Honda’s Gt-4 Crx was America’s first real taste of what’s become a three-decade
long love affair with mugen, has resulted in a number of victories for Honda
As early as the first half of the 1980s, Honda sought to
capture the attention of American performance enthusiasts. Before that, the
company's racing efforts remained exclusively overseas as did the availability
of high-performance wares from its affiliate, Mugen. The solution, according to
Honda's executives, was to test American waters with the company's first-ever
North American racing program, based upon its most performance-minded vehicle
of its day—the CRX Si.
Success would mean an abundance of interest in the company's
grassroots racing efforts and nationwide availability of Mugen goods through
authorized Honda dealerships.
Built at the hands of Honda Special Projects team members
Charlie Curnutt and Dix Erickson — the automaker's in-house North American
quasi-race preparation arm (among many other things)—and in collaboration with
Mugen, the CRX was designed to compete in the SCCA's then GT-4 class. More
specifically, driver and Comptech cofounder Doug Peterson says, the whole idea
was to win the SCCA Runoffs race held at Road Atlanta in October 1985—a big deal
at the time if you ask him.
More specifically,
driver and Comptech cofounder Doug Peterson says, the whole idea was to win the
SCCA Runoffs race held at Road Atlanta in October 1985—a big deal at the time
if you ask him.
Honda campaigned its CRX from 1985 to 1990, securing a
number of wins and pole positions at every GT-4 Runoffs race throughout its
six-year career. Its chassis, draped in Mugen's colors, and its suspension,
designed at the hands of Honda Special Projects, shouldn't go unnoticed, but
it's the CRX's powertrain, initially constructed by Mugen and later refined by
Comptech, that you really care about.
The Block
The Mugen-prepared single-cam engine was
based upon the CRX Si's original engine block. Inside, the block remarkably
retained many of its factory-issued pieces, like its crankshaft, 1mm-over-sized
cylinder liners, and connecting rods that underwent a simple polishing process
before being balanced. Peterson says, “The [initial] block was amazingly stock other
than [its] high-compression, cast-aluminum pistons.” Peterson recalls the
compression ratio measuring in at roughly 12.0:1 once the bore increase and
higher-compression Mugen pistons had been fitted into place.
The
Mugen-prepared single-cam engine was based upon the CRX Si's original engine
block.
Mugen didn't just deliver the fully
prepared long-block to its American affiliates with nothing more than well
wishes, though; it sent along engineer Takashi Uno, who became responsible for
maintaining the engine as well as to protect Mugen's U.S. interests. Peterson
says, the engine's success was “life or death” to Uno, who moved on from the
CRX project but remained in the United States throughout 1988 as American Honda
campaigned a pair of Mugen-outfitted Integras in the IMSA series. Although Uno
remained a fixture among the team for nearly four years, in 1986 engine
development and maintenance was delegated to Northern California racing firm
Comptech. Prior to 1986, Uno had rebuilt the engine three times, but any
development beyond what Mugen had initially done wouldn't happen until Comptech
was called upon.
In 1986, Comptech reevaluated the engine,
including its cast pistons and factory connecting rods. “Beautiful parts,”
Peterson says, “but not very strong.
When I drove the car, I didn't rev the
engine beyond 7,500 rpm if I didn't have to.” As such, Comptech reassembled the
short-block, this time with one-off Carrillo connecting rods and custom forged
pistons that resulted in a 13.0:1 compression ratio—the maximum that could be
achieved, Peterson says, without severely disrupting flame travel. The original
steel oil pan, which had previously cracked upon high-rpm abuse, was also
updated with the Integra's more rigid cast-alu-minum piece. “After we developed
and added stronger components, the engine would run a whole season,” Peterson
says.
As
such, Comptech reassembled the short-block, this time with one-off Carrillo
connecting rods and custom forged pistons that resulted in a 13.0:1 compression
ratio—the maximum that could be achieved, Peterson says, without severely
disrupting flame travel.
