17 replies to this topic

[Pit Babe]

I realise engine specs aren't exactly readily accessible, but I have to ask anyway: why are some engines the model of consistency while others just plain suck? (Forgive the use of the vernacular - it was the simplest way to get to the point.)

For example, at Hockenheim much was said about how the circuit forces a high attrition rate because it's so hard on engines. Casual conversations I had indicated that most people thought only McLaren and Jordan had the staying power necessary to last the race, but no one could give me specific reasons why.

Also, it's no secret the Supertecs have fared poorly no matter whose chassis they wore, yet I can find no detailed explanation for this behaviour.

Comments?

Not a mechanic but certainly mechanically inclined,

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PB ;-)

Always opinionated. Not always right.

[Christiaan]

The complexity of engines allow for great variance among engines.

In F1 I think only 3 things matter at the end of the day
-Peak Power
-Reliability
-Drivability
I could not rank these in terms of importance.

Peak power affects you top end speed. Infact only three things control that, your mass, drag and top end power. Most teams go for high peaks by revving higher, burning more fuel and stuff. Prost apparently has the highest peak power and thus greatest straight line speeds.

Reliability, well the importance is self explanatory. I think reliability is directly related to a teams budget. Ferrari and Mercedes never use an engine in two races. Whereas Minardi and Arrows recycle engine parts. Reliability is also obviously affected by the materials that the engine is built from. Mercedes uses two very expensive ingredients in their engines, an Aluminium Berylium alloy, and Molybedum(forgive the spelling) Sulphate. These two materials are strong, thermally brilliant, and for low stresses do not require lubrication. So their effects on reliability should be obvious.

Driveability- the shape of the Torque curve should be flat, to give the driver the ability to overtake at all speeds. The power curve should peak as early as possible (13 000rpm is the best ), with a broad peak power band so that the driver has more flexibility over his gearing.

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Thats what I think anyway

[palmas]

In spite of what is refered, moste of the differences between engines are not the engine it self but:
a) cooling liquid input and output temperature. If you can have a big delta T (difference between output and input temperatura, then you can have smaller radiators, and better aerodynamics. If you can have a high cooling liquid temperature, means the engine can ran a litle hotter and that you don't waste energy and use less fuel (less weight). If you dont have so much energy to waste, then the amount of circulating liquid is less and the pump consumption and more power for the weels. I beleave we could go on and on on this and many other subjects, but the small differences in engines can make a big difference in results.
There are also some huge differences in some F1 engines, like the new Ford engine, that controls the valves electromagneticly and independently, not using any camshaft..
If you would like to discuss more and with more detail, please tell.

Palmas

[IndyIan]

palmas,
I thought all F1 engines used a pnuematic valve system. I have heard of electromagnetic valves but was not aware that Ford was using them in their car. Hopefully soon these will appear in road cars and then we can all play with our valve timing without buying cams

Christiaan,
I don't agree with your point about the Prost having the highest peak power because it has the highest top speeds, I think top speed has more to do with aerodynamics than peak hp. One way to find out who has the most hp would be to measure the acceleration of the car before the aerodynamic drag really starts to build. Say from 40 to 80 mph, but actually an F1 car would probably just spin the tires with full throttle at these speeds so i guess we can't tell how much power an F1 car makes.

[This message has been edited by IndyIan (edited 08-11-1999).]

[JHH]

I have heard the same speculation from Peter Windsor regarding the Peugot’s peak. I always figured that Prost had his cars running a ratio in 6th that would enable them to out drag to other teams on the straight. I also figured that Prost was running less downforce than the other teams in an effort to gain an advantage in at least one sector. After all, Alain needs to gamble a little given that the top teams have him out-engineered.

Just speculation… but if true, it suggests that the Peugot is not as aggressive a motor as some think.

…James Harold….




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" I have no interest in any ship that does not sail fast, for I intend
to go in harm's way." Captain J. P. Jones, US Navy - January 16, 1777

[Megatron]

Patrick Head has said the major problem with the Supertec is top end power. He has stated that the engine has great drivability and decent accerlation.

A good test to that theory should come this weekend when top end power really does not matter that much at Hungry.

Someone mentinoed the fact that the top runners get basically new engines every race while the back teams gets recycled engines.

While I am not quite sure how true that is for Minardi considering Ford does thier engines, I think that is a problem for Arrows, as they are using the same engine (and car) as last year.

Exactly right about topend power having more to do with the areodymanics than the engine, at least most of the time (unless your at Hockinhiem or Monza).

In Austria, Alex Wurz actually had the fastest trap speed in the Benneton becasuse he had a very low downforce setup.

In Spa last year, in quailifying, Mika Salo (in the ARROWS of all things) had the fastest trap speeds.

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Death through Tyranny - Megatron

[tony]

I have a few questions for all of you. First, each team lists an engine manufacturer, but not a transmission(gearbox) manufacturer. Presumably Ferrari makes their own trans and I imagine Ford may as well. But who makes the tranmissions for Williams, Jordan, Mclaren, etc.... My guess is that the engine manufacturer makes the transmission as well, but it is not listed anywhere.

Secondly, on the more technical side, some of you said that mass effects top speed. In theory this should not be true. It is certainly true that linear acceleration is effected by mass, but the top speed should only be effected by aerodynamics(drag), and power. It would certainly take alot longer for a heavier car to reach a certain top speed but if it had the same power and aerodynamics(drag) it certainly could go just as fast. Mass could help determine the top speed only in a secondary, indirect way. For instance if the aerodynamics were somehow changed by the mass(ride heigth could be effected by mass, and thus change the aerodynamics). Does anyone know of any other indirect, secondary effects that mass could have on top speed, there could be a few more.

What is the deal with wheel tethers. I thought the FIA made them required for this year. If so, why did MH's wheel go flying off at Silverstone. Are the thethers supposed to only slow down the wheels if they become unattached or are they supposed to stop the wheel from flying at all? Finally does anyone have details on how the tethers are actually attached. I can think of a few ways it would work, but most teams seem to have done something more clever than what I have in mind since they can still changes tires so quickly in the pits.

[Megatron]

The chassis manufactur makes the gearbox. In 1995, Benneton ran a 7 speed while Williams, with the exact same engine, ran a 6 speed.

Mika's tire came off because of the loose bolt, the tether is attached the suspenion/wheel using a carbon fibre cable.

If the teathers were attached to the tire, no one could change them! (which might have been better in Germany ).

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Death through Tyranny - Megatron

[SlowDrivr]

I don't think its right to say that aerodynamics are more important than HP for top speeds. Improving either of them will increase speed. The top speed of a car occurs when the sum of the frictional forces (engine, drivetrain, etc + aero drag, which is the dominant one by far at these speeds) balances the torque produced by the engine at the wheels.

Trap speed is different. If you measure it on a short straight then HP and mass are the main factors. I don't know if its customary to measure it on a long straight or not. If it is, then the above paragraph applies.

FYI, I forget where I read it but I thought it was interesting. Just letting off the gas in an F1 car at 180mph will result in a deceleration of 1G just due to aero drag. 1G is about the maximum of what a production sports car can brake at on good tires. So an F1 car lifting the throttle at 180mph is like slamming on the brakes in a street car.

[DangerMouse]

Megatron, Christiian is right and about Minardi reusing engine parts, up until this season all customer Ford teams (Tyrrell and Minardi) had a service contract, this contract dictates what is replaced every engine rebuild and was determined by the individual teams budget, unfortunately there's a catch, then less parts you replaced the less revs you were allowed to run your engine, Minardi had such a skimpy budget than they were running down in the region of 14500 revs against the normal peak revs of about 16,000 for that engine - and they still blew up a lot! Ford (Cosworth at the time) were getting annoyed at the bad publicity created by their customer engines blowing, when it was because the customer didn't want to spend a lot of cash not because the engines were crap!

For 1999 Ford insisted that Minardi have to have "Works Spec" servicing for their Zetec R V10s or not have them at all - it's no surprise that Minardi are having a good season.

Another aspect of engine reliability that is overlooked is installation, The best example is Arrows 1997, they blew their Yamaha V10s with alarming regularity and Yamaha got a lot of stick over it, enter John Barnard a third way through the season, who soon spotted the problem - too much flex in the chassis which was causing the engine (a fully stressed member, as are all F1 engines) to flex beyond it's design limits and so caused numerous failures. John reinstalled the engine with different mounting points to the chassis and built a torsion bar that ran across the top of the suspension mounting points at the rear - The Yamaha's reliability improved dramatically and Yamaha were again able to run the engine at the kind of revs they'd seen reliably on the bench (the D spec was born, which wasn't a new spec at all but the original intended spec!) In other words Yamaha were over-engineering their engine to try and fix problems that didn't really exist!

[Christiaan]

Okay, the top end speed is dependant two fundamentals -power and drag. I will use elementary physics and maths (and good old fashioned guesswork) to explain why I think the power is the bottom line.

A simple equation:-

Power = Force x Speed

The Force is all drag force, which is a function that includes aerodynamics. The drag coefficient of F1 cars is rumoured to be between 0.75 and 0.80. Thats an average of 0.775 with a variance of almost 3.5%

The maximum power output of engines is rumoured to be between 700 and 820hp. Thats a variance of almost 8%.

Based on that, I say that fundamentally top end power is more important. The problem of course is that downfoorce makes things very complicated. I don't believe that Prost is running less downforce than all the others because his cars a stable enough when entering and exiting corners. If his cars have very "tall" sixth gears then it would take him relatively longer to attain maximum speed. The longest "straights" I know of in F1 today are in Hockenheim, but if a driver doesn't exit a corner fast enough he will not reach his top speed.

[SlowDrivr]

Ok, I see what you're saying now.

The drag coeff depends on the setup (hi/med/lo downforce). The only Cd numbers I've seen were in a book about aerodynamics and were from an early 80's F1 car, so they may be way off now, I don't know. Anyway, this book said Cd was 0.7 to 1.4, depending on setup. So, obviously setup greatly effects top speed.

My question then is, wouldn't minor setup diffences have as great an effect on top speed as HP does? Even though Hockenhiem is known as a low downforce track and Hungaroring is high, isn't there slight differences between cars as to how much downforce they setup for (different driver preferences, etc), even on the same track? Maybe one driver likes a bit less downforce than the others to try and pass on a straight?

[IndyIan]

SlowDrivr,
I agree with you that Cd is more important than hp for top speed.
From my highschool physics class I remember that to double the velocity of an object, 4 times the force is needed. If I have time tonight I do some calculations with some Cd and hp numbers to give some examples of what this means.

[Christiaan]

Indyman and Slowdrv. Both of you are right, but I disagree with the alleged variance on Cd's being from 0.7-1.4 depending on setup.

The biggest contributing factor to Cd is a function of the incident area and the aspect ratio of the car. The aspect ratio (my aerodynamics is a little rusty here so please correct me if I'm wrong) is related to the incident height of the car and its length. Or maybe the normarl width, and length?!?!?!

Anyway the point is that the greatest contributions of drag come from the overall dimensions of the car and not the setup. This means that the Cd for the Arrows will be almost that of the Mac.

Think about it. If the Cd for a Mac was 0.7 and an Ferrari 0.9, the Ferrari would need (9/7)^2 the power of the Mac. Thats almost 60% more power just to compete.

Setup makes a difference that is not aimed really at the Cd but more at the driveability of the car. The key word in setup is downforce; more downforce=better handling, less downforce=more speed. It is true that you cannot downforce without grag, but the relationship between then is not linear. In other words twice the downforce does not mean twice the drag.

Mr Aerodynamicist, if you have recently done experiments with the angle of attack of an aeofoil you can verify this.

[PDA]

A little clarification.

Cd is the coefficient of drag, and indicates how "slippery" the bady shape is. the drag is Cd*frontal area.

Road cars .30 - .35 Cd. F1 cars 0.75 in low downforce configuration (Hockenheim) and about 1.0 in high downforce (Hungaroring). Source of this info was an article by Harvey Postlethwaite in F1 racing last Year. The same article also gave the 1 G deceleration from taking ones foot of the throttle.

HP - No one really knows (outside of the manufacturers) but the magazine pundits seem to say Supertech about 760 to Ilmor maybe 820

Electromagnetic valve gear. - I would be very surprised if Ford were using this technology. The experimental EM valve systems about which I have read are much heavier than even coil valve spring systems. They are also quite bulky. I really do think that Cosworth are using pneumatic valves and camshafts.

[Zoe]

First of all I'm no expert in aerodynamics (that does not mean I'll shut my mouth!
I've learned (amazing what sort of stuff engineers learn at university!) that aerodynamic drag is actually the product of:

Drag = A x Cw

with A the frontal area of the object and Cw (as we call it here in Germany) is the coefficient. The last is basically the result of the aerodynamic design. A Cw of 0.3 is quite good for a production road car, whereas an F1 has a pretty high Cw, due to the wheels, wings and all that stuff.

The frontal area A can be calculated, but Cw is really influenced by the design a la Newey. BTW, a wall has a Cw of 1.0

Zoe

[Christiaan]

Ja Zoe, ich glaube du bist ganz richtig und ich habe alle meine daten von mein kopf verloren.

I am very very rusty on aerodynamics. Rather embarrassing for an aspiring automitive engineer I have to read up some more because I have definately confused the facts.

If anybody ever proves me wrong again I will ban them from this forum ;)

[This message has been edited by Christiaan (edited 08-13-1999).]

[tony]

To SlowDriver and IndyIan,

Here is the answer to the questions you were having about doubling speeds etc....The amount of force needed to increase the speed of an object depends on the nature of the forces at hand. For a car moving in air the largest force for it to overcome is that of air resitance. The force of air friction is proportional to the square of the speed,
AirFrictioin = (some number)* v^2. If you double the speed then the force generated by air friciton will go up by a factor of 2^2 or 4. If you triple the speed it will go up by a factor of 3^2 or 9, etc.... This reltaion between air friction and speed is only good over a certain range of speeds. I think the relation changes if you get extremely fast, like above the speed of sound. Those who work with jet fighters may know about this. But for the speeds of a racecar, the relation is the one I've stated. Also interesting is the following:

The kinetic energy of an object is given by the equation: KE = (1/2)*M*(v^2). Thus the kinetic energy of an object also increases in a similar way. If you double the speed the KE goes up by a factor of 4, etc....

Note that the KE of an object is something that is independent of what is causing the increase in the speeds. Thus this is always true. Only certain types of forces depend on speed at all. The only forces I can think of that depend on speed are frictional forces and magnetic forces(which are not really important for a cars performance). Acutally they are present in the ignition system of the engine, but that's not what I mean. Most forces depend on position, ie electic force, gravity, etc....and some sort of other parameter like mass(for gravity, or charge for electic and magnetic forces).