JD_AMG

Learn how to quote.

Don't tell me, SHOW ME. Find me a performance car with around the same weight, same high power output, and number of gears and one with a significantly smaller displaced engine than the other and with a significant increase in gas mileage.

Clearly this is going no where because you don't seem to know anywhere near as much as you want to believe you do. So ill ask this, why don't we have 100cc engines powering modern cars then?
What you keep failing to understand is in a performance application a smaller displaced engine making the same power as a larger displaced engine is not only going to be working harder (using more gas) but will also likely be geared more aggressively to compensate for the lack of low end torque it will have and the higher RPMs it has to spin. That is another thing that will hurt its gas mileage. Why does the S2000 get such lousy gas mileage despite being a 2L I4 making only 240hp? The Corvette of the time using 5.7-6L V8 gets better gas mileage, WHY IS THAT?

AGAIN, this has NOTHING to do with displacement, stop repeating it.

Proof?

F1 forced the limited the displacement, not Ferrari or MB. F1 was wanting to use 4 cylinder and the teams were opposed to it. Lets not pretend like Ferrari truly cares about the environment and decided to make F1 cars more gas efficient because of that.

Warp Factor

Assuming that's correct for a moment, just for the sake of argument: While some Corvette buyers care a lot about fuel economy, how many of them would make a purchasing decision on a 1 or 2 mpg difference one way or the other? My guess would be pretty close to zero.

If Mercedes and Ferrari are the most experienced at getting the most power out of small displacement engines, it only makes sense that they would try to leverage the rules to take best advantage of this in F1.

This is rather unrelated to production cars, where displacement restrictions do not apply.

Darion

It looks as though the implication is being made that because F1 cut out refueling that they doubled efficiency going V6 turbo at 1.6L compared to the V8 NA 2.4L. Thing is that's not how it worked, refueling was banned in 2010 and they were still using the V8 at the time. Teams were required to increase the capacity of the fuel cell to accomadate the changes, that tank essentially doubled in size.

2014 came the switch to the V6 turbo and fuel regulations changed which would require that they use as much as 60% less fuel. Max rpm dropped from the V8, 19k to 15k, fuel flow rates were capped and power initially dropped, Kers was added. Today they are back in the power and still on smaller amout of fuel with a small bump in capacity this year.

So what does it all mean, not much really, these are F1 engines after all and no main stream manufacturer is doing what they do with engine tech and expense.

PC

Darion

Lol, ok, I was just clearing up that the numbers ya used were not current where HP is concerned or accurate for size. I think for the purpose they run, 5 to 6 mpg is pretty damn good. Haha, most of the greenies dont agree though.

PC

JerryU

It's NOT that they can't refuel that makes them use half the gas they did before! Here is some real data in statements some form a few years ago and it's gotten even better! BTW the short term (~6 seconds) KERS is mostly used for passing in a few Track sections and NOT the reason:

• What makes the F1 cars so green is their thermal efficiency. While road cars have been stuck around 30% thermal efficiency, Formula One Cars have exceeded 45% and are continuing to improve.
• Formula 1 cars have gotten much more efficient than the cars of 2002, let alone 1952. In 2002, cars were 3.0L V10's, and refueling was allowed.
• As of the 2014 season, all F1 cars have been equipped with turbocharged 1.6-litre V6 engines. Turbochargers had previously been banned since 1988. This change may give an improvement of up to 29% fuel efficiency
• (This quote is probably translated from German!) Every might know about thermodynamic efficiency of engine from school days they say its 15-20% during those days. During 2015 Mercedes Engineers have achieved 45 % and their target was 50 % for this season. ( ie 50 percent of energy from fuel is delivered to the engines crankshaft. To note it was 29% in 2014 season all the three engines where V6 1.6 liter engines.

I quote the last "probably translated from German" as, in addition to the awkward English, it notes from School Days they knew 15 to 20% efficiency. Not in the US as we don't have many studying science- many do in Germany!

Yep regardless of the foolish info expounded by some posters, large cid engines are NOT as efficient as smaller ones and insisting on "round taillights" will just get EV's here sooner! Fortunately GM is smarter than that!

BEAR-AvHistory

Speaking of Nick Tandy he just was on the podium at the Sebring 12 Hours where Porsche finished 1st. FORD & Chevy also were on the podium with a 2nd & 3rd place finish. BMW's new 4.0L DOHC V8 powered M8 finished 4th. Nice to see all our brands mixing it up.

z06801

And the LS powered Cadillac's went 1, 2, 3, overall and DPI class

JoesC5

Please post up Steve Carlisle's obituary when it hits the newspapers.

https://www.msn.com/en-us/autos/news...cid=spartanntp

As to "friction". my 7L Z06 with it's eight cylinders runs at~1600 RPM when I'm driving a 70 MPH on the highway and I'm getting 29-30 MPG.

My 2.3L four cylinder daily driver has to run at 2800 RPM at 70 MPH to get the same speed and fuel economy.

Do you think that running the 4 banger at nearly twice the RPM has anything to do with the amount of losses due to friction in the amount of work done each mile traveled?

JoesC5

When I was in the Air Force in the early- mid 1960's one of our airmen(E-1) had a 1955 MG TF two seater sports car. It had a cast iron 1.5L 4 banger with 63BHP and 76 lbs-ft of torque.

He swapped in a 1962 all aluminum 3.5L V8 from a wrecked Oldsmobile F85. It had 155 BHP and 230 lbs-ft of torque. He also used a B-W T-10 4 speed from a wrecked Corvette C1.

I doubt the weight of the car changed much , if any. I suspect that the aluminum V8 with the T-10 weighed less than the cast iron L4 with the heavy 4peed it originally came with.

I never asked him a about his before and after gas mileage, but I can sure guess what his response would have been(gas prices ranged from 17 cents a gallon(price wars) to 31 cents a gallon back then.

I do know he could lift the front wheels off the ground when he shifted into 2nd gear, even though he still had the original wire wheels with the skinny width original tires on the car.

BEAR-AvHistory

England's Rover bought the F-85's 215CI tooling to use in its sedans and Land Rover off-road vehicles. I ran a Morgan +4SS which was a modified Triumph engine. They also produced a +8 version which had the Buick 215CI twin of the F-85 engine. The 215 was very popular in its day as a transplant into small European cars.

Darion

I'll take LT2 for the win Alex!

PC

Oh and no extra BS like axel lift, moving aero, electric doors, over the top sound deadening, start stop, lane departure, cylinder deactivation, active suspension, ect. Lol

JD_AMG

This is what I've been telling him but it doens't seem he can grasp this concept.

JerryU

Friction losses are area dependent and probably higher at higher rpm but my guess not in proportion. GM has the numbers.

The surface area conducting combustion gases into the coolant (where ~30% of the energy is wasted) are much more dependent on area.

GM and other manufacturers know the numbers and they produced the 2.7 Liter double overhead cam turbo engine for the Silverado (585,000 sold in 2018) because of efficiency. That is why engines in most parts of the world are smaller, not that they like the buzz!

Only in the US are we enamored with big cid- like my 502 cid! If building a Street Rod today would use the 572 cid crate engine!

Warp Factor

Unfortunately, your F1 examples have failed to furnish evidence for that claim. Sure, F1 engines became more fuel efficient, after the rules required that they do so. The engine displacement reduction was a separate rule requirement, mostly to prevent the cars from going so fast that too many people got killed.

Tom73

It is interesting how F1 is being referenced so much here. So much so that it sounds like F1 is the be all, end all. We must remember that the F1 engines are pure race engines designed to meet specific rules/guidelines. They are not at all streetable. Once you made them streetable you would would probably lose any advantage that they may have had.

Commentary: F1 is so regulated that there is basicly no difference in the top cars/teams. Almost no way to innovate. Their races are nothing more than follow the leader around the track with very little passing/position changes among the lead cars. And the races are so short that they are basicly an extended sprint. Everything depends on qualifications and getting off the starting line.

I watched the Australian race list night. The front four, 1 through 4, on the first lap was the same at the finish line. May as well run a green/white/checker and be done with it.

Zaro Tundov

European registration fees are higher for vehicles with higher displacement engines. That's why they like smaller engines, it has nothing to do with a smaller engine being inherently superior to a larger engine.

Tom73

Also when discussing supercars, gas mileage and gas costs have no meaning. They move in a world that most of us can only dream about. The manufacturers are only reacting to government regulations.

thirtythird

I welcome the diversity.

Getting tired of the same old...Europe/etc does it like this, we should, too. F that!

Warp Factor

I think you're starting to get closer to where you need to be. Friction losses are roughly area dependent, increasing at a 1:1 ratio. Hydrodynamic losses are very different, increasing with the square of speed! Double the rpm, and the drag increases four times!
This is an important distinction, since there is practically no metal-to-metal contact in a modern engine, during operation. In other words, there is next-to-no "friction" at operating speeds. The parasitic drag is due to the moving parts operating in an oil film, and the fluid or hydrodynamic drag which comes from that.

That's why there is so much emphasis on the use of lower-viscosity oils these days. They reduce hydrodynamic drag (thus increasing power and fuel economy). as long as they don't get so thin that they result in metal-to-metal contact.

dcbingaman

Absolutely right - big displacement and low piston velocity is the way to efficiency, not small pistons and high rpm. Ferrari 3.0L DOHC V-12's sing like Pavorati, but are really not very efficient. That is why BIG power (ships, locomotives, trucks) goes with large displacement in-line engines, usually I-4's and I-6's.

With regard to waste heat, force on the crank is driven by pressure on the piston head, That pressure is result of the total volume of air and fuel per stroke. The wall thermal transfer area goes up by the square of the piston diameter and the circumference times the stroke (also a squared number). The volume of combustion gas and thus motive force is a function of the cube of these dimensions. Hence, all other things being equal, a larger piston is thermally more efficient than two smaller ones of the same displacement, even if frictional losses are the same.

OK, so why is the new Silverado 2.7L more efficient than the 5.3L V-8 it is replacing ? Answer is the turbo which increases volumetric efficiency and compression ratio, and the the fact that it is an I-4 which means large pistons. Large turbo I-4's are the future, gents. Couple a 3.0L I-4 with an integral starter generator and a big battery, and you have the IC engine of the future, including Corvette. The DOHC V-8 solves no problems and just adds cost and weight.