Transcript Document 7419833

Fast Motorsports & Cloud 9 Racing
Karting 101
Jeff Cloud
Erik Frank
Types of karts
• Sprint kart
– Sit up
– Weight ~ 350 lbs
– Engines - 2 or 4 stroke
• 100cc Yamaha, Rotax
• 80 – 125cc dirt bike
• Briggs & Stratton
– HP - 8 ~ 40+
– Top speed ~ 100 mph
125cc Shifter Kart
Types of karts
• Enduro kart
– Laydown
– Road racing only
– Engines - 2 stroke
Laydown Enduro Kart
• Piston port (KT100 Yamaha, TKM)
• Reed/Rotary (DAP, Parilla, Komet, PCR)
– Top speed >100 mph
Types of karts
• Super kart
– Wings
– Weight ~ 450 lbs
– Engines - 2 stroke
Super karts @ Laguna Seca
• Rotax 257
• Motocross bike (CR 250, YZ 250)
• 250cc Twin: Rotax 256, Yamaha TZ-250 (G.P. derived)
– HP - 65+ (singles) 90+ (twins)
– Top speed ~ 150 mph
Kart Engines 101
Yamaha KT100
CR-125
100cc Reed
YZ-125
Rotax 257
Rotax Max FR125
SGM F/E
(Rotax 256)
Racing Formats
• Sprint Racing
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Tight, twisty tracks < 1 mile long
Speeds limited to <75 mph
Short races (typically 10-20 laps)
Very quick pace
Very physical
Texas Sprint Tracks:
• Hill Country Kart Club
(New Braunfels)
• North Texas Karters (Denton)
• Gulf Coast Karters (Houston)
• Waco
NTK – Denton, TX
Racing Formats
• Road Racing
– Run on large road racing
courses
– Longer races (usually 30
minutes)
– High speeds - over 100
mph for some classes
– Large fields
– Regional Road Race Tracks:
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Typical 125cc Grid
Texas World Speedway (College Station)
Motorsport Ranch (Cresson)
Oak Hill Raceway (Henderson)
Hallet Motor Racing Circuit (Oklahoma)
Oak Hill – Henderson, TX
Kart Racing Organizations
Kart vs. race car handling
Karts
• Very quick steering response
• Short wheelbase and wide track
• Direct acting steering linkage (typ. 1/3 turn lock-tolock)
• Must be smooth to achieve quick lap times
Cars
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Slower steering response
Longer wheelbase vs. track
Heavier
Smooth is still fast
Kart vs. race car handling
• Brakes
– Sprint kart brakes only on rear
– 125cc Shifter karts and Super karts also
have front wheel brakes
– Approx. ~2G deceleration is possible
Front Brake assy (Brembo)
Rear brake assy (Brembo)
Kart chassis setup
• Kart setup seems to be contrary to conventional
auto practice
– Stiffen chassis and increase weight transfer for low grip track
– Soften chassis and decrease weight transfer for high grip track
• Must lift inside rear tire to go around corner
– Solid axle wants to go straight
– King Pin Inclination (KPI) and caster cause inside front wheel to
drop and outside front wheel to rise which tilts kart to outside of
turn and lifts inside rear wheel (Jacking Effect)
– Caster and front track width (offset) alter jacking effect
Kart Cornering 101
Look!
Camber/Caster Orientation
• Karts will never have zero caster, typically negative 15 degrees
• Karts typically run +/-1 degree camber (will go more negative as
chassis flexes)
Kart Chassis Setup
• Center of Gravity
– Driver is largest mass
• Location has critical effect on handling
– Raising driver increases weight transfer
• Low grip track - higher seat position
• High grip track - lower seat position
– Raising ride height also increases weight transfer
Kart Chassis Setup
•Track Width Adjustments
–Increase Rear track: (decreases rear grip)
–Increase Front track: (increases weight transfer)
•Tire Pressure
–Higher pressures
Increases temperatures
Increases grip
Up to a point!
Safety
Safety is Important!
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Helmet
Gloves
Racing shoes
Neck Collar
Suit or heavy jacket and long pants
– Not fireproof, abrasion resistant
– Typically made of Cordura/Nylon
Data Acquisition
Measured parameters
•Lap time
•Sector times
•RPM
•Speed
•Water temp
•Exhaust gas temp
•Lateral / longitudinal G
•Steering position
•Throttle position
•Tire Temps
•Etc…
Aim Sportsystems EVO 3
Data Acquisition
• Analysis software versatility:
–Eliminate guessing
•Solid foundation for setup changes
–Driver training / consistency
•Lap time comparisons
•Kart behavior at specific locations on
track
–Engine performance
•Engine tuning aid
•Horsepower calculation
–Handling evaluation
Alfano Pro D/A
•Oversteer/Understeer (driver or kart induced)
AIM Sportsystems Race Studio
AIM Sportsystems Race Studio
Kart Engine Tuning Overview
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Intake
Cylinder porting
Ignition
Exhaust
source: http://w3.one.ne
Kart Engine Tuning - Intake
• Mixture setting is critical
– Carburetor adjustments:
• Main Jet
• Needle
• Fuel system (delivery)
– Reed cage setup
• reed material
• aftermarket options
Keihin PWK Carb
V-Force Reed Cage
Kart Engine Tuning - Porting
• Exhaust Port timing is important
– Higher ports  “More top end”
– Lower ports  “More torque”
• Compromise between port area and piston/cylinder life
Inlet Ports
(piston port)
Exhaust Ports
Auxiliary “Boost”
Ports
Transfer Ports
Kart Engine Tuning - Ignition
• Static Advance
– Stator setting on crankshaft
• Dynamic Advance
– Achieved by CDI box (on shifter engines)
– Digital Programmable systems available
CDI Box
Harness
Coil
Spark Plug Boot
Rotor/Stator
Kart Engine Tuning Overview
• Exhaust – Pipe Selection
– Determines Operating Powerband
Experimental Pipe setup – YZ 125
Dyno Testing
• Optimization of YZ-125 for Roadracing
– Porting
– Cylinder head
– Piston
– Intake
– Ignition
– Exhaust
Dyno Testing
YZ-125: Baseline vs. Optimized Configuration
40
35
~3 HP gain
30
~10 HP gain
Horsepower
25
20
15
Baseline Torque
Baseline HP
Optimized Torque
Optimized HP
10
5
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9000
10000
11000
12000
Engine RPM
13000
14000
Road Atlanta - Nov. 2002
• 12 turns – 2.54 miles
• Substantial elevation
changes
• 5000 ft. Long “straight”
• 250cc Super kart lap time:
1:34 (97.2 mph avg!)
Wrap-Up
• Questions?
• Show and Tell