Date: Tue, 04 Jul 2006 19:15:04 GMT
From: Paul Halliday <pjghnospamyonder.co.uk>
Subject: Re: ethanol conversion query


in article slrnealc42.cbu.rotten_NOSPAM_nospamam.example.com, John B at rotten_NOSPAM_nospam.org wrote on 04/07/2006 18:19: > Hi, > > I've been reading up lately on the technical aspects of converting gasoline > vehicles (e.g. a Saab c900 turbo) to run on ethanol or ethanol/gasoline > blends. > I'd appreciate any input on the ideas, and of course any experience anyone > might have doing such a project. > > I've been considering the following facts: 1. gasoline is now rather expensive > (and is likely to stay that way); 2. ethanol is likely to become increasingly > available; and 3. c900 turbos are relatively inexpensive these days. Also, I > understand that turbo engines are particularly suited to running on ethanol > because they can take full advantage of high octane fuels. > > It looks like there are two primary obstacles to running a gasoline engine on > ethanol: compatibility of the fuel delivery system with ethanol, and the need > to inject more fuel per mass of air. > > 1. Fuel storage/delivery > > a. Compatibility of fuel tank and fuel lines with ethanol. > > I'm not really sure what the c900's fuel tank is made of. Is it stainless > steel? Also, not sure about fuel line compatibility. Does anyone have any > idea? Existing fuel lines will be corroded by an ethanol mix of greater than about 10% to petrol. > b. Fuel pump > > The fuel pump may contain internal seals or other parts that dissolve in > ethanol. Probably not an impossible obstacle though. ... As above ... > c. Fuel injector O-rings > > ... must verify that injector o-rings are not ethanol-soluble. Probably > not a big obstacle to overcome. Probably okay, so long as they are new. > 2. Air/fuel mixture > > My understanding is that the c900 can tolerate 10% or maybe even 20% > ethanol/gasoline mixtures, as the ECU can detect and compensate for lean/rich > mixtures via the oxygen sensor. But running on > 20% ethanol probably screws > up > the air/fuel mixture by a greater degree than the ECU can compensate for. I'm led to believe that 10% ethanol from the pump is already commonplace across the US (and elsewhere?), so there is a fair chance you're already running it. Older pre-ECU C900s are probably okay just knocking the timing back a bit - the fuel pressure is much higher than the later ECU controlled cars. I do know that non-Biopowered SAAB 9-5s are okay with E85 .. Not sure about long-term usage, but as a one-off, it worked for a tankful. I've seen an NG900 setup for E85 on garaget.org, so I presume it's not a quantum leap back to the C900 T16 ... Are you thinking Bosch or Lucas FI system? > The solution to this problem must be to inject more fuel. One way to do that > is > to enlarge the injector ports, but that introduces assorted other problems > (i.e. spray pattern and mixture-too-rich when running on gasoline). So another > solution is to change the injection pulse length. There seems to be an > aftermarket product designed to do just this (see xcelplus.com - not > affiliated, etc). It apparently intercepts the signal from the ECU to the > injectors and lengthens the pulse, and you can still switch it off to run on > gasoline. They claim to be compatible with Bosch fuel injection. > > The same people also sell some sort of engine treatment, which they claim > coats > certain engine parts to protect them from ethanol/water induced corrosion. > That's probably the scariest part of this whole thing as far as I'm concerned. > Oh, and they also warn that the ethanol will clean out lots of gunk from the > fuel tank, necessitating a couple of fuel filter changes. I think you're already ahead of us here ... I'll watch with interest; other may have direct experience. Try it out for one tank fuel prior to your next fuel filter change? Fill up, drive 25 miles and then top up with ethanol. That'll be just short of 10%, give or take content already in the "petrol". > So, does this sound like it would be a worthwhile experiment? The total cost > would likely be $2000 - $3000, including the car... I think it does! Paul 1989 900 Turbo S http://saab.go.dyndns.org/

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