Jeff77789

i've always wanted to ask this, and it is that why are the ferraris so free revving?

if you watch the video above, especially on the 599, you can see for yourself how fast the revs drop down

...i dont know about you but i have not seen any flywheel on an rx8 that makes the revs drop like that

alnielsen

iTrader: (4)

Likely a combination of several things. A balanced engine, lightweight flywheel and (I'm not sure on this one) a multi-clutch disk assembly. One other thing that may do it is a change in engine timing during the deceleration period.

RIWWP

iTrader: (2)

The better balanced the engine is the more easily it will rev. A balanced engine will want to maintain speed however, with the pumping losses from expanding and compressing air in the cylinders/housing being the main drag against the engine. Some pumping losses from the engine fluids being moved too.

As Al noted, they could have easily figured out an engine valve timing that specifically maximizes pumping losses when off throttle, pulling in air on the expansion stroke, then closing the valving completely on the compression, then at TDC, vent the compressed air so the engine has to work to pull in more again and keep the compressed air from helping the engine. Or even figure out an inter-cylinder valving system that would feed the compressed air into one or more cylinders at bottom dead center, giving them even more pressure to work against.

In theory, they could even have some sort of engine brake too, though that is added wear where pumping losses are no extra wear.

Or even have fuel and spark to create a small combustion on the compression stroke to provide resistance against the engine. This would require very careful management, but then it is a supercar so it's not impossible that someone would have added something like that.

Mr_Pieper

The way a Ferrari V8 is made is entirely different than say a Chevy V8. The way the crank is made and the cylinders fire makes it more like two identical inline 4s running at the same time off of the same crank. That is also why they have such a cool sound as the exhaust pulses bounce off of each other in a unique manner.

godesshunter

I assume, much like a street bike engine, there's a lot of engineering into lightweight engine internals. Most of those supercar engines have the same rev up and rev down characteristics as street bike engines.

Small lightweight internals allow it to rev fast and high. There's more to it than just flywheel. I could be mistaken but I think I read somewhere that my Suzuki GSXR has a hollow crank shaft to save weight and help rev faster and higher.

Jeff77789

what would be some of the advantages/disadvantages for this kind of setup compared to, lets say, a chevy v8 setup?

comebackqid

iTrader: (13)

A lighter maybe even stronger engine that makes more power from factory and makes a awesome sound revs higher too.

alnielsen

iTrader: (4)

The ability to accelerate faster than another engine of the same size. Gear shift changes. it doesn't take as long to wait for speed change to get the gears to mesh.

blazenblue63

Wait till you see episode 2 of the new top gear season (English not crappy American one) the Lexus LFA revs through it's entire band in 0,9 seconds! That car is so amazing. I love it. Too bad it's so retarded expensive. And Lexus still loses money on each one. Should have been GT-R money.

Jeff77789

I'm pretty sure the LCD screen lags behind.

I never understood why computer interfaces in cars can never be as smooth as iPhone/iPad or even android levels of smoothness. all the cars i've seen, the nav screen is always lagging, and even the tachometer is not as agile as an analog tach.

i'm not sure if this is still true for the new dodge viper and the LFA but it is a very commonplace thing nevertheless.

alnielsen

iTrader: (4)

You should have seen the mechanical tach's that used to be used even in race cars. The needle would sometimes stick for half a second.

blazenblue63

From what was said, the console had to be digital because an analog needle couldn't keep up. Jeremy Clarkson even says it's the best car he's EVER driven. Of course I don't know how much faith or trust you can put in that but that's quite a statement from someone that gets to drive everything we dream of. And the new viper is your typical American piece of junk. You would think American companies would build a better product. But the corvette, new GT 500 and viper are all the same. Cheap materials, terrible build quality and a giant engine...

Jeff77789

you're right. i did see some videos of the LFA and the needle does keep up smoothly.

nothing more can be said about the other cars tho.

User24

iTrader: (1)

The flat plane crank does not employ counterweights. Thus the crankshaft acceleration is very fast.

http://www.ferrari.com/English/GT_Sp...raftshaft.aspx

That 599 v12 seems to have frighteningly fast revs.

It looks like the rx8 flywheel videos, only seem to improve rev speed by 20% or so.

j9fd3s

the Ferrari engine probably costs more to develop and manufacture, but its smaller, lighter, and makes more power. the 458 is 570ps from 4.5 liters, and the Z06 is 505hp from 7 liters. Ferrari at one point also was able to meet the emissions specs without the cat, so its a very efficient engine.

i would imagine reliability is about the same, but neither car is going to be some high mileage commuter

bse50

Reliability can't be the same unfortunately. The high hp\l ratio of a ferrari engine puts more stress on the parts and engineering can only go so far to increase reliability. It's a car that's need to be serviced more often than a 'vette and requires attention to detail even when it's being serviced.
The gearbox is especially delicate. Idiots say it's fragile but the truth is that it is "delicate".
Think about our perky rotary engines, only bigger, better, more powerful and in a fantastic car

All the free revving videos can't describe how awesome the 458 is when accelerating. The transmission is so fast that your body almost feels a seamless transition from a gear to another, despite the fact that the gearbox is not a seamless shifting one

j9fd3s

Reliability and the service schedule are two different things.

reliability = the ability of a person or system to perform and maintain its functions in routine circumstances, as well as hostile or unexpected circumstances.

i don't disagree that the Ferrari would take a more detailed service to be reliable than that corvette does, but a more service work doesn't mean its unreliable, it just means it needs more service work.

the corollary to that is that GM probably isn't able to service a Ferrari properly. (Mazda is almost there with the Rx8)

Maybe we mean durability? if you did all the maintenance, which one would wear out first? i just say its hard to tell that, as not many people are going to drive either car that far!

but yeah the 458 looks like a really amazing car!

bse50

Yeah I meant durability.
The 'vette will last longer