I Broke the First ZR-1
ZR-1 Engine Development at the GM Desert Proving Ground – 1987
The following story is from my memories of working with the Engine Development Group engineers from Lotus Engineering out of England in the late 1980s as they first arrived here in the United States to do engine development and calibration on the new LT5 Corvette engine.
First, let me give just a quick summary of this Corvette program as background for those that don’t know everything there is to know about the 1990 ZR-1 / King of the Hill Corvette. Dave McLellan, Chief Engineer of the Corvette at that time, got together with Tony Hill, Chief Engineer of Lotus Engineering in England, and designed a new dual overhead cam, 32 valve, fuel injected engine for the Corvette. The RPO designation for this High Performance engine was the LT5. This engine had to fit within the confines of the current C4 Corvette’s engine compartment, and produce around 400 horse power. Most know all these history facts but what I want to pass along are a couple stories about the development of the engine at GM’s Hot Weather Facility, the GM Desert Proving Ground {DPG) in Mesa, Arizona.
It was the beginning of the summer test season in Arizona, 1987, when I received a call from Guy Lafalce, cooling development engineer for the ZR-1. He called to tell me he would be coming to the DPG soon to work on this new Corvette program developing the engine cooling system to handle the hot Arizona ambient temperatures as the engine ran through its entire range of operating parameters. It had to run cool at 600 rpm idling all the way to Wide Open Throttle at 7000 rpm during maximum speed testing on our five mile circular track. Guy said I would also be getting calls from Lotus engine calibration engineers soon informing me of their calibration trip plans and needs. Sure enough, a short time later, Lotus engineers Mark Berry and Ian James called from England and introduced themselves to me. They told me a test car was being shipped to my attention at the DPG and that they would also be showing up at the same time to start hot weather engine calibration. I was very excited to be working with all these engineers on GM’s newest and most powerful Corvette yet.
Sure enough, a beautiful C4 Corvette (with a widened rear end to accommodate the huge rear tires) showed up at the DPG and was left parked in the shipping lot until the Lotus engineers arrived. I was very anxious to drive the car but knew I better not touch this very expensive development vehicle. The next day Mark and Ian arrived, took possession of the car and gave me a call at my office. The conversation went something like this, "Jim, cheers. This is Ian. Mark and I just arrived, collected our car and would like to have you take a ride in it to get started." After doing a great job of controlling my emotions and not screaming for joy in the phone, I agreed to meet the two of them and check the car out. We sat in my office for what seemed to be an eternity getting to know each other and trying to get past each others’ accents. Then we started talking about their test plans, what they needed to accomplish in the hot climate here in Arizona before traveling to Michigan with the car for cold weather calibration. It finally came time to drive the First ZR-1 in the U.S.
We walked out to the car, opened the hood (bonnet, as I learned it’s called in England) and examined the new engine installation in the Corvette. It certainly filled the engine compartment but looked very impressive. Ian James hopped in the passenger seat and I jumped into the driver’s seat. I drove from our building area out towards the Vehicle Ride and Handling Road to just get a feel for the car and how the engine performed. I was very, very impressed on how smooth the LT5 idled and how tame it performed during part throttle maneuvers. This was the first production engine GM was going to produce with close to 400 horse power and it was amazingly tame. You see, at that time in history, if you built a special engine with 400 horse power, it would have been carbureted, had a high lift camshaft with plenty of valve overlap and would have had to idle at 800+ rpm just to keep idling. And then don’t even think about good part throttle drivability. Wide open throttle is what an engine with 400hp was made for.
Continuing…we drove out to this track that is about a mile and a half oval with the roads leading to it and back having a few curves and dips for handling purposes. Not wanting to beat the car or damage anything, I took it very easy and just got a feel for how the engine performed. It was on the way back to the building area where Ian said to go ahead and push the Vette a little as we got into the curvy bits of the track. Down shifting the car into 3rd gear, I started building speed and engine rpm as we went through the “S” curves. Now keep in mind, I’m taking it very easy trying not to abuse the car thus winning Ian’s confidence in me that I’m not a hot shoe type of engineer just wanting to thrash everything I drive. This way maybe I’ll get more seat time in the car as the development process continues. Well just as I got into the first part of the S, probably about 60 mph and 4000 rpm, something broke, the engine stalled, and the power steering assist went away! This promptly put us four wheeling off into the Arizona desert as I struggled to guide the car back onto the track. Well, you can imagine how I felt. I had just met these gentlemen from England, wanted to make a great impression on them and then break their development vehicle. I’ll never be able to touch one of these high performance machines again.
I could not believe it. The first ZR-1 with the new LT5 engine all carefully tucked in under the bonnet and it appears I’ve broken it. We got a push truck out to the track, pushed the car into the garage and found the timing chain for one of the cams had broken. Thank God, it wasn’t my fault! My recollection is that the engine was pulled, another sent from Lotus Engineering in England and it was installed so development could continue. Ian, Mark and I developed a very good relationship over the few months they were here at the DPG and yes, they did let me drive the ZR-1 again. I hope my experiences with the new ZR1 go a little smoother than this episode 21 years ago.
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