Corvettes?

[evolutionmovement]

No, but the US one is still less than 2/3 the weight. Besides the bigger engine, the difference is in the Elise's construction (bonded and riveted alloy chassis), size (small and cramped), small engine with less power (allows smaller brakes, tires, chassis and suspension doesn't need to cope with massive torque and so can be lighter) and lack of creature comforts.

[jamesqf]

Originally Posted by evolutionmovement

...the difference is in the Elise's construction (bonded and riveted alloy chassis)...

And I always thought the Corvettes were made out of fiberglass so they'd be lighter...

...small engine with less power (allows smaller brakes, tires, chassis and suspension doesn't need to cope with massive torque and so can be lighter)...

But it still has comparable/superior performance, depending on exactly what & how you're measuring. Either one is capable of going fast enough to enable the driver to collect a sufficient number of speeding tickets for license revocation :-)

...and lack of creature comforts.

Humm... It's supposed to be a sports car, isn't it? Which means that the lack of certain things is a feature :-) Besides, I have a hard time figuring out just what sort of "creature comforts" could add half a ton to the curb weight. These days a decent stereo system weighs a few pounds at most (unless you're building a boom car), anything else electronic adds ounces. Cup holders weigh zip... Add a few pounds for multi-way adjustable seats, but what more is there? Maybe a hot tub & Swedish masseuse?

[hyperyaris]

A giant V-8 with six long gears can cruise at highway speeds at very low RPM and thus get good mileage.

[The Atomic Ass]

Originally Posted by bluetwo

I don't know if it's common knowledge or not but Corvettes CAN actually get really good fuel economy. I've known about this for years because there was a time when I wanted one and I spent a lot of time on Corvette forums reading up on 'em.

So it hit me, what if someone took a Corvette of all things and modified it to get some seriously good gas mileage? It would have to have a small economical engine so it wouldn't be fast any more! Depending on how crazy someone wanted to go with it there could even be some serious modifications involved and obviously there are a lot of people who would cry blasphemy, but who cares? ...if somebody wants to ecomod their car it's their business.

ANY low-slung car with a V8 is going to be a good candidate for relative highway MPG. My mother's Cadillac Eldorado, a car that weighs nearly 5,000lbs curb, with a 4.6L V8, still manages 28-30 on the highway.

The statement in bold does not need to be. Before Brammo motorsports started selling EV motorcycles, they did ICE components for race cars, building some and importing others. They imported for a time, a British, 2.0L (A 2.5L version was available as well), purportedly 400HP N/A V8. This engine went clear to 12K RPM, and still managed a respectable 150ft. lbs. of torque at 1,500 RPM. Take the standard 6-speed from a Corvette, widen the ratio's a bit, and you would have the same equivalent power in the low gears as a 5.7L V8, but low cruising RPM's on the highway, say around 1,500 in 6th at 65 MPH. Lots of potential.

[evolutionmovement]

The Lotus and the Corvette are both fiberglass. The chassis are alloy vs. steel. Are we arguing the benefits of Elise vs. Corvette or talking about why there's the weight difference? I thought it was the latter. I'm a Lotus fan, but the C6 with a comparable driver would probably walk all over the Elise at anything but the most tight road course (check their respective Nurburgring times). Max power/weight and published acceleration numbers aren't the whole story (though the C6 still wins). The Corvette's larger, flatter torque curve make it a far faster car in practice. The Toyota engine in the Lotus is known for being torque deficient. on an auto-X track, on the other hand...

The cars are built for different customers and the market for what the Elise is is smaller than that for the Corvette. I might not mind minimalism (the trike I'm building will be about the same as the Lotus inside), but I'm a minority. Most people (Americans at least, accustomed to the lazy bottom end power of a V8) judge the power of a car by how much it throws them back when they tap the gas. And many people expect a performance car to deliver that, not to have to cane it to get it to move (a problem many people also have with the Honda S2000, another car I love, and the one I'm taking the drivetrain from for the trike). Lotus also has to innovate to survive (their engineering division traditionally makes more than their car manufacturing), since they can't compete on a mainstream basis. The mainstream cars, on the other hand, appealing to a larger audience, also have to play it more conservatively.

I think the Corvette is remarkable for what it is. Check the mileage of the Ferrari F430 with comparable performance and far greater price tag. And serviceability costs?

[jamesqf]

Originally Posted by evolutionmovement

Are we arguing the benefits of Elise vs. Corvette or talking about why there's the weight difference? I thought it was the latter.

Me too. So where is the weight difference - half a ton or so - coming from if not the bigger drivetrain?

The Corvette's larger, flatter torque curve make it a far faster car in practice. The Toyota engine in the Lotus is known for being torque deficient. on an auto-X track, on the other hand...

Which is why the handling matters more, IMHO, than sheer power, at least for the majority who'll be driving on roads rather than racetracks. Plenty of twisty roads around here where you can use reasonable sports-car handling, not many where you can really use a top speed over 100 or so - and being that this is Nevada, most of the roads where you could open the throttle a bit without undue risk of traffic cops tend to be occupied by cows :-)

But this is all drifting away from the original question, which was how much of a Corvette's weight could be replaced by batteries for an electric conversion. After all, we know that a similar Lotus conversion works quite well. So how about a Tesla-vette?

[evolutionmovement]

Should be able to hold more batteries. The big, heavy steel chassis should be able to support more as well as having lots of room under the hood.

[jamesqf]

Originally Posted by evolutionmovement

The big, heavy steel chassis should be able to support more...

But would also mean more non-functional weight to haul around, so less range/performance from a given quantity of battery. I was hoping most of the weight would be in engine/drivetrain, so it would go away and be replaced by batteries.