ChrisGamlin
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| posted on 8/12/05 at 01:13 PM |
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I know it looks simple but a few decent engineering minds have put a fair amount of effort into making these boxes reliable, so to plan a homebrew
with the intention of it being much cheaper and for it to work first time without problems or needing significant development is going to be a bit of
a risk. Having said that, like you say if you're prepared to forsake reverse it does make it simpler.
David - It doesnt matter when they are in different gears, the box links the two output shafts together so they can only rotate at the same speed as
each other, so if one engine is in a lower gear it will just be revving higher than the other engine, you do need to be careful not to over-rev the
one in the lower gear though, because the other engine could push it up past its rev limit if you're not careful.
Im not so sure what happens when the other engine is switched off though, I guess just put it in neutral and let the output shaft be turned by the
other engine.
[Edited on 8/12/05 by ChrisGamlin]
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ChrisGamlin
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| posted on 8/12/05 at 01:22 PM |
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Also, do a bit of maths on power / weight before you embark, dont forget that a 600cc engine weighs hardly any less than most 1000cc engines (R6 is
about 4kgs lighter than an R1 for example), so add in the extra engine weight, the transfer box, two sets of exhausts, extra bracing / plumbing etc
and you'll probably end up with no higher power to weight than a single R1 install, that won't handle as well because of the additional
weight.
[Edited on 8/12/05 by ChrisGamlin]
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NS Dev
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| posted on 8/12/05 at 01:52 PM |
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quote:
Originally posted by David Jenkins
Surely one of the problems with designing a transfer box is handling the situation when only 1 engine is running - you have to transfer from one
engine while ignoring the other. Then do the same when the other engine is running and the first is stopped.
Then what do you do when the engines are in different gears...
Aaargh! 
David
Not that bad, remember the box is linking bike engines WITH GEARBOXES attached.
With one engine running, the other is in neutral, so the gearbox output just spins with the drive from the running engine. Put your foot on the
clutch, and you disconnect the drive from both engines to their respective gearboxes, put "it" in gear (both gearboxes) and both connect
together and to the transfer box, if the second engine wasn't running, as long as it's ign was on, it now will be!!!!
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ChrisGamlin
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| posted on 8/12/05 at 02:00 PM |
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I think one of the hardest bits is to get the clutches, throttle openings and gear linkages all set perfectly so they work in unison, otherwise you
end up doing things like pulling away effectively on one engine (with the lower clutch bite point) only shifting one engine on occasions, and only
have one engine at 100% throttle opening.
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NS Dev
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| posted on 8/12/05 at 02:13 PM |
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quote:
Originally posted by zzrpowerd-locost
Transfer box £3k Although in some alipcations you dont mind paying for proven and reliable products, but this is locost!
I have had lots of machining exp and know lots of people! Transfer box without reverse shouldnt be to hard??
Have alot of contacts in the agri engineering business so should be easy to get hold of three gears and some bearings that will easily cope with the
150 ft lb of torque! And a small pump
I can do the chassis myself, will be building from new which will be easiler
Most of my experience is in agri engineering (as is my degree funnily enough) as well!!
Geoff Berrisford is a toolmaker for the automotive industry by trade. He does toolmaking for big customers such as Ford among others, and does really
know his stuff, so rest assured his stuff is well developed, and if it fails, it was not simple to make!!
I do have to say though, that I would be surprised if a Borg Warner Silent (Geared) chain drive could not be made to work in this application.
Especially when you think that a SAAB 900 Turbo transmits all it's power from clutch to gearbox via one of these chains, and failures as far as
I know are unheard of!
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greggors84
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| posted on 8/12/05 at 02:55 PM |
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Looking at it simply, surely the 600 arnt that much cheaper than the 1200. Like has been said the weights are very similar. If you are going to twin
engine and spending around 10k you might as well spend a couple more K and use two 1200 engines.
Slightly O/T but this thread did start off discussing it.
If you were at a trackday and your car was registering 98dB, does this mean you would have to half the noise to get it down to 95dB? What was said at
the beginning of the thread really confused me, I understand logarithmic scales but this sounds a bit different. I guess it depends what the dB is
comparitive to as someone said. Going to have to do some net research.
[Edited on 8/12/05 by greggors84]
Chris
The Magnificent 7!
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DarrenW
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| posted on 8/12/05 at 03:09 PM |
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to reduce by 3dB means halving the SPL. Noise is a very complex process to understand fully. So many factors affect it. At SVA i was careful to make
sure the exhaust wasnt pointing at anything solid (like another car, wall etc).
Unless you have studied it in detail it will be hard to pick up all that is needed to be known to design something to allow you to pass track tests.
Trial and error is about the only method we can normally use.
I was happy with 93dB at 3,900 revs. Hopefully this wont rise too much at full chat.
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David Jenkins
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| posted on 8/12/05 at 04:15 PM |
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quote:
Originally posted by greggors84
If you were at a trackday and your car was registering 98dB, does this mean you would have to half the noise to get it down to 95dB? What was said at
the beginning of the thread really confused me, I understand logarithmic scales but this sounds a bit different. I guess it depends what the dB is
comparitive to as someone said. Going to have to do some net research.
Although the numbers are confusing regarding dBs, in general term 1dB is roughly the increment that can be discerned by a human - if a 98dB noise
dropped suddenly to 97dB then you'd notice the slight change. So 3dB is 3 increments down as far as the ear is concerned, even though the
actual audio power has dropped by a half.
David
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zzrpowerd-locost
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| posted on 8/12/05 at 08:17 PM |
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quote:
Originally posted by greggors84
Looking at it simply, surely the 600 arnt that much cheaper than the 1200. Like has been said the weights are very similar. If you are going to twin
engine and spending around 10k you might as well spend a couple more K and use two 1200 engines.
Slightly O/T but this thread did start off discussing it.
If you were at a trackday and your car was registering 98dB, does this mean you would have to half the noise to get it down to 95dB? What was said at
the beginning of the thread really confused me, I understand logarithmic scales but this sounds a bit different. I guess it depends what the dB is
comparitive to as someone said. Going to have to do some net research.
[Edited on 8/12/05 by greggors84]
Couple on ebay at the mo both less than £200 Just want to to something different, to show off my skills 
I agree totally, if i can find a 1100 or 1200 thats the way i will go! Its finding one thou at the right price, or should i say, my price  The
last 1100 i had i got complete with the damaged bike for £420, made £300 back on ebay selling the remains of the bike, only thing i have left is the
swinging arm! Just sold the engine for £400 
Going to build a chassis then look for a replacement
[Edited on 8-12-05 by zzrpowerd-locost]
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ChrisGamlin
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| posted on 8/12/05 at 09:42 PM |
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There were a couple of ZX12s advertised recently for around the £1500 mark, something like that or even a £1k R1 is going to be a far better prospect
IMHO, even if you can build a dirt cheap transfer box its still going to cost more to do the twin by the time you've factored all the extras the
twin needs (two exhausts, two rev counters, extra front prop, extra plumbing etc etc). If you're heart is set on a twin though, why not do it
with a couple of ZX9s, at least that way you get the performance benefit and you can pick them up for about £500 each so the extra cost isnt huge
compared to the overall cost.
I know Im coming across rather negative and I apologise, its just that apart from the challenge of building it and possibly pose / pub talk value I
really can't see many benfits, and can see a shed load of drawbacks. I can understand the desire to have something unique and to explore
uncharted territory, but if its going to be at the expense of reliability, useablity and possibly even performance, is it really worth it?
cheers
Chris
[Edited on 8/12/05 by ChrisGamlin]
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zzrpowerd-locost
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| posted on 8/12/05 at 09:45 PM |
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quote:
Originally posted by ChrisGamlin
There were a couple of ZX12s advertised recently for around the £1500 mark, something like that or even a £1k R1 is going to be a far better prospect
IMHO, even if you can build a dirt cheap transfer box its still going to cost more to do the twin by the time you've factored all the extras the
twin needs (two exhausts, two rev counters, extra front prop, extra plumbing etc etc). If you're heart is set on a twin though, why not do it
with a couple of ZX9s, at least that way you get the performance benefit and you can pick them up for about £500 each so the extra cost isnt huge
compared to the overall cost.
I know Im coming across rather negative and I apologise, its just that apart from the challenge of building it and possibly pose / pub talk value I
really can't see many benfits, and can see a shed load of drawbacks. I can understand the desire to have something unique and to explore
uncharted territory, but if its going to be at the expense of reliability, useablity and possibly even performance, is it really worth it?
cheers
Chris
[Edited on 8/12/05 by ChrisGamlin]
Probally not!
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ChrisGamlin
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| posted on 8/12/05 at 09:59 PM |
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As long as you know what you're getting yourself into then who am I to complain
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zzrpowerd-locost
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| posted on 8/12/05 at 10:16 PM |
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quote:
Originally posted by ChrisGamlin
As long as you know what you're getting yourself into then who am I to complain
Oh i knew what i was getting into!
Been involved on afew "projects" before. See attached, only had to plumb in the oil cooler circuit and fuel system on that one, it was
headache enuff!
 
Rescued attachment swaprk1.jpg
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