What transmission...

Gearbox questions & answers etc..

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Benzine
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What transmission...

Post by Benzine » Fri Jan 27, 2012 11:17 am

I've been gathering parts for my reverse trike over the last year and I'll soon be starting to do some mock ups. I'm still undecided on what to use in terms of transmission. I'm torn between a pre-unit gearbox or a CVT setup. Can a CVT setup be as efficient as manual? That's what I'm really after.

Pre-unit looks cheaper but more complicated, CVT more expensive but easier.

The smaller CVT setups I've seen (comet, CVTech) seem to specify lower BHP ratings, do I have any options for CVT?


Other info that might be relevant: using a lombardini 2 cylinder, 20ish bhp. RWD. Overall weight of trike will be heavier than a bike (trying to keep it down as much as I can)

Thanks for any info

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coachgeo
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Re: What transmission...

Post by coachgeo » Fri Jan 27, 2012 5:23 pm

Have you read thru the CVT forum on here?

tappy
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Re: What transmission...

Post by tappy » Sun Jan 29, 2012 6:20 pm

A CVT will always have more power loss than a manual transmission, but if it has a broader range of ratios then it will allow the engine to rev lower when cruising at a given speed. Normally aspirated diesel engines are very inefficient at high revs so having the engine revving much lower could easily offset the bigger loss through the CVT.

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Benzine
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Re: What transmission...

Post by Benzine » Sun Jan 29, 2012 6:54 pm

Thanks for the info :)
tappy wrote:Normally aspirated diesel engines are very inefficient at high revs
is there a 'rule of thumb' as to what RPM or % of total power a small diesel engine is at it's most efficient? Can't seem to find much about it on the interweb. I remember for petrol engines it's something like 1/3 total power (so for my old volvo 740 that meant 1900/2000rpm which, after doing some long mpg runs, turned out to be spot on for best mileage)

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