Lightest tire to free up some horsepower for Dyno #s

Which dyno guy said this? I want to stay away from him for my race tuning needs... :up:

 

Morons over-straping them trying to get a 400hp nitro to hook up. Think come-alongs.... After a few pulls the tire temp is dangerous.

 

Unlike on the race track where a tire is aided by constantly moving around the surface of the tire as the bike changes direction it always on the center of the tire. That leads to a build up a heat. Nothing to worry about on a single sweep test but if you are loading the bike every 500 or 1000 rpms on a bike that revs out to 16,000 that's a lot of time to shove heat in that tire while tuning. We keep an infared temp gauge in the truck and check it regularly.

Not a big deal on the smaller bikes but the Nitro and Turbo'd Busa's require you pay attention to it.

There's not a lot of issue with slip on the Factory Pro low mass drum but when you start moving over 300hp those can overwhelm the available traction. Strapping them down tighter to avoid slippage is foolishness.

 

get a 16.5" rear rim and mount a really skinny tire on there?

 

Putting a lightweight tire on is not going to change air fuel ratio. That's all that matters if you want to tune for maximum power and torque. You need to question your dyno guy's motivation for wanting to change the tire. Keeping variables out of the equation is important. If you change the tire, you add a variable that you don't need. I have a couple of dyno tires that I mount for each bike to keep readings consistent. Most good dyno guys do the same.

If you just want to tout a big number, make something up.

 

WOW! What responses to my question. A friend led me to this forum because of the knowledge a lot of you possess. I guess my post count qualifies me to be treated like a squid. I apologize for asking about a lighter tire. Thank you to everybody that provided me with feedback, both positive and negative.

thrak410, you asked about my dyno tuner......Normally I wouldn't throw out his name for such a request....because you appear to want to slander him. Well...you know what...You would want this guy wrenching on your bike, creating a custom map that produces HP across the revs. He is not a roadracer....He is a proven, well known, AMA Drag racer, a previous NHRA Pro Stock motorcycle racer. He's been in many motorcycle magazines for articles on bike tech.... He's in the June issue of 2 Wheel Tuner piloting HTP Performance's GSXR 1000 in the MiRock Superbike Series. He's Ryan Schnitz of Schnitz Racing. http://www.ryanschnitz.com/RacingAboutRyan.htm

I hope you research his accomplishments before slander him.

 

Thank you for your feedback. :up:

I don't want to make up a false number. It's not really that important to me, I just wanted to see what the bike could pull. Several guys want to see if it could achieve 200 RWHP with a lighter tire, 520 conversion kit, lightened rear brake rotor, and custom map for MR9. I'm at 185 now with the PP 2CT....This is where it was mentioned to me about the lighter tire....to free up a few.

 

From what I read, the competition is strickly to get the highest number measured on a inertia dyno. Nothing else.

While I struggle to understand the source of amusement of this endeavour (much like playing golf or watching baseball), his goal of getting the lightest tyre is a correct one.

Were it on a brake dyno, that would be a much different story...

 

this is all sillyness. Why not just have Ryan make a pass on your bike at a dragstrip to see if it has the "stuff"???? 200hp dyno printouts are stupid and prove nothing to anyone with a modicum of knowledge.
The only problem with Ryan riding your bike is you'll be forever emotionally scarred because he will make you look like a limp wristed fool that couldnt find a throttle stop.

 

From a physics standpoint, the guy has a valid point. It takes more power to accelerate more mass in a rotating application.

Hence, a tire with less mass would be a (very) slight advantage.

I would think that it would make more sense to go with a better rear wheel, where the difference can be measured in pounds rather than a couple of ounces.

As always....YMMV

 

I never intended this thread to go in the direction of silly. Everyone has their different views and I totally respect that. Some motocross guys view us as silly for riding on the street, dragging knees on pavement, etc. Some Road Racers, Track day guys, think motocross is crazy...jumping a dirtbike 25-30 feet in the air over doubles or triples. I get why guys are calling this silly, crazy, etc.

I'm not sure Ryan would make a pass on my motorcycle because of liability. I would assume he's under contract with HTP Performance....and there would be a clause about such cases. Not certain....just guessing.

 

Everything you do to "free up a few" IS a false number... why not just put on a 55 tooth rear sprocket to trick the dyno you're making more torque?

 

Because it will reduce speed... thus HP.

 

so light weight stuff
520 kit
carbon wheels
no valve cap
used up tire
but you have the same motor with the same fuel mixture and same gas, now you make and xtra hp with those mods.

 

I'd have to confer with Charlie again but I don't think the tire weight would have an effect on the Factory Dyno. If I remember correctly since it uses a load cell to measure the forces applied the number should not change much versus the given mass accelerated over time math equation.

I'm not 100% on that....

 

lol...theres that "liability" thing again.

Im sure if he's at a strip testing and tuning and knows your bike... it wouldnt be out of the question.

Anyway... put up a big MPH or just write N/T on your windscreen if you wanna pimp like you have a fast bike. :up:

 

Since the drum is freewheeling, there's no load to measure. A brake dyno will have a load cell.

On an inertia dyno, the HP at the wheel calculation is derived from the angular acceleration of a traction drum of a known inertia, nothing else. Torque is calculated by picking up the engine's rpm during the test.

Any inertia between the engine sprocket and the wheel is a add-on, lightening it will effectively give a relative power "gain" as far as an inertia dyno is concerned.

The lighter tyre idea isn't bad, there's a good article from Sam Fleming on the new Michelins in the previous month RRW.

 

thats not right, is it? Doesnt it measure tq and then uses math to determine hp.

 

That is absolutely correct for a brake dyno.

As said in another post, inertia dyno will measure HP at wheel and calculate engine torque by connecting a pick up to a coil.

 

I don't get why some of you guys want to sit on here and run your mouths about shit you have no idea about. Some of you have made very good talk about this and the others well the dribble you post says enough. You will gain HP due to rotating mass is lower just like in a car or so on you have a loss in hp due to your drive train. So its a easy way to free up some HP by doing a lighten brake, 520 conversion, lighter tire, aftermarket wheels, and some time even ceramic wheel bearings, You might even have other but those are just common things people do. The harder and lighter the tire = the better due to when a soft tire heats up and gets stick to the drum. I could go on about a lot of this but there is really no point because 90% of these post are ignorant in some way or form.

BTW if Ryan's at the track I'll make sure he will go for a spin on your bike