Best way to have a fuel efficient tune in race car

We race endurance races, we have a LS3, 6.2.. Racing up to 25 hours in some races, Probably overkill.

Currently we have a GM E67 ECU, it's a pretty stock tune, it's a little rich for longevity.

Im looking at moving to a Link or Motec ECU, for many reasons, especially the CAN bus integrations, with the AIM system we have, ABS and to develop a traction control strategy.

In my ideal world, we would be able to swap Map/Configs, based on our needs during the race, sometimes fuel stints are not a factor, some times, we need to run 6-8 hours maximizing fuel. In the 1980's (or today for some) I would just put a smaller carburetor on, but with EFI we can do much more !

I need to build a low performance, fuel saving tune. Does anyone have experience developing tunes for race engines with fuel saving in mind..

What types of things I should do in this alternative tune ?

- reduce TB opening to limit airflow, which based on a second set of fueling tables ? - AKA smaller Carb

- anything I should do with timing ?

Anything else

Anyone else worked on this and can they share experiences and results ?

Hi Aaron,

In order to quantify how much of a reduction in fuel consumption you are seeing based on the changes you make you would ideally want to use fuel flow meters.

If you are using a GP based firmware there's quite a few parameters you can adjust on the fly which would allow you to change how much fuel is being consumed both directly and indirectly.

There are driver switch axes for the fuel mixture aim in the form of a separate table and also a percentage trim. You also have a driver switch to adjust the pedal translation to reduce the maximum throttle angle if you have drive by wire.

There are calculated fuel flow channels which are quite accurate if you have good injector data which feed into the fuel used channels for logging purposes.

Scott, thanks for the ideas, Im planning on installing 2 flow meters, so I can track fuel pulled from the tank, and fuel returned by the regulator, to calculate consumption..

Hi Aaron

MoTec M130, M150 etc. have a software function called "Average Load".

Average Load functionality lets you calibrate automated corrections of various kind, ie. leaning out whilst average load is low, richening under enthusiastic driver condition, just to mention an example.

Same goes for ignition and boost.

The opposite is "Race Time" feature.

https://www.hpacademy.com/previous-webinars/044-average-load-and-race-time-functions-motec-m1/

While 2 fuel flow meters are an option, if the goal is to make calibration changes and observe a change in fuel used in realtime during the tuning process, you can do that without flow meters using the Link or Motec ECUs you mentioned.

Link ECU calculates fuel consumption in realtime and accumulated as part of the virtual fuel tank system, so that can be sent to a dash for display, as well as logged for review, and viewed while making steady state changes in real time. As long as you're monitoring fuel pressure, using it as part of a modeled calibration, and using ID injectors so they're properly characterized, the data has been good. I don't measure or monitor fuel level on my road race car because I only want to be within 0.5 gallon accurate per tank and the virtual system has consistently done that.

With Motec M1, fuel pressure sensor, and injectors Motes has fully characterized, you can monitor fuel used.

In terms of the changes, some great ideas have been given. Both ECUs can accommodate a CAN based, analog rotary knob, or simple switch input to change mapping. Both ECUs can vary DBW, fuel targets, timing, etc. based on that input.

In my experience that particular engine likes to be a bit richer than some at full load with max power timing, but with a little safer timing you can lean them out quite a bit.

Guys, thanks for the good suggestions, I experimented in the S/W with the virtual fuel tank and I feel this will be perfect for me to use as an input.

I will report back on my progress.

The other thing that you might benefit from in terms of saving fuel is fuel injection timing. Not much but still better than nothing.

https://www.motec.com.au/forum/viewtopic.php?t=769