Engine hp

120 and 200. As long as there is enough force to overcome the drag. Seems like a lot of work.but downforce could be the limiting factor. Didn't want to get all techy on ya but someone had to.
 
I would say weight does effect handling. The more weight you have going through the corner the more centrifical force or is it inertia that is going to want to pull you off the bottom the faster you try to go. The tires can only hold so much force before they give up. They will also build more heat as the race goes green and when some tires get any heat in them they totally give up. I believe Burris tires rate temp max at 120* if I remember right.
 
Wes Snow said:
I don't understand why you would say torque is irrelevant. My weed eater revs up pretty quick but it has no torque and I would not expect it to accelerate my kart. You can multiply your torque with gearing but you better have some torque to work with. Any top notch engine builder should know what RPM he is trying to achieve peak torque and peak hp. He should also know how broad of a power band needed to get around a track. I try to build power to cover at least 3000 RPM. If you can accomplish that you will be competitive. I have some experience in calculating acceleration, mass, aero with different amounts of hp. There were slide rules that would do this 30 years ago. And the money we spent reducing rotating weight, reciprocating weight to help out motors accelerate faster was considerable. If you are trying to accelerate mass at a fast rate without torque, then you are quite simply defying the laws of physics.
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Who stated it is irrelevant? I said the most important aspect is acceleration rate. Just knowing the torque is misleading. The same goes with HP. Acceleration rate tells you exactly what you need to know about performance.

Mike
 
Mike, I don't think f1 or nascar would have me.. I'm just a redneck, hillbilly, jet a/c mech. and paid attention in school, and picked up a little bit on the way.. it is just theory., I do know one thing, if you have time to balance your dirt tires, you got more time on your hands than I do.. LOL...

We're only racing karts not space shuttle's.. everyone has their own ideas, thats what makes karting so exciting..

Ted, what you would gain with skinny-er tire (side bite), you lose with a smaller contact patch.. go ahead and use skinny tires the competition will thank you..

Brian, thats why I would suggest working on your VCG, and get your initial setup more neutral to take advantage of the heavier weight., (get that extra weight off the right rear.)

If the weight is such a big deal, why are the jawa's doing a pretty good job?

Having run both big and small engines, they both take a different setup, pick what works for you.. I don't think there is a clear cut answer..
 
azrcr said:
Downforce adds weight, no matter how weight is added, it is still weight.. so with more downforce nascar has to build more hp to overcome it or take weight off the car..

Theres a point of diminishing returns, I don't think 430#'s hurt the big engines, I think it helps, you could probably add weight, without seeing a speed/handling issue..

Downforce and mass, totally different.. but you need both... take the same kart with a wedge, and run a straight body and the same weight and see what happens..
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If you change values in the velocity column of the AJ Designs calculator, you will see that slower velocities, less downforce is applied. With increased velocity, downforce is increased. That means that as velocity increases, so does downforce.

Is ballast adjustable on the fly? Does it go up and down on the fly? That is why ballast is very different as compared to downforce. It can not be seen as the same. To add to that the drag is a part of that equation. That is why a better understanding of air is very important. Bernoulli's Law is but a grain of sand on an entire beach in the topic of "understanding air".

You don't balance your tires? Seriously? Take a RF tire on the spindle and surface grind it with a flapper wheel grinder. A tire that is out of balance will shake uncontrollably. Balance it and that goes away. All that vibration is greatly affecting the footprint the tire maintains with the track. This is HUGE. I've been balancing my wheels for years. Not doing in on tracks that requires velocities of 50mph or more is huge. I have had handling go away and lose front end grip. When I came in, I looked at the tires and noticed the weights were off the RF....no lie. You really should consider spending time on your tires and wheels. They are your interface with the track.
(I always grind tires on the RF spindle. It will immediately inform me if there is an obvious problem. I never do it on a tire grinding machine for that very reason.)

Mike
 
Mike, how do you (you personally) measure acceleration rate? real life? what type of dyno does Buller use? do you use a mychron? do you just go by Bullers dyno chart?
 
Wow , Mike Grady has 17 posts on Engine hp this is good reading I hope it keeps going
azrcr said:
Mike, how do you (you personally) measure acceleration rate? real life? what type of dyno does Buller use? do you use a mychron? do you just go by Bullers dyno chart?
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MikeGrady said:
Who stated it is irrelevant? I said the most important aspect is acceleration rate. Just knowing the torque is misleading. The same goes with HP. Acceleration rate tells you exactly what you need to know about performance.

Mike
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Mike my 450 out accelerates most anything at the track jawa omitted. Now that fricken thing got me from center off so quick it was a real big problem getting that mass back down to make a good run through the corner. having the most acceleration is not the key. I could never get close to just stabbing the throttle wide open. My 250 on the other hand acts so much like a sudam I can stab it wide open center off, It out accelerates the Sudam big time but then the same issue arises. get the darn thing to slow back down and get into the corner. So I've been looking to find that blend, that sweet spot that allows me to out accelerate the current small bore kart engine yet retain a great entry speed.

I don't understand you I guess. Your choice for the optimum engine choice is a 131 Sudam. It's down on Torque, has a very narrow window of optimum acceleration HP=force/rpm range. How ever I may have detected a slight movement on your part over to the Jawa. he,he.

The big money people look for ever inch of torque HP and down force they can muster given the rules packages they live with. I see no problem for us karting dumbys to do the same research using the same basic methods to obtain those comparisons.

It's all fun It's all exciting and I'd much rather talk this science than bicker about all the other crap. Steve I apologize I was wrong this has been a fun thread.
 
Taft , just trying to keep this engine hp going . Lots of good info . Not picking on anyone. Mike has his good points.
 
azrcr said:
Mike, how do you (you personally) measure acceleration rate? real life? what type of dyno does Buller use? do you use a mychron? do you just go by Bullers dyno chart?
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Inertia dyno. I think it has a 450lb wheel. He has sensors and a computer. If he was just giving me one dyno sheet, it would be worthless. I have all of my engines. I know what to expect.

The truth is, HE knows what I want. I want acceleration rates with the "heat sink" numbers. That is how much the engine gains temp during a run. It is key that it does not vary too much. If it does, the engine will overheat during a race.

I really don't care what the numbers are anymore. Everything I get, I am happy with. He doesn't allow junk to leave the shop. I will be very interested to see how the latest twins do vs the Sudam stuff. I am especially interested to see how much the second timing curve can tame the engines down and how fast....and how fast they can recover once the 1st curve is restored. That will be key. Might never matter though. That's up to the tire medicine.
Mike
 
Taft Racing said:
Mike my 450 out accelerates most anything at the track jawa omitted. Now that fricken thing got me from center off so quick it was a real big problem getting that mass back down to make a good run through the corner. having the most acceleration is not the key. I could never get close to just stabbing the throttle wide open. My 250 on the other hand acts so much like a sudam I can stab it wide open center off, It out accelerates the Sudam big time but then the same issue arises. get the darn thing to slow back down and get into the corner. So I've been looking to find that blend, that sweet spot that allows me to out accelerate the current small bore kart engine yet retain a great entry speed.

I don't understand you I guess. Your choice for the optimum engine choice is a 131 Sudam. It's down on Torque, has a very narrow window of optimum acceleration HP=force/rpm range. How ever I may have detected a slight movement on your part over to the Jawa. he,he.

The big money people look for ever inch of torque HP and down force they can muster given the rules packages they live with. I see no problem for us karting dumbys to do the same research using the same basic methods to obtain those comparisons.

It's all fun It's all exciting and I'd much rather talk this science than bicker about all the other crap. Steve I apologize I was wrong this has been a fun thread.
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I have driven a pretty decent 450....actually 2 of them. Mashing the fuel was not an issue. Maybe we just have more bite up here on our shorter tracks.

I do believe a speedway motorcycle engine is a really good piece for what we do. I'm not going that route though. My kart was getting a bit heavy so....a Sudam based engine is out. Well, it will be a spare.

BTW, I like this MUCH better as well.

Mike
 
While I'm at it, I might as well pile on. Here's yet another reason why having the ability to accelerate is so important. The easiest way to make a clean pass is to have the driver in front of you blow the corner and give up the preferred line. How often does that really happen for the lead though? Getting a run in the corner and pulling along side down the straight is the next best thing. How do you beat them from point A to point B? You out accelerate them down the straight, that's how. That generally gives you a preferred entrance line and they yield the corner if they are smart.

You can't achieve that by just playing follow the leader and you sure don't do that on a lazy engine. You need something that as Chris Seay states, "puts FORCE to the rear wheels", and thus to the ground in a forward direction. Without that, racing is B O R I N G!

Mike
 
MikeGrady said:
Well, explain the same kart, the same day, with the same tires, no weight and 32lbs of weight added. .2 seconds a lap difference. The MyChron Gold had near same corner speed. The acceleration, top speed and braking were the areas lacking.

Just "guessing" is a waste of time. The gauge doesn't lie when you use the track mapping option. This is a small dirt track. "Hooking" up the kart isn't an issue. I was applying the fuel well before the apex of the corner. Corner entry is the big weak point of this track. Slowing down a kart that weighed 30+ extra lbs had a huge negative effect on the kart.

I have added ballast to a kart to help it before. It is a crutch. Chassis school taught me something. Don't take away from something to help something else unless it is a last resort. Figure out the real problem and find a solution to that problem.

As for a laydown engine vs an upright engine, consider the effect a large piston going up and down has on the chassis vs that same piston going forward and backward. There are engineers at more than 3 different race bike companies that believe it makes enough difference to spend millions of dollars on development.

Mike
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And yet they still build race engines with near vertical cylinders. Whats with that?
 
arc100 said:
And yet they still build race engines with near vertical cylinders. Whats with that?
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Here's the deal....same as in Australia.
This thread could more accurately be called the "Engine Output Speculation" thread.
There is no science here....and no scientists.
 
MikeGrady said:
While I'm at it, I might as well pile on. Here's yet another reason why having the ability to accelerate is so important. The easiest way to make a clean pass is to have the driver in front of you blow the corner and give up the preferred line. How often does that really happen for the lead though? Getting a run in the corner and pulling along side down the straight is the next best thing. How do you beat them from point A to point B? You out accelerate them down the straight, that's how. That generally gives you a preferred entrance line and they yield the corner if they are smart.

You can't achieve that by just playing follow the leader and you sure don't do that on a lazy engine. You need something that as Chris Seay states, "puts FORCE to the rear wheels", and thus to the ground in a forward direction. Without that, racing is B O R I N G!

Mike
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Hey I think your catching on, Now isn't UAS racing more more exciting than the old Sudam spec class it was turning into? Just being a smarty pants lol.
 
MikeGrady said:
All gyroscopic forces are not concentric. Making them as concentric as possible is a huge benefit for what we do.
Mike
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I think if you replaced “gyroscopic” with “centrifical” you would be closer to what is happening.
Comments, compliments, criticisms and questions always welcome.
 
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