hp capacity of B belts

Jan 23, 2010 25 Replies

Would 2 7" 4 groove B belt pulleys transmit 100-150hp. I am building airboat and a chev 350 will have 1 pulley and the shaft with prop will have the other. I am putting a spring loaded belt tensioner in there as well. The engine will never go above 3000, want a 1:1 final ratio. Will there be much slipping, short belt life or should this work OK. Thanks


It'll work, if you don't mind a belt life measured in minutes.

Google for belt size calculators or belt selection calculators.

Mark Rand RTFM

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That link might help you.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

Here=92s another source that might help you. See section starting at page D-42:

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Of course not...I had a friend who was naval architect and when he built his 40' sailboat, he wished to offset the engine to the starboard of the centerline. He used 4 "B" belts with a 25 HP diesel. It was a nightmare that almost killed him. Belt choice is all about drawbar pull and speed. Work the numbers against the belt manufacturers rating. If a belt must be used, you are talking of a 6 to 8" wide toothed belt and 15" diameter pulleys. Then you have the same problem discovered by the designers of hovercraft boats and that was noise. At the speed these belts ran, the air trapped between the belt and the pulleys would create the most incredible scream. It was deafening. Their solution was to cross drill the pulleys with air bleed holes. Steve

I forgot one other small point, the radial loading on the support bearings will require pressure oil lube with a cooler or they will burn up. Steve

40' sailboat, he wished to offset the engine to the

nightmare that almost killed him. Belt choice is

manufacturers rating. If a belt must be used, you are

the same problem discovered by the designers of

trapped between the belt and the pulleys would create

drill the pulleys with air bleed holes.

I'd go for a chain drive. Commonly used on motorbikes up to around

180HP so all parts available off the shelf anywhere. It needs a Kevlar laminate chain guard in this application to contain it safely if it ever fails.

Fit a Scottoiler to keep it properly lubed and happy.

Pity you aren't using a bike engine. It would already have the sprocket and be designed for the side load on the bearings.

I rather like belt drives. And they work very well on motorcycles. Harley is one example.

Gunner

Whenever a Liberal utters the term "Common Sense approach"....grab your wallet, your ass, and your guns because the sombitch is about to do something damned nasty to all three of them.

Yabbut not V belts:-)

Mark Rand (had a nice belt drive 440 Kawa for a while) RTFM

rote:

Should be interesting, I tried to explain this to my father in law but he insisted to order the pulleys and belts. So if/when this fails what is the next best option. Can you buy toothed belts and cogged pulleys like a harley uses, do they use split tapered bushings? What are they called, would a belt/bearing supplier be able to order this stuff? I guess the cheapest route would be some heavy chain #60 or so and some sprockets. Thanks

You should be looking at one of the proprietary toothed belts. Gates Polychain GT is one that'll do over 100HP at 3000RPM. They're not cheap, and you still have to be concerned about side loads on the engine's bearings, though the load won't be as bad as with V-belts.

Chain running at those speeds will need some sort of lube system.

When you say the gates GT system is not cheap are you talking 500,

1000 or more for the 2 pulleys and a belt? Do motorcycles lube their chains?

Wrong engine but might give some idea regarding belt drive capabilities

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. Interesting project, I think you need to investigate carefully each drive system option and weigh up the pro and cons. Any multiple or wide belt drive system will require careful alignment. You might also want to look at poly V belt drive. Contitech have a good technical document. Here are their drive belt options
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For two 8mm pitch x 62mm wide pulleys, a belt, and 2 bushings -- about $400. If you go thru the selection procedure and give me part numbers I can give you a closer cost estimate.

You aren't stuck with Gates. There are similar products from other mfrs.

Motorcycle chains don't operate at 5000+ feet/minute.

Those prices seem reasonable, I will look into it. The 4 groove 7" sheaves I ordered are just over $100.00ea. plus bushings and 4 belts.

If a motorcycle is in 5th gear (1:1) and the engine is turning @5000rpm isn't that faster than what I am planning?

Could you recomend the pulley diameters, widths for the gates poly chain...I want 1:1 ratio and the 2 shafts are approx. 34" apart. The engine would produce 200hp max. but we only be running it at 3000rpm.

My bike is geared down at the primary about 5:3 and at the final drive something like 2:1 . The 70 tooth rear wheel sprockets are often available on ebay for a few bucks - but they're only good for about a hunnerd horses . These pulleys use a centering bore and 5 bolts . You might consider a belt designed for motorcycle primary drive , they see higher RPM's .

I am really surprised that you want a 1:1 ratio. I am not an aeronautical engineer but I thought that propellers worked best at about 2000 rpm. At higher rpms they generate more turbulence.

Dan

No. Get out your Machinery's Handbook.

Pete Stanaitis

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mark wrote:

The critical point is the speed of sound. The tips of the blades should never exceed, or practically approach too closely, the speed of sound.

Cheers,

John B. (johnbslocomatgmaildotcom)

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