Kart race engines vs. the big displacement....

[alvin l nunley]

Al I don't think I miss understood you. And I think your confused about your own statements. How can a jackshaft multiply torque and not multiply force ie hp?

Torque and force are pretty much the same thing. Torque could be defined, and is, as force over distance. Horsepower, on the other hand, is a calculation.
Do you know anybody with a dyno? If you do, ask them what device on the dyno measures the horsepower. You will find there is no device on their dyno that does that.
This is the definition of horsepower as defined by James Watt. Most any dictionary will have this story. I’m pretty sure it’s in Wikipedia.
If you lift 550 pounds 1 foot in one second, (550 lbs ft of work. Notice that that is not ft lbs) you would be working at the rate of one horsepower. If you lift it 60 feet in 60 seconds you will have done 33,000 lbs ft of work. Divide that by 2Pi radians, (3.1415x2, the number of radians in a circle) and you get 5252.1. So if your engine is producing 1 ft lb, (notice that is not lbs ft) of torque at 5252.1 RPM, that would calculate to one horsepower. Torque x RPM / 5252.1 = HP. So you see, horsepower is a calculation. It’s a rate of work. Work is defined as force over distance. Something has to move.
If your engine is turning 6000 RPM and producing 10 ft lbs of torque that would calculate to 10 x 6000 / 5252.1 = 11.42 HP
If your gear ratio is 4-1, that would mean you have 40 ft lbs of torque at your Axel, and with that gear ratio the axle would be turning 1500 RPM. 40 x 1500 / 5252.1 = 11.42 HP. The same as the engine.
You know I wasn’t born with this knowledge; I went to the books to find out.
I think my favorite saying in karting is; torque off the corners and horsepower down the straight. Makes me laugh every time I hear someone say that.
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.

 

[arc100]

What most here seem to be missing IMO is a decent set of on track analysis figures. Prodominantly rear wheel slip % numbers. Who has a Mychron with GPS with a wheel speed sensor (to negate possible clutch slip) to verify they arent spinning the rear wheels?

There are many WoO drivers that cant tell you when and how much they are spinning the wheels. I know it sounds crazy but its fact. Just because someone says its so dont take there word for because they are a well known full time driver.

Sprintcars often have a hard time getting the throttle flat while still making good acceleration, sure they accelerate but at what rate, can they tell you for a fact that they pulled an average of 1.25 Lat G at the 400ft mark instead of 1.29G all while knowing they are at 88% throttle position with the same rpm as the race 40 minutes ago.

Point I'm trying to make is you need a good unit of measure you can quantify before you can say one engine is performing better than another, the wheel slip or slip angle as its more well know will tell you if your at the maximum acceleration rate. If you make 5-8% wheel slip with 1.10Lat G at the lap beacon and your 100% throttle then thats about it your not going to go any faster in a straight line, your flat down, you need more power, if you have the same exact same weight placement with a different engine that has more power you might find that you cant get to 100% throttle at the beacon before the wheel slip figure starts to go skyward and the Lat G numbers starts to fall, if however the G number becomes higher even though the wheel slip % goes to 10-11% then thats clear evidence the current setup can take more power and the wheel slip is still within limits of the pressures apply to the tire.

When I was at Lasoski I never really noticed anyone laying black marks the whole way down the chutes, I also never noticed any front wheels pointing skyward, I did notice the Jawa seemed to slip up the track even across the start line, in what appeared to be caused by power, IDK, I would of liked to have seen some data numbers on that. maybe he wasnt flat over the line.

 

[GeorgeHenry]

Now finally someone came out and said it. Time to grow a pair, keep it in the throttle longer , and 'git er done.

Have you 2-stroke mx'ers been putting the heavier woods flywheel weights on to gain some driveability? Seems like that might tame the hit some too. All I can say is that if I ever manage a win with this 125 mx'er, that should end the debate. I may need the gearbox to keep up on starts, but seems to me that corner speed is key -- if you don't have to slow down, you don't have to speed back up. And if you don't have to speed back up, it takes far less TQ to maintain momentum than gain speed. I think we're all getting beat by a different Yow than the one we think is beating us. Actually, I take that back. They're both beating us. Time to grow a pair, keep it in the throttle longer, and 'git er done.

 

[Taft Racing]

Torque and force are pretty much the same thing. Torque could be defined, and is, as force over distance. Horsepower, on the other hand, is a calculation.
Do you know anybody with a dyno? If you do, ask them what device on the dyno measures the horsepower. You will find there is no device on their dyno that does that.
This is the definition of horsepower as defined by James Watt. Most any dictionary will have this story. I’m pretty sure it’s in Wikipedia.
If you lift 550 pounds 1 foot in one second, (550 lbs ft of work. Notice that that is not ft lbs) you would be working at the rate of one horsepower. If you lift it 60 feet in 60 seconds you will have done 33,000 lbs ft of work. Divide that by 2Pi radians, (3.1415x2, the number of radians in a circle) and you get 5252.1. So if your engine is producing 1 ft lb, (notice that is not lbs ft) of torque at 5252.1 RPM, that would calculate to one horsepower. Torque x RPM / 5252.1 = HP. So you see, horsepower is a calculation. It’s a rate of work. Work is defined as force over distance. Something has to move.
If your engine is turning 6000 RPM and producing 10 ft lbs of torque that would calculate to 10 x 6000 / 5252.1 = 11.42 HP
If your gear ratio is 4-1, that would mean you have 40 ft lbs of torque at your Axel, and with that gear ratio the axle would be turning 1500 RPM. 40 x 1500 / 5252.1 = 11.42 HP. The same as the engine.
You know I wasn’t born with this knowledge; I went to the books to find out.
I think my favorite saying in karting is; torque off the corners and horsepower down the straight. Makes me laugh every time I hear someone say that.
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.

As far as I'm concerned Al Torque, Force, HP They are all based on forms of calculations. They all measure one aspect or another.

I've always remembered the water volume = torque the water speed = HP A large amount of water will move tons, a high rate of speed of a small amount of water will cut steal.

 

[arc100]

Now finally someone came out and said it. Time to grow a pair, keep it in the throttle longer , and 'git er done.

IDK if you're joking I assume you are, but if thats what you think will get you to the finish line first and in one piece then you already lost the race.

 

[Sjg22]

You just stated what i was saying a 2stroke has a very narrow power band 3000-4000 rpm. You make a mistake and you have to get it back into its powerband to accelerate quickly. The 4stroke will make up for the mistakes much quicker becuse of their much larger powerbands.The Jawa and 450mx make more torque at 4000 rpm than that 250mx at 11000. Torque is the force needed to accelerate not hp. The 250mx will make the best package of all the 2smokes in UAS once you get the pipes and port work figured out, on that i agree. Some of the old mx pipes were made to peak torque at a lower rpm band but will be hard to find. Used to have an honda el and could say that it was always very pipey,very narrow band and when it hit the pipe almost uncontrollable. I believe this will be the problem of adapting them to karting. I agree the Jawas are expensive and the GM are even higher, but i dont think there is any ather engine that can put out the potential for winning that they do especially on 1/5 mile and up tracks. There draw back will be the smaller bull rings where a 2smoker can be geared to out accelerate them for a very short period of time. I know the rules are set but the wankels and 2 strokes need cc adjustments to help them against the big cc 4strokes

?"????? How much rpm drop do you think you get ??? My PK250 has a 4500 power band but only uses on a bad day about 3200-3300 of it

 

[MikeGrady]

When Robby Yow gets off the kart and says, "wow, we just got out motored." Then we will adjust our program. That hasnt happened. Hasnt been close. He has accelerated with and out accelerated all he has run with. There is only one exception to that and the jurys still out. That exception is Steve Gleasons personal PK250. That motor has more chute speed than anything we have witnessed. Now Stephen has a little more testing than TAFT does on his 250 cases, but I can bet someone wil soon get one of these reving and pulling as quick as anyone. The JAWA is a great motor, but Cody racing doesnt have anymore cause I know who bought the last one. And he didnt really want it just didnt want someone else to get it. (haha) There may be some thrashed on used ones around but investing in anything "Czech" is questionable. The few speedway bike racers in the US for the most part use the much better quality GM motor. And I have good reason to believe one of these may debut soon , Higher quality, Iltalian made and much stronger. So until then, RACE ON LITTLE MOTORS! and keep winning races!

Chris,
There is reality and there is perception. You have to accept the perception some people have. You also have to realize that not everyone has a 145 lb driver. I'm giving up 40+ lbs to you, no matter what. To add to that, I'm on the light side of the average UAS karter.

Don't confuse what I'm saying. You're not dumb. Not considering the validity of other racers' perceptions is dumb. I was 400 lbs on the Rotax kart. I'm 390 on my Sudam based kart. I can't get to minimum weight. Neither can 80%+ of the UAS racers. I never had a problem with spinning the tires on the 250. That's because it doesn't accelerate like I want it to at 430lbs.

The rules don't create a level playing field because most can't make the minimum weight. That forces them to choose a larger engine. That's where their reality and perception cross and that's why the 450s and Jawas will continue to steal marketplace from "karting based" engines.

As for the GM engine, we both know that is happening. I sent the guy to you.....LOL.
Mike

 

[alvin l nunley]

As far as I'm concerned Al Torque, Force, HP They are all based on forms of calculations. They all measure one aspect or another.

What we have here is a failure to communicate. (cool hand Luke)
Sorry I’m so bad it.
Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.

 

[MikeGrady]

As far as I'm concerned Al Torque, Force, HP They are all based on forms of calculations. They all measure one aspect or another.

I've always remembered the water volume = torque the water speed = HP A large amount of water will move tons, a high rate of speed of a small amount of water will cut steal.

Torque is not a calculation. It is a measured force. HP is a calculation. It is based on a measured factor of torque and a measured amount of RPMs.

That's how it applies to us. Confusing "calculations" with "measurements" is a mistake. They are totally different. While HP and torque are related, they are not the same. HP is a calculation with a HUGE fudge factor included with it. Comparing HP between 2 different engines can be a HUGE problem. Compare a pickup engine and a over the road truck engine. They can both make 400 hp but they are no where close to the same. Just looking at HP is a batch of misinformation just asking for a mistake in understanding the complete picture.

Mike

 

[GeorgeHenry]

JAWA bad to the boneeeeeeeeeeeeeeeeeeeeee

 

[Taft Racing]

Torque is not a calculation. It is a measured force. HP is a calculation. It is based on a measured factor of torque and a measured amount of RPMs.

That's how it applies to us. Confusing "calculations" with "measurements" is a mistake. They are totally different. While HP and torque are related, they are not the same. HP is a calculation with a HUGE fudge factor included with it. Comparing HP between 2 different engines can be a HUGE problem. Compare a pickup engine and a over the road truck engine. They can both make 400 hp but they are no where close to the same. Just looking at HP is a batch of misinformation just asking for a mistake in understanding the complete picture.

Mike

Better go tell all the NASCAR engine builders. They spend millions of dollars searching for every last hp they can. And also their speedway racing engines use short stoke high rev engines. Just saying

 

[PD Power]

I think chris had it correct al. He stated the jackshaft multiplys the torque of the smaller engine allowing it to perform with the bigger displacement engines. Much like a block and tackle allows a limited human being to lift (force) much heavier weights than one could lift 1:1. Just the way I read and understand the physics.

The final ratio is all that counts. Any desired ratio can be arrived at without the use of a jackshaft.
The jshaft has value in our usage, but not necessarily in finding a desireable axle/engine ratio.

 

[alvin l nunley]

Better go tell all the NASCAR engine builders. They spend millions of dollars searching for every last hp they can. And also their speedway racing engines use short stoke high rev engines. Just saying

What should we tell these NASCAR engine builders? They talk in terms of the horsepower because they know that's what you'll understand. (at least they think you do) They know absolutely that their dyno only measures Torque and RPM.
Tell me why you mention a short stroke high reving engine.
If the data does not support the theory, get a new theory. It's hard to let go sometimes.

 

[alvin l nunley]

The final ratio is all that counts. Any desired ratio can be arrived at without the use of a jackshaft.
/QUOTE]
OK, tell me how to get a 10.5 gear ratio on a kart, with normal tires, without a jackshaft. 10-105 would be a 10.5 ratio but how would you fit that to a kart? Let's be realistic!
Now if you had 11.5 diameter tires? Of course with tires that big you would be changing your overall ratio.

 

[ttownwideglider]

First of all the engine doesn't just instantly and magically come up to lock up speed. we set the lock up speed in the rpm band that the engine produces max torque. With most two strokes its 10,000- 13,000 rpms. The time to get there is a short period, but it is a second or two from full off throttle to full back on and clutch lock up. During that period of reacceleration not only is the engine in a severe power loss but the clutch slippage is causing a loss of forward drive. With the Jawa locking the clutch at 3,000 to 3,500 the torque is still aviable to drive the kart forward and the clutch may never even disengage in a full throttle off and back to full throttle on situation. That's the advantage I was talking about that the fours have. The same as the wankle with a flat torque curve making max torque just off of idle. It wasnt the hp of the wank, 131 sudans made more hp, it was that beautiful torque line 3000-10000 perfectly flat. And able to provide enough torque at low rpm to keep the clutch locked up and keep driving the kart forward. That's the recovery after a mistake advantage I was talking about. I have also seen a 2 stroke driveline setup I run a buller jshaft and bully clutch and know how they operate quite well mr arc100 LOL. By the way Rear wheel slippage is not a factor of motor performance that's a matter of setup and tire prep. any good driver will tell you he would rather have all the engine power he can get and hell use what the set up will let him use. We don't have to dead foot these things to drive them throttle control is a good drivers ace in the hole. I love a hot rod that handles really good down the straits. Hey Mike I like your point my Duramax makes 425hp with a programmer, there are a lot of gas engine trucks that will do that. But can the same gas powered trucks produce 900lbs of torque at 1800rpm, don't think so. That's very similar to the analogy with the 2strokes and the 4strokes its all about low end torque.

 

[Neo]

It's not about being "able to compete". It's about taking every advantage you can to increase your potential for performance. I'm a fan of the air cooled 2cycles that are kart only engines. I don't make the rules. The rules have been changed over and over again, including larger and larger engines. It isn't bringing nearly as many new guys to karting as it is forcing current karters to dump their old stuff and buy new stuff. They can't stand by and let the rest of the world pass them by unless they are willing to quit.

STOP making new engine rules. Enough is enough. MX engines aren't cheap. JAWAs aren't cheap. Yea, you can go buy a used MX engine for $500 to $750 but it's used and it needs work. Go buy a case and a jackshaft and clutch...... Go have it made for a JAWA! It's BS. A bone stock 450 makes more hp than any fully modified Sudam ever will. You can still go modify the 450! 75hp is very realistic. The JAWA is more than that.

How much did people have invested in a 131 stroker, dual carbs, Birky clutch and have a spare 131 stroker setting in the trailer?

Grady, you keep saying the new engines aren't cheap, you like the old aircooled 2 strokes. How much would I have in getting a 131 stroker with dual carbs and Birky setup on my kart?

 

[Swindle]

Buy at the right time of the season and you might pick one up for less that $2000

 

[ttownwideglider]

That's what sportsman classes are about keeping cost down. That's why the clone class is so big these days. The UAS is about the top of line equipment and most powerful engines money and innovation can create within the rules package. If a guy cannot afford to be competitive in this class go to the class you can afford. Everyone has different budgets and priorities on which they spend their hard earned cash. The UAS was developed for this reason and only the guys with lots of cash or those willing to sacrifice everything else to put all their cash into racing will be competitive in it. That also is why there will always be a limited number of people in this class. If you are willing to not be competitive and just drive around in the back , anyone can run in it. But most racers have the drive to win and there lies the truth of the situation. I myself am in this situation, if iam willing to spend all my money on racing I can afford to be competitive. But I aslo love to fish Bass tournaments and ride Harleys, so I must make a choice and I choose to race karts in the Yamaha class for this reason. Kart racing is expensive and pays very little in ruturn. AT least in my tournament fishing I have the opportunity to win substantial amounts of cash (20,000- 60,000) for the money invested. Thats not true in any form of racing. It cost 20 million to run a nascar for a season, that's why even the richest owners must have sponsorship. Karts are about the fun of the adrenalin rush from driving fast in a competitive atmosphere. This is reality and why I say race where you can afford to and enjoy the rush!!!!

 

[Neo]

Buy at the right time of the season and you might pick one up for less that $2000

That would be just great for me but what about the others that want to get into UAS? They most likely won't be getting a deal like that, if they are why are top of the line UAS packages going for $2000? Maybe a poll is in order, how many current UAS drivers have sold their 131s and switched to 450s and such?

 

[ttownwideglider]

There is no way a top competitive package can be had for 2000$.A top chassis is around 2500 and up then a body, tires, mychron, power plant and drive train. I have a lot more than 2000 in my Yamaha kart just to be competitive in that class. Your living in a dream world if you think that a Uas package can be put together for that amount. why did the Jawa package sell for somewhere around 15,000 recently, complete package. We are talking about complete package here top of the line everything. I know some of you think you can be competitive with mediocre equipment. But you are not that much better at set up and tire prep to beat the guys that have the best. That would be like me fishing out of a alum boat with a 25hp competating against guys with 21ft boats and 250hp engines. As I stated before there may be some people that are content to drive around in the back just to race in the UAS, but that's no fun for me. Iam trying to figure out a way to come up with the money to buy a Jawa or GM because I already have the chassis and all the other components. But at 4500-5000 for the power plant That's a tough deal to fly. But if Iam going to go there then I want a fighting chance. You don't think that the guys with top of the line equipment can set up a kart as good as you can, HA HA. I just spilling the cold hard facts here. My brother had a sprint car with a westmar 410 jj chassis and lots of set up talent and driving ability, but he had to worry about blowing up his engine leaning it out to make max power.The drivers with a extra powerplant and chassis in the trailer didn't. Therefore he won very little against andy Hillenberg with an unlimited budget, that is the facts myfriend. Racing is all about money everything else being equal. on a different note the Shootout just finished and a lot of okies won in their different classes. The Chilie bowl is starting next week. Gonna be some more great racing this year. Well see if Swindell can hold off the big dogs again this year.