KZScott
Needs a life
high on speed
Posts: 7235
|
posted April 20, 2009 04:23 PM
tire growth at speed
how much does a tire usually grow at speed? I want to know how much room i have to have between the tire and nitrous bottle 
thx!
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
  
|
NOX
Needs a job
PMRA / TMRC Super Street 4022
Posts: 3745
|
posted April 20, 2009 04:44 PM
Leave an inch and you will be good.
____________
42 Wins
21 Runner-ups
2010 TMRC Super Street Points Champion
2010 PMRA Super Street #3 Points
2009 PMRA Super Street Points Runner-Up
6 Time Centerville Dragway Points Champion
Sponsored by:
Scorpion Helmets
Galfer Braking
AMSOIL
Steve's Speed Shop
Kawasaki Sports Center
Mickey Thompson Tires
Catalyst Racing Composites
Conway Cycle
Syed Leathers
|
KZScott
Needs a life
high on speed
Posts: 7235
|
posted April 20, 2009 04:53 PM
 Edited By: KZScott on 21 Apr 2009 01:30
not sure if this matters, but its for a regular street tire for LSR
I dont want to hang the bottle from the side of the bike and i want to run a 5 pounder and keep the shortest WB possible, while making the maximum bracing possible for drag strip use when its at 68 inches
this is my initial concept for a brace/bottle bracket for the swingarm I got today(6-12 no underbracing) its not really to scale yet. (im open to ideas  )
im thinking of tigging either a 1/4 or 3/8 in piece of curved plate in front of the tire(shinko 190 50 shown at the min wb) boxing in the top and bottom with 1/8 and cutting holes for the nitrous bottle. ill attach some sort of bracket to the top and bottom to hold the bottle in place. depending on the bottle/box size, I may look into using the boxed in section as my secondary gas tank
tons of room at max wb
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
tcchin
Zone Head
Posts: 867
|
posted April 20, 2009 06:38 PM
Before they released the new N-Tech construction race tires, Dunlop used to recommend a minimum of 14mm spacing to the swingarm. With the N-Techs, I think the recommended spacing has been changed to something small, like 6mm. Like the N-techs, Pirelli race tires grow very little at speed. I still leave at least 3/8" (10mm), just to be safe.
If you mount the bottle off-center in the swingarm, you will have more tire clearance, as tires tend to get narrower and pointier in profile as they grow at speed.
|
entropy
Moderator
Posts: 8671
|
posted April 20, 2009 09:58 PM
KZ, if it were me, i'd leave a healthy margin, you have plenty of arm.
I've run most of the Miles at 68", 10" arm.
Did the last one w/ 6" arm.
6" better off the line, no difference at the big end, same 3.5% difference between calculated (higher) and measured speed
____________
This moderator uses moderation in moderation
|
tcchin
Zone Head
Posts: 867
|
posted April 20, 2009 10:07 PM
So you're attributing that 3.5% difference is wheel spin? Your lockup clutch must be a lot more efficient than the normal superbike-style clutches.
I agree on the plenty of margin recommendation. You can always add bracing. Besides, with the axle in place, you don't need a lot of bracing to keep the arms from spreading. What you need is torsional stiffness to keep the arm from twisting and getting the wheel out of alignment.
|
entropy
Moderator
Posts: 8671
|
posted April 20, 2009 10:14 PM
I'm thinking that the lockup locks up solid, heavy springs and weights on the arms.
I dunno if it is tire slippage or the way i am calculating, but for double damn sure, shown again and again, when i measure tire circumference on a stand the resultant calculated mph is 3.3-3.5% high compared with trap speed.
____________
This moderator uses moderation in moderation
|
almost_les
Zone Head
Posts: 590
|
posted April 21, 2009 12:13 PM
couldn't you just mount the bottle off to the side where its not next to the apex of the tire?
|
Shane661
Needs a life
Posts: 11494
|
posted April 21, 2009 12:17 PM
quote:
So you're attributing that 3.5% difference is wheel spin? Your lockup clutch must be a lot more efficient than the normal superbike-style clutches.
What would be the expected percentage of clutch slip on a standard clutch (as mentioned above)?
|
tcchin
Zone Head
Posts: 867
|
posted April 21, 2009 12:33 PM
I'm not sure how much can be attributed to clutch slip, but most superbikes see about an 8-10% difference between front wheel speed and rear wheel speed on long straights.
|
Shane661
Needs a life
Posts: 11494
|
posted April 21, 2009 01:02 PM
Edited By: Shane661 on 21 Apr 2009 21:04
quote:
I'm not sure how much can be attributed to clutch slip, but most superbikes see about an 8-10% difference between front wheel speed and rear wheel speed on long straights.
I assume that is taking into account the different tire diameters? That's kind of odd. I think most of us have found gearing calculation (with tire measurement) to be within about 2-4% at Maxton.
Shane
|
Shane661
Needs a life
Posts: 11494
|
posted April 21, 2009 03:58 PM
Scott, don't forget how short of a tire the Shinko is. Make sure you figure clearance for a tall tire, like the Supercorsa or Power Race 180's.
Shane
|
KZScott
Needs a life
high on speed
Posts: 7235
|
posted April 21, 2009 04:08 PM
ok thx for the info guys, greatly appreciated 
this is version 2.0 using the dimensions(roughly) for a 5 pound bottle. i think the green section would make a nice fuel cell for my wet kit(keeps weight down and down low). my guess is about 1 litre if i make it the thickness of the swingarm. if i get the cross brace all the way back to the extensions, and have it boxed in similar to the front of the stock arm, i think it will be much stiffer, and be a lot less prone to twisting
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
tcchin
Zone Head
Posts: 867
|
posted April 21, 2009 04:18 PM
Shane - Do you mean different tire diameters front and back or stationary and at speed?
Good point on the sidewall height. Dunlop KR-108 195/65R-17 and D211GP 200/55ZR-17 have 25.83" (656mm) static diameters, and are about the tallest tires I've ever used. I've had to install longer chains to get these tires to fit in the swingarm on many occasions.
|
tcchin
Zone Head
Posts: 867
|
posted April 21, 2009 04:35 PM
Scott - Check out this aftermarket swingarm:
http://www.superbiketoystore.com/sport/products/swingarm-kits/carrozzeria-factory-superbike-swingarms-suzuki-gsxr1000-20032008/
Notice that the bracing is above the plane created by the axle and the swingarm pivot by quite a distance, and the windows between the braces and the main arms are filled in as much as possible, while still allowing for the chain to pass through. This is the kind of bracing you want to add to increase your torsional stiffness. The upper and lower areas are in tension/compression and the material that fills in the windows is in shear. You won't really add too much to your swingarm's stillness until you get some material away from the axle/pivot plane.
|
Shane661
Needs a life
Posts: 11494
|
posted April 21, 2009 04:40 PM
What I meant was that the front and rear wheels will obviously each turn at a different rpm. The front wheel will have to spin faster than the rear, due to the smaller outside diameter.
So, comparing front and rear wheel speeds and their variance in order to derive slip would seem very complicated due to the differences in tire diameters at speed, wheel rpm, and other variables.
Measuring the installed height of the rear tire in tandem with gearing calculators and true engine rpm would seem to eliminate a number of variables.
Shane
|
tcchin
Zone Head
Posts: 867
|
posted April 21, 2009 04:55 PM
Since you know the diameter of the front tire, measuring front wheel speed by logging wheel RPM is trivial. Doing the same for the rear wheel will give you an estimate of rear tire spin only (not clutch slip - I mis-stated that earlier). Comparing engine speed with rear wheel speed should give you an estimate of clutch slip. Comparing engine speed with front wheel speed will give you an estimate of total drivetrain slip.
|
Shane661
Needs a life
Posts: 11494
|
posted April 21, 2009 05:02 PM
Edited By: Shane661 on 22 Apr 2009 01:10
But you don't truly know the diameter of the front tire at speed...do you? For the purpose of which we are speaking, it has been found that the total variance is under 4% overall...so the 8-10% seems quite a bit off...in our application.
10% would equate to 20 mph on 200 mph gearing. That would be more than 3 rear sprocket teeth. Maybe we are not on the same page with this?
Shane
|
tcchin
Zone Head
Posts: 867
|
posted April 21, 2009 05:54 PM
My 8-10% is a comparison of front to rear wheel speeds. You guys are measuring engine speed to rear wheel speed and getting 4%. If you were to measure front wheel speed or GPS, then we'd be on the same page.
|
Shane661
Needs a life
Posts: 11494
|
posted April 21, 2009 05:57 PM
Edited By: Shane661 on 22 Apr 2009 01:57
We are able to test and verify our 2-4% by both timing lights and GPS.
At any rate, interesting discussion.
Shane
|
tcchin
Zone Head
Posts: 867
|
posted April 21, 2009 06:23 PM
Yup, interesting indeed. Thanks!
|
dougmeyer
Needs a job
moderated
Posts: 2713
|
posted April 21, 2009 10:59 PM
Lot's of things in play here. So Here's my .02
Even a a healthy stock clutch has virtually no slip. A lockup certainly has no slip. On a good traction day on The Salt, there a consistent 5-6% of wheelspin. With a good tire at Daytona, Superbikes (ten years ago) would spin 2-3% on the banking (lot's of induced weight). On a flat straightaway, I'd expect to see 3-4%. But remember, this all depends on the availability of EXCESS hp. If the HP available is greater than that of the tire's ability to transmit it to the ground against the aero drag, the wheelspin % goes up. Your combination's speed is always limited by these factors, singley or in combination:
1. Aero drag, 2. traction, 3. distance, or 4. HP
Tire guys have told me that growth is less than .5" on the diameter, which, of course is only .250" on the radius.
Depending on the wheel/tire this is about a 1/2 a percent or less.
____________
It's not that I think you're dumb, it's just that so much of what you know isn't true....
|
shiphteey
Needs a job
Posts: 2529
|
posted April 22, 2009 03:55 AM
quote:
Before they released the new N-Tech construction race tires, Dunlop used to recommend a minimum of 14mm spacing to the swingarm. With the N-Techs, I think the recommended spacing has been changed to something small, like 6mm. Like the N-techs, Pirelli race tires grow very little at speed. I still leave at least 3/8" (10mm), just to be safe.
If you mount the bottle off-center in the swingarm, you will have more tire clearance, as tires tend to get narrower and pointier in profile as they grow at speed.
+1 on both the Ntechs and the Supercorsas in dyno runs.
____________
Gemini Motorcycles
Topping out everything from Ninja 250s to nitrous ZX-14s.
|
KZScott
Needs a life
high on speed
Posts: 7235
|
posted April 22, 2009 03:50 PM
that Arm looks very strong Tim(triangular shape) but personally i think its pretty ugly. I kinda like the type of under bracing that comes on Arms like what Shane had done at Spencer, (better look, same triangular design, only with tubing) but i think the bracing Im doing should hold up for the power level im planning on running. (decided against going over 80 hp) and bolt on extensions set at 8 in were fine with 90. a solid arm with the tank/bracing should be fine at 11 in unless im seriously overlooking something. i will add underbracing next yr when i put bigger jets in the wet kit
____________
01 ZX-12R 8.84 @ 156.3 no bars, DOT tires. Pump Gas, NA.... turbo 8.47 @ 164.
00 ZX-12R 8.62 @ 165.2 no bars, slicks, Pump Gas, 55 shot.... turbo 8.32 @173
00 ZX-12R Fastest NA Kawasaki in the world 1: 222.046 1.5: 226.390 Loring AFB
00 ZX-12R street turbo 1: 227.9 1.5: 234.1 Loring AFB
00 ZX-12R LSR turbo 1: 263.1 1.5: 266.5 Loring AFB Worlds fastest ZX-12R
CMG Racing RCC Turbos
|
Gixx1300R
Expert Class
Posts: 218
|
posted April 24, 2009 06:21 PM
Tires can grow as much as 14mm at high speeds
|
|
|
HOME
NEW TOPIC