CVT??

[RuffRyda]

I've been researching transmissions for a while and nothing seemed to match what I want. But I just recently learned about the Continuous Variable Transmission and it seems to be everything that I want.
However, I don't know how to tell what size CVT will fit what size engine?
Does the CVT input pulley need to be an exact fit directly onto my engine shaft?
Or is there another means of connecting it?

Any help is appreciated!
Thanks

[roverthetop]

cvt's come in various sizes and specs. most are standard sizes and should go onto most standard sized shafts. get the one which fits correctly and rated for your specs. i like comet cvt's. well built and their "info guy" - Don Jackson- phone number on website is EXTREMELY knowledgeable and helpful.
what engine and what are you wanting to do?
b

[RuffRyda]

I'm trying to squeeze a turbocharged Yanmar L48 into a 50cc scooter so I can have both efficiency and speed. The engine only has 4hp but with a turbo and low weight I'm hoping to get to at least 80mph. What is a good CVT for that application?
Where can I find Comet CVT's to buy?
Also what is the standard size for crankshafts?

Thanks

[taildraggin]

Probably the Model 30 for the L48. The TAV2 looks neat, too.

http://www.hoffcocomet.com/comet/afterm ... erters.asp

[RuffRyda]

The Torq-A-Verter looks cool but it doesn't look like it could handle 80mph?
I like the Magnum but would that be too much for a turbo 4hp?
Do Comet Cvt's include the automatic clutch or is this all I need?
What is low and high rpm engagement good for?

Thanks

[taildraggin]

Yes, the forward pulley has a centrifical clutch that squeezes the plates together, the taper forcing the belt 'out' (increasing ratio) while decreasing slippage.

The TAV2 looks like it squeeze from both pulleys.

Calling it a "continuously variable transmission" makes it sound like there's a computer inside. I think the price goes from $12 to $200 when you stick a label like that on it.

[oilburner]

The Torq-A-Verter looks cool but it doesn't look like it could handle 80mph?
I like the Magnum but would that be too much for a turbo 4hp?
Do Comet Cvt's include the automatic clutch or is this all I need?
What is low and high rpm engagement good for?

Thanks

To get an idea of the size of CVT required, check the various formulas etc. available elsewhere on the internet. 80 mph will require 18+ horsepower.

[sbrumby]

Yeh I was gonna say if you can get 80mph from 4hp, bike + rider would have to weigh about 3kg and drag coeficient of nil. My first bike Yanmar 6hp does 41mph but on the plus side 225mpg. Just bear this in mind a man cannot stand on his feet in a 80mph wind. So the faster you go the more power is required.

[Diesel Dave]

I'd have to agree with Sam on this one 80 is beyond reach unless you have found a way to cut drag to nil.

I'd be interested in the size of Turbo you intend running, mitsubishi TD02's are the smallest on the regular market but would still be too large for the 4Hp motor.

As a rule of thumb turbo's on a diesel can gain you about 30%, adding decent intercoollers and the biggest possible flow rated turbo may get 50% at the expense of engine life.

You will also need to uprate the fuel supply to inject into the very high compression, the injector break pressures will need increasing considerably and will also need a feed pump before the jump pump to raise fuel pressure by about 8psi.

The last supercharged IB30 I heard about snapped a crank! and that's with the Hatz forged item.

Dave

[Dan J]

I think I'd be extremely wary of any forced induction on these small industrial diesels - they are simply not built for it. Maybe I am being overly risk-averse but I don't fancy anything that is going to reduce the life of my engine.

Everything, on the whole, these days is made by companies who have accountants/bean counters sat at the top. Things tend not to be over-engineered today (more's the pity) and are often in fact designed not to be around for ever or as cheaply made as the company can get away with (probably a large factor in Fiddler's recent experience). Listed companies owe duty to their shareholders bottom line, not their customers.

Many years ago I was lucky enough to have a tour of Ford's Dagenham factory which included a full tour of the "Puma" diesel line (which at the time made only Transit engines, today also makes the 2 and 2.2 "TDCi" engines for the Mondeo). I was very intrigued to see the non-turbo diesel and various power turbo diesel engines - all identical capacities - being fitted with different pistons, con-rods and crankshafts, injectors and doubtless all manner of other items. I was told it was simply that the "lightest" parts were always fitted wherever possible such that the engine met all its functional requirements. Now - this is common amongst all engine manufacturers and this is no way a dig at Ford - the engines were being built to last x miles under a, b and c conditions. But sticking a turbo or supercharger on afterwards when the "hidden" parts simply weren't built to that spec sounds like a recipe for disaster to me.

I've seen an overstretched V8 stick a conrod through the side of its engine - it's one thing in a car but in a bike, with the engine right by your legs and family jewels? I think I'll stick with 10hp!

Mind you, the engine is in an Enfield and I don't think I'd fancy anything over 60mph anyway

[RuffRyda]

Yea blowing the engine is a definite risk, but I've got to try!
I'll be careful when setting the psi and slowly notch it up to the limit and hopefully I can avoid that.

The Mitsubishi TD02 is my first choice but its not the smallest, its just the cheapest. The Garret GT1241 is the smallest and I think the Yanmar IHI RHB31 is the 2nd smallest. However those two are $600+ while the TD02 is $300.

The intercooler idea sounds pretty good to raise HP too! 80mph is my goal just because I had to set one so I will get as close to it as I can, but the main purpose is to max out the smallest engine available!

So about how much more HP can I expect from all of this work to my engine?

And which CVT would best fit my engine for this application?

[oilburner]

Hugh MacInnes , author of the book Turbochargers, in the section on diesel engines says:

An arbitrary limit for increasing power output without modifying the engine is 20% to 30%. This depends on the engine and how high it was rated naturally aspirated.

In any case, the rule of thumb is to keep the exhaust gas temperature below 1300F. Higher exhaust gas temperatures will probably require piston cooling to prevent ring sticking.

Higher temperatures may even require lowering the compression ratio to keep the combustion chamber pressure from going too high. Checking combustion chamber pressure can only be done with elaborate equipment not available to the average shop.

The next step is to recalibrate the injection pump to obtain the higher horsepower. This should be done on a fuel pump test stand by a specialist.

The pump must not only be timed correctly, it must be adjusted for the proper torque backup. Torque backup is the ratio of maximum torque compared to the torque at maximum speed. It is generally expressed as a percentage.

[Sphere]

Do you have a picture of what you will be performing the transplant on?

[oldbmw]

You will not get 80 mph from 4 hp.
A tiger cub with 10hp barely does 65
an 18hp enfield is struggling to reach 75
it takes around 25/30 hp to get to 85/90
smaller lighter bikes with efficient fairing can do slightly better

[andrewaust]

Even with a turbo, tuned plenum chamber, modifications to valve train, injection system, gas or even nitro injection will never get you near 80mph, you might get 55mph before it self destructs running most if not all of the above .

Why bother with a 4hp engine if you want to go at a reasonable speed? invest in the 10hp engine if you can fit it in, at least your good for 60-68 in ideal conditions (depending on gearing etc).

[Lasse]

Did you ever finnish this project RuffRyda?

I have an Yanmar L48N in my shed waiting to be fitted to a scooter.
Not going to turbocharge it as I think it will be hard enough to fit the engine itself in the small frame of a 50cc scooter.
If I achieve around 60km/h I will be more than happy as this will be a city scooter hunting the best mpg figures man have seen
Just hope it won't drop dead on the many hills I got here


Anyone know of someone that have converted a 50cc scooter to diesel?

[Sphere]

I saw one in Hamm on an old Vespa-like model. The engine when where your legs were supposed to go. Didn't seem comfortable.

[Tetronator]

This one I'm guessing.

https://youtu.be/Zt-scqiSV5U?list=PLGEV ... uR0bTw-l2G

[Lasse]

Seen that one and a grey Vespa with a L100 engine. Both of those engines are way to big and a bit heavy.
My L48N are a little bit smaller to say the least and on a modern scooter I am hoping to fit it under the seat by offering up the luggage/helmet storage room. Out of harms/praying eyes way

[Sphere]

Just make a cardboard mock-up of your scooter's innards and put it around your L48. I'm skeptical.

[Lasse]

I haven't bought any scooter yet as I am wounded up in to many other project so maybe I start on it in a years time or so. But looking at my sisters scooter it looks feasible. I also have a generator with the L100 engine in it and that looks to be almost twice the size. If you look up the specs on the L48N engine you will see that it is a tiny bit smaller.

Looking for a comparison picture, but couldn't find one