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WOW do I feel stupid

Old 03-17-2004, 01:02 AM
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Default WOW do I feel stupid

a fellow boater was telling me about his friend who had a merc racing engine from the factory in his corvette.. I called BS welp I never knew the ZR1 motor was built by mercury marine how the hell could I not know that..

LT5 Documents

In the October 2000 issue of the National Corvette Museums
Americas Sports Car I wrote an article about the building of the LT5 engine
as seen through the eyes of Allen Kersey. Allen was a machinist at Mercury
Marine who through pride in workmanship halved the specification on the
balance of the LT5 crankshaft; this spec then became the required one during
regular production. Allen also helped store the documents created by Mercury
Marine during the manufacturing of the engine. Mercury Marine has turned
those documents over to the National Corvette Museum. I sat down and talked
with Allen in order to get an idea of what was in that documentation.
During the building of the LT5, Mercury Marine created documents
in accordance with SPC (Statistical Process Control). SPC is a method of
tracking the build process of a project you are working on in order to insure
quality and repeatability. During the production run of the LT5 Allen
machined the heads. He said that there were over 6 pages of machinists prints for the heads alone, with over 600 measurement specs for each head.
During the LT5 production Mercury Marine worked with new ways of
machining that no one else was yet doing. At the time these methods were
highly classified. One story that Allen told was the way that he put in the
valve guides. He machined the heads to very precise specs and then would pull
the seats out of liquid nitrogen (this was done to cool the guides and make
them shrink slightly). He would then insert them into the head and machine
them. The tooling head in the machine that he used for this process cost
around $65,000 by itself! It would machine the angle for the valve in the
seat and stop, then another tool would come out of the middle of that tool to
machine out the hole for the valve stem to very precise specs. Allen said it
was very touchy machining steel and aluminum together.
While not all 600 specs where measured on every head, Allen said that
over 100 were done every time. Critical measurements like diameters of the
cam bore, concentricity of the cam bores were checked on every head. The
other specs were only checked at regular intervals. All these measurements
were recorded for the SPC charts. This documentation was included in a build
log. The build log contained documentation concerning that individual engine.
It was record of every part and every test done on each engine. Data from the
foundry and who built what were also part of the build log. At the end of the
build each engine was run on a dyno and the results were documented. Allen
recalled that the build logs were over 1 thick. These LT5 engines were very
thoroughly documented engines.
At the end of the LT5 production Allen stayed in the area and helped
dismantle the tooling from the LT5 build. He also carried boxes upon boxes of
documents to a storage area across the street from the Mercury Marine plant.
When I asked him what was in those boxes he could not exactly say as they
were all sealed. Based on the amount of documentation produced during the LT5
build, Allen surmised that the SPC data was a lot of what was packed in those
When I told Allen that Mercury Marine had donated those documents to
the National Corvette Museum he exclaimed, That must have taken a semi to
haul all that over there. From what I have heard that is what it took. There
is a lot of documentation surrounding the LT5 motor and this now resides at
the National Corvette Museum.

Howard Dickman
Founding Member # 2951
National Corvette Museum
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Old 03-17-2004, 01:55 AM
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Hey packinair,

Still haven't caught up with you yet.

Yes, the above is true ... I have a black '90 ZR-1 Vette with 11,000 miles. This car is awesome! Tested @ 182 mph (by Road & Track, not me!).

The engine was designed by Lotus and produced at the Mercury plant in Stillwater, OK. It's a 32-valve, double overhead cam , 350 c.i. Chevrolet-based block turning 375 H.P. in 1990, 405 H.P. in later versions. This motor starts to open up above 5000 r.p.m. and pulls hard to a 7000 r.p.m. redline!

Someone stuffed one of these in a 25 foot Baja in the early nineties and called it the "wette-vette". Just not enough torque and problems with the computers prohibited wide-spread use in the marine environment.

Lingenfelter Performance Engineering in Decatur, Indiana did a lot of performance upgrades to this engine. A while ago, they had a guy at their shop who originally worked for Lotus in the design of the engine.

There is some impressive plumbing under the hood of this car! Each cylinder had two intake runners and two fuel injectors, with a "valet key" on the dash that could be used to shut off the secondaries when you left it in the hands of the adolescent, pot-smoking valets so there was still some tread left on the rear tires when you retrieved the car from them following dinner!

Let me know if you would like to stop by and see it sometime!


Last edited by RedDog382; 03-17-2004 at 02:11 AM.
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Old 03-17-2004, 03:05 AM
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I would love to.. I picked up a C4 from a fourm member and would love to take a ride in a ZR1 you have almost 150hp on me if I am not mistaken Scott 419-509-1882
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Old 03-17-2004, 07:14 AM
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Mercruiser also helped Saturn Motors out in the beginning with " lost Foam casting processes also"

I seen a documented show 1 time with ladies at Merc building these motors 4 corvettes they claimed merc had more precise engine building techniques. It was on the History channel I beleive. It just had me walking away wondering why GM would admit that Merc built more precise with-in spec. motors then them?
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Old 03-17-2004, 08:44 AM
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Default Mercruiser Engines

The ZR1 engine is very highly toleranced, and GM Tonowanda engine facility could not build them at a reasonable cost.

The engine has reverse cooling, which later came out on the LT1 engine. The Brits love to design overly complicated systems.

The ZR1 engine also is very susceptbile to cooling problems, so Red Dog DO NOT let it overheat.

However, 14 years later you will be able to buy a 2005 corvette that makes as much HP as a ZR1 (400) and is in a tighter, more solid package for less $.

That's progress.

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Old 03-17-2004, 10:06 AM
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I know that these engines were installed into several boats. Strangely enough, they were ski boats.
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Old 03-17-2004, 10:17 AM
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think that bad.. take a look at this
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Old 03-17-2004, 09:59 PM
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Isn't "Mercury" and "reasonable price" mutually exclusive?
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Old 03-17-2004, 10:02 PM
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When I worked for Saturn I was at the SpringHill Tenn plant the engine room had saturn motors n merc. motors side by side torn down HMMMMM
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Old 03-17-2004, 10:13 PM
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Wonder how much it would cost me to put a couple of "blown Saturn" motors in Outlaw?
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