air to fuel on diesel

[ZL1Killa]

hey guys, im starting to get into this and I was wanting to know about AFR on diesels and where they like it and such.

i understand this is a completely different world than gasoline, but whats the curve like gasoline: 14.7 stoich, ls1's like it around 12.8~12.9 or so peak power and down low around 12.2

i hope this isn't a silly question

also, I have looked at the different timings for the different levels of tunes from a bullydog; whats safe timing for a diesel or just use the same idea as with an ls1 for that?

[Cobra#3747]

I dont think anyone ever goes off an a/f for a diesel.

Diesel more fuel more air, more power. Basically, you want to get as much fuel in to use up all the air going in. Thats when you start ending up with alot of black smoke.

Timing, anything over the 28-30* range has min. gains. Some run up into the 36-38*, but when playing at the track, I havnt found much power increase.

[kbracing96]

This was just posted on The Diesel Place the other day, it's some of the very limited AFR info I've seen in diesels. Looking at some of his logs he sent me, seem that AFR is above 20:1 during most driving conditions till you really go on the throttle.


Depends what your intended goals are, if tuning for increased top end HP a much lower AFR will be required than if you building a mileage tune or tow tune. The AFR of a diesel can fluctuate between perhaps 70-80:1 at idle, 40-60:1 under cruise or light pedal conditions all the way down to 10:1 or under at WOT depending on fueling and air flow.

Here are a few characteristics I have found on my LLY.
Less than Stoich results in smoke, ie: 10:1 = very thick black smoke, 15-18:1 = light haze, 20+:1 = clean.

As far as WOT tuning goes, I would start around Stoich and go from there based on dyno runs or mph from an ET slip.

Originally Posted by sweetdiesel http://dieselplace.com/forum/images/buttons/viewpost.gif (http://dieselplace.com/forum/showthread.php?p=2000226#post1998152)
thanks im looking for 18.1http://dieselplace.com/forum/images/smilies/biggrin.gif
DID you hook this up to your EFI if so did you then make a calc PID?
did innovative MS or green light MS get you rigged up with all the fixens?

im gonna check out the site right now but i would like your input

thankshttp://dieselplace.com/forum/images/smilies/smile.gif

Originally Posted by Race Hemi
We've bought 2, one from a local dealer and one online. The only thing you will need is a std 18mm O2 bung which usually comes with the kit. The one thing to be aware of is that the range of output from the LM-1/LC-1 is limited to between 10:1 and 20:1 even though the LM-1(not familiar with LC-1) itself can measure AND display between 10:1 and 80:1. So if you are logging steady state cruising at 55mph the log will show 20:1 until you get deeper into the throttle and AFR drops below 20:1, although the display will show the measured AFR. No biggey, simply use Flashscan's filter function to eliminate the higher AFR's. EFILive already set up calculated PIDs for the common WBO2's, the one I use is named CALC.AFR_PLX1.

For monitoring combustion outside the 10:1-20:1 range I have been using a calculated PID for Equivalence Ratio originally posted by Fingers. It's not by any means but I feel it's better than nothing when working on throttle transitions and so forth.

[ZL1Killa]

thanks kb, what my buddy wants me to do is play with his superchips tuning chip that he has on his truck...idk yet what its capable of, I have a stock Duramax tune to go off of and a stage 2 bullydog tune to go off of...and I can see why it makes a power difference...STOCK spark tables on a diesel SUCK!!! LOL

[kbracing96]

His diesel has a SPARK table???:confused::nixweiss::muahaha:J/K. I think your referring the the injector timing table;). I have been subscribing to the 50/50 idea of timing on the diesels with the fuel being injected evenly over TDC. I use a custom PID to set the time by just driving the truck and it creates a map with what the timing should be for the 50/50. Basically, 3 table's make power in diesel, the base injected quantity, the Main injection pulse, and injection timing. If you join over at www.thedieselplace.com (http://www.thedieselplace.com) you will have access to the tune library with several built tunes to look at.

[ScarabEpic22]

Umm, and if you start tuning the actual ECM, I wouldnt run another piggyback module like the Superchips, it might not like it very much. Ive always heard use a handheld only or tune only, dont mix n match. if you can take the superchips tables and then tweak them, then flash them to the ECM that would be the better way to do it.

[Racehemi]

Umm, and if you start tuning the actual ECM, I wouldnt run another piggyback module like the Superchips, it might not like it very much. Ive always heard use a handheld only or tune only, dont mix n match. if you can take the superchips tables and then tweak them, then flash them to the ECM that would be the better way to do it.

The Superchips is a handheld not a piggy back unit. I assume ZL1Killa is talking about SCT (Superchips Custom Tuning) which in the Ford world is comparable to EFILive, HPtuners, LS1edit, etc. in the GM world.