02GF74
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| posted on 25/9/07 at 09:20 AM |
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that second crank won't be happy for sure.
the more pistons you have on a crank, the bigger the torque will be so the second crank, clinder 1 will see the torqye from the previous engine, at
cylinder 4 it will see 2x torque it was designed for.
I've read somewhere that cranks do get beefier towards the flywheel end to account for this - think rover v8 is one but not sure.
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smart51
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| posted on 25/9/07 at 10:21 AM |
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Why not ditch the diff all together and have each engine drive just 1 wheel?
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sgraber
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| posted on 25/9/07 at 01:41 PM |
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I do understand what you are saying about the crank breaking, et all. We will scrap that idea for now. 
quote:
Originally posted by smart51
Why not ditch the diff all together and have each engine drive just 1 wheel?
That's a real smart thought there. I had that one drawn up early on, but didn't think it would fly. But since everything else has failure
written all over it, why not?
Direct drive each wheel. When one wheel loses traction, the other continues to receive power. Isn't that like driving them with an LSD diff? If
both engines had traction control via ecu then you could get a lot of power down that way.
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Dangle_kt
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| posted on 25/9/07 at 02:53 PM |
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quote:
Originally posted by sgraber
I do understand what you are saying about the crank breaking, et all. We will scrap that idea for now.
quote:
Originally posted by smart51
Why not ditch the diff all together and have each engine drive just 1 wheel?
That's a real smart thought there. I had that one drawn up early on, but didn't think it would fly. But since everything else has failure
written all over it, why not?
Direct drive each wheel. When one wheel loses traction, the other continues to receive power. Isn't that like driving them with an LSD diff? If
both engines had traction control via ecu then you could get a lot of power down that way.
What would happen if one of the engines wasn't running right?? crab situation? I guess it would show up in excessive tyre wear...
(they are all questions, not statements - I'm just an interested party, with questions to bring to the table rather than answers!)
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thomas4age
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| posted on 26/9/07 at 08:50 AM |
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Don't bother about doint that.
Just a very different thought if you have that sort of room so stuff with engines and the lot, why not stuff an extra diff up front and run a prop to
it
twin engines
4 wheel drive
no drive connection between engines
seperate ECU's
just a gear linkage to hook up, do air shift and have it on the button.
the possibility of shutting one engine down by putting it in neutral.
should be by far the easiest sollution,
Zcars did it Ultima did it with the twin busa turbo GTR.........
easy to maintain No chains stock parts
ps the coupler box design I put up is used extensivly in tractor pulling so should be quite strong if you do it right.
the engine joining at the cranck can be done but will break, seen that on twin subbaru boxers, flat 8 flatplane without turbo's, went bang in
half an hour
grtz Thomas
If Lucas made guns, Wars wouldn't start either.
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Peteff
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| posted on 26/9/07 at 10:08 AM |
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When one wheel loses traction, the other continues to receive power
With an engine driving each wheel it would work in a straight line but when you corner there will be no differential action unless you slow down the
engine driving the inside wheel. It would be more like driving with a spool or a locked differential.
[Edited on 26/9/07 by Peteff]
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Minicooper
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| posted on 26/9/07 at 10:20 AM |
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Twin engines one driving each wheel no differential appears to work for this guy
http://furorecars.co.uk/pics.php
Cheers
David
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smart51
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| posted on 26/9/07 at 10:46 AM |
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quote:
Originally posted by Peteff
With an engine driving each wheel it would work in a straight line but when you corner there will be no differential action unless you slow down the
engine driving the inside wheel. It would be more like driving with a spool or a locked differential.
[Edited on 26/9/07 by Peteff]
If you go in to a corner the inside wheel will slow and the outside wheel speed up taking the engines with them. Remember that the engine speed is
not goverend by the throttle or fuel as such but is held down by the resistance of the vehicle.
You would have as much differential action as you'd need.
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Minicooper
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| posted on 26/9/07 at 10:53 AM |
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Years ago there was a twin engined wolfrace wheels demo vehicle, it had two rover v8 engines to two complete differentials, one open dif and one lsd
diff
This is the only thing I can find
http://www.supercarworld.com/cgi-bin/prototypes.cgi?startfrom=61&sortby=atoz
Cheers
David
[Edited on 26/9/07 by Minicooper]
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NS Dev
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| posted on 26/9/07 at 12:14 PM |
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quote:
Originally posted by thomas4age
should be by far the easiest sollution,
Zcars did it Ultima did it with the twin busa turbo GTR.........
easy to maintain No chains stock parts
ps the coupler box design I put up is used extensivly in tractor pulling so should be quite strong if you do it right.
grtz Thomas
Ultima DID NOT build the twin engine car. It was built by Z Cars, and was not great as far as I know.
I know cars with individual drives have been done, and I know that they can be made to go very quick in a straight line, but I have yet to see one
that handles!!
For this very reason autograss cars were banned many years ago from having seperate drives from seperate engines to seperate wheels.............at
some point the drive has to be coupled.
PS yep the spider box coupling you talk about has been used in tractor pulling for years and has proved reliable transmitting over 5000hp and 7000lbft
of torque in that application!!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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thomas4age
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| posted on 27/9/07 at 02:34 PM |
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You're right about the ultima, reading it i remember knowing that,
the car is with it's owner in spain now iirc
Grtz Thomas
If Lucas made guns, Wars wouldn't start either.
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ChrisGamlin
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| posted on 27/9/07 at 04:52 PM |
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quote:
Originally posted by smart51
Remember that the engine speed is not goverend by the throttle or fuel as such but is held down by the resistance of the vehicle.
Agreed but that resisting force has to come from somewhere and its that force that will cause problems IMHO.
Im thinking this through a bit as I type but to better explain my thinking, imagine a triangle with a pivot in the middle, something like this
Image deleted by owner
A and B are two equal forces (equivalent to the engine forces), the blue blob is the pivot.
If you apply a vertically downward force at C (as if you were turning the front of the triangle to go around a corner), unless A suddenly increases
it's force (which it doesn't) C is having to apply a force to overcome B to make the triangle turn.
In the real world this force is in addition to the forces the front wheels are subjected to anyway due to the car's mass wanting to carry on
going straight ahead. What this will mean is that for any given corner, you've got less front end grip available (compared to a car with an open
diff) to generate cornering force because some of it is already used up fighting the force from the inner rear wheel.
I.E. it will comparatively understeer like a pig and not be able to generate as much cornering speed!
I think
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