[Big Dave]

When somebody like Bruce Crower talks, I listen, but I am a bit puzzled he hasn’t put this baby on a dyno yet. Normally when somebody like Crower or his type can get the engine to idle, they want to put it under load and see what she’ll do.

I suspect he’s got injection problems. Ideally, he should have two injectors – one for fuel, the other for water. That’s why he started out with a carbureted gas engine – so he could use the injector for water. But for a man of Bruce Crower’s savvy and means even a one-off special hear and camshaft drive, so he must have a severe problem somewhere. Maybe he is having problems with the injector. Water has very low viscosity and friction in the injector may be giving him fits. Maybe he is having problems getting the water to flash to steam fast enough. Maybe the water/steam is causing lubrication problems.

Presuming he can overcome his mechanical problems, this engine should be an elegant means of improving thermal efficiency and even power in a given size. Always compounding (that’s sorta what this is) has used a separate “engine” (such as a turbocharger or the turbocompounding engines used in the mid 1940s) but crower uses the same piston and crankcase.

If he can recover and use half the rejected jacket heat, he could be looking at a 10-15% improvement in thermal efficiency. That is huge. Maximum thermal efficiency has not moved in over a half-century since the Napier Sabre and R-3360.

Back in the 70s Cummins tried a different approach. They used a ceramic liner to take the heat of an uncooled jacket and recovered the power in a better turbo. My understanding is that they had lubrication problems.

BTW, the big drawback to a Stirling engine is the size and complexity of the machinery required for a given amount of power. To make the power of a chainsaw engine, a Stirling would have to be the size of a big US V-8 SUV engine. The size and cost have up til now always overwhelmed the efficiency. Other than the little toy engine kits you can buy, I doubt there are a half-dozen Stirlings on the planet.