[Page1:Intro] [Page2:Track Results] [Page3:Mods] [Page4:Future Plans] [Page5:E85 Conversion] [Page6:Projectors/HID]

This page will be a general overview of the conversion to E85 for the 2003 GM L67.

The process is really quite simple as the fuel system is already ethanol compliant, the only change that is needed is to increase the flow of fuel into the engine. This is done with larger injectors. The only other thing that needs to be changed is the fueling tables in the PCM. I did this with the DHP PowrTuner. This is basically it, the rest is tuning the engine to work with the new fuel and its properties.

The tuning begins with updating the IFR table with the data for 60# injectors (or whatever size are being used). The next thing to be changed is the MAF table, it needs to adjusted to add approximately 30% more fuel. The o2 sensor will tell you if it wants more or less fuel in closed loop, the wide band o2 sensor will tell you how you're doing in open loop. After a little work the fuel trims will be very close to zero in all closed loop situations. At this point the vehicle will behave just as if it was running on gasoline while idling and cruising around.

Now we can get ready for WOT. With gasoline we were aiming for an air/fuel ratio of 11-12.5:1 depending on the level the engine was modified to. With E85 we'll be aiming for an air/fuel ratio of 7.5-8.4:1, again the characteristics of each individual engine will determine the ideal mixture. When tuning Power Enrichment(PE), start rich and work your way leaner, this will help keep you from breaking things. This will take a little work to get just right, but the wide band makes this very easy to do.

Now that PE is tuned in for the engine, there should be almost zero knock at this point. It is very possible that there is a little knock in the transition from closed loop to PE, this is where Acceleration Enrichment comes in. This gives the engine an extra shot of fuel when there is a large change in throttle position. Adding some fuel here (15-30% more, depending on mods) will cure this small spike of knock.

Now we have absolutely zero knock, what next? Let's add some timing and get some free horsepower. While running E85 we can run more timing in all situations, the trick is not to go overboard here, there is a point where too much timing will detract from performance. I've had good results running around 46* of timing during light cruise and 22* of timing at WOT, your results may vary.

This concludes the E85 conversion. You now have a vehicle that has the same performance as if it were running on 105 octane race fuel. Any questions/suggestions can be posted in the guest book and will be adressed on this page. Thanks for reading!

[Page1:Intro] [Page2:Track Results] [Page3:Mods] [Page4:Future Plans] [Page5:E85 Conversion] [Page6:Projectors/HID]