Can a V8 Sports Car be Fuel Efficient?

[niky]

Indeed. That split-turbine trick is so radical, it'd be interesting to see if they could get it to work well enough for on-road use. A split-turbo also opens up the possibility of a turbine energy recovery system which doesn't put too much heat stress on the electric generator/anti-lag motor.

-

Even without that... it's possible we could get a high-powered V8 to 40 mpg (official) sometime in the future. All you need is a very slippery body, direct injection, cylinder deactivation and a turbo... with or without ERS. (I love the idea... but I will never call regenerative braking KERS)

The Vette already has three of the four. Adding boost for extra "oomph" in four-cylinder (or even two cylinder) mode during lean cruise should get it to economy numbers its V6 competitors can only dream of.

-

As for whether the Vette engine is better bigger or smaller, there may come a point in time when too big is too big. We're obviously not there yet, considering economy is still incredible compared to the competition. The big bad Porsche 918 hybrid, for example, only gets a measly 20/24 on the EPA compared to the Vette's 19/29.

 

[Slash]

That's oversimplifying it a little - it's worth pointing out that modern performance cars are typically quicker than old ones regardless of gearing, and that fuel economy is a byproduct of inherently more efficient engines than cars used to have. Tighter tolerances, better fueling, more efficient intake designs and of course more gears in the transmission in the first place - several for acceleration and several as overdrives, effectively.

Well I intentionally simplied it for the fact that we all here know basically what you are saying, I was just making a point. But yes you are entirely correct.

The average econobox these days has gearing biased towards efficiency, but then that's arguably how it should be.

I think given the time period these days that yes cars should be geared more efficiently but arguably that should have been the case back then. Technology has indeed come a long way.

I suppose it's also worth noting that the pursuit of efficiency is a lot more refined than it used to be. As you noted, in the 1970s they just slapped emissions controls on everything, strangling the engines in order to reduce emissions. Now, you can make an engine continually more powerful yet improve its fuel efficiency too.

Indeed they were. While later engines of the 70s had started to become a tad more refined and biased towards these new parts (though areguably not much), when they first started switching to that stuff, the change was terribly and hurt economy. I would argue a higer compression engine burns cleaner and better than a low compression "smog" engine and could increase fuel economy. Less compression means less is being burned and I would think pre smog engines actually could achieve better economy with proper gearing (and this has shown to be true based on many, many tests in the car world). Now admittedly, a 7.5L V8 is not going to get good gas mileage anyway you look at it, but the small blocks with modern gearing actually do quite well, especially when you start swapping out the cruddy stock parts for, as I said before, better flowing, breathing and burning parts. But some of those engines were so ridiculously detuned (looking at you, Ford 302 and AMC 304) that not much is going to improve fuel economy without some seriously high gearing and a total engine rebuild

 

[Zenith]

Didn't Detroit Diesel do the split turbine/compressor thing a while ago?

 

[huskeR32]

Is it possible to make a V8 sports car that is good on gas (28-30HW MPG perhaps)...?

It's been possible for 20 years now. My old fourth-gen (LT1) Z28 pulled 31-32 multiple times on long highway trips. My buddy also had a fourth-gen Trans Am (LS1) that got about the same.

Gearing was the key, the T-56 had a nice long 6th gear (I didn't see 2k rpm in 6th gear until around 80 mph IIRC).

Now, you didn't specify what level of performance you require in this scenario, but I wouldn't say either of those cars were a slouch, especially the LS1-powered models.

*EDIT*

Should probably add a disclaimer here. The majority of the time, I saw probably 27 or so. Crept into the 30s a few times by short shifting and skipping gears (thank you V8 torque!), keeping it around 65-70 mph, and probably getting lucky with no head winds.

So, to the original question of "is it possible? Yes, totally. But I wouldn't say it's easy.