King Motorsports Unlimited, Inc. - Mugen Performance Products for Honda and Acura

Mugen SCCA GT-4 CRX (Updated)



The Mugen SCCA GT-4 CRX. This race car was very important step in Mugen history, as it introduced Mugen to the American market. It was designed and built in 1984 by the Special Projects division of American Honda in Gardena, CA.


This team was led by Dix Erickson, Charlie Curnutt and Mugen lead engineer Takashi Uno. The 1.5 EW engine was designed and produced by Mugen and produced 165hp. Design features included a dry sump lubrication and twin 45DCOE Weber carbs on a Mugen intake manifold. The transmission was a close ration 5 speed also designed and built by Mugen.


This car destroyed the GT-4 competition and won several SCCA National Championships between 1985 and 1989.


Yes- Mugen had arrived.....



Here is the exhaust manifold for the GT-4 CRX being made at Mugen. The Mugen technician that built this exhaust manifold also built all the early Honda F1 exhaust manifolds!




Here is a finished Mugen GT-4 exhaust manifold. Amazing craftsmanship!




Here is a very rare picture of the Mugen GT-4 CRX at a pre-race season test session. Notice no decals, numbers or race markings yet- early days in its life as a racer!




Update 8/14/2012: An old friend from American Honda "Special Projects Department" stopped by yesterday and dropped off some really great old articles on the Mugen GT-4 CRX. Check out this one from the 1985 Runoffs edition Sports Car Magazine:



Update 10/19/2012: Below are scans from an article about the SCCA GT-4 RACING PROJECT. The race car was a key promotion for the launch of Mugen performance parts in the US. It was quick, biblically quick ...


Here's the text of the article and specs:

 

The 1984 American Honda Motor (A.H.M.) and Mugen jointly decided to enter into Sports Car Club of America GT-4 racing using the Honda CRX. The CRX is the car that Honda produced as their second generation sports car. When the CRX started rolling off the production assembly line, A.H.M. and Mugen started making race plans. Mugen took care of engines and drive trains, and A.H.M. took charge of the suspension and body works, which were done by Dix Erickson and the Special Project Team.

 

In 1984 two prototype engines were made and sent to the United States. The engines were tested in the stock CRX body. Based on those prototype engines, 3 race engines were built by Mugen's Formula-II racing team. The engines were equipped with a dry sump lubrication system. This project was completed within two months. Even though they primarily worked on Formula-II V-6 engines, the team really enjoyed developing this in-line 4 cylinder engine.

 

Meanwhile, Dix Erickson's team was hard at work, stripping down the CRX and installing the roll cage. They believed in the CRX's potential and left the standard suspension layout on it. They did not use tube frame construction for the same reason. The body was painted in traditionaly Mugen colors.

 

In May 1985 the car won its very first race at Road Atlanta. After that, gears, exhaust systems, brakes, wheels, and suspensions were continually refined. In 1985 Doug Peterson won the National Championship in GT-4 driving the CRX and 1986 Parker Johnstone won the National Championship in GT-4 driving the Mugen CRX.

 

"On August 8th, 1985 we went Carlsbad Raceway with Mugen GT-4 car to attend SCCA National race. There we saw several GT-1, 2, 3 cars, and our GT-4 CRX had to race with them. But by Doug's Driving, at the qualifying Mugen CRX beat big cars and got the pole position. During the race it was repeated again, Mugen CRX finished First and became the overall winner."

 

QUALIFYING RESULTS

 

POSITION - CLASS - CAR - DRIVER

1 - GT-4 - MUGEN CRX - DOUG PETERSON

2 - GT-2 - FERRARI 308-GTB - HOWARD F. PYNN

3 - GT-1 - CHEV CORVETT - JIM DOUGHTY

4 - GT-3 - DATSUN 200 SX - JOE CARR

5 - GT-4 - DATSUN 510 - DEREK MCKESSON

6 - GT-1 - CHEV CAMARO - DAN CROFT

 

DESIGN SPECIFICATIONS


NAME: MUGEN XA-1 USR


TYPE OF ENGINE: IN-LINE 4 OHC 12-VALVE


DISPLACEMENT: 1529cc


BORE x STROKE: 75 X 86.5


COMPRESSION RATIO: 12.3 : 1


HORSEPOWER: over 165ps / 7800rpm


TORQUE: 17.0kg-m / 6000rpm


CARBURETION: WEBER SIDE DRAFT 45-DCOE


IGNITION: C.D.I.


WEIGHT: 111kg (with T/M)


GEAR RATIO:

1ST 1.824

2ND 1.474

3RD 1.227

4TH 1.047

5TH 0.920


FINAL:

4.067

4.267

4.429

 



 

Update 12/4/2012: We found this super rare photo of the Mugen SCCA GT-4 CRX race engine in our archives! The Mugen engine code for this engine was XA1 USR. 1592cc with a 75mm bore and a 86.5 mm stroke at 12.3:1 compression with dry sump lubrication, this engine made over 165 PS @ 7800 rpm. At first Webber 45 DCOE carbs were used, then switched to Mikuni 44 PHH. The Mugen GT-4 CRX dominated SCCA GT-4 competition for many years......

 

Right-click the image to see a larger version of this work of art!