AO

I'm seriously considering changing over to e85 on the GT, but would prefer to stay with the LH ECU if at all possible. Has anyone tried it?

I already run open loop, so i think the only consideration is can I get enough atomization and decent idle using 56# injectors.

Anyone BTDT?

Lizard928

I have run many 928s on 60# siemens injectors, perfect idle.

Go for it.

The injectors run around $400 for a set of 8

potdog

Hi what does open loop mean . Being unsure about many things is this thread about PSI pressure on injectors . could you used 30 lb injectors on STD car

The Forgotten On

You need about 20% more fuel when you run e85 so you would need larger injectors. You will also need to adjust the spark timing as e85 has a much higher octane rating than normal gasoline.

You will also need to replace ALL FUEL LINES and o rings as the alcohol dries them out and can cause massive leaks and fires.

Open loop means it doesn't use a 02 sensor to influence the fueling of the engine.

If you shark tune it properly I don't see why you couldn't do it with the stock computer.

SMTCapeCod

Have you followed the thread on the development of the updated ECU with Windows controllable parameters? Was just bumped up within the last few days. Seems apropos.

AO

Thanks guys... I appreciate the response.

I actually have the prototype replacement LH, so I will talk to Francois about using that, but I really wanted to see if the stock LH can support it. Sounds like it can, so that make me a happy camper.

I already run 42# with my twin screw SCer and am intimately familiar with Shark Tuning. All my fuel lines are new and all o-rings are new as well - so I'm good there.

I run the 044 pump, and I believe that should flow enough to give me top end performance.

Colin,
Have you noticed a wide fluctuation in e%? I've heard that e85 means up to 85% ethanol, but not guaranteed. If there is a wide fluctuation in e%, how do you control for that, if at all?

Lizard928

AO,
There can be a wide fluctuation, and there is not much of a way to moniter it without the use of GMs flex fuel device.

You can however wire it in line with a tool like the smt6 and adjust the pulse widths to adjust.
Though it would be much easier to enable O2 adaptation with the installation of an innovate digital MTX-L and then going in to the programming, and changing the simulated narrowband output to be correct for E85. Once that us done the LH will be uncanningly targeting the correct AFR for E85....
Once that is done, I recommend using the latest version of software and turning off O2 adjusting at anything above idle. This allows you to program for response and power in all rpms.

marks gt

What about this thing?

http://www.zeitronix.com/Products/ECA/ECA.shtml

AO

Perfect! Exactly what I needed to hear. Also got your PM. I'm several months away from this, but am excited to give it a try. Will document the conversion process for future posterity.

jcorenman

I think there is no need to recalibrate the wbo2, whatever model it is. The wbo2 sensor is reading residual O2 and estimating AFR based on the type of fuel, but "stoich" is still stoich independent of fuel. Your initial target (for idle and light load) is still Lambda=1.0 for any fuel mix. The AFR number will vary, 14.7 for gasoline, 10 for E85. Sharktuner gets an analog voltage from the wbo2 controller, which is Lambda i.e. relative to stoich and independent of fuel.

For these reading along, AO's rebuild thread is relevant starting here:
https://rennlist.com/forums/928-foru...l#post11054285

AO

Hi Jim,

Thank for chiming in. I am aware of the WB being able to read O2 on a variety of fuels including e85. I think, however the issue is that e85 can vary widely and using an WBO2 may not be Wide enough to compensate. Hence, Colin's suggestion for running O2 adaptation at idle, then running open loop after that.

I'm willing to give it a try, however. I assume I can use the NB simulated output from the WB to drive this, no?

Also, the driver for this, in case you are curious, is that the intercooler on my GT sprung a leak at SITM 2 years ago. It's not repairable and a replacement is going to be CRAZY expensive. I figure I can run non-intercooled with e-85 and make similar power safely.

So that's the plan! Gonna be a fun Winter and Spring.

jcorenman

We're talking about two different things, I think. The physical air/fuel mixture for ethanol needs to be different for complete combustion, AFR is around 10:1 for E85 vs. 14.7:1 for gasoline. So certainly the ECU needs to inject more fuel, and the injectors need to be large enough to do that. Using the LH's adaptation, with appropriate maps, may well be all that is needed.

And certainly limiting the operating range where adaptation is active will be important, ST can do that now. I don't know if it is necessary to limit it to strictly idle, I think idle and light "cruising" might be a better choice-- but that is what testing is for.

What Colin was talking about was re-calibrating a MTX/L. You don't want to change the analog-output that goes to Sharktuner, nor the simulated-NBO2 signal that goes to LH-- stoich is still stoich as measured by residual O2.

What will be wrong is the AFR display, but that is just the gauge display (and ST's AFR display). You could re calibrate the MTX/L for the fuel mix in use, or change it to display Lambda, or ignore it. Or stick with whatever wbo2 and nbo2 sensor you have now.

BC

Yes.

Easy.

get Flouro based fuel lines for engine bay.

Make sure injectors are... big.

Sharktune couldn't hurt.

No intercooler? Maybe also spray into ports to cool charge.

E85 is 9.7:1 Stoich, but that is confusing to most. Stick with Lambda. Lambda is 1 - no matter the fuel.

Go rich than that - more torque. Get a clean engine. Nearly no detonation.

Ask Todd. He has gone full hog on e85.

Yes, there is mix change. Winter may be as low a E70. Summer is E85 mostly.

Make it rich, and you will be fine. Watch AFRs.