IMSA GTU
UNDER 2.0 L FOUR CYLINDER, 2 VALVE, FUEL INJECTION, TURBOCHARGED WITH INTERCOOLER
Wheel Base 101.0
Front Track 56
Rear Track 56-1/2
Overall Width at Front Axle 68 inches
Overall Width at Rear Axle 70 inches
Ground Clearance (Front) 3.0 to 3.75
Ground Clearance (Rear) 3.5 to 4.25
Overall Height to Roof 50-1/2 at 3.75 in. grnd. clearance
Weight Dry 2,100 lbs.
Weight Distribution 50/50
2.0 FRONT GEOMETRY AND DETAILS
Roll Center Height 2.0
Virtual Swing Arm Length 2.2 x track
Bump Travel 3.0
Droop Travel 2.0
King Pin Inclination 0 °
Caster Angle 2.5 ° to 3.5 °
Scrub Radius 2.0 inch
Camber Characteristic Bump Travel Camber Angle
Bump +3 -1.5
+2 -1.0
+1 -0.5
0 0
-1 +0.3
Droop -2 +0.8
Wheel Size 16" Dia. x 11 Rim Width
Tire 22.0 x 11.0 - 16
Brakes, Disc Lockheed CP 2261, 11.97 Dia. 1.1 inch thick
Brakes, Caliper 4 - Piston Lockheed CP 2279, 1-3/4 inch dia. piston
Shock Valving As specified by ÖHLINS
Wheel Rate 350# / inch
FRONT SUSPENSION DESCRIPTION
Wishbone upper and single lower link
PROFAB front hub, NC machined alloy upright
Adjustable stabilizer bar
ÖHLINS shock absorbers - adjustable gas pressure
Adjustable ride height
3.0 REAR GEOMETRY AND DETAILS
Roll Center Height Adjustable 2.0 to 4.0 inches
Virtual Swing Arm Length 2.2 x track
Bump Travel 3.0
Droop Travel 2.5
Camber Characteristic Bump Travel Camber Angle
Bump +3 -2.5
+2 -1.6
+1 -0.7
0 0
-1 +0.3
-2 +0.5
Droop -2.5 +0.5
Wheel Size 16" Dia. x 12 Rim Width
Tire 24.5 x 12.5 - 16
Brakes, Disc Lockheed CP 2261, 11.97 Dia. 1.1 inch thick
Brakes, Caliper 4 - Piston Lockheed CP 2271, 1-1/2 inch dia. piston
Wheel Rate 350# / inch
REAR SUSPENSION DESCRIPTION
Independent rear suspension
Kent Racing differential with Hewland ring & pinion
Fabricated steel upright
Unequal length upper and lower arms
Parallel equal length locating links
Center lock hub
Coil springs over ÖHLINS gas pressure adjustable shock absorbers
Wheel rate adjustable by changing coil springs
Ride height adjustable by threaded collars on shock
Cockpit adjustable rear stabilizer bar
Rack and pinion with capability of addition of power steering.
5.0 TRANSMISSION
Weismann 5-speed with quick change output ratio.
Center mounted in chassis.
6.0 DRIVE SHAFT
Steel tube
7.0 AIR JACKS
Grant King - 3-1/2 inch diameter x 13 inches
8.0 AERODYNAMICS
Semi-ground effects underpan
Rear wing
Front Spoiler
Internal ducting between front spoiler and firewall
9.0 BODY
Merkur XR4Ti sheetmetal
Fiberglass by Hartman, Costa Mesa, CA, hood, front fenders, rear fenders, doors, front spoiler, rear bumper, rear deck frame (hatch),
rear wing.
10. CHASSIS CONSTRUCTION
Space frame constructed from 1.50 inch diam. 4130 seamless tubing.
Main hoop, left side bracing, left side door beam, lower fore and aft
tubes - wall thickness .090 inch.
All other tubing - wall thickness .065 inch.
Notes: Brake calipers and rotors were changed by Dave Kruse in the 1988 season to take-offs from the Brabham Nissan GTP Car.
11. ENGINE SPECIFICATION
Engines by Drake Engineering, Irvine, California, based on Ford Lima 2.3 liter, 4 cylinder, 2 valve motor, with fuel injection, turbocharger, and intercooler.
Displacement reduced to under 2 liter per IMSA GTU rules.
Displacement 1981cc (std), 1996 (+.015")
Bore 3.785"
Stroke 2.685"
Compression Ratio 7.5:1
Rod Length 5.5"
Pin Diam. 23mm
Big End 2.0"
Crankshaft Velasco (4340 billet)
Rods Carrillo
Oil System Weaver Brothers multi-stage pump
with dry sump
Water Pump Offenhauser
Clutch Tilton multi-plate
Bellhousing Zakspeed
Injection Bosch mechanical unit (Porsche
924 GTR Carrera Turbo)
Ignition Bosch
RPM 6 - 8000
Horsepower 350 hp at 1 bar boost for endurance races
400 hp at 2 bar boost for sprint races