Corvette From The Inside by Dave McLellan - Chapter Nine: The Crucible of Showroom Stock Racing

7/29/2019 Corvette From The Inside by Dave McLellan - Chapter Nine: The Crucible of Showroom Stock Racing

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DOES RACING IMPROVE THE BREED? You bet it does, because racing forces

you to optimize everything in the car. Improvements can then be passed

on to the production car. However,in racing series other than showroom

stock, I would give a much more abstract answer. Does the mechanics ofFormula 1,CART, or NASCAR cars translate into production cars? At best,

the link is tenuous.

As we were developing the 1984 Corvette, we thought it could be a

competitive production-based race car. However, while we were busy

designing,developing and testing it for the consumer, we didnt have time

to deal with it as a race car. By the time we introduced it to the automo-

tive press at Riverside Raceway, in the autumn of 1982, we knew we had

a car that at least felt good and performed well during racetrack demon-

strations, especially the Z51 configuration. We, somewhat naively,

assumed that all the testing we had done on the Proving Ground, to build

reliability and robustness into the car, would translate to the racetrack.We were further encouraged, later that year, when Kim Baker took his

1984 manual transmission Corvette and won the SCCA SSGT national

championship. Even though he was down on power, the fact that he had

superior braking, car preparation,and driving skill, allowed Kim to beat

out the favored 300 ZX turbo. We had also heard that John Greenwood

was racing a 1984 Corvette, but was having wheel bearing problems.

CORVETTE GOES ENDURANCE RACING

In the summer of 1984 we learned that the SCCA was planning to expand

its Playboy-sponsored Showroom Stock Endurance Series for 1985 to

include the Corvette, Porsche 944, and Nissan 300 ZX turbo. We alsolearned that several racers were planning to prepare Corvettes for this

series. We reviewed what we knew with Don Runkle, Herb Fishel,who was

responsible for managing Chevrolets racing programs, and Ralph

Kramer, head of Chevrolet Public Relations. They agreed that Corvette

The Crucible ofShowroom Stock Racing 9


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C O R V E T T E F R O M T H E I N S I D E

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Engineering would provide technical sup-

port for the racers. Quite simply, we knewa lot more about the production car than

anyone else, and stood to gain the most

from GMs involvement.

Our Corvette Development Manager,

Doug Robinson, added racing support to

his assignments. And, with the help of the

entire Corvette product team:power-

train,chassis, body, and electricalwe were

off to the races. Since the 1985 series con-

sisted of 3, 6, 12, and 24 hour races, we

immediately recognized that we needed toknow more about the car in an endurance racing environment. With a

road car you may wear out three or four sets of tires during the vehicles

lifetime, but a day in the life of a race car on a 24-hour track is signifi-

cantly more stressful for the tires. Half a dozen sets may be worn out

entirely. Quite simply, endurance racing puts extreme and unusual stresses

on the whole car.

Dougs strategy for 1985 was to work directly with the team that

showed the best potential. He chose the Tommy Morrison, Jim Cook,and

Dick Gulstrand team. Doug started by supplying the team with a 1985

manual transmission Corvette, and a plan to thoroughly test the car in a

simulated 24-hour race.We wouldnt let them take it out for competitionuntil we were satisfied that we had sorted through and solved all the prob-

lems that occurred in our simulation. The involvement of Morrison,

Cook, and Guldstrand in the testing gave them an edge over the other

Corvette competitors, but since these were our tests, we would also share

the results with all the other Corvette teams. Our group also managed the

relationship with SCCA, and provided special parts as soon as the SCCA

approved them.The objective was to beat the non-Corvette competition,

and having several capable Corvette teams competing with one another

made it even more difficult for the non-Corvette competition.

Our racetrack test program used experienced team managers,drivers,

and mechanics, who were all focused on preparing the car for the race-track. From the start, the 1985 Corvette already differed from the 1984

the new car had a 230 nhp port fuel-injection engine and stronger wheel

bearings. The rules in showroom stock racing required that the car run

on street tires, although not necessarily the OEM tire, so Goodyear pro-

Doug Robinson, Corvettes develop-ment manager, supporting the Mor-rison-Cook number 88 IMSA GTclass Corvette. With additional mod-ifications, the production Corvettewas capable of competing far abovethe level of showroom stock.


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N I N E : T H E C R U C I B L E O F S H O W R O O M S T O C K R A C I N G

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duced a sport compound Sversion of the

Gatorback, which most of the cars ran on in1985. Girlock, our brake supplier, devel-

oped improved racing pad compounds and

a quick change strategy for replacing hot

brake pads.

The test vehicle, from which we devel-

oped the 1985 race car, ran at about 275 hp

with an open exhaust system. Test sessions

were used to develop camber and toe set-

tings that were tailored to racing condi-

tions. These adjustments were allowed by

the SCCA as long as we stayed within pro-duction tolerances. Probably the most significant thing we learned in test-

ing was the importance of synthetic lubricants,as a way of extending the

life of all lubricated components under racing conditions. Before we

were finished,we were using synthetic oils in the engine, the power steer-

ing system,the manual transmission,and the axle. The power steering sys-

tem was a good example of what happened with conventional lubricants

in racing conditions. The continuous hard driving and dithering of the

steering wheel would continue to heat the power steering fluid until it

reached temperatures where it tended to break down, causing premature

wear of the steering components. With synthetic power steering fluids,

the same system ran cooler and exhibited a much longer lifetime, beforewearing out.

Everything we learned in these test sessions was shared with all of the

Corvette racers. Armed with this information,they built up the 1985 race

cars.These cars were developed to the best of our ability, in the time avail-

able and within the showroom stock rules.The Corvette racers were rac-

ing against Porsche and Nissan drivers, as well as against each other. So,

starting from our basic specifications,each team continued to develop its

car, independently, to be the fastest and most reliable car they knew how

to put on the track.

The 1985 season opened with a 24-hour race at Riverside Raceway,east

of Los Angeles. The Morrison-Cook team was well prepared, from theirtest sessions.They had developed a fueling rig,and practiced tire and brake

pad changes. The team prepared three Corvettes, and assembled a bevy

of experienced race drivers and mechanics to support them.

John Powells number 50, underdevelopment on the track atMosport for the original PlayboySCCA Showroom Stock series.


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Success in endurance racing is all about prepa-

ration and pacing the car on the racetrack. Thelast thing you want to do in a 24-hour race is go

flat-out. As we learned from all our testing, and

our years of competitive racing, as the car is

pushed harder and harder,its reliability decreases

and the chances of mechanical failure increases,

while the consequences of driver error become

more severe.

Our strategy for a 24-hour endurance race was

to establish a lap time, or pace, that we were rea-

sonably confident we could maintain for 24

hours. We would then adjust the pace during therace if other competitors demonstrated that we

were too conservative. With three cars, the Mor-

rison-Cook team could play the tortoise and hare

game by assigning one of its cars to be the rabbit

and the other two cars sticking to the planned

pace for the race,adjusting as the race progressed

to stay within striking distance of the lead. The

rabbit car was there to push the competition into

driving as hard as they could. Going as fast as pos-

sible is the natural response for race drivers, so the

hardest thing for a race driver to do is to slowdown to a managed pace and drive the car smoothly to minimize the wear

and tear on the car.

These 24-hour races were boring to watch. The cars just seemed to go

on endlessly with little competitive racing. After many hours it was hard

to keep track of who was really in the lead without consulting timing and

scoring. It was imperative for the teams to have their own timing so they

could manage their strategies.Working in the pits and trying to stay alert

for some 30 hours means you have to put up with periods of tedium when

the cars are simply lapping the circuit. However, that can quickly turn to

sheer panic when you discover that one of your cars is missing.

The Morrison-Cook Corvettes continued to lap the Riverside trackthrough the night and into Sunday morning. As the finish of the race

approached at noon on Sunday, we were all incredibly awake and

excitedas we had stayed up all night worrying. In the end, the Morri-

son-Cook team finished first and second overall, and won its class. The

Top: A routine pit stop for Powellscar number 30 took less than aminute and included fuel, tires, andeven brake pads

Bottom: You can see the tension intheir faces as Doug Rippy and hiscrew try to sort out a problem whilethe pit stop clock is t icking on them.


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third car in the team came in several places down, but was at least able to

finish, despite problems it experienced during the night.Including the season finale at Atlanta, the Corvettes won every 3, 6, 12

and 24-hour race; an almost unheard of accomplishment for any car, and

certainly for one in its very first year of competition. The competing

Porsche and Nissan competition teams certainly didnt expect this out-

come: They came back race after race, trying even harder. But so did we,

and we were able to continue to keep just ahead of the competition.As a

result,we helped develop capable Corvette teams that would put us in the

best possible position to start the next season.

SECOND SEASON SAME AS THE FIRST

In 1986, Porsche upped the ante by bringing the 944 Turbo into the fray.SCCA continued the showroom stock series, and created a new GT Class

for the Corvette, 944 Turbo, and Nissan 300 ZX. With this new class, the

other cars running in class A had at least had a chance at a victory,

although the Corvettes, Porsche 944, and Nissan 300ZX would surely

dominate the overall wins. As in 1985, Corvette engineering continued

to support the major teams, building test mules and sponsoring test ses-

sions that would develop chassis, suspension, brake, and powertrain

components to the highest possible state of reliability.

When we introduced anti-lock brakes on the production Corvette,we

also encouraged the use of ABS on the Corvette race cars. We were satis-

fied that ABS was suitable for the race car and would make a big differ-ence during the races, particularly on a wet and slippery track or in

emergency avoidance situations.

Four-wheel ABS was new to the automotive scene, as well as in racing.

The generation of race drivers who were

driving Corvettes had never driven with

ABS, so they approached it with a great deal

of suspicion. Because the ABS is so driver-

interactive, we finished its development at

John Powells driving school on the Mosport

race track near Toronto.

John Powell and his race drivers devel-oped anti-lock brake training that would be

useful for all the drivers competing in show-

room-stock Corvettes. During the early

races of the 1986 season, John conducted


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Although not part of the SCCAShowroom Stock series, several ofthe Corvette teams also participatedin the 24-hour, Longest Day of Nel-son Ledges. In this June, 1986 race,

the winning Morrison-CookCorvette, driven by John Heinricy,Don Knowles and Bob McConnellfinished 13 laps ahead of its nearestcompetitor.


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ABS driving schools before each race, in order to give the drivers famil-

iarity with the capabilities of the braking system.We still had a number of drivers who wanted the system turned off,

but we encouraged them to drive with the ABS engaged. Toward the end

of the season, drivers learned to use it to their advantage. We even had

instances of drivers pulling into the pits during a race because their ABS

light was on. The good news was the drivers were using the ABS effectively;

the bad news was that we couldnt fix a malfunctioning ABS during a race.

For the 1986 season, Porsche returned with a showroom-stock version

of the 944 Turbo. In a typical race, the best Corvettes, and the quickest

944 Turbos, would qualify very close togethersometimes the 944s took

the pole position, other times Corvettes qualified on top. Even in

endurance racing, there are advantages in starting from the front. The firstbenefit is that any spins or crashes in the early minutes of the race occur

behind you.The second advantage is psychological.Being on the pole tells

your competitors that youre faster than any of them. However,this could

also be a disadvantage if the governing body of the series tries to balance

the competitors by adjusting the rules mid-season. As a result, hammer-

ing the competition in qualification could very well lead to a weight

penalty being imposed for subsequent races.

The tight competition between the Porsche team and the several

Corvette teams continued all season long. The Corvettes had the advan-

tage in numbers. Even though this was supposed to be endurance rac-

ing, the competition became so heated that there was oftenwheel-to-wheel racing, with Corvettes and Porsches taking each other out

with spins and crashes.

Corvettes won all of the races coming into the event at Portland, Ore-

gon. But Porsche came to each race determined to win,and the team cer-

tainly had a good chance at Portland. The German cars started from the

pole, and were able to maintain an unassailable lead on even the best

Corvette. About a half hour before the finish of the race,it started to rain.

Charging to stay ahead, the leading Porsche spun on the drenched track.

The driver of the following Corvette saw the plight of the Porsche and was

able to slow down in time, using the anti-lock brakes. Slipping past the

spinning Porsche, the Corvette took the lead and stayed there to the fin-ish. The Corvette team finished out the year by winning the subsequent

races and established a two-year record of winning every race in the

SCCA Showroom Stock Endurance Series.


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For 1987, Porsche was rumored to have bought a 1986 Corvette and

to have thoroughly tested it on the companys Weissach test track in Ger-many. From this comparison, they developed a 944 Turbo racing pack-

age, featuring more power, bigger brakes, and ABS.

Porsche had developed the 944 Turbo as a serious race car for European

competition.For the SCCA Showroom Stock Series, the company was only

mildly constrained by the rules. It brought whatever it needed to the

track,whether it was in production,about to be produced,or experimental.

SCCA bent over backward trying to help Porsche get into the winners

circle. Even though we would complain about the concessions made for

Porsche, it was the right thing to do for the racing series. For SCCA and

the spectators, having Corvette and Porsche each winning half the time

would have been just right. SCCA also had a received assurances that theNissan 300 ZX turbo would return, and that Mazda was also consider-

ing entering the series.

Given the concessions that SCCA had made for Porsche, and that the

944 Turbos were as fast or slightly faster than the Corvettes on a straight-

away, Corvette felt it had the right to petition SCCA for more freedom

in engine preparation. With the improvements that were agreed to, the

Corvettes would run at 350-375 hp, which was still down in power from

where we expected the turbocharged Porsches to be. But, with the

Corvettes excellent torque curve and the better fuel economy of the nat-

urally aspirated engine,we felt this was a reasonable balance,particularly

for the longer endurance races.At full power,the production Corvettes engine management computer

is programmed to run rich, to protect the engine from the extremes of

the ambient environment.Very high temperatures,very low humidity, and

low-octane fuel can cause detonation that a somewhat-richer full-throt-

tle mixture will avoid. A production car spends very little of its time at

full power. Youd have to be driving in excess of 140 mph continuously

to get into the full-throttle enrichment system. So, this enrichment pro-

tection is invisible to the average customer, however, under racing con-

ditions it dramatically increases fuel consumption, because the car is

running at full power up to 40 percent of the time.

One of the real secrets to successful endurance racing is to maximizefuel economy. At the track, we know what the ambient temperatures are

going to be.We know what the humidity is. We have good control of the

fuel thats being used.As a result,we can run a fuel calibration much closer

to stoichiometric, without concern for detonation or over-heating.


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The ideal mixture, combined with a driver

trained to maximize smoothness at a calculatedpace, could literally double the racing fuel econ-

omy (and halve the pit stops). The Corvettes were

regularly achieving as much as 7-1/2 mpg while

winning.

THIRD YEARS A CHARM

When it was time for the 1987 racing season, our

1988 chassis was almost in production, so the new

chassis changes that would benefit racing Corvettes

were introduced. These changes included a modi-

fied rear suspension and big brakes on all of thecars. Late in the season, we also introduced the six-

speed ZF manual transmission that was being

developed for the 1989 Corvette and the ZR-1.

The 1987 season developed much as SCCA had

planned it. Porsche was very competitive,and took

most of the pole positions. Nissan showed up at a

couple of races with what looked like a very com-

petitive car once it was developed, but it never went

anywhere. Mazda never showed. Porsche typically

fielded three cars with a team of internationally

respected endurance drivers.They had every chanceto make it into the winners circle but, with crashes,

mechanical failures, and the extreme competitive-

ness among the Corvette racers, this was not to be.

In the end, twelve great races from 3 hours to 24

hours in length were all won by Corvettes,and Kim

Baker, with his number 3 and 4 Corvettes, won the

series and clinched the manufacturing champi-

onship for Corvette.

SCCA must have been bombarded with com-

plaints from the racers in the other classes, about

being overrun by the Porsches and Corvettes, andnever having even a chance at the overall win. It was

not unusual for competing Corvettes and Porsches

to blow by on each side of a competitor from a dif-

ferent class. So for 1988,both cars were kicked out


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Top: Baker Racings number 4 car on the starting grid for theEscort 24-hour race at Mid Ohio. The 944 Porsche Turbo is

lurking right behind, hoping to out-drag the Corvette.

Middle: In this 1987 race, Baker Racings cars number 4 and 5lead a bevy of Corvettes sandwiching a lone 944 Porsche Turbo.

Bottom: Baker Racings number 4 takes the flag to win the 198724-hour race at Mosport in Ontario.


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of the series. Corvette was out for winning all the time, and Porsche was

barred because the 944 Turbo was still so much faster than any of the othercars that they would have dominated the series without the Corvettes.

Needless to say, the series lost much of its interest that year. Meanwhile,

with the momentum we had built up with the cars and racing teams, we

went off to play on our own for the next two years, in what became

known as the Corvette Challenge.

THE CORVETTE CHALLENGE

The Corvette Challenge was the dream of John Powell, who had run one

of the Corvette teams in the SCCA Showroom Stock Series. These races,

held in conjunction with a major SCCA Trans Am event, were one-hour,

no-holds-barred, sprint races which typically fielded 15 to 20 Corvetteswhich were, essentially, identically prepared. These races produced some

of the best wheel-to-wheel Corvette racing ever seen.

Several of the automotive journalists who wrote for the major car mag-

azines were also amateur race drivers and were part of the scene at the

Showroom Stock endurance races, getting rides from competitors in

various classes. We looked on this as an opportunity, and encouraged

Corvette competitors who had a third car running to include the jour-

nalists among their drivers. This gave us the opportunity to train the jour-

nalists on anti-lock brakes in a racing environment, and also for the

journalists to get a chance to experience driving Corvettes in the heat of

battle. From this experience they got to know the carand usmuch bet-ter. The writers also gained first-hand knowledge of the cars robustness.

The car could take pretty big hits before serious damage was done. Even


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Twenty Corvette Challenge race carsline up for their one-hour race.


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damaged, the cars were often repairable and could be sent back out on

the track to continue racing.By the mid 1980s, FM radio communication with the drivers was

common, but data telemetry was still very unusual.We began by teleme-

tering the digital instrument panel data from the car back to an instru-

ment panel set up at trackside.From there, we went to telemetering more

data as required. With a computer interface, we could watch the driver

on the track to make sure the car stayed within rpm and temperature

parameters. In this way, we could detect problems long before the driver

could, and reccommend corrective action where possible. Relieved from

having to watch the instruments, the driver could concentrate on racing.

We also experimented with the G-Analyst electronic device to study

the gravitational forces being generated. This helped the different driv-ers compare their performances.Drivers could profit from observing each

others detailed performance, and learn how to go faster everywhere on

the track.

These five years of racing were incredibly important to Corvette.With

the help of the teams and the drivers, including Tommy Morrison, Dick

Gulstrand, Kim Baker,John Powell, and Doug Rippy, we took the Corvette

from a 1984 car, that had potential but no pedigree, to a 1989 car that was

world class as a production sports car and was capable of no-holds-

barred competition. We would next drop in the 400 hp LT5 engine and

turn loose the pressand Corvette enthusiastsin the fastest produc-

tion sports car on earth.


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Corvette From The Inside by Dave McLellan - Chapter Nine: The Crucible of Showroom Stock Racing