Recently Corvette Online released some “spy pics” of what could well be the new C7 ZR1 engine. The photos show what appears to be a supercharged fifth generation LT1; inside information suggests it’s a 6.2 liter engine and will be pushing out 650+ hp.
I find myself with strangely mixed feelings over this idea. As a C4 ZR-1 owner I can’t claim to not like power, but to me this represents yet another instance of more brawn and less finesse.
When the ZR-1 was released in 1990 it represented a huge leap in performance. The base vette at the time produced 250 hp and the ZR-1 was rated at 385 – a massive fifty-four percent increase! Those numbers would grab anyone’s attention and they certainly did – mine included.
Having spent several years in a drag racing team I’m very familiar with the old adage “there ain’t no substitute for cubic inches” but this wasn’t what happened with the LT5 engine designed by Lotus and fitted in to the ZR-1. The engine capacity was exactly the same as that of the base Corvette: 5.7 liters/350 cubic inches. What’s more, the LT5 engine was even more fuel efficient than the base L98!
The achievement encompassed in those numbers is truly mind-bowing. To take an engine, make half as much power again at the same engine capacity and have better fuel consumption is almost unbelievable and what made it possible was the inherent greater efficiency of the overhead cam engine design. This allowed the engine provide better head breathing characteristics and less parasitic loss in the valve train. This is why just about every other performance car manufacturer in the world (outside the U.S.) uses this configuration.
The dirty little secret here is that making power is easy, as the drag-racer saying explains. Add more engine capacity, as the dinosaur-esque muscle cars of the 60s exemplified. There are other easy options too, like adding superchargers or similar forced air systems. The problem with all of these ideas is they all come at the cost of efficiency. Add more cubes and you burn more fuel. Add a supercharger to force more air/fuel into the engine, and you burn more fuel. Sure, it works, but don’t be fooled for one minute that there is anything “clever” about it.
Look at the base C7 engine as an example. The new LT1 is 6.2 liters and puts out 450hp yet again raising the bar on the vette’s base power rating. If we look at the LT5 in comparison and just work out the relative power per cubic inch though it doesn’t look quite as impressive:
LT5 HP per cubic inch: 1.1
LT1 HP per cubic inch: 1.19
And that extra 0.09 hp/ci has the advantage of over twenty-five years of technology development plus the use of lightweight exotic materials.
And what about efficiency? The C7 is rated at 28mpg, which is pretty much the same as the C5 and C6 vettes have been rated. In essence GM are trading efficiency for more power (hell, I can get 26mpg out of my ZR-1!) As they have no incentive to increase fuel efficiency (saving the planet apparently isn’t enough), all their efforts go into the far more “glamorous” direction of increasing the power numbers that impress twelve year-old boys.
To be fair to GM, other North American car manufacturers are no better (though Ford has had considerable success recently with it’s quad overhead cam “modular” engines.) It’s not even the car manufacturers’ fault as a whole. The real problem is cultural: people are essentially brain-washed into thinking that everything must “get better” or “improve’ and that we must consume ever more to survive.
I hope that GM sees the light and comes up with a powerful AND efficient engine for any future ZR1. I hope they will return to the overhead cam design of the LT5. I’dlove to be able to see their announcement and feel proud that they’d avoided the “brute-force and ignorance” approach; to see them do something with the same kind of sophistication that was shown with the LT5 and I’d love them to make use of something like the stunning new Mercury Marine QC4V!
Sadly, I won’t be holding my breath.