Dang man, In one post you took crack shots at just about everyone that post on this forum. Please tell us how you really feel!!

 

Listen here you varmits!!!!

Na, just joshin ya.

Yes, I need about 200hp out of my 730 to stay up with some of you. No Doubt. As far as doing such great things in the last year with 2 strokes... That's exactly my point! I'm sure that when you have success, others will follow and it will cost an arm and a leg at first. Then, as always, more and more companies will start to produce or sell their own the prices will go down. Even if only one company sells the stuff, because there is like 2 million shees around, the price will drop drastically over time. Not saying that two strokes aren't fast, just argued the first point that everything being equal (especially weight) the 2 will win. It's math at it's finest. Obviously if it's real close, the jockey himself could be the difference.... but that's another story all together now isn't it.
Put a guy like Beech on my bike or better yet Bomber's bike.....they're going to be real tough to beat. 222 already proved that this year at Glamis.
Do I think that Bombers nasty two strokes will beat his war winning bike. Absolutely, but I'll let bomber comment on his bikes.

ONLY objection to Y's post is that 2 vs 4 comment early in this thread.

Also, I wish I would have gotten to read the long "rough draft" of the reply. This is a good conversation, and what sets us apart from the rest of the yahoos/forums.

Good rappin' with you cats. Also, no smiley faces on this typing machine. No worries.

 

Theres alot more and more and more questions. I have some answers but I cant reveal the shizzle my ninjas... All I can say is that ive seen alot of potential in motors and alot of untapped hp due to dialing in on dynos with the wrong load. If you do the math you can get semi-close to "dialed" by figuring it out on the hill. good luck!!


I like my old trq curve that peaked very early and held on long.. That curve was for a big hill.

 

Did anyone at anytime come on here and say CC for CC a fourstroke is going to win? Didnt think so. You bring your 80hp two stroke, I'll bring my 80 hp four stroke, we will match the the weight evenly, and run them.

No fourstroke is going to run with an evenly cc two stroke. But match the hp, and the weight, and the fourstroke wins.

 

isn't there a rule 125cc 2 stroke you can use a 250cc 4 stroke? well with a 105 pound engine to start the rotax has something to overcome, but as we are beginning to see it can be done. i'd like to see a lot of the big ds riders lighten there rides, and put the torque engines in there machines, figure if they could get there machines down to375- 400 that would make most of them in the pretty fast range, the look on all the light weights, would be priceless!!! then we would get more buyers and the price would change for the rest of us.

 

I just told you what a small 2-stroke made for torque then you said

nobody compared cc for cc, there was a comment that a 4-stroke out-torques a 2-stroke and that is completely false.

 

well i know this is going to be frowned on but i feel the 2 strokes can still take the 4 strokes, but the gap is closing fast, but our parent company has a pretty neat boat engine commerical going on right now that shows very well for the 2 stroke, but when it comes to endurance the 4 stroke rules[img]i/expressions/face-icon-small-smile.gif[/img]

 

Fair enough.
But a fourstroke does out torque a two. A stock ds at 42 hp has like 36 ftlbs of torque. A 80 hp ds has like 65 ftlbs of torque.
My 1000cc two stroke has 190hp, but only like 115ftlbs of torque.
The R1 spinoff they put in snowmobiles creates 150hp, and 110 ftlbs of torque, and holds 60% of its torque over half its rpm range.
My 190hp 1000cc holds 60% of its torque over about 1500rpms.
Anyhow my drift in all that crap, was a four stroke does create more torque per hp than a two stroke, not saying that a two does not create good torque, just not as much per hp.

 

this is why I didn't let you guys sucker me into answering the question!! There are a few responses that are agreeable to me and a alot that are not.

Think about the questions a little deeper and get some good reasoning behind the theories.

....but this is all keyboard and paper racing- theories are proven on the track! I'm open for suggestions [img]i/expressions/face-icon-small-smile.gif[/img]

222

 

Viper, I like this and I want to take it to the next step. Remember the Hayabusa at 4sw's? That was a 4 stroke that made over 500 hp as I recall and did 106 mph on Olds hill. If I am off on the hp, I know they are making over 400 hp in the mini rails at least. Is there any 2 stroke that could keep up with that 4 stroke on Olds hill?

If you compare a 500 2 stroke to a 500 4 stroke they will make similar torque numbers because of displacement and how much air and fuel is moving through per rpm. It will make approximately twice the hp though because a 2 stroke fires every revolution whereas a 4 stroke has to take a revolution off to push the exhaust gases out. Since hp is the product of torque multiplied by rpm if the 2 stroke has combustion twice as often at the same rpm and as roughly the same torque, it will make roughly twice the hp at a given rpm. Obviously that is oversimplified but the basic theory I think is valid.

If you take a 4 stroke with roughly twice the displacement (DS vs Banshee), the DS will make roughly twice the torque meaning almost equal hp at a given rpm. If these two bikes weighed the same, I don't think anyone is arguing that the lower torque motor would be quicker or faster.

Ok, so the question is why not make the 2 stroke as big as the 4 stroke and make twice the hp and equal the torque? Well, you can do that to a point before you reach physical limitations of the materials and technologies of how engines are made. At some point you would have to build a 2 stroke like a diesel for it to have the structural integrity to handle all the power it makes for its size which by then the efficiency is gone and there is no longer a hp advantage. I motor can handle tremendous amounts of torque, it is hp that threatens the motors reliability (torque threatens tranny's and clutches and drivetrain but hp threatens the motor because it is a product of rpm.) Based on that, at a certain point in displacement and power you are far better off to go with a larger motor that makes equal power and twice the torque to run faster times and be able to do it again and again with acceptable reliability.

Now I know that my ratio of torque to hp is overgeneralized and I am sure many of you will cite exceptions but I want people to think about the basic theory. As someone said before, there is a reason Topfuel cars don't use 2 stroke motors that make 15,000 hp. Instead they use 4 strokes that make 7500 hp.

I am still waiting to hear someone's theory as to why a 600cc 4 cyl 4 stroke makes about the same torque as a single of the same cc's but makes twice the hp.......