Italian V8 vs American V8- the Difference?

Even if you were correct (Ferrari, Judd, Cosworth, Honda, Toyota, Mercedes Benz, and BMW just to name a few of the people that would disagree with your conclusions) peak horsepower never won a race. The guy that is making the most power at the end of the straight will get there behind the guy that is making the most coming off the corner. Peak horsepower looks great on a dyno sheet, don't do ***** on a racetrack.

 

I think in F1 there has to be many tradeoffs to achieve the power they produce, and we would all have to admit that a 2 valve, no matter the combustion chambers design, would never rev to 19,000 rpm. And its those rpms as much as anything that allows any engine to make that much power.
Yes, I admit that heavy valves being slung back and forth twice the distance will lose to two half the weight moving half the distance in the rpm war, and they do flow more air all things being equal, but at low engine speed the Hemi can make more power. Somewhere I just read of a Hemi diesel that either just came to market or is in development. Perhaps someone should try a true Hemi 4 valve head and see what it does? I am thinking its cost prohibitive, lol

 

What are the advantages of a flat-plane crank?
What are the disadvantages of a flat-plane crank?

 

I believe the dealer blamed the engine failure on abuse of a new engine

 

I am sure you know this, but a V-12, a V10, basically nothing other than a flat four, an inline four, an inline twin two stroke, or a V8, can use a flat crank. A V-12 has to many cylinders to have them only hit every 90 degrees in a 60 degree V. A V-10 has to hit every 72 degrees. Any four cycle engine has to fire half its cylinders in 360 degrees of rotation, except for a radial aircraft engine, which has to have an odd number of cylinders ( 3,5,7,9 ) to fire smoothly, so in the case of a 7 banger it fires 1 3 5 7 2 4 6......

 

I read/posted something the other day that basically said the flat-plane crank's advantage is that it doesn't require counterweighting so is light, therefore easier to spin to high revs. However it isn't perfectly balanced so you get some harmonics or something - I believe that is why the 348 has the Bioth damped flywheel thingie in order to take up some of those vibrations.

Happy to have any of the engineer types who know what they are talking about give you more precise info.

Cheers
Kevin

 

High RPM balance. The counterweights on a split crank limit responsiveness and RPM. A split crank is larger and heavy which also raises the engine height and the CG of the car itself.

More difficult and costly to machine I am told. The split crank is easily balanced by drilling in the large counterweights. Actually the vibration of a flat crank in the second order is higher then a split crank. The longer the stroke, the heavier the pistons and con-rods, the more second order vibration generated. So note Ferrari's use of short stroke and in some cases titanium con rods. The flat crank offers advantages in breathing I believe.

 

That explains it, my hoover vacum must have an I5.

 

The difference is low end torque. Torque is what pushes a car forward. The C6 makes gobs of torque even below 2,000 rpms giving it the ability to power the car at highway speeds to attain that kind of mpg in order to avoid the gas guzzler tax. My 600+ hp Viper got 23 mpg driving at 80 mph on its way back from MO when I first bought it. It even has 3:55 gears in it. IF I had stock 3:07's I probably could have gotten 25mpg. Then again, the best I have gotten on a tank of gas since then has been 10-12 mpg. It just depends on how heavy your right foot is. The usual has been in the 8-9 mpg range.

 

The flat plane crank generates a very large 2nd order force, but is otherwise balanced. This 2nd order is easily damped in the engine mounts. The 90°crank creates large first order forces which need large counter weighting which someone here correctly said reduces the maximum rotational speed.

For a given displacement power is directly related to engine speed. The Breathing of the engine gets worse as the engine turns faster. 4 valve technology extends the possible engine speed before this drop of in breathing.

Combustion chamber design today is essentially determined by valve layout and is, dare I say, unimportant for petrol engines. Most engines run 4V's and a pent roof.

A flat plane crank sounds like two screaming 4 cylinders.

Cheers
Simon

 

Hi, Karen. I hope that you can sift through all of the above information and find the answer to your question.

JimZ is right on. In addition, all Ferrari V-8s have dual overhead cams (4 total), while most of the American V-8s have a single camshaft. In the Ferrari, the cams act directly on the valves. In the American V-8, that camshaft is in the middle of the engine, and works pushrods that then in turn work rocker arms, which finally act on the valves.

--Matt

 

By the way, for a completely different sounding American V-8 check out these sound clips.
http://www.vanpeltsales.com/FH_web/engine_starts_idles.wav
http://www.vanpeltsales.com/FH_web/shifting_gears.wav

They're flathead Fords, introduced in 1932. The valves are actually right next to the piston, not above it. It's pretty poor for airflow, but flatties make a huge amount of torque. It almost the opposite of a Ferrari engine in most respects.

 

These are figures for your 360? I've done much better for some reason. In average driving (some fast freeway, some aggresive back-road) I've averaged 14 - 15 (I had one tank I got 19 at a steady 90), and I even measured my track day mileage at 7.9, which is better than I used to get in my E46 M3. I'm pretty happy with the efficiency of my 360.

Gary

 

He was talking about a 600 hp Viper.

Erich

 

I also read it produces a better airflow at the intake side?

 

Yes I remember those engines. First hotrod I had was a 1946 Ford halfton given to me by my dad. He said it needs a little work and you will learn how a car runs son. Yes it did run, barely. You had to crank it for along time in order for it to start. Once I figured out what was wrong, ( left side all had ZERO compression , right side had 2 cylinders with 30 lbs). Looking back on it now, dad was just watching out for his wild son by giving him a "power limited" hot rod. I just drove it everyday after school in the fields until one day I got it too hot and probably fried any rings that were left. One thing about those engines, if they were kept cool and full of oil they were very hard to 'killl'.

 

The key to the 4 valve power was the long valve stem. It went like this: Because of the metal technology, the 2 valve engines needed large diameter valves, but because of the weight had short stems. That meant that the opening and closing mechanism had to be close. That in turn, lowered the top of the port. When Honda looked at the design, he figured that with 4 valves, they would be smaller, the stems could be longer, the engine could turn more RPMs with lighter weight valves, and because of the longer stem, the top of the port could be raised, and the turn that the fuel and exhaust had to make could have its radius increased, thus increasing the flow. The combustion chamber also got redesigned, and because of the pentaroof design the flame throw is less, thus requiring less and less octane.

When I was racing Ducatis in the 70s and 80s, we'd weld up the ports, raise the bottom, turn it from an oval into a d shape, and we'd get a lot of horsepower. By the way, Steve Wynne, the guy who tuned Hailwood's bikes was my tuner in the 80s, when I won a championship or two. Great guy.

It is true that you can make a 2 valve work almost as well at the 4 valve, if everthing else is equal. However, the 4 valve will have better mid range tork, won't stress the components as hard, in short a better motor.

Art

 

Okay, here is what I am trying to say, lest we get more confused. 4 valve technology was known before 1900, in fact more than a few racing cars had them before 1900. 4 valve engines are what gave World War 1 fighter planes in Europe the edge they needed to succeed by being some of the first internal combustion engines to make 1 horsepower per cubic inch. The Allison and Rolls Royce V-12 aircrft engines of WWII also used 4 valve heads. But all of these engines turned less than 3000 RPM and never made more than a horsepower per cubic inch. Metalurgy was also not that great back then, and valve springs were not anywhere near what they were by the 1950's and 1960's, hence, you couldnt get a 2 valve to pop its valves open as far as we can today and expect very high rpm with any endurance.

I am not trying to say that a 4 valve won't make more power than a 2 valve "Hemi head", I am saying that a 4 valve wont make as much power in the 3000 to 7000 rpm range. What I am seeing, and someone correct me if I'm wrong, is that a 4 valve will not respond well to any more cam lift, or duration, much beyond stock in making more power.

If we were to agree, that a highly cammed, small bore twin cam 2 valve hemi head 4 cylinder engine, say between 1000 and 2000 cc's, set up to full race specs, 12:1 compression, porting, polished rods, etc., etc., could make 200 HP per liter, and more, in the 10,000 -11000 rpm range, and that a 4 valve cannot make that kind of power in that rpm range, then the answer has to lie in the combustion chamber design. My belief is that the 4 valves advantage lies not in its combustion chamber shape, but in its sheer ability to flow more volume and stay together at higher rpm, not at its efficiency at burning fuel. At some point the speed probably negates any combustion chamber efficiency anyway

Someone show that I am wrong and I will humbly appologise. Show me any 4 valve engine making over 220 HP per liter at speeds below 11000 rpm.

The Ferrari F1 engine is somehow, as amazing at it still seems, producing power at speeds that border on insanity, as are all the teams engines, making power at over 19,000 rpm's. I would be a fool to not admit that 4 valve technology is not the biggest part of that. A 2 valve just could never operate at those speeds

 

You can believe whatever you want but it is in direct contradiction with the collective knowledge of a whole bunch of engineers world wide that spend their lives researching internal combustion engines. That is a field of study that has had more brain power poured into it in the last ten years that it had for the prior one hundred.
You may know more than them and if that is the case I suggest you patent it and prove it. You will be a very rich man.
If you want an example of my position look to the 550. Twelve cyl motors are generally believed to be capable of less low end torque than a V8. Find any V8 or twelve for that matter with 2 valve heads with all other specs being equal that produces the low end torque and high RPM power of that thing.
From idle to red line there is no wrong gear in one of those, and 4 valve cyls is one of the major reasons why.

 

Wow. Talk about splitting the atom.

1.) All engines are just big self powered air pumps. Period.
2.) Differences with them are how they get the air in and out.
3.) Fuel efficiency and emissions are a sign of engine efficiency.

I love Ferraris. Are they the best engine makers? These day's I'd say that's up for discussion. As seen above.

As far as Corvette getting 28mpg believe it. I've got a friend that tools around all day like he's driving a Honda until he jumps on the throttle. Then all hell brakes loose. Hate the interior of the car though... They might be using the same system as Dodge is on the new Hemmi wagon. At cruising speeds they cut fuel and ignition to some of the cylinders. As soon as you jump on the throttle fuel and spark return for immediate results. Remember, it's just pumping air.

And as far as how many valves operating is better, I can't believe no one's even mentioned the V-Tec.

I also can't believe no ones mentioned the Pantera in this thread. American V8 with short pipes. Admittedly very nasty automobiles when they left the factory. But, if you ever get the chance to drive a well sorted out one jump on it! Just an awesome experience. So much torque you can just ease off the clutch at a stop without pressing the throttle and the car will start rolling.

Fun sights and sounds:
http://www.sleepy-fish.com/pantera.htm

 

Hi FerrariDriver
My 1998 Toyota Corolla RSI,produces 160 BHP at 8300rpm(These were specially produced by Toyota South Africa,as far as I know).It currently has 48000km and no problems yet.My friend did 208000 km on his before it died.At 5500rpm the variable valve timing kicks in and the cam changes its profile,than that little sucker really gets going.
Marco

 

Cool! As you state, it makes for a poor road car with a 20 hour life expectency! LOL It's a real leap forward that today we have cars which are perfectly streetable with over 200 HP in a similar size engine, with better gas mileage and a long life.

Ken

 

Yes, these figures were for my 600+ hp Viper.

 

You forgot to ask the most important thing, the thing I have been talking about all along. It makes 200 HP at 8500, whats it make at 3000? 50? 40?

Four valve motors make good power at 8500 and can turn the tires to rubbish at 3000, and accelerate hard at 1500