engine testing and integration

[Spencifer_Murphy]

Someone asked what I meant by the integration on the Engine & Chassis. You are right the engine has been designed to fit into the chassis well (it can be changed very quickly) but when using the term integration i mean something different. An F1 car, as you'll know, is more than just bolting an engine to a chassis. The engine is a fully load bearing, part of the car. Added to this the engine creates its own vibrations etc. (I don't know the intricate details on the engine department, I'm more of an aero man myself) but when an engine is mated to a chassis they have to compliment eachother perfectly. This one of many reasons why the Saubers are not up with the Ferrari's now. They are using a car tht looks remarkably like the ferrari from last year, with this year's ferrari engine and gearbox. But the ferrari engine and gearbox are designed to fit in perfectly with the 2004 Ferrari...not the sauber. The integration of the whole package is how the parts of the car compliment eachother.

Put it this way: trying to fit a Jordan with a williams nose will not make the jordan faster, it might even make it slower. It won't work because the frontwing & nose structure is only the first part of the car to cut through the air. The frontwing & Nose on an F1 car are designed to not only create downforce but also to direct the flow of air in a manner that compliments the way it will flow over the rest of the car. It is one part of an aerodynamic package that has to work in harmony. Its the same with an engine and a chassis the engine is just one part of the package, but it has to work in harmony with the chassis and tyres etc.

Thats the best i can explain it, I hope that answers your question...sorry it was very long winded lol

[marcush.]

ah yes the integration thing.
Are you serious ,Sauber is able to copy the whole car but not able to caopy the engine mounts?
As far as Iknow they were a little miffed about the fact they had no choice but use the ferrari mounts for the first time ,as they have the same engine as ferrari now wheras before the interface wa s strictly sauber....
The diffrence between sauber and ferrari is:the emmen windtunnel has a limited value as Bentley has experienced too,and the new tunnel was a long way from operative when the new car was designed.
So sauber had for years bad correlation from their tunnel work and of course they donot have the budget to evaluate every possible setupchange in every conceivable environment.So they will always take longer to arive at the best possible setup.Unfortunatelly the weekend is over by then,whereas ferrari arrives at every track with perfect simulations applied .that is the difference.Ferrari would possibly win with sauber´s car very soon and sauber could not maximise the potential of theF 2004 as the new tunnel is not tried and proven so they have to build their confidence first.
As for the engine mounts,you have to design them giving good torsional stiffness,but allowing for the alloy to expand whereas the monocoque stays pretty the same dimensionally....vibrations?what do you mean?
I cannot believe the chassis vibrates in a manner to harm the engine...

[Enzo]

I agree with Spencifer_Murphy here.
Modern Formula 1 is not just a matter of "fit a Cosworth DFV everywhere and win". A modern F1 designer has to dedsign a chassis that is stiff enough to compensate with the various loads with which it will have to "play" with. These loads are aerodynamic loads, from the engine, brakes and inertia loads. And while F1 is a dynamically loaded machine we must talk using frequencies. The stiffness of the chassis will determine the natural frequency of its modes. The principle freqs are the car on its suspension which is about 6 Hz, wheel hop about 15 Hz and the engine about 250 Hz!!! The natural freqof the chassis cannot be more thn 250 Hz of course so if you have a not so much stiff chassis you must fit some proper engine mounts. This last is quite bad for the performance of the chassis. And there are numerous other reasons why the Sauber is not performing well such as weight distribution, distance of the main masses from the CoG-> yaw inertia, suspension geometry, center of aero pressure in relation to CoG etc, etc, etc....

Marcush, chassis "vibrations" and lateral forces in general can harm the engine. You must have a stiff chassis with little deflections in order to prevent the possibility to deflect your engine. Engine deflections will distort parts you will twn have more friction etc... Often we hear technical directors to say: "We must investigate the cause of the failure, we have never facet it before". Engines are tested in the engine rigs and there you can simulate several things. But you can never simulate there the g forces. Also the mounting of the engine on the test bed can never simulate the actual mounting of the real engine to the real chassis with its own real natural freq. characteristics.

P.S. Sorry for the double post but i have a problem with auto logout every time i close my browser...

[Scuderia_Russ]

As far as Iknow they were a little miffed about the fact they had no choice but use the ferrari mounts for the first time ,as they have the same engine as ferrari now wheras before the interface wa s strictly sauber....

That surprises me given the amount of engine failures they were having all through last season.

[marcush.]

I´m very sure the problems of having an engine revving at18000rpm is a bigger problem for the chassis and all things you try to hang onto the engine as the other way around.
what may be a problem is bending and torsional issues ,as well a sg-forces making oil,water and air fuel mixtures doing different things that you would see on a dyno.
What on hell could sauber do to make their cG height or position so much worse than ferrari...come on boys the car shares the same engineand gearbox,together with the driver where would you see the possibilities to mess up in a way to loose 2 seconds on the concept of the car?You could place the ballast on the rollhoop perhaps....
ok ,sauber has some engine cooling issues ,that is my impression also.

[marcush.]

very interesting thoughts about the frequencies....if you were right ,just let me know why they don´t put the whole car on the dyno just to make the rig testing more accurate....I bet if tthis frequency thing was really an issue they would not bother extending the dyno room that little bit more,would they?
On the side of this ,would increasing the tyre pressure change the frequenvcy of the whole car enough to make the engine fail,excuse me....
Of course ,they design the engine as a loadbearing member and of course they make the chassis as stiff as possible as there is not much crossectio available,and try to not create a change in stiffness where chassis and engine meet,so the whole package reacts as a unit in bending and twisting.

[Enzo]

Marcush,

How would it be possible to test the engine inside the car i.e. to connect the engine with the dyno while it's inside the car and at the same time to simulate the vibration generated by the suspension movements? Do you mean to connect the 7 post rig along with the engine test bench? Perhaps one day this will be possible! And how they can simulate the g loads inside a testing room? Only if they could rotate the whole system of the car-engine test bed-7 post rig....

From all these freqs you will end up with a total torsion freq from axle to axle. And you must damp in some way this total freq. By dampers and joints between engine and gerabox as well as joints between other mech. components. The decision is yours. Whether you put engine mounts with a higher natural freq in order to compensate this total freq. and having finally an unstable car or you make the system more rigidly connected and have reliability problems...

[marcush.]

it is not so dificult ,as the dyno is driven off the clutch side anyway...
the thing with the 7post rig is an interesting thought and why not put the whole thing into a centrifuge.....well that will be the point where even toyota will cry enough....
so back to square one:How on earth can Jaguar put that agricultural vehicle on a front row starting position?all those high aspiring calculations leed to nothing if the speed is just not there.
Speed is more a function of creativity confidence and maximising your potential when it counts.
anyone out there who wants to elaborate on changing frequencies when changing front wing angles or springs or moving ballast somewhere else...

[marcush.]

sory ,one more question about the frequency issue:
If the engine has a frequency of around 250 this cannot be a constant one as it revs up and down with big accelaration figures ,so the time to ecite the thing is very short.On the other side the natural frequency of chassis and suspension is around 6hz so what is the problem? I feel the amplitude of the vibration is more of a concern then the frequency itself and carbonfibre is not really that well suited to build an guitar or a horn....I had a carbonfibre Bicycle some time ago and I rmeber it being very different to an alluminiumbike in ways of resonating on impacts and loads an alloy bike makes sounds and vibrates quite a lot wheras the carbonfibre was more dead from a feeling of any resonance.
ah yes the sauber theme:
Just read a n interview with mr.Sauber,and guess what he stated:We might have a very good engine and gearbox ,but that is not the important thing .We do not maximise our potential on the weekend,we have to understand the new tunnel to move forward,we expect more of our drivers and engineers in the future.
By the way ,did someone spot the Hacksaw style vents of the mclaren side pots in bahrein?Icannot believe they analyse frequencies and do not find the time to build some proper sharkvents or chimneys....

[Guest]

How on earth can Jaguar put that agricultural vehicle on a front row starting position?

He,he your guess is as good as mine and Webbers!

[Enzo]

Engine and transmission is an integral part of the chassis so it's there to transfer all the suspension and rear axle loads to the chassis. And just because they transfer the loads they also are suffering from them. As for the frequencies the engine is generating a max freq of 250 Hz which is transferred to the chassis and dampers. Anyway as i wrote before we have a total axle to axle torsional frequency of about 40 Hz. If your chassis is not able to overcome this freq. then you don;t just change your chassis but you should fix some engine mounts and joints between engine and gearbox with a higher natural frequency which is affecting overall performance. Here the choice is for the mechanics. Add to that the small cross section of the modern engines which make them less stiff. So what i wanted to say and to relate it with the title of the thread, chassis and engine-transmission must be designed in common as the performance of the former is affecting the performance of the latter and vice versa.

Another issue is the catastrophical g loads for the engine which cannot be simulated at least at the time. These loads are generating vibrations and just imagine the situation in Maggots and Beckets at Silverstone! Quite exciting!

[marcush.]

let me put it this way:of course it is a different world to have the actual car driving thru maggots or eau rouge...I always said that .
designing the oil tank of the drysump system is anther challange to tackle with all zhose G-forces...
Or design of a good fuel system ,wich seems to be a big issue not mastered very well by Sauber Toyota jordan and others ,it seems those fuels of late sem to have a tendecy to build vapor locks or they all don´t know really what they are doing....but you learn by making mistakes.....so maybe toyota and sauber will soon be the real cracks at desining the ultimate in fuel supply.....
back to the frequencies...you are deadly serious...changing the springs and changing the front wing can kill your engine....and there are people saying they could design a mount preventing it without loosing performance...and those same people do a lap simulation for bahrein wich is 7 seconds of the reality and 3or 4 gears away from what they thought they need....let´s put it that way:I do not see Ferrari using a Engine support to make life easier for the engine ,just because someone says there might be a problem....but to solve it we have a fexicar and will loose time in almost every corner...

[Enzo]

back to the frequencies...you are deadly serious...changing the springs and changing the front wing can kill your engine....and there are people saying they could design a mount preventing it without loosing performance...

I never told it in such a superlative way actually. I never said that by changing a front wing you could kill your engine (although i have been talking only for rear suspension loads as only the rear suspension is being mounted to the engine-gearbox assembly). Only the fact that the suspension loads are being transmitted to the chassis passing first from the gearbox-engine assembly is a factor (small or big factor i am not 100% aware of) of harming your engine.

[marcush.]

Hm...we were talking of engine mounts and integration problems.
You were talking of harmful frequencies from the chassis side and the problem that these have to be controlled and damped to avoid harm to the engine.
My talk was load and performance orientated and my suggestion was the engine and gearbox are the ones doing harm as they vibrate at high frequency and high amplitude (you hear Aero forces and frequencies quite seldom,in Indianapolis with IRL cars ,as they rumble at high speed .
As you change anything you stick to the engine be it a different spring or a different frontwing you surely alter the natural frequency of the whole assembly.It is possible that a particular combination will be the death knock for your engine or anything else on the car ,I would not debate this.And of course you try to make life for the parts as easy as possible but you would surely not compromise installation stiffness just because you fear the chassis might have a unknown influence to the engine performance.that was my point.There are ways to design a mount to be stiff in bending and under torsional loads without transmitting vibrations
too much.

[Enzo]

As you change anything you stick to the engine be it a different spring or a different frontwing you surely alter the natural frequency of the whole assembly.It is possible that a particular combination will be the death knock for your engine or anything else on the car ,I would not debate this.And of course you try to make life for the parts as easy as possible but you would surely not compromise installation stiffness just because you fear the chassis might have a unknown influence to the engine performance.that was my point.There are ways to design a mount to be stiff in bending and under torsional loads without transmitting vibrations
too much.

It seems that we absolutely agree now (actually i have not understood 100% you post which you posted on Mon Apr 12, 2004 8:19 pm). I was talking only about harmful frequencies from the chassis side to the engine as it is something not that obvious. This doesn't mean that i don't agree with you that there are loads from the engine-gearbox side to the chassis and these loads are for sure more severe and i didn't actualy mention that because it's something more obvious and logical.