onenastyviper
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 posted on 25/3/12 at 04:23 PM |
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rear/mid-engine mounting - thought exercise
Afternoon All,
What would your opinion be against mounting a bike engine longitudinally but connect directly (or through a cushion drive) to the rear differential to
form a sort of short mid-engine layout?
Just a thought exercise, so let the comments or suggestions fly!
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imp paul
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| posted on 25/3/12 at 04:33 PM |
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its been done lots of times just have a look at the spire gtr should help you see how to do it 
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Ivan
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| posted on 25/3/12 at 04:37 PM |
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Don't see any problem with the idea - some others do just that, the "short propshaft" will take the longitudinal space taken by the
clutch, flywheel and part of gearbox in a conventional transaxle.
But don't really see the advantage as compared with a chain drive transverse layout as you can get very similar location of the engine centre of
gravity either way and the chain drive diff might be lighter.
[Edited on 25/3/12 by Ivan]
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zilspeed
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| posted on 25/3/12 at 04:39 PM |
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That's how the Turner LMP did it.
I've also seen an MK GT done like that too.
First thought is that you have to keep all of the diff, which is a weighty bit of kit.
Second thought, there's a load of drag in a fully built up diff compared to a chain and sprocket setup.
On the plus side, mounting the engine longitudinally pushes a major mass ( the driver) away from the rear wheels.
The means he's either nearer the front wheels or you've lengthened the wheelbase.
Whatever the case, there's a strong chance you've given the front wheels a bit more to do and the rears a bit less, so it may influence
ultimate grip levels.
Not sure it would be enough to offset the extra drag of the final drive.
I would say that longitudinal is of course the way that all car engined racing cars are ( apart from one which use a FWD package in the back, but
that's done for reasons of cost.)
It's also the case that pretty much every bike engined mid engined racing car I've ever seen had a transverse engine.
I have seen a longitudinally mound bike engine driving straight into a a diff, but that was a Clan Crusader which must maintian that orientation for
the class it ran in.
For a long time, that car had catastrophic understeer until they rectified it all by engineering in some more front end bite.
Make of all of the above what you will.
I can see your reasons though, just not sure I would have the courage to make what is a pretty bold manouvre and flies in the face of what the rest of
the world seems to have accepted as standard practice.
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onenastyviper
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| posted on 25/3/12 at 04:40 PM |
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quote:
Originally posted by imp paul
its been done lots of times just have a look at the spire gtr should help you see how to do it
Thanks, I can start looking. I didn't know if it had been used before.
Just did a quick forum search and found a few threads discussing it. It helps when you use the right key words!
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onenastyviper
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| posted on 26/3/12 at 04:15 PM |
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quote:
Originally posted by zilspeed
That's how the Turner LMP did it.
I've also seen an MK GT done like that too.
First thought is that you have to keep all of the diff, which is a weighty bit of kit.
Second thought, there's a load of drag in a fully built up diff compared to a chain and sprocket setup.
On the plus side, mounting the engine longitudinally pushes a major mass ( the driver) away from the rear wheels.
The means he's either nearer the front wheels or you've lengthened the wheelbase.
Whatever the case, there's a strong chance you've given the front wheels a bit more to do and the rears a bit less, so it may influence
ultimate grip levels.
Not sure it would be enough to offset the extra drag of the final drive.
I would say that longitudinal is of course the way that all car engined racing cars are ( apart from one which use a FWD package in the back, but
that's done for reasons of cost.)
It's also the case that pretty much every bike engined mid engined racing car I've ever seen had a transverse engine.
I have seen a longitudinally mound bike engine driving straight into a a diff, but that was a Clan Crusader which must maintian that orientation for
the class it ran in.
For a long time, that car had catastrophic understeer until they rectified it all by engineering in some more front end bite.
Make of all of the above what you will.
I can see your reasons though, just not sure I would have the courage to make what is a pretty bold manouvre and flies in the face of what the rest of
the world seems to have accepted as standard practice.
Thanks for the info.
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