MikeCapon
|
| posted on 6/7/11 at 07:22 AM |
|
|
quote:
Originally posted by coyoteboy
I keep coming back to this as, while playing around with a few bike engines, I can't seem to get them to mis-shift in a way that would allow one
to shift and one not - if it doesn't shift it jams the shift lever on the engines I've been faffing on. If they're both linked
rigidly and one jams, what's the chances of the other going in? Genuinely quite curious to hear more from those who've done it like you
froggy. A pair of vfr 750s would knock out 200hp and weigh around 120kg (engines only) which is pretty competitive. Never get something for nothing
though I suppose!
I'm with you coyoteboy on this one. Twin bike engines are an awesome idea. Also, as you point out, it opens the way to other bike engines that
would otherwise be a bit short on power for a BEC application such as the excellent VFR 750. I love these motors for a number of reasons.
First off an endless love for the RC30 and the noise  Secondly they are are in plentiful supply and they are cheap cos they pretty much never
break. I worked in a building we shared with a huge bike breakers over here for a few years and was always fascinated by the engine stock. There were
one or two GSXRs, ZXRs, and YZFs but there were dozens and dozens of VFRs on the shelf. If ever they sold it was for peanuts compared with the rest of
the big Jap motors.
We actually built a VFR engined cross car (tubular chassised off roader normally fitted with 600 I4 bike engine) for fun, but on dirt the VFR did not
grip. It just wanted to dig holes everywhere  This would not be a problem on tarmac though.
As for your gear selection question beware if you're playing around with motors that are not running. Bike boxes rely on the rotation of the
gearshafts to line up the dogs when shifting. If you are trying this out with dead engines the boxes will be very reluctant to shift. Once rolling
they slip into gear much more easily.
I'm sure it would not be difficult to rig up some kind of security? Perhaps some kind of gear display that compares the two and cuts the
ignitions if they don't match? Worth the effort IMO for the advantages of 8 cylinders, 200 hp and a shedload of torque, all for less money than
an old Fireblade motor?
Cheers,
Mike
ETA Or just a rev limiter that limits both motors but triggered by either???
[Edited on 6/7/11 by MikeCapon]
|
|
|
|
|
loggyboy
|
| posted on 6/7/11 at 09:10 AM |
|
|
There have been a couple of notable twin engined tintops, one being a Nova (Corsa A) built in germany for Regal (shudder). It had 2 Calibra Turbo
(C20LETs) with about 300hp each. It lead to a 2.8 sec 0-60 and a 11sec 1/4 mile IIRC.
http://video.google.co.uk/videoplay?docid=-8933077605569731631&q=nova#
The other was a Golf (mk3 IIRC) that had 2 VR6 engines and had some equally impressive stats.
http://video.google.co.uk/videoplay?docid=-3582964599649062492&q=twin+engined+golf#
The hardest thing ive heard is sorting the gear change linkages to ensure both engines engage the same gear at the same time.
|
|
|
coyoteboy
|
| posted on 6/7/11 at 09:26 AM |
|
|
I'd not be going to a jack shaft, I'd be running two separate outputs for simplicity.
|
|
|
Dick Axtell
|
| posted on 6/7/11 at 10:08 AM |
|
|
quote:
Originally posted by Fred W B
I don't see a problem with two engines driving a common output/jackshaft.......Biggest issue from what little I've read is controlling the
chain slack/tension, if chain drive.
Cheers
Fred W B[Edited on 25/5/11 by Fred W B]
Ever heard of an old timer called the "Sedici Cilindrini"? I culled this from a Maserati history site :-
".....the real highspots in Maserati fortunes being reached and plumbed by that perennially amazing brute, the 16 cylinder twin-eight. Whether
the 1932 edition of this fearsome freak was a new car or a rebuild of the original 1929 4 litres is a question that has no known answer at this
writing but the fact remains that as raced in 1932 the 16 cylinder had two 2.5 litre 8 cylinder GP engines mounted side by side, as on the
first 4 litre three years earlier. As in the case of the 4 litre, the new 5 litre 16 cylinder was fast - too fast for its roadholding, too fast for
the circuits of the time and, on one terrible day, too fast for its driver."
Because the 2 engines rotated in the same rotational direction, the resultant torque could provide some interesting chassis characteristics (it
twisted horribly, especially on left hand bends).
Work-in-Progress: Changed to Zetec + T9. Still trying!!
|
|
|
coyoteboy
|
| posted on 6/7/11 at 11:36 AM |
|
|
quote:
As for your gear selection question beware if you're playing around with motors that are not running. Bike boxes rely on the rotation of the
gearshafts to line up the dogs when shifting. If you are trying this out with dead engines the boxes will be very reluctant to shift. Once rolling
they slip into gear much more easily.
Fair points, and noted (I've been testing on a frame-mounted running engine or two but not with any loads yet) but what's the actual
process that occurs during a mis-shift - is it simply a blocking non-shift that remains in the original gear? I was under the impression that
it's physically impossible to shift into a fake neutral on a bike engine? I need to learn more about it.
|
|
|
coyoteboy
|
| posted on 21/7/11 at 01:46 PM |
|
|
I'm thinking a hydraulic shift mechanism might be used to provide the shifting required. Providing enough time is allowed with ignition cut,
hydraulic cyls on each shifter would provide equal pressure and maintain force until electronic confirmation of engagement (full lever travel),
allowing ignition cut to both engines should a mis-shift occur on either. If the mis shift feels like a normal shift (i.e. full travel) , this still
leaves a problem. If it doesn't, the electronics could control a downshift on the missed engine, or repeat the shift as required on one engine,
just with a big stutter!
|
|
|
Ninehigh
|
| posted on 24/7/11 at 01:21 AM |
|
|
This made me curious today, does anyone know of (or know of a reason not to make) a vehicle that has an engine driving each wheel. It would make for
the ultimate traction control that's for sure.
|
|
|
