SOI Advice

[Signature620]

Hi all, I'm looking for opinions on SOI increments for an Aussie CM871 E after @m*m^2. I currently have a few on the road set at 4 degrees. A couple of these trucks do a lot of high torque/load work so I just want to know if I should go a little closer to 0 since 4.5 is the recommended max for the bigger injectors.

Cheers.

[AussieISX]

I wouldn't run any more than 8 degrees in the 395mg/Str areas . Won't gain enough fuel economy to justify cracked Pistons .

[Signature620]

Is that 8 degrees in total or as an increment?

[Rawze]

Setting one to 4 or 4.5 (8 for smaller tier engines) is all about fuel mileage, and not for higher torque applications. It is ok to set one out that far only if you only use higher torque on occasion, and your average engine loads are 30% or less (typical of a highway truck in usa.). for higher torque applications though,.. this is a bit risky.

I would not recommend more than about 2 or 3 in constant high torque applications on one. I have even heard of a few guys set it to -0.7 for road trains for optimizing the 1650 RPM range.

[AussieISX]

(01-24-2017 )Signature620 Wrote:  Is that 8 degrees in total or as an increment?

8 degrees total

[Unilevers]

typically most trucks under heavy load run 1-3.5 in the SOI tables. A max (and slightly risky) would be 8 degrees BTDC total which would give you 4.5 on the increment to be there. Personally i would run the increment down to 2-3 to give you more of a safe margin and a total BTDC of 5ish.

if you are unsure of the driver and loads run a 0 increment to be on the safe side. a running engine is better than i blowed up efficient one.

my 0.02c

[kmk]

I always thought that the cm871 has knock limiting tables that take precedence over user soi increment and torque demand? Can you guys go into further detail. Thanks.

[AussieISX]

(01-24-2017 )Unilevers Wrote:  typically most trucks under heavy load run 1-3.5 in the SOI tables. A max (and slightly risky) would be 8 degrees BTDC total which would give you 4.5 on the increment to be there. Personally i would run the increment down to 2-3 to give you more of a safe margin and a total BTDC of 5ish.

if you are unsure of the driver and loads run a 0 increment to be on the safe side. a running engine is better than i blowed up efficient one.

my 0.02c

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.

[Signature620]

I tried one at 2 degrees today and it ran about 150 deg celsius hotter on the pyro and the coolant temp rose quicker than normal. Where can I read up on adjusting the SOI tables for a 2965/3774?