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Old 12-30-2010, 01:12 PM
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Default Cummins Timing and MPG

just looking for some input on what you guys think, I've been told the more timing you can safely give the engine a diesel one the higher the mpg should be at the prime mpg getting RPM which by my knowledge is right around 1800-2000 rpm, thanks for any input
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Old 12-30-2010, 02:38 PM
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Normally if you add a couple of degrees timing you generally add a little mileage. I have heard claims of up to 4 mpg, but I can't verify that. The only problem is if you need to get an emissions inspection you have less margin for error (NOX goes up for example). What engine are you thinking about?
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Old 12-30-2010, 02:51 PM
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I went from stock timing (13.5) to 16 (maybe more) on my Bosch P7100 and didn't notice a thing. I did notice all my low end power was gone. I didn't really realize it till I went back to 13.5 and said DAMN! For the amount of time I spend over 2000 (never), I will keep it stock.
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1997-12V-NV4500-Dana 80/3.54/2wd-350k---21-27mpg
Removed AFC--No Plate--13.5* timing--BHAF--5" Exhaust--Valair Clutch
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Last edited by stodg73; 09-15-2012 at 08:30 AM.
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Old 12-30-2010, 05:38 PM
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Quote:
Originally Posted by ISX View Post
I went from stock timing (13.5) to 16 (maybe more) on my Bosch P7100 and didn't notice a thing. I did notice all my low end power was gone. I didn't really realize it till I went back to 13.5 and said DAMN! For the amount of time I spend over 2000 (never), I will keep it stock.
That's strange. I went to 16.5* and I have quite a bit of low end power......
Here is a quote from Dodgeram.org:
Advancing the timing will...
Decrease exhaust temperature
Increase cylinder temperatures/pressures
Increase fuel economy (yes, economy is better)
Increase your output of NOx (a pollutant)
Decrease your output of Hydrocarbons (a pollutant)
Increase the amount of black smoke at peak torque
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound

Last edited by stodg73; 09-15-2012 at 08:31 AM.
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Old 12-30-2010, 06:32 PM
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Have you ever gone back to stock after advancing it? I didn't even notice the loss when I advanced it but after going back to stock it was like, holy crap.

I know it changes the range where you have power and it did have more on the high end (which I never used). It was more noticeable on the low end after going back though.
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1997-12V-NV4500-Dana 80/3.54/2wd-350k---21-27mpg
Removed AFC--No Plate--13.5* timing--BHAF--5" Exhaust--Valair Clutch
1994-Jeep Cherokee-5spd-3.07-4wd-202k---16-19mpg
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Old 12-30-2010, 08:41 PM
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I do know that the higher the timing the higher the power band is. I never saw any advantage to lower the timing. My dyno sheet shows a real flat torque curve starting at about 1500 rpm all the way to 2250 rpm.
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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Old 12-30-2010, 09:27 PM
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You got pics of those sheets? Think it would be interesting.

I drive under 1500 a lot haha.
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1997-12V-NV4500-Dana 80/3.54/2wd-350k---21-27mpg
Removed AFC--No Plate--13.5* timing--BHAF--5" Exhaust--Valair Clutch
1994-Jeep Cherokee-5spd-3.07-4wd-202k---16-19mpg
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Old 12-30-2010, 09:30 PM
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Give me a little time and I will try to scan the dyno sheet and get it on here.
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1996 RAM "Custom Ground" 100 plate 3/4 forward, 300 injectors, 16.5 timing, Goerends Auto = 365HP, 833TQ Third Gen Rims, Aluminum Headache Rack
Duct Tape can't fix stupid, BUT it can muffle the sound
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Old 12-30-2010, 10:10 PM
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Was your timing matched with some way of adjusting the wastegate on the turbo? Or was it even a wastegated turbo?
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Last edited by dknaks; 12-30-2010 at 10:45 PM.
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Old 12-31-2010, 12:41 AM
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I'm talking on my style truck (common rail) but i think the principal applies across the board to diesel engines, don't know if the 12v or 24v get the pre-ignition noise that the cr's do because they have one big injection event where the common rails have 2-3 injection events per power stroke
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