Technology changes all the time so I am not current on this. I have seen a suggestion of a multi-fuel engine to be used in larger sedans like a Lincoln town car. (Full size US sedan if you're not familiar.) For this system to work I would think that they would have to have fairly high compression. A gasoline air mixture will self-ignite at around 14-15:1 compression if memory serves. My guess would be that they use a compression ratio higher than that if they want to run diesel as well. I'll take a look and report back. If the system uses high copression it really wouldn't work for the rotary. Our practical limit is around 10:1. Higher than that and the chamber flattens out so much that it will quench the flame front and stop the burn in the close fitting areas. This is the problem that they ran into in the old flathead piston engines. To get the compression higher with the side valves they made the piston almost hit the head. They found out there were limits to how close they could get the parts and still have combustion. The minimum clearance ended up being around .015 inches (.38mm). Closer than that and the fire goes out. 234 HP and 38.8 MPG to us english unit hangers-on is pretty good for a < 2 liter engine.
Bill Jepson
-----Original Message-----
From: George Lendich <lendich@optusnet.com.au>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Wed, 12 Dec 2007 11:52 pm
Subject: [FlyRotary] HCCi Engine Technology
Bill,
Here's a question for you - are you across the HCCI technology - Homogeneous Charge Compression Ignition Engine?
These engine combine the advantages of a petrol and diesel engines, whereby a mixture of petrol air and recycled exhaust are ignited spontaneously as in a diesel engine, resulting in lower peak temp, low nitrous oxide emissions and a 15 to 20 increase in fuel economy. I don't know if they use spark plugs - I'm guessing NOT.
Sounds perfect for the rotary - we already have the exhaust emissions fuel and air mix with the PP. I guess the difference between this and detonation is flame front speed and how that's controlled ( perhaps with the exhaust contamination).
An 1800 cc HCCI engine (in a large sedan) develops 175KW and uses 6.1 Litres per 100Km.
George (down under)