revtothelimit - motorbike forum

What would you say if I told you that a 2T engine exists that is as power dense as 'conventional' 2T motors, but does not need oil in the petrol, is as environmentally clean as a 4T engine and has comparable economy figures to a 4T engine? You'd probably tell me to go forth and multiply, and while I'm at it, lay off the wacky baccy.

Well it really is A Thing (but not yet commercially available. D4A explains:

Rolls-Royce were doing this 80 years ago!

Obviously some differences (one is a 900kg aero engine, one isn't, the R-R used sleeve valves etc etc) but it's remarkable how similar other things are. The mooted figures for the R-R engine were a final figure of 5000bhp from a ~1000kg engine, which is actually a higher power to weight ratio than ^^^ this

Gotta be honest and say I'd be a bit surprised if this goes very far. Not 'cause I don't think it will work but because getting the budget/motivation together in today's automotive climate would be tricky.

https://en.wikipedia.org/wiki/Rolls-Royce_Crecy

Yeah, two stroke junkies like me would love it, but I can see most of the rest of the world saying so what? Gimme a Tesla/BYD/whatever EV.

Which is a shame...

Bikes though, TBF, could be a goer.

Those power/weight figures are impressive for an ICE but an electric motor absolutely wipes the floor with them. Elephant in the room (or perhaps floor pan!) is that the battery you need to power that motor is both large, and heavy, for now at least.

We have actually been entertaining enquiries for electric motors to go in hybrid superbikes from OEMs (not gonna say who obviously). This ^^^ thing could be a really interesting combo. High power density and lighter small 2T plus an electric motor for 'torque fill'.

Where's me patent forms....

No smoke?

They already put fake noise in a lot of vehicles, maybe they could do some sort of smoke tie up deal with local DJs.

Mr. Dazzle wrote: Sun May 25, 2025 10:12 pm They already put fake noise in a lot of vehicles, maybe they could do some sort of smoke tie up deal with local DJs.

Smoke is bad, but environment friendly vapour, perhaps scented with Castrol R..........

The real innovation that could preserve internal combustion engines for ever is actually electronic transmission control. That is to say hybrid vehicles such as the one I drive right now ( Nissan E-power ). If the ICE rpm range does not need to be restricted because of a mechanical connection to the wheels its designers a free to use any format which keeps power delivery operating at the best specific fuel consumption that can be achieved. That is to say for any given power demand the engine provides that power by running at its most fuel efficient point possible.

Nissan have come up with a four-stroke which has a variable compression ratio by mechanical control of the stroke length. But plenty more innovations, including this two stroke, are made possible once the final drive is by electric motors which don't need gearboxes.

None of this is ever going to provide the raw power delivery of the two-strokes we knew and loved. But even restricted to clean fuels such as hydrogen the internal combustion engine will hopefully live on.

TBF Priuses and the like have being doing that ^^^ for 20 years now, but the slow death of ICE continues anyway.

If it goes ring-a-ding and you can fit spannies, i'm in!

Skub wrote: Sun May 25, 2025 10:02 pm No smoke?

There must be a way of fitting a magazine of disposable vapes to it.

Vapes always smell like leaky engines/radiators to me anyway, so it's probably not much of a leap.

Mr. Dazzle wrote: Mon May 26, 2025 10:17 am TBF Priuses and the like have being doing that ^^^ for 20 years now, but the slow death of ICE continues anyway.

{With apologies for drifting off topic}
Very true but Toyota's hybrid solutions involved sharing engine power mechanically; with both the engine and electric motors connected to the wheels. Brilliant but expensive and complicated. My crystal ball says that HGVs will be forced down the hydrogen route and if there is hydrogen on the forecourts it will be available to all. Toyota are once again leading the way on this for cars. I'll never be able to buy a hydrogen powered bike but I'm hoping I might live long enough to see them on the road.