[Diy_efi] Tuning for E85 Fuel

[Torbjörn Forsman]

Typically, the fuel flow must be increased by about 30 %. In case of a 
conventional EFI system, it is most easily done by increasing the fuel 
pressure or replacing the injectors by bigger ones.
If the fuel pressure increase is done by fitting a second pressure 
regulator in series with the return line from the original regulator, 
then it is easy to change between gas and E85 with a bypass valve 
parallel to the second pressure regulator. Most fuel pumps have no 
problems with the higher fuel pressure, although the pressure reserve 
for clogged fuel filters etc is smaller than usual. The only known fuel 
pump problems are on very worn pumps and on some japanese vehicles using 
centrifugal pumps.
Often, more enrichment is needed at cold start and warm-up than we are 
used to from gas engines. A simple way to fix this is to connect a fixed 
resistor in series with the engine temperature sensor (assuming that it 
it a NTC sensor), together with a switch to short the resistor after 
starting.
In some cases, one can benefit from using earlier ignition timing than 
for gas, but it is normally not necessary to change the ignition timing 
of a high performance engine that is already tuned for relatively high 
octane gas.

To get good fuel economy and low HC emissions in cold weather, some kind 
of intake air preheating is strongly recommended.

For E85 discussions, i can recommend http://etanol.nu/forum/index.php .
Although most discussions are held in swedish, there is an 
"International" forum where english is used.

/Torbj?rn Forsman

Tim Marsteiner wrote:
> Looking for some info on tuning a late model air
> cooled V-Twin motorcycle to run on E85.
> 
> Thanks,
> Tim
> http://www.superxtune.com/
> 
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