How Super High Rpm is achevied

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
ss.vamsikrishna
0
Joined: 24 Nov 2005, 14:02
Location: USA

How Super High Rpm is achevied

Post

How Super High Rpm is achieved in formula one engines
r these the following reasons ,

1. fuel is burned really fast so faster ignition frequency
2. pistons are hallow and so less weight so less inertia so faster they move
3. air is pushed at high pressure and with lot of pressure .

i cannot think of anything radical, which takes engine to that super high rpm.I am missing anything which makes F1 engine move at such high rpm.
any ideas :?: :?: :?: :idea:
i think Cosworth came up with first of kind
with this kind of engine

manchild
12
Joined: 03 Jun 2005, 10:54

Post

It wasn’t a radical leap. 15 years ago they reached some 13k, than it started growing over the years as electronics was developed, including the injection and exhaust. One season usually meant + 500 rpm (more-less)

User avatar
Steven
Owner
Joined: 19 Aug 2002, 18:32
Location: Belgium
Contact:

Post

Well the variable trumpet lengths also helped to achieve faster burning of the fuel so far. However, from 2006 on these are banned, which is another reason why the new V8 engines are well behind in performance to the V10s

DaveKillens
34
Joined: 20 Jan 2005, 04:02

Post

I would not characterize fuel burning as a key to higher RPM, it's about achieving more ignition cycles per second.
Pistons are indeed hollow, but they have followed that path for a very long time. The key is the use and understand of better materials, heat management, material strengths, and things like that. Allowing a component to have less mass, yet have as much strength is one major key in the steady progression of power and RPM. And don't forget that in present Formula One cars, cost and replacement of components is one thing they are willing to live with. It's really incredible how much and different components are used once, or maybe just a few times, before they are scrapped and replaced. When a Formula One engine receives a major rebuild, just about every component that moves in any manner, from the pistons to crankshaft, to valves, cams, etc. goes out and new parts installed. Yup, that beautiful, machined, seemingly perfect crankshaft will probably be yanked on any rebuild and wind up in the scrap bin.
The key to higher RPM (and thus, more power) is to have components that can survive that environment. Some parts find it relatively easy to survive, while things like valves live a life of pure wreched agony. In fact, usually it's the valves that limit RPM. That is one major reason why we see cams on top of the cylinder, to reduce the mass of any valvetrain components. Different methods have been tried in an attempt to keep the valves from floating and striking the piston. One of the big breakthroughs came when the pneumatic valve system was implimented. It greatly reduced the mass of the valvetrain, and RPM's made an impressive jump.
In NASCAR, where they are restricted in engine design, and must use metakl valve springs, valves too are the weak link. They use 5+ liter V-8 engines and are allowed only one intake and one exhaust valve per cylinder. So what do they do? They run high spring pressures, and thus, the springs run VERY hot. Red hot, in fact. To keep them alive, they are kept in a spray of cooling oil. Maybe "spray" is an understatement, more like a deluge.
I don't really understand the idea of air being pushed at higher pressures, unless you refer to the turbo era. We do have better airflow management, however. Most of the intake and exhaust rules have been known for many years, at least since the 30's. But we now have computers and experience to refine those functions. Thus, air flows in easier and with more efficiency, and the exhaust the same. That is not to say there were improvements. Once upon a time, the general practice was to have individual exhaust megaphones for each cylinder. But it was learned that using the pressure waves into a 4 (or 5) into one collector would result in improved scavenging.
There are few places where "breakthroughs" occured in the steady progression of engine power and RPM. The only two I can think of was the discovery and mass production of high compression fuels (WW2), and the pneumatic valve system.

JL
JL
0

Post

You guys covered most of it. The only other thing is very short strokes. This helps several ways: Reducing Max speed and acceleration, weight and improving breathing. The resulting cylinders are very oversquare and they have therefore a large area available for the valves. For high rpms you nead easy, low-loss breathing.

JL

manchild
12
Joined: 03 Jun 2005, 10:54

Post

An example:

FIAT 128 engine 1300 ccm version (35 years old) - bore 86.4mm stroke 55.5mm

That is not far from F1 engine bore stroke ratio and I think it is the most extreme bore stroke ration ever seen in mass produced passenger car. Even so, it reached max power of 65 hp at less than 6000 rpm even though that racing versions with huge changes could reach 11000 rpm.

Those are racing versions with carburetors, 2 valves per cylinder and spring valve actuation. Now imagine that with what F1 budget can afford - years of constant development, electronic injection, computer engine management, 4 valves per cylinder, exotic materials... and you'd get quite close to rpm from modern F1.

Guest
Guest
0

Post

manchild wrote: is the most extreme bore stroke ration ever seen in mass produced passenger car.
I dont remember off the top of my head the bore/stroke ratio of a rotary, but its definitely up there. Just another example of oversquare -> high rpms. Also, no valves -> high rpms

RH1300S
1
Joined: 06 Jun 2005, 15:29

Post

manchild wrote:An example:

FIAT 128 engine 1300 ccm version (35 years old) - bore 86.4mm stroke 55.5mm

That is not far from F1 engine bore stroke ratio and I think it is the most extreme bore stroke ration ever seen in mass produced passenger car. Even so, it reached max power of 65 hp at less than 6000 rpm even though that racing versions with huge changes could reach 11000 rpm.

Those are racing versions with carburetors, 2 valves per cylinder and spring valve actuation. Now imagine that with what F1 budget can afford - years of constant development, electronic injection, computer engine management, 4 valves per cylinder, exotic materials... and you'd get quite close to rpm from modern F1.
By comparison the R8 Gordini of a similar age was 75,7 x 72 mm - a revvy engine that can go to around 8000 rpm with pushrods. Just shows how extreme that Fiat engine is.

manchild
12
Joined: 03 Jun 2005, 10:54

Post

Here is the cross section of that 86.4 x 55.5 http://www.angelfire.com/wa2/x75sd/images/75sd31.jpg

*copy url into address bar because it will not open otherwise

Berg
0
Joined: 18 Mar 2004, 05:18

Re: How Super High Rpm is achevied

Post

Quoted:
1. fuel is burned really fast so faster ignition frequency
2. pistons are hallow and so less weight so less inertia so faster they move
3. air is pushed at high pressure and with lot of pressure .

Berg
0
Joined: 18 Mar 2004, 05:18

Re: How Super High Rpm is achevied

Post

[quote="ss.vamsikrishna"]....
1. fuel is burned really fast so faster ignition frequency
2. pistons are hallow and so less weight so less inertia so faster they move
3. air is pushed at high pressure and with lot of pressure .
....
[/quote]

The first 2 reason are true, they are 2 reasons of some that make an engine can rav so high. But the last point is not true for F1 engine, since turbo/super-charging is banned.

There are 2 more reasons that make F1 engine can rev so fast:
1. A very high [u]Bore to Stroke ratio[/u]
2. Pneumatic valve spring

Actually, the above 2 points is the most important things to make high rev.

The 1st point means a very short stroke that lead to less piston acceleration. In the road car engine the ratio is about 1:1, and in the F1 engine it is more than 2.2:1

The 2nd point is very important. Before pneumatic-valve-spring utilization (1st by renault in 1986) the rpm max is about 15k. This is due to convensional spring natural frequency limitation. Those convensional spring could not move faster because of their inertia. With pressurized gas in penumatic system, the spring stiffness can be so high without mass inertia penalty.

Rgds,
Roy Berg

manchild
12
Joined: 03 Jun 2005, 10:54

Post

It should be mentioned that passenger car engines are designed to last at least 100.000 km while F1 engines are designed to last only two races (lately). So, every element of F1 engine is designed just for two race distance and nothing over that. It would be ideal if F1 engine as well as whole car and gearbox would behave like Ferdinand Porsche suggested (my signature). :wink:

ss.vamsikrishna
0
Joined: 24 Nov 2005, 14:02
Location: USA

Post

Hi berg
it was a good explaination , but i still did not get the first point
and how is that going to help like bore to stroke ratio, see if stroke length is less then a very less powerful stroke right so , ultimately less BHP right.
so y they do that.

thanks
krishna :?: :?:

ss.vamsikrishna
0
Joined: 24 Nov 2005, 14:02
Location: USA

Post

Hi DaveKillens ur reply was really informative and complete , it was really cool.
thanks
krishna

DaveKillens
34
Joined: 20 Jan 2005, 04:02

Post

With a fixed displacement, shortening the stroke results in a larger bore. Remember, that despite the bore and stroke, about the same amount of fuel/air is introduced into the combustion chamber, and when ignited, release the same amount iof energy. With a shortened stroke, the crankshaft offset is less, and thus you get a shorter leverage. But there really isn't less power produced. The horsepower and torque characteristics may be altered, and efficiencies may be also changed.
So please do not assume that "a less powerful stroke" results from this geometry.
When you deal with pistons, longevity is a major factor in design. And one parameter engineers look at is how much the piston has to travel up and down the cylinder, and the acceleration forces acting on it. So broadly speaking, a cylinder that has to endure a longer stroke suffers higher acceleration forces on it, and thus, if spun at the same revolutions as a shorter stroke engine, would probably fail first. So if a shorter stroke piston can withstand forces better than a longer stroke piston, it can be revved higher. And if you have more revolutions per minute, you also get more power strokes per minute. More power strokes over the same time period is just that, more power.
http://www.epi-eng.com/ET-PistnVelAccel.htm