OK,

I have heard so many opinions that I don't know what to believe. I've owned several quads and looking a big bore (650cc and greater), I'm trying to figure out from a design stand point what makes the most torque and horsepower AND WHY?

I currently have a 2009 Suzuki KQ750 that I bought new and it has 49hp. It is very powerful. I did have a 2005 Kawasaki BF750 carb and it had 49hp and it was very powerful. I felt the BF750 had more power in the low to mid and the KQ750 had more power in the mid to upper range.

Now I have a 650 Can Am Outlander DPS Max and it even has more power @ 62hp. But I hear people say a big single will have more torque, yet other people said a v-twin has more torque. I've even heard a parallel twin has the best balance of torque and horse power.

Can someone explain the design differences as to what is the truth and why?

 

aahhh...there are literally books written on this subject. There are soooo many factors that go into an engine's final output. The configurations are often a factor of cost...a single cylinder engine is considerably cheaper than a V4, for example. Bore & stroke have a significant influence over HP & torque curves as well. V-anything will likely be a more vibration free experience as the rotating mass kinda offset. More cylinders mean the engine's load can be shared, so they tend to have a longer service life at high output numbers vs. a single cylinder. I could go on & on, but I don't think anyone can fully answer your questions without writing a book or 2...

 

I'm no 5 star mechanic but here are my observations.

Single cylinder has more of an uneven thump at idle than the twins. Factories usually add a counterbalance so it doesn't vibrate as much as it would without one. Per turn of the crankshaft the single piston delivers more power (larger cylinder) than the twin that divides the turn between two cylinders. Each smaller cylinder provides the power for 1/2 turn of the crankshaft. They also counterbalance each other for a smoother running machine.

Personally, I don't see much difference between a straight twin and a V-twin. Both offer smooth acceleration and idle. The straight twin, like Polaris uses, is more narrow than the V-twins like Kawasaki and Can-Am use. For a guy like me at 6'3" the wide Can-Am doesn't bother me as my legs are long enough to get around the extra engine width. I notice on my son's Scrambler 1000 there is much more area for floorboards and you can easily get your legs around to clamp the front in turns. Not a huge difference for me but might be a nice thing for smaller guys.

 

Thanks for the replies. Like you said, there is so much information out there and truly I'm not sure anyone fully knows. But, if we were to take the same size, say 750cc single vs a 750 v-twin and they both had the same compression, bore and stroke, which makes more HP and more torque and where at?

I know this is a loaded question. I'm just trying to educate myself. To me, the v-twins that I have owned (Prairie 700, BF750 and now Outy650) seem to be more powerful from the start to mid range. My big single KQ750 shines in the mid and upper range. But then again, I might be missing things like clutching, etc.

 

From what I've seen, a vtwin vs an inline twin, the vtwin is quicker on bottom end while the inline twin is faster on top end. Once you get to 1000cc( like a Scrambler 1000(inline twin) vs a Renegade 1000(vtwin) for example) you have so much power that it really doesn't make much difference. The inline twins do make for a narrower engine, which is nice on an atv. Singles just aren't as smooth as they are harder to counterbalance than having 2 smaller cylinders. Singles will use less fuel though, if that is important in your buying decision. With pretty much all larger atvs being efi now, really poor fuel economy is sort of a thing of the past. I'm sure the newer efi Brutes get much better fuel economy than my dual carb 650, which is quite a thirsty beast. Maybe its partly my own fault as its just too much fun to crack open the throttle even when I don't really need too, even if its for only a few seconds at at time.

 

I guess you haven't heard my Arctic Cat 700 Diesel, haha. It's a side by side and I'm hopefully, about a week from finally getting it intercooled and turbocharged. Most people think it sounds like crap, to me, it sounds like power, or maybe torque, haha. Sitting on it at idle is a bit like a Harley, you get a bit of up and down thump. I'm hoping for 50 hp and 100 ft/lbs.

 

The Sportsman 800 used to put out 50-54.8 HP depending on who you believe. Information is a little sketchy but it was 760cc. Shouldn't your 700 diesel put out more power than that with the turbo?

BTW the Sportsman 700 was 680cc and put out 44-45 HP. If anyone can find the horsepower rating for the other 700s we can start comparing them. Or compare the 760cc Sportsman 800 to the 750s.

Edit: I forgot there were some numbers listed in the first post. We already have a starting point for the 750s. The Polaris with the 10cc bigger parallel twin has more power than the 2 750s but not much.

 

Here are some ATV horsepower numbers that I found.

 

Good job finding the chart. I see 5 of them are hovering around 48-50 HP. And it's just sad that the Rincon 680 has 5.6 HP LESS than the Sportsman 570. What the heck are they doing with those extra 110ccs? Over the years a few people have acted like I didn't know what I was talking about when I said how under-powered all of Honda's utility quads are. I've even told people considering Honda to get at least 150ccs bigger than what you think you need. It should be noted too how Can-Am generally has way more power per cc except for the 1000.

 

I agree with you. Honda has been missing the boat by resting on their past reliability record. There is no reason they shouldn't increase the HP in their quads. IMHO, I think this is what HP should be in each cc range because these quads are getting heavier.

800cc to 1000cc should make a minimum of 70hp
600cc to 800cc should make a minimum of 60hp
500cc to 600cc should make a minimum of 50hp
400cc to 500cc should make a minimum of 40hp

Yet we have a 680cc Rincon that only makes 38hp and a 570cc Outlander that makes 48hp???? Just doesn't make sense.

When I look at my 35 years of ATV riding and the quads I have owned along with what I hear, I rank the following.

Reliability
1st Yamaha
2nd Honda
3rd Kawasaki
4th Suzuki
5th Can-Am
6th Polaris
7th Arctic Cat

Yet when you look at HP per cc class of quad
1st Can Am
2nd Polaris
3rd Kawasaki
4th Suzuki
5th Yamaha
6th Arctic Cat
7th Honda

If Honda and Yamaha made more powerful quads, they would be at the top in everything IMO. I would love to see a 2-seater Yamaha Grizzly 700cc to 1000cc that made a minimum of 60hp.