Can a V8 Sports Car be Fuel Efficient?

Grandea GTR

Grandea GTR

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United States
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That_sneaky_azN
Is it possible for a sports car to have good gas on a V8? Or would that just greatly negate performance? Is it possible to make a V8 sports car that is good on gas (28-30HW MPG perhaps)...?

I know, too many questions, heheh :embarrassed: I would like the :gtplanet: Community to give their view on it đź‘Ť

Edit: forgot to put a poll... Crap.
 
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Yes.
I can make something up real quick in Automation, if you'd like. How much HP? How much MPG? Specific 0-60 time?
 
I've seen built Bronco's get 30mpg with small blocks if you do it right and keep your foot off the gas.

So I'd say it's possible.

As far as racing them? Not in our lifetime. Electric cars will probably take over before then.
 
Well, I'd say it's possible. Today with semi-auto gearboxes that have up to 8 gears, start/stop systems, advanced fuel injection and engine management systems, and cylinder deactivation systems I think it's completely feasible.

Sure, you won't get Polo Bluemotion levels of economy, but you'll get a relatively great fuel economy...at least when you drive it like you'd drive an economy car. You can't expect almost anything to sip gas when you're giving it all your foot...
 
ildd
Yes.
I can make something up real quick in Automation, if you'd like. How much HP? How much MPG? Specific 0-60 time?
Click to expand...
Of course, power that can be about as comparable to modern V8 sports cars (360-400+ HP)
As for MPG... Good on gas would be considered at least 28-30.
Not sure what to say about 0-60 time...
 
Pretty bad question.

First: Unclear criteria. Define fuel efficient. Efficiency is not binary, it's a sliding scale that changes with time and context. You need to establish a more solid metric. Will X type cars ever be as efficient as Y type car is slightly better.

Second, engine layout has little relevance to fuel efficiency. Cam profile, valve arrangement, gearing, and injector and spark tuning are far more important.

But, if we must proceed with this thread, according to the American EPA estimates 6.2L Camaros will get a combined MPG of 19, 5.0L Mustangs get 20. Most non-hybrid, not CVT passenger sedans will get around 30 combined. The Nissan 370Z gets 21, so if we're comparing against other sports sedans it seems that American V8's are already up to market standard for efficiency, especially considering the engines are moving two ton bricks through the air as opposed to lighter, sleeker bodies.
 
Smh... I just made something in Automation and realized I use an I6 engine. I shall be back within 30 minutes.
 
As @Zenith suggested, a "sports car" is a very broad term, as is efficient. However, this is what I came up with.
This is a sports car body, which is made entirely of carbon fiber. The chassis is also carbon fiber.
20140422_233244.jpg

As you can see, it is very light (2700 lb, with luxuryish interior). 7 gears. 0-60 in 4.9 seconds. Sounds pretty sports car to me, and then you throw in nearly 39 MPG.

It has a 4.2L twin turbo V8 with direct injection. As you can see, it is rather expensive and labor-intensive to produce. And runs on premium gas.
20140422_233157.jpg

VVT and VVL. And dual overheads with 4 valves/cylinder...
20140422_233202.jpg


In the end, of course it's possible... but it's expensive. If I had to estimate, the above would cost about $200k... If I replaced the chassis/panels with aluminum, it would weigh maybe 3300lb, get 34 mpg and have a 5.1 0-60 time, but it would also cost much less.
 
While not fuel efficient in the sense that you're referring to, V8 vehicles here can save a significant amount of money on fuel by being literally on gas ie. LPG. You do burn through LPG quicker than petrol but it's about 50-75c per litre cheaper than 91 octane so you end up getting a significant saving per distance driven.

It is also more environmentally friendly.
 
Technologically speaking I'm sure that its possible.The McLaren MP4-12C for example uses a twin-turbocharged V8 that produces 616bhp and still manages to get 22MPG mixed. I'm sure that they have the engineering know-how to design a tamer V8 engine producing 350-400bhp and hitting the 28-30MPG mark.
 
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ildd
As @Zenith suggested, a "sports car" is a very broad term, as is efficient. However, this is what I came up with.
This is a sports car body, which is made entirely of carbon fiber. The chassis is also carbon fiber.
View attachment 146230
As you can see, it is very light (2700 lb, with luxuryish interior). 7 gears. 0-60 in 4.9 seconds. Sounds pretty sports car to me, and then you throw in nearly 39 MPG.

It has a 4.2L twin turbo V8 with direct injection. As you can see, it is rather expensive and labor-intensive to produce. And runs on premium gas.
View attachment 146227
VVT and VVL. And dual overheads with 4 valves/cylinder...
View attachment 146229

In the end, of course it's possible... but it's expensive. If I had to estimate, the above would cost about $200k... If I replaced the chassis/panels with aluminum, it would weigh maybe 3300lb, get 34 mpg and have a 5.1 0-60 time, but it would also cost much less.
Click to expand...

Would removing the Twin Turbos reduce efficiency?
 
Grandea GTR
Would removing the Twin Turbos reduce efficiency?
Click to expand...
Yes. And power. I would have to play around with compression, A/F ratio and others, but removing the turbos would probably give me 375 hp and an efficiency of 26% or so. Which is about 28 MPG, maybe.

edit- i'll remove the turbos and post the results.
 
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Tornado
There's an entire casserole of things wrong with this sentence.
Click to expand...

Yep I thought about the argument I was making some more and it doesn't make a whole lot of sense. My point about McLaren having the know-how to make a fuel efficient V8 stands, though.
 
My T/A gets around 18/25 so I'd say it's possible. But when you look at the market, you see M3's, S4's, 370Z's, and S2000's getting low 20's so it's not the fact that it's a V8 that is killing efficiency, but the performance.
 
Here's the same 4.2L V8, with no turbos, and a mass of things changed regarding top end and fuel stuff. I'm actually surprised at how well my estimate was.
Using same chassis/frame, with a slightly different gearbox. I have no idea how it's nearly the same speed-wise... I guess because it's 200lb lighter.
20140423_002549.jpg
20140423_002612.jpg
 
Soda01
Yep I thought about the argument I was making some more and it doesn't make a whole lot of sense. My point about McLaren having the know-how to make a fuel efficient V8 stands, though.
Click to expand...

The McLaren's economy is more about form factor (versus the brick-wall Mustang) and the amount of money put into the car, rather than know-how.

Damnit, @Wolfe , I was going to post the Corvette.

Popular Mechanics did an eco-run. Stuck in cruise control at 55 mph (and, for the uninitiated, let me tell you, cruise control sucks for fuel economy), the Stingray does 37.3 mpg, at a mere 1,100 rpm.

With even better aero (drag coefficient is just 0.29, but better is possible if you're willing to sacrifice downforce and if the extensive cooling vents could be shuttered during low-stress cruising) and narrower tires, 40+ mpg is likely possible.

So, yeah, you can make a V8 sports car fuel efficient (on the highway) if you give it cylinder deactivation, a slippery shape and an intergalactic overdrive.
 
While it is possible a 3.5l V8 is only going to be so efficient even when driven granny style.

Now if you had a 1.6l V8 you could do it, who says V8s must have high displacement?
200cc per cylinder wont give much power per cylinder but you only really need 50hp or so for city driving.-
 
Part of the reason sports cars with big engines aren't efficient is that people drive them hard. A big, lazy engine can get pretty reasonable economy if driven gently. A smaller, revvier engine is somewhat less likely to be as efficient. But it's all about how you drive.
 
Wolfe
View attachment 146280
Click to expand...

That's what I was thinking :crazy:

Like the Corvette, there are some sports cars that are fuel efficient. Tech like cylinder deactivation & smooth aero improves fuel economy. Even driving habits change it. Something like Mercedes' AMG series obviously will not work because their engines pile a lot of fuel in the cylinders. The SLS AMG for instance has a 6.2L V8 and only gets 13 / 19 mpg. The Corvette actually has a similar engine yet it gets better economy. That's because it was built with efficiency in mind.
 
Bopop4
Cylinder deactivation and a tall 6th gear.

I know @ND4SPD was able to get pretty good highway mileage with a C6.
Click to expand...
I was getting around 30 plus mpg on the highway on my road trip last year with my Corvette. I made it from southern Ontario to the midle of Quebec on one tank.

Super tall 6th gear helps quite a bit. I can only imagine what a C7 can achieve with a 7 speed and cylinder deactivation.
 
I wonder what old relatively lightweight cars like the Sunbeam Tiger got/get? Then again, similar principal to the Cobra and I don't think those are particularly economical :)
 
ildd
As @Zenith suggested, a "sports car" is a very broad term, as is efficient. However, this is what I came up with.
This is a sports car body, which is made entirely of carbon fiber. The chassis is also carbon fiber.
View attachment 146230
As you can see, it is very light (2700 lb, with luxuryish interior). 7 gears. 0-60 in 4.9 seconds. Sounds pretty sports car to me, and then you throw in nearly 39 MPG.

It has a 4.2L twin turbo V8 with direct injection. As you can see, it is rather expensive and labor-intensive to produce. And runs on premium gas.
View attachment 146227
VVT and VVL. And dual overheads with 4 valves/cylinder...
View attachment 146229

In the end, of course it's possible... but it's expensive. If I had to estimate, the above would cost about $200k... If I replaced the chassis/panels with aluminum, it would weigh maybe 3300lb, get 34 mpg and have a 5.1 0-60 time, but it would also cost much less.
Click to expand...
What is that? :D
 

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