How do I convert to E85 on a LQ9 engine ?

[Ram Air IV]

I consider to change fuel from petrol to E85 on my Firebird -68 with LQ9 engine(LS1 intake).
What should I pay attention to when I change to E85?
First of all are there any parts in the fuel system that are not compatible with E85 such as fuel hose, injectors, etc?
What should I change in the tune file except for AF Ratio.
I have used the excelent Calc.VE tune guide for tuning my engine for petrol, can I use this for E85?

M

[joecar]

Hi RAIV/M,

I'm sorry for the lateness in my reply.

You would change the stoichiometric AFR (B3601).

You may or may not need to increase fuel in PE mode (3618); if the PE table is at least as rich as EQR 1.175 then it may be ok.

You may also need to use a larger injector (you can either calculate the needed injector size, or you can observe injector duty cycle, it should not exceed 80%). [ If you change to a larger injector you will need to edit the injector tables ]

Calc.VET tuning adjusts the VE and MAF tables so that they correctly model the engine's physical cylinder airmass throughout the operating range; cylinder airmass is not dependent on fuel used (i.e. is independent of stoichiometric AFR), so yes your VE/MAF tune is valid for E85.

Also do this (as explained in the Calc.VET tutorial):
- in the tunetool use EQR units for fueling.
- in the scantool use Lambda units (or EQR units) for the wideband.
- in the scantool log GM.EQIVRATIO instead of GM.AFR.

[N0DIH]

Or multiply the injector flow values X 0.74 and then leave stoich alone. Go apply the ethanol timing table changes to the main tables and call it done.

Tweak injector flow as needed to get LTFT's to 0. I have tried both ways and this is much easier and faster to get spot on and cold start driveability is that of gas.

And of course, run the larger injectors, use the gas injector flow numbers X 0.74.

[Ram Air IV]

Thanks for the input, I will sure give it a try. Right now we have 10 inche of snow i Stockholm so I have to wait 4-5 weeks before I can test it on the road.

[N0DIH]

Send us some snow, we need it this year! We may have had 10 inches this year total, we normally get around 40!