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The latest copy of ‘Corvette’ magazine has a feature on the ZR-1 and exploring its demise in the kind of derogatory tones that I’ve gotten used to seeing quoted in far too many places.

The resounding idea from the article is that the car’s engine, the mighty LT-5, was too expensive and that it became obsolete and unnecessary because good ol’ Yankee ingenuity made the aging small-block Chevrolet almost its equal.

As an example of this, it tells the story of how the GM engineers developed reverse-flow cooling systems for the small-block that allowed them to create more power from the engine without the heads melting.

Traditionally, engine cooling feeds cool water from the radiator in at the bottom of the engine, this works its way up and the hot water is sucked out of the top. Hot water naturally rises, aiding the flow and all is well.

Except, by the time the water gets to the cylinder heads (the area most in need of cooling as that’s where combustion takes place) the water has been heated in its journey through the rest of the engine block, making the cooling effect less effective and constraining the power levels achievable.

With reverse-flow, as you might imagine, the cool water is introduced at the top through the heads where it can be most effective and is forced down by pressure, where it is removed at the bottom. This gives more cooling up top and allows more heat (power) to be generated without having to suffer lots of unpleasant things such as detonation or combustion chamber meltdown.

A great refinement. Good engineering. A deft solution to an old and stubborn problem.

Perfected by Lotus engineering on the development of the LT-5.

Corvette magazine seems to be following the GM sponsored doctrine to see automotive history rewritten, at least as far as the ZR-1 is concerned. The ZR-1 was a failure, it was expensive, it was complicated, no one wanted it, and in fact it wasn’t even that good.

Apart from the cooling ‘mistake’, the article goes on to tell the story of how the LT-1 brought near ZR-1 levels of power for a fraction of the cost. Again this is a highly questionable claim.

The L-98 delivered 245bhp, healthy enough at the time even if it looks a little anemic in comparison to its descendents. The ZR-1’s LT-5 engine produced 375bhp in its original form, 100bhp difference is hardly insignificant. When the LT-1 was introduced in ’92 it raised the base level to 300bhp (and finally, 330bhp in LT-4 guise).

So the gap reduced to 75bhp, but think about it. We’re still talking of a 25% power difference in favour of the LT-5. How many ‘vette owners would hand over large amounts of the folding stuff for performance parts to get a 25% increase in power? Lots.

Then in ’93 the LT-5 was updated to deliver 405bhp. Not only matching the difference between the L-98 and early LT-5 but upping the difference by a further 5bhp!

To make things worse for those trying to claim that the LT-1 was ‘nearly as good’ as the LT-5, by ’92 engineers already had a 450bhp version engineering complete and ready to go. Imagine that. A ZR-1 that would have had 50bhp over and above the latest 2006 C6 and what’s more, without having to increase the engine capacity! And, available 13 years before the C6s arrival.

Further plans included 500bhp and ultimately 550bhp versions. So the LT-5 would have delivered more power than the new 2006 C6 Z06 (which is way too many 6s by the way).

Yes, the LT-5 was expensive. It was new, it was low volume, it was largely hand-made – anything that falls into these categories is. But these problems would have worked themselves out, that’s what engineers do. The Japanese seem to have no problem producing high output, Quad Cam engines for a variety of ‘sports cars’ (what’s more they typically sell for around half the price of a current Corvette so they don’t seem to find them too expensive to build either!). The price would have come down – GM knows this.

It seems to me that what’s really the issue here is something much more human than simple ‘bean counter’ mentality.

GM set out with the goal of building a world-beating sports car and the ZR-1 was all that. Like any good engineer Dave McClelland sourced the best he could find, wherever he could find it to achieve that. The only problem was that, with an engine designed in England and manufactured by Mercury Marine, and a gearbox built by ZF in Germany, what they actually proved was that GM ultimately couldn’t build such a car.

Since then corporate angst and embarrassment has been growing and they have set about trying to bury their embarrassing ‘mistake’. So much so that only 10 years after it produced a seventy thousand dollar supercar, they are already discontinuing parts for it and try to deny its existence at all times (barely celebrating key anniversaries as just one example).

Or through the likes of Corvette Magazine – trying to rewrite history wholesale.

Until next time.

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