Multi cylinder engine or just multi engine???

[Rex Schimmer]

One of these days my roadster will be done (getting closer all the time!) and I can then start on my Bonneville car but I still do alot of thinking and planning. My general thinking is a "I" class lakester so the standard thing to do would be to use one of the available 4 cylinder 1000 cc motor cycle engines that are fairly plentiful, all of them are in the 150-165 hp at the rear wheel, no problem. BUT I want more hps! So my question is: If I take (4) 250 cc motocross engines,two stroke, again it could be Yamaha, Kaw, Honda doesn't really matter and removed their transmissions, clutches and everything except the head, barrel, piston/rod/crank, crankcase, and mag and then built a "container" that has a common shaft that I can connect all of these to  and then run that shaft to a transmission, DID BUILD A FOUR CYLINDER ENGINE OR IS THIS A MULTI ENGINE AND NOT LEGAL IN THE LAKESTER DIV?

The logic is that 50-60 hp from a modern 250  two stroke motocross motor is probably possible and 4 of them would make someplace between 200- 220 hps. This is just blue sky thinking but it is interesting.

Your opinions please.

Rex

[Sumner]

I've thought about this approach in the past only to of course find out others have already done this to a degree.  

I think your configuration as explained, in my mind, would be you would have a multi-engine car.  Now if you made a common crankcase, machined one up, that held the 4 cranks and the 4 barrells and they were tied together within the common crankcase, via a chain primary drive or a gear primary drive, similiar to an Aerial Square Four with an output shaft you would have built a single engine.  I considered this for two 750's for the 1500 class or say two 'busas for the 3 liter class, but determined it was probably way past my machining skills .

The common approach as been to use the cylinders, heads off of say two 'busas (this has been done and there is a link on one of the other threads) and make a new crank and crankshaft and end up with a V-8.  This I would for sure qualify as a single motor and is way, way past my machining skills.

The simple approach to your problem is called a turbo, but of course that moves you to a different class .

c ya,

Sum

[John Burk]

Rex
You might want to verify that 250 bike engines actualy put out 50 or 60 hp . In the 70's a guy named Jack Hoare built a Canam car with 4  Rotex  2 cylinder engines , one driving each wheel . On paper it was good but the  2 cycle engines had less than expected power and the car was very disapointing . If you look up Jack Hoare Canam you can see pictures of the car .
John

[Dean Los Angeles]

The 250 motocross engine might be one choice, but they only make moderate power.
From the Yamaha brochure:

2003 Yamaha TZ250 Power Output (SAE Hp / kW @ rpm)  91.73 / 68.4 @ 12,500 V-twin, 2-cylinder, 249cc, Water cooled two-cycle, Crankcase Reed Valve

That's as shipped from the factory.

As far as the engine arrangement, if you graft the complete engine to a common case, you would have 4 engines and a huge gearcase.

If you don't use the cases and build a custom case that holds the cranks and barrels feeding a transmission, you would have a stronger case for calling it a single engine.

If you built a custom single crank it would be no question. I sure as heck would get a ruling before I went down any of these paths!

[Stainless1]

Innovation is how people succeed at Bonneville.  
I would guess if you have a common crankcase, you have 1 motor.  Mate a bunch of them together and head to the big white dyno!
You might want to try the motor out in the roadster first, I think that ring-da-ding would sound great in a roadster....and a lakester!