Ciro Pabón wrote:Thanks, Edis, very nice post. The ones by Belatti, riff_raff and safeaschuck in pages 2 and 3 of this thread are, too, jewels. Thanks also to Professor for the opportunity to bump this thread and to MC for the nice pictures.
I cannot avoid to think, after reading your post, Edis, that for many of us this is another "layer" to discover in F1. I've never heard of (almost!) sole providers for some high performance parts like the ones you mention (Del West, Schrick). Those are sites I have to visit.
This "monopoly" is achieved by means of quality, you have to assume (and price, you have to fear!
).
EDIT:
Del West is an all-american company aerospace company that, somehow, switched to racing, and it has a manufacturing plant in Switzerland. That's a strange story.
I also loved the phrase at
Schrick: "We produce prototypes in series".
Can I ask why the racing engines have such small stroke? Why it is more eficient an engine when a piston moves little but very rapidly? Would the ideal engine have pistons with almost zero stroke and almost infinite speed?
The reason camshafts are sourced from only a few manufacturers is because the use of compound valve angles; that is the valves are angled in two directions. This means the camshaft have to be made with lobes that also have a small angle. Only a few companies have the equipment for that.
By the way, did you notice the Bugatti Veyron block and heads at the AVL Schrick website?
Another company that supply components to almost all F1 teams are american MOOG's british operations which supply the micro servovalves used for control the actuators for gearchange, the clutch and similar. These are a smaller and lighter version of their servovalves originally intended for missiles.
I think a company called PMG was a supplier of valves for a period too, during the 'titanium aluminide valve' era. Brush Wellman, an american company that specializes in beryllium was also a quite exclusive supplier of the beryllium-aluminium composite used for pistons, liners and brake calipers for a time.
A few other companies that supply multiple teams:
Hitco, Carbon Industries and Brembo supplies brake discs and pads
Chambon, now part of Capricorn Group have supplied Ferrari and Renault with crankshafts
Grainger & Worrall, supplies engine castings
Not only is high quality important, but to be able to find a supplier that can make the small series needed could be just as difficult.
In many cases the same companies also sell their parts to different racing series, Mahle Motorsport for instance, not only do they supply several F1 teams, but they also supply several MotoGP teams, WRC teams, DTM teams, Le Mans teams and I believe around a third of the NASCAR field. They are not the only ones to do so, Grainger & Worrell cast engine parts from Cosworth F1 engines to Chevrolet NASCAR engines, and Del West isn't only a big supplier in F1 but also in NASCAR and other racing series, they even supply GM with some of the valves found in stock Corvette engines. The trend is also that the suppliers become more and more international, as one NASCAR engine builder put it, in the past almost all parts in the engine was american, today most of them are from international suppliers.
autogyro wrote:So the high tech pistons are made to stretch the engine to high revs or in the case of diesels to deal with extreem forces.
Surely much better to harvest the wasted energy from the emgine after all they are only around 20% efficient anyway.
A piston must offer a good fatigue strength at high temperatures, typically in the range of 150-400 degC, a high stiffness and good wear resistance. A production gasoline engine is subject to around 80 bar peak pressures, a F1 engine probably around 110 bar or so, but obviously it is subject to much higher intertial loads. A diesel is subject to much higher peak pressures, when the common rail passenger car engine was introduced in the late nineties the typical peak pressure was around 140 bar, today it's around 180 bar. Commercial diesels see pressures as high as 200-250 bar, and should the oil spray cooling of the pistons fail under full load they wouldn't survive long. Large diesels, such as those found in ships for instance, usually use oil or watercooled pistons. Larger high output diesels use a steel piston, or a steel/aluminium hybrid.
The efficiency of a typical NA gasoline engine is around 33% or so, but the average efficiency is much lower since they usually operate at part load. Exhaust energy recovery would be of little benefit under such conditions, and isn't really that great at full load either. There is a NACA paper where some performance data of blowdown turbines are published; the power lost from the engine due to increased pumping losses and the power gained due to the turbine.
A direct injected gasoline engine is slightly more efficient, 35-37% or so, about similar to a pre-chamber diesel. A modern direct injected and turbocharged passenger diesel is around 42-43% efficient, and a commercial diesel, as found in trucks and buses, reach around 44-46%. What limits the commercial diesel engine efficiency is mostly NOx emissions which form at high load. Caterpillar has a paper which discuss what modifications are required to reach an efficiency of 50%. But the big difference between the gasoline and diesel engine is the latters much higher part load efficiency, a result of much smaller pumping losses.
Heat recovery using the Seebeck effect is only good for a few hundred watt, say half of the electricity normally produced by the alternator.
If Nicolas Léonard Sadi Carnot were still alive, he would have told you that you can achieve a greater efficiency with a higher temperature difference between the two reservoirs which the engine operate from. In case of the piston engine, the highest temperature is seen during combustion, then the temperature drops and with it, the potential to extract energy from the heat.
manchild wrote:
Most interesting, can anyone comment on that flywheel assembly type of thing?
It's a circa 4" multiplate carbon/carbon clutch. For a while they were even below 90 mm in diameter. The 'cage' is titanium, the plates carbon/carbon and the spring 'fingers' steel. The clutch has pull type operation. Today I think it's more common to place the clutch on the gearbox input shaft rather than the engine output shaft. The axial shaft play there is smaller, which is beneficial for the precision of clutch operation.
There are two big suppliers of these clutches for F1, Sachs Race Engineering and AP Racing.
http://www.zf.com/media/media/document/ ... 132_zf.pdf
http://www.apracing.com/info/index.asp? ... tches_2789
mep wrote:My professor teached us that the maximum average piston speed for engines currently lies at 25 m/s so there is a limit to this. I checked it with some Ferrari engine data’s and it perfectly fits.
Some engines run as much as 30 m/s, I know some speedway racing engines are around here. But it is rare.
Basically, what limits the piston mean velocity is the velocity of the air in the intake port. If we say that the intake ports are 1/3 of the bore area, we can relate the piston mean velocity to air intake velocity. With some practical experience of volumetric effciency vs. piston velocity, and of course mechanical efficiency vs. piston velocity, it's rare to see peak power speeds higher than 25 m/s.
mep wrote:In fact very big, slow moving, long stroked Diesel engine are the most fuel efficient ones.
Check this out:
http://people.bath.ac.uk/ccsshb/12cyl/
Fuel consumption at maximum economy is 0.260 lbs/hp/hour. At maximum economy the engine exceeds 50% thermal efficiency. That is, more than 50% of the energy in the fuel in converted to motion.
For comparison, most automotive and small aircraft engines have BSFC figures in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range.
For peak efficiency you want the engine to run at a certain speed that can be related to the cylinder size. For a passenger car engine with 0.5 liter cylinders that's around 3000 rpm, for a commercial diesel with 2.5 liter cylinders it's around 1200 rpm and for a big diesel like the one above, it's probably around 100 rpm or so. Why? Well, heat losses decrease with increased engine speed and increased cylinder size, frictional losses increase with piston mean velocity. So you want to balance heat losses against frictional losses; high speed is benefitial to minimize the heat losses while lower speed is benefitial to minimize the frictional losses. With larger cylinders, this balance will occur at lower engine speeds.
Regarding the efficiency of the Wärtsilä RTA96C (info and specifications, see the link below) it isn't that much higher than a commercial diesel, around 45% vs 50%, but then again, what limits the efficiency of one of these engines is the cost as one Wärtsilä engineer put it. They are also optimised to power big container ships at a constant speed using direct driven fixed pitch propellers. It's all about maximum economy, and compared to road vehicle engines, they are not that limited by emission regulations.
Also, 25-30% is a bit of an underestimation of the efficiency of a gasoline engine. 25-30% is more typical what you see during highway cruising conditions.
http://www.wartsila.com/,en,productsser ... ,,8000.htm
