flyrotary@lancaironline.net Mailing List Archive

Your hypothesis about the Saab power reduction while running on Gasoline sound right on the mark to me, Bill. There is no question that you can produce power with Alcohol - it does appear to have some nice fuel characteristics - disregarding its toxic by products and corrosion. But, the bottom line is you need considerably higher quantity of alcohol to produce the same amount of power you can on gasoline. This might not be a big consideration for a short drag racer run or even with a ground/water based vehicle - but it is certainly a determent to aircraft performance .

----- Original Message -----

From: WRJJRS@aol.com

To: Rotary motors in aircraft

Sent: Wednesday, September 07, 2005 12:49 AM

Subject: [FlyRotary] Re: Alternative fuel

OK guys,

So you will understand I have built alcohol engines for 1/4 migets, Turbo drag bilkes, and cars. Typically you will up the compression to around 14:1 as just a start. For a piston engine that means a different piston and usually rod to handle it. Cams need to be optimised for alcohol, and often you will do a different valve seat. (thinner dur to cooling effect of alcohol) Then comes the induction system, even with injection systems I changed every o-ring to one KNOWN compatible with alcohol. If you ar running a carburator you need brass (not plastic) floats and need to be sure every seal starting with the float needle is compatible. If you are not running a stainless steel exhaust system and muffler you better get one. One of the combustion byproducts of alcohol is formaldhyde, I'm not sure if this is what attacks the exhaust system or just the water generated does it but the oxidation is aggressive. Usually we would remove the plugs after the race and squirt top cylinder lube like Marvel Mystery Oil in the cylinder and turn the engine a few times to prevent rust prior to the next time we started the engine. Other than that I hardly ever touched anything except the jetting. :-)

By the way Ed I can guess how the specs on the Saab happen. If setup for alcohol it runs fine, (on alcohol), when running gas it tries to detonate but the knock sensors kick back the timing and run the system open loop rich to keep the temp down. There would be the reason for poorer power and mileage.

Bill Jepson