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Tuning Diesel for fuel economy

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In one of Andre's videos, he only adjusts timing and keeps everything else the same and shows how max torque for the same fuel quantity can be achieved by adjusting the timing. I'm aware of this, but don't know how well I'll be able to do this on the road without a dyno so I don't hurt my engine. I probably already have it too advanced and should retard the timing some.

More importantly, is there a specific lambda to target that is most fuel efficient? In one of the webinars on gas tuning, it was mentioned that a lambda of about 1.1 is good and better for efficiency in light load conditions.

For a diesel, if there isn't a specific lambda to target to achieve max fuel economy, is economy instead driven by the turbocharger design and is different for each turbo? In that case, will max fuel economy be had when there is a 1:1 boost to drive pressure ratio?

Are there any other keys to watch for to help attain peak fuel economy?

I've also been struggling to get my bigger 65mm turbo to spool even with bigger 60 over injectors, although I did dial them back to output levels same as stock for now by datalogging with afr and correcting PW until expected and measured lambda were equal. Any thoughts on this?

My LBZ only got a peak of 16 mpg unloaded on a road trip travelling 80 mph and that was the best I could do after making tuning adjustments. Before the adjustments, it was around 14.5 mpg. I've heard of much higher numbers even for trucks that are bigger than mine. I have no lift, but do have 33" tires which I understand does have an effect on mpg.

Ive attached a datalog for more information.

I appreciate any input and advice in advance. Thanks!

Attached Files

Well fist step toward better power and fuel consumtion is jump as fast as you can to main injection only. One big injection event drivers combustion temp/pressure up a lot better but you will need some boost to reduce diesel noise nock what ever to make it work so it sound better to what we want to hear form our diesel engines. LOL

Advance injection timing. Can be tricky, data logging or use a dyno recommended same goes for the rest as well.

Lambda or AFR. Ideal depend on engine type. The more efficient your engine type is the more rewarding things get around Lambda 1 on full load but note things can get very hot reducing engine live. Ideal Lambda or AFR in relation to fuel efficiency. Well how good did you make your fuel system modifications. Most engines are unable to deliver fuel quantity on hi RPM in relation to air mass stroke reducing your options to run lean on o2 make more power so you could end up with a hi 16:1 AFR ratio already producing smoke.

Think there is no answer to all of this other than taking it step by step trail and error comparing data from runs looking @ acceleration, EGT,s or hope for someone that did his homework well will to chare things for your engine model.

So in short go in hard and fast with fuel delivery where you can so one main injection and get the fuel pressure up if there is headroom there to do so.