Corvettes?
 

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.

As I was walking by a C4 in my parking lot today it hit me that a big part of the good MPG these cars get is due to the areodynamics of the car along with, of course, power to weight ratio.

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.

Somebody oughtta do it. :D

A C5 or C6 can easily get in the low 30s as they sit with just reasonable driving.

'Vettes are fairly light and have fairly good aerodynamics. 6 speed 'C5 and C6 'Vettes have a nearly optimal drive train.

Too bad the GM 4.5 liter V-8 diesel was lost in theGM holocaust. Best option available today might be a Cummins 4BT3.9. A bit heavy (about the same as a 454 gas engine) but very efficient. It might be too tall to fit in the engine bay without a bulged hood.

The little Cummins should easily put a 'Vette into the 40s.

^^ Definitely...

I feel there are some other things that could help it too like low rolling resistance tires of a narrower variety. Vettes come with some REALLY wide tires and that burdens them considerably.

I was thinking of a smaller engine too, maybe not even a V8 or V6 though I admit I have no idea which engine it could be right now. Most Corvettes weigh over 3,000 lbs. so less displacement would certainly mean you'd have a much slower car. So the question would be where on earth would you look to find a RWD engine that would get good mileage while having to work as hard as would be required to move that much weight.

I'm sure there aren't a lot of weight saving mods to be done so does that leave aerodynamics to improve after that? Maybe I daydream too much but hey, sometimes that's what it takes to make something better.

Narrower LRR tires would certainly help. If you want big MPG without going hybrid, go diesel. Also they have gobs of torque and nearly as satisfying to drive as a LS2.

IfI were doing it, I would start with a convertible. I'd make the windshield a bit taller (I sit as high as a man 6'10" tall) and get a custom made coupe top made for it. Of course in addition to the Cummins diesel.

Stock vette is .28cd, boat tail, LRR tires, and air damn= Aerocivic that looks good.

Nearly as satisfying? IDK about that, RPMS sound good.

So.... bear with me because I think my theory is sound. Lets say you take a truck engine that gets 25 MPG and put it in something WAY more aerodynamic, it should get a significant jump in fuel economy.

So maybe the 2.9 liter 4 cylinder from the Chevy Colorado could help? Truck guys talk about the rear ends of their trucks all the time and by reading a little I saw that a different rear axle could make the truck a lot better on gas at highway speed so that might be something to look at too.

How many people think I'm completely crazy? Ha ha...

Not crazy, stupid for wanting to ruin a Corvette. ;) jkjk

Yes, get a rear diff that gets the engine RPM's at the best efficiency at say 55mph.

Ha ha ha ha ha!! ...stupid, now that's a good one.

I'm telling you somebody will do it one day, maybe even me. What's also funny is no one would ever know it didn't have the original motor because Corvette guys almost never race their anyway. It would look totally normal to just putter around in it all slow.

I hope this sparks some ideas at least if not for the Vette at least for something else. Who's to say there isn't a Corvette body just sitting somewhere, needing an engine and tires and it would actually be worthwhile?

Direct-injection 2 liter turbo Ecotec from the Solstice/Sky.

I know some of you have seen this already...

http://ecomodder.com/forum/showthrea...-avg-1128.html

.

There it is! I had a feeling somebody had thought of something already.

Still I wonder what a gas engine could do if it had all the right advantages.

I don't think it's aero or weight that is responsible for the Vette's decent highway MPG. It's the gearing; the C5 (I think it was) will cruise down the freeway at 60 MPH in top gear running something like 1400 RPM. That's good FE territory...

That's my theory, and I'm'a stickin' with it!

-soD

I don't blame you for that because it makes sense to a degree, but Ford 150's will do the same thing if not run at an even lower RPM. The horrible aero of a full size pickup and nearly 4,000 lbs. of steel make it's fuel mileage drop like a rock.

Corvette
 

The opening shot of my TV show was a head shot of Pamela Anderson at the wheel of a Corvette,cruising down Pacific Coast Highway.She was doing talking points about road horsepower as the camera slowly pulled back finally to reveal a V-twin Briggs&Stratton riding lawnmower engine under the hood,as this was all the car needed for highway speeds.----------------- Well this was the TV show of my head back in the 90s.-------------- Since high school,when I was driving my Morris Minor 1000,I knew that one could bolt an Iron Duke 4-banger into any Corvette and have a "show-stopping" fuel-sipper.---- Will you be the 1st?

Holy crap that's awesome. I knew those V-twins made some big torque for the size but to move a car is pretty cool. I imagine it might have had some decent acceleration at highway speeds too. I have an SV659 motorbike and that little engine is seriously torquey.

I'd love to be the one to put a measly 4 cylinder in a Vette and of course the end result is it be very, very economical without looking like some kind of oddball science experiment. Maybe it'll happen one day.

I'm sort of in the market for a few things, basically whichever comes first affordably (my kind of affordable).

I'd love to have a 94'ish Corvette - C5, is it? The ones that still have the square-ish tail lights.

I just looked it up here: Chevrolet Corvette - Wikipedia, the free encyclopedia

I can never remember the darn Vette generations anymore. I used to be able to tell you all about the engines and what set each year apart but that was years ago. I do think what we would need is a small diesel but the possibilities are quite abundant.

50-60 HP could propel the 'Vette comfortably at highway speeds, and still have enough power to "evade", should the need arise. I doubt it takes even 30 HP to keep the thing going 70 on a flat road, calm day, considering it only takes 25-35 to keep my Caravan going 65 MPH.

This of course depends on your standards for pretty good fuel economy. To me, 30 mpg or so highway seems pretty darned bad.

But the Corvettes aren't all that aerodynamic, with Cd values over 0.3 (depending on model). The aerodynamic engineering (as opposed to styling) that does go into the design is probably aimed more at creating downforce at speed, rather than reducing drag. They do get some advantage from having a fairly small cross-section area, so CdA is probably lower than most cars. But they're also pretty heavy.

If you want something similar, I'd start with a CRX (I got over 40 mpg with mine even the way I drove it :-)) or del Sol, a Miata, MR2...

All very true, and I know all that, as do most here on this site I think. There are still people who think the Corvette is much like the common muscle car where it just drinks gas and has no aerodynamic benefit, so thankfully that's not the case. For a BIG V8 Vettes can get really good mileage, of course if you're comparing a CRX it's not really too good at all.

I've occasionally thought that a Corvette might make a decent candidate for an EV conversion. If a lot of the excess weight is in the engine & transmission rather than the basic body structure, then you wouldn't be adding so much extra in batteries.

The LS motors are one of the lightest V8's.

Yeah, there are heavier I4s than the LSx. The Miata also doesn't get very good mileage, I've heard of people with C5 Corvettes getting closer to 40 (supposedly) while the few people with 1st generation Miata (1.8s) I've known only got in the high 20's—the gearing sucks and the aero is worse than the Corvette. Weight doesn't matter as much once at speed. That said, I'm sure a Miata could get into the 30's if driven like an old lady, but that's not impressive whereas a 5.7 liter engine doing that is. On the other hand, there's probably not much more to gain from a Corvette without changing the drivetrain out, while a Miata with RX-7 gears and a drastically reduced CDa could get into the 70s by my calculations (though my design would then be a single seater).

Annoyingly double-posted...

You gotta be kidding me. A 6-speed 'Vette drivetrain is optimal as is. Simply swap in a diesel and bingo! Big MPG.

ARGHHHHH Diesel Dave has shown his soot covered face once again. :p

A better gear ratio for the 6 speed would get better mpg.

quote:
"Diesel Dave shows his soot-covered face again.

Dave says:

You're durn tootin'. The whole point of the site is fuel economy. Says so on the home page. Do you think I'm gonna ignore an engine that is 50% more efficient? Do you think I'm gonna ignore an engine that does not have to be made less efficient to modulate power? Do you think I'm gonna ignore an engine that can run a wide variety of fuels? No, no, and no.

As for the Corvette, a manual 'Vette gets a 3.42 gear. One with an automatic gets a 2.73 gear. Put the automatic R&P behind the T-56 and now your top gear is a combined 1.36:1. You toodle down the superslab 70 MPH @ 1000 RPM. BTW, what but a diesel can make that kind of torque at a paltry 1000RPM? A 4BT3.9 Cummins does so easily.

Maybe so, but then I suppose there must be a lightest sumo wrestler, too :-)

But seriously, if all that excess weight - 3100+ lbs - isn't in the drivetrain, where is it? Lotus can bring the (European version) Elise in at around half that weight...

European Lotuses do not have to pass US crash tests.

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.

And I always thought the Corvettes were made out of fiberglass so they'd 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 :-)

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?

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

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.

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?

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

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?

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.

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.