hp = 33 x 7000 / 5252 = 44 hp (this must be a crankshaft hp number). Now using the 39 hp measured on the dyno, we can see the efficiency of the entire driveline. 39 / 44 = .886 or 88.6% efficiency. Right where it should be.

The only missing link here is a crankshaft hp number for the Hot Seat engine. We could use that to determine the actual PVT losses, which I expect are a lot higher than you may think.

Oh, I believe the Powerjet dyno is the name of the dyno that Dynojet makes.

BTW - how much would it cost to remove 100 lbs from the Polaris??? Pricing is only relevant if you make ALL things equal - weight, power (at the rear wheels), handling, suspension, reliablity, etc. AND - is that $4900 out the door??? I paid $5960 out the door for my '99 Banshee. What'd you pay out the door???