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s4door

92 F350 6.7 cummins/allison swap & MPG questions

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Hello everyone. I'm new to the Mopar1973man site. I joined to show my conversion so I could maybe be of help to someone doing something similar. I would also like to reach out to see if anyone has tips for tweaking my EFILive tuning to possibly increase my daily driving MPG's. I currently get a steady 15 MPG with regular driving around which is mostly 2 lane roads and highways at 55-58 MPH. On a couple of longer Highway trips I've averaged high 16-17 mpg. Those numbers are logged over 20,000 miles since I did the engine rebuild/conversion.  I've read the earlier posts on VP tuning on the earlier fuel systems and was wondering if some of the  tuning that worked well on those systems would work on my setup.  I know that It's a boxy big truck and maybe that's as good as it can get with the weight and wind drag ect. As with a lot of you guys I'm always wondering if I could do better. As I stated earlier if anyone is thinking of a similar conversion I'd be glad to answer any questions you might have.

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That's an awesome truck!

 

Who did your current tuning?

 

I've done a fair amount of CR tuning, but haven't delved into the VP world as its fairly different. 

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Thanks. Not sure if I'm allowed to mention businesses on the forum as far as my tuner. Be glad to name them if it's allowed. They specialize in high performance. I have data logs I've recorded on my V2. They were wanting to know my rail pressure,  fuel pressure desired and fuel pressure actual and timing at cruising speed's. They made a change to my tune in the timing. I don't have my notes with me to what they were and what they are now. I can get that in the morning. I do the Allison tuning myself.

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Those are the parameters that will need adjusted to tweak mileage. 

 

My best advice is to continue to work with your tuner, unless you want to start tuning it yourself. 

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They are willing make adjustments for me. I'm just looking for suggestions that have worked that I can relay to them. I'll post the data tomorrow for you to look at and see if you think I'm where it should be or if changes should be made. I'm very pleased with the power. With 5 CSP tunes, I figured it would be nice to dial in one for mileage. What do you think of the mileage I'm getting now?

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I think your mileage is pretty good, there may be a little to be gained but without looking at the tune it's hard to tell. 

 

45% over injectors shouldn't be too big for good mileage. 

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I'll get you the datalogs tomorrow for where I'm at currently. Thanks for your help.

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Here is the last email I sent my tuner before he made the recent changes.  Red numbers are current readings after they made changes to the tune. Let me know what you think.

 

I am attaching a data log. It was a trip from home to my shop. It's about a 20 minute file so I took the important info and it is as listed below to save you some time. The three examples would mostly cover my daily cruising speeds either in 5th or 6th gear. This is with the truck  loaded with what I normally carry as far as tools and weight goes, but no trailer. Truck is 4wd but no front driveshaft is in the truck and it has unlocking hubs. EGT's at these speeds are roughly around 700-725 on my Pyro gauge. Probe is pre-turbo. Boost gauge is at 0 at these speeds. These were logged running Porcupine_4 tune 
 
Frames 22000-25000 are 58 mph on 2 lane rd comparable to Rt 42 on a nice flat straight away.
6th gear                                                         After tune mods
Pilot timing 14-15 degrees                               17 degrees
Main timing  2 degrees                                       4 degrees
Post timing -25 degrees                                    23 degrees
FPD_F 84                                                              86
FPA_F 83                                                              84
RPM 1400 +\-                                                      1472
TP_F 14-18%                                                        17%
Tune 3
 
Frames 25,000-32000 are me switching from 6th gear to 5th gear same speed and road conditions
 
5th gear
Pilot timing 18 degrees                                    19 degrees
Main timing  5 degrees                                     6 degrees
Post timing -24 degrees                                   23 degrees
FPD_F 88                                                             88
FPA_F 88                                                             89
RPM 1676 +\-                                                     1711
TP_F 17-19%                                                       18%
Tune 3
 
Frames 6000-7000 two lane country road 45-50 mph 5th gear (these numbers are basically the same. They may have only changed the higher MPH ranges)
 
5th gear
Pilot timing 15 degrees
Main timing  3 degrees
Post timing -21 degrees
FPD_F 75
FPA_F 75
RPM 1440 +\-
TP_F 12%
Tune 3

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I am surprised to see post timing not at 0°, are they using a post injection?

 

The main timing could possibly go a little higher, but the rpms are low so that might work well too. 

 

Do you get any hazing at cruise?

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At the cruising speed in 6th gear here are injection values (if this is what you're looking for)

 

MAININJD_F Main Injection time  722 US

PILOTINJ1Q_F  Pilot 1 Fuel Quantity  2 mm3

PILOTINJ2Q_F  Pilot 1 Fuel Quantity  0 mm3

MAININJQ_F    Main Injection Fuel Quantity 37 mm3

POSTINJ1Q_F  Post 1 Fuel Quantity     3 mm3

POSTINJ2Q_F  Post 2 Fuel Quantity     0 mm3

POSTINJ3Q_F  Post 3 Fuel Quantity     0 mm3

POSTINJ4Q_F  Post 3 Fuel Quantity     0 mm3

 

I haven't really paid attention to see if I have any hazing. Prior motor I had in this truck was a 93 12V VE Pump so this setup compared to that seems a lot cleaner.

I have noticed if I put a stick on pedal to do a fast idle it is kinda hazy which I was surprised at that.

 

On the V2 when I monitor the values the Post timing number 25 reads as 25 but on the computer when I run the data log its value has a minus sign in front -25 . Is that relevant?

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It should be -25°. 

 

I don't know why they are running a post injection event. I don't think it's needed with your setup for spool, and will just decrease mpg and add EGT's.

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Posted (edited)

So a possible change would be to remove the post injection event which would include the:

POSTINJ1Q_F Post 1 fuel Quantity 3 mm3  and

Post timing -24 degrees (or all values to 0)  for both.

 

I've often thought my EGT's were a little high cruising and while cruising when it starts to lug a little. Based on my compound turbos, cam and exhaust setup I anticipated the EGT's being lower. I've experimented with cruising in 5th or 6th at 57-60 mph and it seems to do a little better mileage wise when running in 6th. I have no trouble spooling. The latest tune where they increased the timing a couple of degrees has helped spooling a little bit. 

 

Hi 98whitelightnin.

 

Originally I had an NV4500 behind the 12V and I got average of 17-18 mpg. Couple of times on highway 20 mpg going just under 65. When the NV4500 broke, and I installed the Allison mileage dropped to about 15-16 highway and 13 driving around. As the 12V got older mileage got worse. Guy I sold the 12V to rebuilt it and said it needed valve work. Said exhaust valves were bad for whatever reason. 

 

The 6.7 gets better mileage with the Allison than the 12V did. Even if I am unable to get any mileage improvements with tuning I am still very pleased with the 6.7. Much more towing power than I had with the 12V. With my equipment trailer my combined weight is between 21,000-22,000#.  And if I want to play around a little when not towing there's plenty of get up and go to do that too.

Edited by s4door
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Ok. I emailed my tuner last night to see his thoughts on eliminating the Post. Is there any benefit to eliminating the Pilot too? Do you have any timing changes you think I should ask for too? 

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I got a response from my tuner. He said from their experience they haven't noticed much mileage improvement when they eliminate the post (just a little more injector clatter) but would be glad to send me a tune so I could try. I asked them to send me one so I could try. That way I'll know.

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