Date registered: Feb 2005
Vehicle: 1989 W201.029/M103 3.0
Mentioned: 0 Post(s)
Quoted: 4 Post(s)
It depends largely on the value of the engine to you.
Engines are designed to run on specific fuels, everything from the metallurgy to chambering design, setup and tuning necessarily changes when a different fuel is used.
What people achieve with alternative fuels is a preference at compromise.
A popular example is dual fuel LPG conversions, a widely accepted alternative fuel change. In fact the engine must be regularly operated on conventional petrol frequently to prevent damage from long term LPG use. A better alternative is one of the dedicated LPG-only conversion kits, which involves an engine rebuild using different piston rings and ideally much higher compression than a petrol engine, with different setup and tuning, so that the net result is similar performance and longevity to the petrol version using the alternative fuel. In fact the LPG-dedicated conversion would have greater torque and less upper range, it's a bit like going halfway to a diesel performance but still retains greater flexibility than a naturally aspirated diesel and uses a conventional spark ignition.
My point is: specific engineering for specific fuel type and grade.
Like the way a petrol engine can run a dual-fuel LPG conversion you can just take a diesel engine and use an alternative fuel like hydraulic fluid or vegetable oil. Initial problems are mainly related to a much thicker fuel requiring thicker lines and stronger pumps, plus a heat exchanger for warming prior to intake. Other problems however are related to the metallurgy, setup and tuning of the base engine designed for a completely different fuel type, which may not lend well to operating on alternatives for any length.
A British friend of mine did actually convert several diesels to run on vegetable oil, including an old Rodeo ute, a Prado turbodiesel and even a Jaguar 2.0 turbodiesel sedan. He made extensive modifications, upgrading fuel lines, pumps, filters and installing various heat exchangers, he distilled his vegetable oil properly, was quite an expert on it. Each worked well for a few months then destroyed the engine. The Rodeo he blamed on being on the way out anyway, the constant problems running the Prado this way on being an over-engineered engine, but the Jaguar was the last straw as that turned out to be rather expensive damage and it was basically in very good condition to start with, he tried to remedy that by switching to hydraulic fluid for this one and the Prado but the damage was done. Each car after several months of running alternative fuels blew such terrific clouds of smoke that driving behind it was like driving through a thick fog, you literally couldn't see the car through all the smoke it poured out the exhaust. I'm guessing it killed the rings and seals.
He bought the Jaguar for his girlfriend but that's ruined and hardly drives so he bought her a Citroen turbodiesel. She managed to convince him not to convert that to any alternative fuel, but just leave it to run on the fuel the engineers designed the car to run on.
driving a fast car should feel like falling off a building.