How is the engine/gearbox assembly mounted to the tub?

[rktech]

I would think that incorporating tapered "bushings" welded to the mounting plate (as well tapered bores on the receiver plate) would help ensure a more true fit time after time whether hot or cold including a more even distribution of stress.

See diagram or link below.

There are several benefits to this config that not only would improve structural integrity and predictability, but could also directly translate to minor performance improvements.

http://i976.photobucket.com/albums/ae24 ... 2cb3b1.png

[xpensive]

I believe that waist is to ease parallel movement of the thread during thermal xpansion without deforming the thread itself,
like the flexures on suspension parts if you like. A waist like that will not reduce the stress due to torquing in the rest of bolt.

Thermal xpansion can be a scary thing if you don't give it enough room to grow, stress build-up can be quick and enormous,
the Concorde aircraft grew almost 200 mm in length during flight, think about it.

[rktech]

Certainly a good point but the good news is we're not talking mach 2 speeds and unlike the expected movement of suspension parts, I would think one would prefer rigidity over movement at the central part of the chassis. I'm guessing here so please bear with me.

Honestly, I don't know the temperature ranges in this region of the car. But assuming the joinery is not in the direct line of open exhaust I suspect the temp range to be in the 150F to 250F range at most without any wind chill. If so then any thermodynamics should be fairly minimal.

Regardless, assuming we're talking mating similar materials any expansion and contraction should be more uniform across the mounting plates and fasteners with the tapering concept and more of the stress on the mounting plates rather than the fasteners. The tapered bores and cononical protrusion sizes would obviously be tailored according to the anticipated thermodynamic expansions.

The F1 industry is not my particular area of expertise but my area of expertise is somewhat universal in that it spans many industries. So I only speculate here.

If I'm right about the temp ranges and if you're mating similar materials which it seems you are, I'd opt for improved structural integrity and rigidity at this main or central joinery for a number of possible reasons including:

1. more evenly distribute the stress of the main parts of the chassis.
2. improved safety due to less stress at the fasteners / threads,
3. greater predictability (improved handling),
4. easier, quicker, and much more precise mounting hot or cold,
5. hopefully make 2 disparate objects more congruent.

Not only should any thermodynamic affects be more uniform across the joinery and hopefully the mounting plates, any improved congruency here could also translate into improved performance (hp) by greater engine operation efficiencies, albeit minimal. But then again, I assume the goal is to always try to squeeze every last drop of blood from the turnip.

[xpensive]

"...thermodynamic expansions."?

I'm afraid that you will have to accept relative movement in the interface between chassis and engine as the latter heats up, whether you like it or not. As for the elongation of the Concorde, it has nothing to do with speed itself obviously, but with heat.

[rktech]

Thanks. I attempted to take into account thermodynamics but my guess of the temperature at the mounting plates was a bit low.

As I recall, the Concorde expanded due to the amount of friction induced at the skins as a direct result of the plane's speed and as a result the entire fuselage shell heated up and hence expanded.

[xpensive]

Perhaps you should read up a bit on materials' thermal xpansion before posting on the subject.

[rktech]

Perhaps you should read up a bit on materials' thermal xpansion before posting on the subject.

As you can see from the original question, this was not a thread directly related to thermal expansion, nor was my response, though it certainly is a consideration as you were kind enough to point out.

[bigpat]

F1 engine mounting systems are simply long studs into the cam covers, and a large shear plate between the sump and the underside of be tub. Been the same for over 25 years people.....

There is no preheating of the engine, nor allowance for expansion, as the studs are a sliding fit into the holes. From what I'm told, an F1 engine expands up to 2.5mm. Yes it adds stress to the metal, and tub, but it is allowed for in the design of the cam covers. In the optimised world of F1 it doesn't sound right but its a necessary compromise. I know this information is correct, because it came from Mario Illien ( Mercedes F1 engine designer) himself.

This problem is not unique to F1, but all the junior formulas below it with carbon tubs and stressed member engines, where they are all mounted exactly the same way....

[xpensive]

2.5 mm?

As Aluminium xpands 23 microns per meter and Kelvin, that would mean that a 500 mm wide engine runs at some 250 C.

Even if so, that lateral and vertical xpansion has to be taken up somewhere wether you like it or not, logically the studs are long in order to bend easily, sliding in the holes I just don't believe, Mario Ilien must have been misunderstood there somehow?

[bigpat]

Growing 2.5mm would be a maximum value then, at a mean temperature of 150deg C, its no drama I would think. I strongly doubt Mario Illien got it wrong. I don't see many others that would be as qualified as him to know.....

As I said, carbon tubbed raceacrs have used this solution around the world for decades with success, why doubt it???????

All that happens is that it puts stresses into the engine's cam cover structure. Growing 1 mm or so per side isn't the end of the world is it?

[rktech]

Growing 2.5mm would be a maximum value then, at a mean temperature of 150deg C, its no drama I would think. I strongly doubt Mario Illien got it wrong. I don't see many others that would be as qualified as him to know.....

As I said, carbon tubbed raceacrs have used this solution around the world for decades with success, why doubt it???????

All that happens is that it puts stresses into the engine's cam cover structure. Growing 1 mm or so per side isn't the end of the world is it?

BigPat, thanks for your explanation. And yes, it seemed to me also that any thermal expansion in these ranges and for this joinery were more of a minor concern rather than major.

[aspetuck]

So the Lotus 49 was apparently the first Formula 1 car to have the engine bolted directly to the chassis, and the transmission and suspension to the engine. There's a video of Chapman observing them mounting the engine on and I can't figure out how they did it. It looks like these little metal arms bolt on to the back of the chassis. Are these actually engineered into the engine block, or are they also bolted on. If so, how? Could this be done to a regular engine?

[Lycoming]

This question has been asked before.

http://www.f1technical.net/forum/viewto ... f=4&t=9110

The answer you are looking for is probably somewhere in those 12 pages.

[flyboy2160]

Merged the topics.

[Tommy Cookers]

So the Lotus 49 was apparently the first Formula 1 car to have the engine bolted directly to the chassis, and the transmission and suspension to the engine. There's a video of Chapman observing them mounting the engine on and I can't figure out how they did it. It looks like these little metal arms bolt on to the back of the chassis. Are these actually engineered into the engine block, or are they also bolted on. If so, how? Could this be done to a regular engine?

designed and cast into the engine heads and block by Cosworth
the H16 BRM in this respect beat it by a few years
the F1 tipo 160 Alfa Romeo similarly (not to be confused with the 159 modded as a test of rear seating concept)
the Mag alloy engine/transmission tunnel formed also the whole structure of the car (4wd flat 12 mid engine rear seat)
(the H16 layout was 4wd adaptable, clutch placement on the gearbox input side caused problems that F1 has now overcome)
the Lancia F1 D50 (front engined) also used its V8 engine structurally

before about 1930 road cars used the engine structurally
torsional stiffness in the front half of the chassis came mostly from lugs/arms cast into the crankcase and bolted to the chassis
eg model T Ford
the rear half of the chassis had little torsional stiffness

in a dual purpose road/track car you might limit yourself to engine types that have little vibration, and plenty of width and depth
ie a V8 with 2 plane crank
you could weld bits on to an existing engine casting

http://www.alfabb.com/bb/forums/alfa-ro ... 160-a.html

http://members.madasafish.com/~d_hodgki ... -e-H16.htm