There’s been a lot of talk on the ZR-1 forum and others about the removal of Zinc from motor oil, specifically Mobil 1 and the potential detrimental effects on the LT-5 and other Corvette/high performance engines. Opinions have varied and I’m certainly no expert so I decided to do the obvious – I asked Mobil through their support line. The response was –

The new ILSAC GF-4 motor oils (10W30 and lower viscosities) do have reduced (0.08%) ZDDP in the formulation for longer longevity of the catalyst converter and system. This is not a problem on newer vehicle designs that utilize the roller cam, valve train technology however, if you have flat tappet cam, valve train technology you generally want higher ZDDP levels. Mobil1 15W50’s, Mobil1 diesel motor oils, Mobil1 motorcycle motor oils and Mobil1 High Mileage 10W30 and 10W40 have high ZDDP levels and would be the best choices for these engines.”

I also found some good online resources discussing this issue and additives in general –…ech/index.html

Hopefully this will help people make an informed decision.

The deed is finally done!

After all this time I have finally bought a ZR-1.

The vehicle is currently in Michigan and has 33000 miles on it, the bodywork is almost flawless and so is the underneath. It has a custom exhaust and wheels, but comes with all the original parts (including the original 1991 tires!) and even has the original window sticker (original price $66000!)

The previous owners have really kept the car in amazingly good condition and a big thank you goes out to all of them.

1991 Corvette ZR-1
Pictures Here

Of course, the story is not quite that simple. It never is it seems :-) – in this instance the car is in the US and I’m in Canada, so now I have to go through the importing process.

My first thought was that I would drive it back Continue reading

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.

Continue reading

There’s a ZR-1 for sale on the registry site for $5000. Now, hold on just a second, before you go running off to get the number to call the seller, there’s something you should know. It’s been rolled.

There’s no engine or transmission. Most of the front and bodywork is gone and there could be some rear damage too, there also appears to be some damage to the top of the windshield too possibly.

Okay, so now it’s a junker, right? Why am I wasting your time with this?

Well, there are some real possibilities here.

First of all, the overall condition of the chassis and the passenger cell etc. looks in good condition. The parts that are damaged are mostly the parts that are standard to any C4 so plentiful and cheap.

So what you have here is one hell of a fantastic project potential.

First there’s the obvious scenario. Rebuild the car, find an LT-5 and transmission and drop it in. The problem with that idea is that LT-5s aren’t exactly hanging around on street corners waiting to be bought and when you can find them they’re expensive. Still allowing around $10k for the engine, $2k for the transmission and maybe another $6k for the rest of it still leaves you with a fairly good priced ZR-1.

Some other options spring to mind though. Let’s say you do find an LT-5, originality isn’t an issue here so how about mounting the ‘Heart of the Beast’ to an automatic gearbox? The mounting should be a fairly easy fabrication for anyone with a decent home workshop or could be farmed out to a good shop. I can hear the purists gasping in horror at the thought, but hell you’d have the only slush-box ZR-1 on the planet probably.

As I said an LT-5 is pretty hard to find and expensive. So how about dropping an LS-1 or LS-2 in there. Again this might be sacrilege to many, but in many ways the new C5 and C6 engines are the descendents of the mighty LT-5 (albeit a somewhat side branch of the family).

A standard LS-1 will give power levels approaching a pre-93 ZR-1 and with some fairly simple bolt-ons will surpass it, at least on a pure horsepower level, if not in terms of refinement and top end.

The newer engines are also very amenable to tuning; there is a bewildering array of power-adders and updates for these engines. What’s more they are plentiful and relatively cheap. And on top of that, like the LT-5, they’re a completely aluminium engine so the power to weight ratio is excellent.

The fabrication again shouldn’t be too hard. The LS series engines were tested in the C4 chassis while GM was doing early testing with ‘mules’ so should present few problems. The gearbox and instrumentation may need some work but hey we all like a challenge don’t we?

Lastly, how about this for an idea. Install a C5-R 427 or similar. This probably wouldn’t cost any more than trying to find a replacement LT-5 but the power levels would be fantastically insane. One thousand horsepower should be easily within reach with this kind of setup. Adding in super or turbo chargers would provide enough power to move a small planet :-)

Maybe it’s just me, but the idea of rescuing a fallen warrior and breathing new life in to him, giving him the weapons he needs to rise again, that sounds very cool!


I’ve been looking at a ZR-1 for a few weeks now, exchanging emails and phone calls with the owner. So far it looks like it might be a ‘go’. The photos of the car look okay – not stunning – but okay.

There is a little surface rust underneath (C.V. joints etc.) and it definitely shows signs of being ‘driven’. That’s okay though, I intend driving it too and as long as you’re aware of any possible problems it’s no big deal.

I have to say that the people on the ZR-1 forum have been invaluable in looking at the pictures with a more clinical and knowledgeable eye. It certainly has helped immensely getting their feedback.

The next stage is to go and look at the car to see if it’s as good ‘in the flesh’ as it is in the photos. The owner is in Wisconsin and I’m in Northern Ontario, so it’s around a 2000km round trip in deteriorating weather conditions – not ideal circumstances, but worth it to potentially get a ZR-1.

The vehicle I am looking at is a ’92, so one of only five hundred and two made. It has a black exterior and interior, which isn’t my favourite colour but that’s okay too – Dark Red Metallic (my favourite) are so rare that I don’t really have much chance of getting one, so a respray will be in order.

The owner has it advertised at $28k US and describes it as in ‘excellent’ condition, an assessment which the photos don’t really hold up. I’d judge it to be ‘fair’ to ‘good’ based on the guides on KBB. This gives it a value of between $22k and $24k – just inside my budget.

Although it’s looking good, the one thing I won’t do is get pulled in to a bad deal. I’d rather walk away and put the trip down to experience. That said the opportunity is there and looks good so far.

There’s a ZR-1 for sale on ZR1.NET. My favourite year/colour – ’95 Dark Red Metallic. It has a beige/saddle interior which I’m not keen on, but I’d still take it!

Sadly it’s $48k US, which translates to almost $60k CAN and far beynd my budget. Yes I’m searching for a ZR-1 but that doesn’t mean I’m made of money or won the lottery.

At the moment I can go up to about $25k US, which buys several ’90/91sand a couple of ’92s that I know of. There were a couple of ’94s that I would have jumped at, but I wasn’t able to move fast enough financially. A ’94 for $25k is a bargain.

By Spring my budget should be up around $30k US which brings more cars in to play – it’s always hard when you have a tight budget. There is always the thought lingering at the back of your mind that you have to get the absolute best deal for your money. The problem is that sometimes that makes you hesitate and end up losing out on what would have been a good deal.

It’s very hard being in this position. On the one hand, I could never have afforded to think about getting my dream car in England where I grew up, but here in Canada it is actually doable. On the other hand, when you see something you tend to jump for joy and start making all sorts of plans, then the doubt demons jump up and you start ‘what-if’-ing yourself out of things because of fear.

I’m fighting hard against it.