450cc Triple eligible for F3

[Taz]

I suggest getting 9 RG50 motors and putting them together. More cylinders = more power!

4 cylinders up front, 3 rear. RC211V style. It could work. Got to do engineering so I can actually make these silly ideas...

Your maths needs some work.........

[lostinflyz]

What about cutting up the head to only have 3 cylinders, shortening the cams, cutting one cylinder off the block, shortening the crank, and filling up the crankcase hole where the other cylinder was?

this may be possible but youll run out of money long before you ever get there. You would need to manufacture a whole new crank. then youve got to do the vavlves/cams and all that good stuff. dont even want to think about the trouble of cutting up or shortening heads and blocks. cant just simply shorten the crank as it is timed and balanced for 4 large metal objects being faced about it with some ridiculous force. plus you would end up with a rather long period of no power when one of the cylinders should be firing.

not to mention reorganising the electrics to fire this way.

Munro/Britten/Newcombe ect thought outside the box. true. but they stayed close to reality. Basic physics didn't make thier ideas excessivly difficult.

That being said it is cool to think of the possibilities

[koba]

plus you would end up with a rather long period of no power when one of the cylinders should be firing.

That is a good thing.
Ever heard of big bang motors?
It is why singles make good dirtbike motors that gap is good for traction.

I Think it is a great idea.
The balancing wouldn't be all that bad- Remember It doesn't have to meet the same standards of refinement as a road motor either....

[koba]

You could leave the guts of the cylinder that isn't running in there and cut holes in the piston to stop it compressing.
The piston could be re weighted and then act like a supermono type balance shaft.
This way it could also be air/oil tight with a plug in the spark plug hole.
Ring drag could also be minimised, maybe just run the oil ring?
It would work well to start with and could be developed to work very well, maybe with a rocker type locator on the rod if you were getting serious.

I would do it myself if I had the money and less other things already on the go!

[svr]

This has been discussed previously.
Balance shouldnt be an issue if you leave the 4th piston in (just take out the inlet valves). In theory you'll get 3/4 of the power of a decent 600 (say 90 - 95) so a good advantage over the 3 or 4 national level sv's out there (and maybe even Andy Bolwells old zxr 450?) Like any race bike it'd be cheap enough to get going but you'd start to spend on chassis, quickshifter, wheels, more power etc and end up with a 30k `investment'.
Jason Eastons svx 550 in 125 gp chassis should in theory still be the bike to beat in F3 this season. Should be interesting though.

[malcy25]

This may well be an option. Shorten the rods and shave metal of the head/block/base.

Would probably rev like a bastard too...

Would still be a 600 too....Rod length is not stroke. Capacity is defined by bore & stroke

You could have a con rod 10 feet long or 6 inches long, but if the stroke is the same for both the capacity is the same for both.

[koba]

Jason Eastons svx 550 in 125 gp chassis should in theory still be the bike to beat in F3 this season. Should be interesting though.

Nice! Pleased to hear someone is going to try that, should be great to see how it goes

[svr]

Would still be a 600 too....Rod length is not stroke. Capacity is defined by bore & stroke

You could have a con rod 10 feet long or 6 inches long, but if the stroke is the same for both the capacity is the same for both.

You'd need a `de-stroker' crank - can't imagine there's a big demand for those or anyones tooled up to make them!
Detuning goes against a lot of deap-seated beliefs that racers hold dear.

[scott411]

Jason Eastons svx 550 in 125 gp chassis should in theory still be the bike to beat in F3 this season. Should be interesting though.

i would have thought he would only be able to go to 500cc, that is the twin limit unless it comes under the exemption with the production parts (ie SV650's)
sounds really fucken cool tho, even with the SVX450 motor

[Hoon]

This has been discussed previously.
Balance shouldnt be an issue if you leave the 4th piston in (just take out the inlet valves). In theory you'll get 3/4 of the power of a decent 600 (say 90 - 95) so a good advantage over the 3 or 4 national level sv's out there (and maybe even Andy Bolwells old zxr 450?).

I'd estimate more like 1/2-2/3rds of a decent 600. There is an overhead cost involved with each cylinder that is usually covered by the net output of that cylinder (i.e. drag of piston going up and down the cylinder, valve train, effort on the compression stroke, etc).
Say a 600 puts out 120hp, each cylinder might produce 40 hp but lose 10 hp to drag/overhead. You remove the power of one cylinder but are still left with the 10hp bill.

Thats just that cylinder. The gap in the firing order will cost the next cylinder hp as well as it will catch the engine on deceleration instead of picking up where the last cylinder usually left off. This will result in that next cylinder not reaching the peak output it usually delivers either and having to work harder than the other 2.

Intake and airboxes will be affected. The reflected pulse of the intake stroke which is used to assist drawing in the next charge will be screwed. Can't see how you can tune for that while keeping the other 3 optimal.

Likewise with exhaust tuning and scavenging.

But hey I'm no engine expert and you may have all this already covered and more (assuming you've put much thought into this and not just a "brilliant" idea you had over a couple beers). Probably way easier ways to achieve the same result but I'd be glad to be proven wrong.

First thing I'd do is put the 600 on a dyno with one of the plugs off. This will give you a starting point and indication of how much work you'll need to do.

[Coyote]

Your maths needs some work.........

It was the morning, that's my excuse

Course, how smart can I be when I'm thinking of making a 9 cylinder 450...

[quallman1234]

It was the morning, that's my excuse

Course, how smart can I be when I'm thinking of making a 9 cylinder 450...

Don't think a 9 Cylinder 450 2 Stroke would be eligible for F3

How about a 4 cylinder 250 2 stroke? Get an RG500 and sleeve it down, put it in a nice frame and have massif chambers coming out all directions and use 250GP fairings. Done and Done.

[Coyote]

Don't think a 9 Cylinder 450 2 Stroke would be eligible for F3

Fuck fuck fuck, getting everything wrong today, maybe I should call a quits and go to bed early.

What's a fairly decent performing 50cc 4 stroke anyway? Don't know why I was thinking an RG50 was one... Never even tried pot...

[quallman1234]

Fuck fuck fuck, getting everything wrong today, maybe I should call a quits and go to bed early.

What's a fairly decent performing 50cc 4 stroke anyway? Don't know why I was thinking an RG50 was one... Never even tried pot...

How's the mighty GP100 going?

[svr]

I'd estimate more like 1/2-2/3rds of a decent 600. There is an overhead cost involved with each cylinder that is usually covered by the net output of that cylinder (i.e. drag of piston going up and down the cylinder, valve train, effort on the compression stroke, etc).
Say a 600 puts out 120hp, each cylinder might produce 40 hp but lose 10 hp to drag/overhead. You remove the power of one cylinder but are still left with the 10hp bill.

Thats just that cylinder. The gap in the firing order will cost the next cylinder hp as well as it will catch the engine on deceleration instead of picking up where the last cylinder usually left off. This will result in that next cylinder not reaching the peak output it usually delivers either and having to work harder than the other 2.

Intake and airboxes will be affected. The reflected pulse of the intake stroke which is used to assist drawing in the next charge will be screwed. Can't see how you can tune for that while keeping the other 3 optimal.

Likewise with exhaust tuning and scavenging.

But hey I'm no engine expert and you may have all this already covered and more (assuming you've put much thought into this and not just a "brilliant" idea you had over a couple beers). Probably way easier ways to achieve the same result but I'd be glad to be proven wrong.

First thing I'd do is put the 600 on a dyno with one of the plugs off. This will give you a starting point and indication of how much work you'll need to do.

I had thought about pumping and friction losses, but really know nothing about them and would be just guessing the numbers - anyone know what they'd be? assuming no compression, no compression ring, no cam drag and little intake or exhaust flow resistance - 10hp from one cylinder sounds high (some 150cc 4 stroke singles dont even make that). Intake and exhaust resonance issues are more problematic to decifer. Probably a `suck it and see' for the guy doin it (who knows his stuff - which points to these problems being surmountable)