trying to get the most mpg @70mph

[sledbuilder]

A big part of buying efi live for me was to get better mileage .That being said I do get more miles per tank with out regenerating the DPF.
I have some genral questions
From what I have read less boost is in play when trying to get more mileage
Is this true at face value or is it the net affect of later combustion?
#2 , I have a LMM I plan to change boost in the 6 or so cell around the 30-45mm3 and 1600 1800 rpm range .Is table B2235 (transient) the one I would do it in? From what I have read the transient tables are used for steady conditions like 70 mph on the highway
#3 Am i on the right track?There are some very smart guys on here, if i am not even close in my theory or you been there done that didnt work well please let me know.
Thanks for any info!

[LBZoom]

Hey sledbuilder, I have an LBZ which in many ways is similar. I however do not have the transient tables, or know when they come into play vs. the desired boost tables. You can log some data and find out that way, however I would start with just the regular desired boost table (low altitude).

If net MPG increases from lower boost it is because the engine has less "thermal feedback" in other words, less boost pressure decreases cylinder temps and therefore reduces some friction and pressure within the cylinders. Lower it too much however and sacrifice power and response and you're back at square 1. Hope that makes sense. I left my boost stock and get about 21 at 70mph. 4-4.5 psi of boost...

Timing is also a huge benefit to mileage, find the timing calculator tool on this forum (search for it) or on Diesel Place, if you can't find it I can email it to you when I have the other computer. My LBZ gets about 22.5-23mpg at 65-67mph. I gained around 2mpg with EFI Live.

[sledbuilder]

Thanks for the info.
so far I have lowered boost in the 16to1800 rpm and 20 to 35mm3 rangeto under 120 kpa and also moved timing to 6.5 was around 5.
Iam adjusting in small steps(bacause I dont know what I am doing)
Digging through old threads It sounds like 3-4 lbs of boost and no more than 10 deg timing is some kind of sweet spot.
Thanks again for the info.

[LBZoom]

No Problem, one more tip...click the edit tab at the top of the window, and select configure display units. Choose to select all, and change everything over to imperial (standard), it's easier to understand than metric haha. No problem man!

[sledbuilder]

Thanks kept missing the "all" imperial.

[killerbee]

I do get more miles per tank with out regenerating the DPF.


If you are saying that you have reduced regeneration, can you please explain?

[sledbuilder]

Sorry for the misunderstanding the DPF is removed. I will say a more eficent regen has been on my mind for a long time,Glad to see some of you guys working that angle.

[sledbuilder]

If peek performance is achieved when peek cylinder pressure is @12-14 deg ATDC does that always happen when you split injection timing 50/50 over TDC?
How much is the excel worksheet for timing doing?
Is there a worksheet that centers Peek pressure based on fuel and boost?
I am sure that would be a ton of work for someone!
(Ps. where the he** is my spell check.)
Thanks for the info

[killerbee]

As a prelim finding, I found that lowering cruise boost sped up regen, maybe 20%. It had a clear 50F improvement in EGT1, helping the process along.

FWIW, normal regen started at 45g, ended at 7g. It happened rel quickly so experiments were short.

[killerbee]

...if the powers are wanting to know, :), it would highly useful to have some parameters to adjust regen process, start-stop pressures, etc. I found that a regen at 90g occured at twice the rate as a regen at 45g.

[LBZoom]

I don't know that peak pressure should necessarily occur at 12-14 degrees ATDC, but it should definitely occur no later than that I think. I tried 50/50 timing and noticed it was less efficient than having more advanced timing. And remember when thinking about timing, it's all about starting the injection at the right moment so that the ignition occurs at the precise moment that you want it too. In my mind I want full combustion near TDC and so far no issues. Just my opinion however.

[killerbee]

Here is an ARTICLE (http://members.cox.net/td-eoc/Timing%20the%20Diesel.pdf) to help with timing. It is non-specific, for concepts. In many cases best economy comes with the full pulse occuring before TDC. This still results in peak pressures well after TDC. The biggest factors are load and fuel pressure. IMO

http://members.cox.net/td-eoc/Timing%20the%20Diesel.pdf

[sledbuilder]

Thanks Guys