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Old 02-26-2009, 03:26 PM
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Default The GNX vs. Callaway Corvette Video ... behind the scenes!

Scott Keller has been corresponding with the son of a major player in the video hosted on our site and got a fascinating and entertaining story behind the video as a result . I thought I'd share the interview and post it here until Scott can get it put up on the site as part of the video ....


GNX vs. Callaway Twin-Turbo Corvette (video clip)

The video clip was taken in March, 1987 as part of a “photo shoot” for Popular Mechanics at Milan Dragway. GM often used Popular Mechanics (Jim Dunne) to preview new vehicles in the press.

Some background:

My name is Thomas W. Weber and at the time I was the Chief Technical Officer at ASC. At the time, ASC & McLaren Engines were interconnected financially.

The concept for the GNX was started the prior year during the “rained out” Indy 500, where the C4 Corvette Convertible was the “pace car”. While Chevrolet rarely acknowledges it, the C4 Corvette Convertible was engineered, designed (with the support of Chevy Engineering) and
parts tooled and supplied by ASC and provided to the Corvette Assembly plant in Bowling Green, Ky. During the rain-delayed Indy 500, the GNX idea was born during a BS session with seriously bored, Buick, ASC and McLaren engineers. As is typical with many engineering BS sessions, one idea let to another, then another, etc. To make a long story short, both ASC and
McLaren started the project in the “backroom” without approval and no official funding.

However, it is difficult to keep a project like this hidden. Eventually, Buick called ASC & McLaren together in Flint and issued as set of design “rules” because Buick engineers wanted to do their own version. Further, there would be “beauty contest” to select the winner. After we left the meeting at Buick, I told both ASC and McLaren engineers, there is no way we are going
to lose to Buick, so “pull out the stops, ignore the rules and do the GNX right”. If anybody gives you any crap about the rules, have them come see me. It was “no contest” when Buick’s version and ASC-McLaren’s version of the GNXs were rolled out of the covered trailers. ASC McLaren’s
version won the “beauty contest” hands down.

As part of the “beauty contest”, there was no way I was going to let the Buick engineers outshine us in the quarter mile. So I instructed the McLaren engineers “do what it takes” to win the drag race, but don’t tell me how you intend to do it in advance. To be honest, I needed “plausible deniability” should I get confronted by Buick engineers.

So after winning the “beauty contest”, ASC-McLaren also won the “performance contest” as it was outlined in the Buick GNX book. It was afterwards that I found out that the ASC-McLaren GNX was running 110/120 octane fuel and the PROM was swapped (with ‘juiced” parameters) just before the “performance contest” to assure a win. Of course, this was what I was hoping McLaren engineers would do.

Knowing this is essential to understand what happened on this digital video.
When we were told by GM to bring the Buick GNX to Milan for a photo shoot, we were also told that there would a twin-turbo Callaway Corvette as part of the photo shoot. We were also told by GM personnel there would absolutely positively be no drag races between the two vehicles. So we planned accordingly and were prepared for “absolutely no drag races”. Of course, this meant that the GNX would be loaded with very high octane fuel, “juiced” PROMs, etc.

As you can see in the video, it was a cloudy, cold day ...ideal for making power, and the GNX had the ideal driveline for delivering “best power” to the largest tires available in the industry at that time.

Photo shoots are long and boring. So late in the afternoon, someone had the bright idea that we ought to do some “performance comparisons”.
In the first drag race, despite the cold weather and cold track, the GNX “hooked up” nicely and made a nice 13s quarter. However, while the Callaway Corvette engine was making plenty of power, the manual transmission driveline could deliver the power, but the power was too much
for tires and the tires simply “smoked”.

So it was decided to re-run the drag race. Very simply, it was too embarrassing for the red Callaway Corvette to lose to a big, black Buick V6 sedan. While the Corvette engineers tried a different launch strategy, the results of the drag race were still the same. Again, the Corvette engineers wanted to re-run the drag race, using another launch strategy. Of course, the outcome wasn’t even close.

A small but important detail: During GNX development, ASC-McLaren was told that it was GM policy that the Corvette was to be the “fastest” GM vehicle. So we decided that if we had to be second to Corvette in top speed, there was no GM policy that said we couldn’t be the “quickest” vehicle. So the rear suspension was optimized for one thing: delivering the power to the biggest tires available in the industry. Further, there was a torque-arm to keep the transmission and axle properly aligned during high energy launches. In addition, the five-link rear suspension also assisted in diminishing any undesirable axle/wheel vehicle motions yet maintain appropriate vehicle attitude during high energy launches.

One last thing: The computer and transmission was set-up for very quick shifts. In other words, there was very little clutch overlap during high-energy up-shifts. To realize the best (and most consistent) quarter miles, it was simply a matter of putting the transmission in drive, put a foot on the brake, bring the engine rpm to ~1800-1900rpm and let the computer do the rest.

In essence, the GNX was engineered for best performance for the quarter mile and would start running out of power about 50-100ft beyond the finish line. As a result, the GNX was the “quickest” production vehicle in its time. It was just that simple.

As a result, the Callaway twin-turbo Corvette with a manual transmission did not stand a chance. So once it was obvious that there was no way that the Callaway Corvette was going to beat the big ol’ black Buick V6 sedan, it was time to have some fun.

So one of the McLaren engineers asked if I wanted to take Angie (my wife) for a ride in the GNX, since she was with us and had been very patient during the long and boring photo shoot. So I asked her if she was interested ... and she said “yes”.

However, since we did not have a child seat with us, she decided to hold Todd in her arms while I took her for a ride down Milan Dragway’s quarter mile. So I did the prerequisite “burn out” to show her what it’s like and why it’s done. However, as I was pulling up to the line, one of the Corvette engineers jumped out and was giving me a hand signal to stop.

I looked out my window and noticed that the red Corvette was pulling up to the start line. So I turned to Angie and said: ‘Hang on ... this is for real! It wasn’t supposed to be this way, but there is no way I am going to lose to the red Corvette!”

As you can see in the video, I brought the power up to ~1900rpm and waited for the “Pinks style” arm drop. The GNX hooked-up and just started pulling away from the red Corvette and continued to out accelerate the Corvette all the way down the track.

As we were coming through the “traps”, Angie said to me: “Why is the Corvette slowing down?” I told her: “The Corvette wasn’t slowing down. We were pulling away from the Corvette!”

During the drag race, I noticed that someone was taking an unauthorized “movie”. When we returned to the start line, I inquired “who was taking the movies?” No one had a good answer. However, one of the McLaren engineers said: “You beat the Corvette with Angie and Todd in the passenger seat. At least someone has it for posterity.” I then remarked: “This wasn’t such a smart thing to do, but at least it ended well.”

Now, let’s fast forward 20+ years. We have a 19-year-old son, Patrick, who is studying mechanical engineering at the University of Wyoming. In one of our conversations, we got on the subject of the Buick GNX. Lo’ and behold, Patrick pulls up a video on the Internet and wanted to know what I thought about the video clip he found of a GNX racing on the drag strip.

You can imagine the surprise when we saw ourselves on the Internet at the Milan Dragway! We are in the GNX in the last race in your clip. We aren’t sure what other specific information you might be interested in, but we would love to get a better copy of your video clip. How often does anyone have an opportunity like that, and then find themselves on the Internet 20 years later! Thanks.
Tom Weber
Ken Mosher
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Old 02-26-2009, 09:28 PM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

That was Fantastic!!! Thanks for sharing... Tom G.
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Old 02-27-2009, 02:31 AM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

That was an AWESOME post!
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Old 02-27-2009, 07:54 AM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

Thanx for the post Ken. That last pass was AWESOME - the GNX sounded like a missile flying by....
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Old 02-27-2009, 09:38 AM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

excellent !!!
Phil Underwood

My Turbo Buick
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Old 03-08-2009, 12:31 AM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

YEAH SON! Great vid!
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Old 03-11-2009, 09:54 PM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

This is great I never like corvette's anyway
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Old 03-12-2009, 09:08 AM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

Simply, wow. now that was cool.
Just another not stock regal. P&P heads/intake, 61mm GT, SLIC w/neck, SMC boozamahol, Sewer sized DP, 60#inj, TT 93, Hofer tranny, fuel cell, A1000 pump, stock cam/pistons, 100lb springs, titanium retainers, SS polished TA valves.
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Old 04-01-2011, 09:49 AM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

this is amazing! great video you got there.
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Old 12-21-2011, 12:09 PM
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Default Re: The GNX vs. Callaway Corvette Video ... behind the scenes!

that was awesome post dude i have copied it
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