SOI Advice

[Marajin]

(01-24-2017 )AussieISX Wrote:  There is nothing slightly risky about running 8 degrees total in either 3774 or 2965 Cpl cals , As the stock cal peaks at 7.5 degrees @1650-1750 Rpm in the alpha 1 tables . That is why I said 8 degrees total advance . If he added the 2-3 degrees you advised he would have ended up with a total of 10.5 degrees. Just putting an incremental increase on these tables is bad in my opinion and they should be edited correctly . I think before giving advice you need to be familiar with the cal in question. I have trucks running in the north of Australia pulling 167,000 kg ( 368000lbs) on 24hr operations using the same timing I suggested. Those trucks are not owner driven and have been running this tune for nearly 2.5 years without any cracked Pistons or any problems outside of normal issues.

I agree that about 6-8 deg.(total, not soi setting) is all you want in an engine that is going to be used in high torque a lot. Personally, I have seen better results at about 6 degrees or so at 1650 on the occasional dyno testing I have done with them. Yup, it also matters what program you have in your engine as far as how the user SOI settings effect it.

The newest version (unreleased) "T" of MM - 2 that has been around for about 5 months now has all the advances for fuel mileage in the tables instead of SOI setting. Because of this, it no longer allows for any more than about 1.5 - 1.8 degrees in the main user SOI settings max.



This is an example of a high hp table for the bigger injectors that I regularly use that already has an SOI advance of 4 degrees in the lower end for a bit of fuel savings and cleaner oil. The orange bar across the top shows the amount of advance. It should work good for someone but I take no responsibility for its use or abuse. User SOI setting must be at zero when using this table.

Like AussieISX has pointed out, it is better to do the corrections in the tables for engine reliability under constant high torque, and for older engines that may have weaker liners to prevent liner issues.

Here is a post I did a while back that is related.
http://rawze.com/forums/showthread.php?t...21#pid3421

take a look it it too.