60% over's on mine and I put about 50+ miles a day on mine. So far mileage isn't a concern at this time but it will be soon. I'll be interested in what you find out James.
Thoughts on fuel pressure and timing for a mileage tune
- Thread starter gmduramax
- Start date
Will do Pat. I really like your theory about the stock sticks too. that had me quite intrigued
Pat
Larry, neens and I use to do this on the ol race tune of urs. We did it to get rid of the cummins rattle and it semed to help? Is is right? We were not engineers so it didn't matter
That's how we had it the first time, saw a little increase in mpg by upping the pressure close to stock levels.
I really wish we knew how big those injectors really were, I fear that lowering the pressure is leading to not enough atomization, and the use of more pulse to get the same amount of power to the wheels vs the higher pressure and lower pulse.
Have steve build forty some tunas and pull his hair out tweaking....its the only way we can get some knowledge:joker:
henry and i think only one or two other guys on here are the only ones i knew of that actually put a good amount of miles on their built motors. im sure there are plenty of other guys out there that do the same. Personally, id rather keep the miles off her, not for the motor but just cause shes my baby
. so far i have 15k on this motor in the year and a half ive had it. has yet to be on a tune less than 550hp im sure that will only increase. then a fuel cooler would be needed
To this day I've seen best results from the old mc105 tune slighty modded. I've tuned tuned and retuned my lly for milage and from what I've read in diesel economy paper onSAE and othe internetz don't work in real world! I read a paper saying that iirc 1000* egt produce best burn. This did not work! Low boost also did not work! I talked to zach and a few others while doing this and they noticed the same.
After that I didn't care about my milage and just mild race tunes
Ive only really started into messing with mpg on this pig. on the stock sticks, it didnt take much to average 20mpg on the highway. then i put the twins on and my towing mpg went way up. now its like a whole new realm lol. so far i/we've got it up 2mpg from where i was but i feel there is more left by finalizing some more tables and/or cells. im sure at some point soon ill say "screw it, this is good enough for me" :roflmao:
For sure! i know anthony is in the hunt for this as well and he and i have been bouncing ideas off each other as well as steve and others out there. im actually surprised ive not found alot more people who have really tried for the best mpg they can get out of bigger injectors
well, or they did and they prefer to keep their info to themselves which i can absolutely respect
yeah but we f***ked with timing at the same time so it may have hurt our gain a bit. ill pull it back and see if i notice rattle drop out as well, then see how the truck does. towing the zuk to camp verde this weekend on the flat bed so that can give me some kind of idea of what it changes
hahaha i think he'd show up at my house with blood shot eyes, breatheing heavily in my bedroom window and writing in the condensation on the window "you will die"
When I was on a quest for mileage (stock sticks) I ran timming up until it started rattle more then I was conferable with then backed it down. Then did the same with RP and after that I started pulling out PW until mileage stopped going up. When I took to much out it drove different too. It took me 2 years or so to really get it as good as I though I could. But my commute would change every few days and then traffic was different every day, so it was a real pain to be consistent. When I really thought I was getting it nailed down I would spend a few hrs one day making the same 50m round trip over and over on different tunes.
IIRC I was running 12* on my LBZ for a while which is way over 100% before TDC
IIRC I was running 12* on my LBZ for a while which is way over 100% before TDC
I used to get 21mpg on the freeway until I cracked a piston and honed the cylinders. Now I only get 16mpg on the freeway but other things could be affected. Maybe I should get my injectors checked. I have 55,000 miles on my built motor in 4 years.
but other things could be affected. Maybe I should get my injectors checked. I have 55,000 miles on my built motor in 4 years.
How much pulse did you take out at a time in the cruise area? Dropping 100uS made a noticeable difference in throttle response that we wound up changing back. Maybe 30-50uS decrease wouldn't be as bad?
When I got my best mpg I raised pulse in my tune alot, ran a shit ton of pressure and timing. Only reason I raised pulse was because around 2000rpm the truck would hang like it was starved for fuel. After raising pulse the truck ran great. Smoked alot under acceleration but didn't hang or rattle and got great fuel mileage.
I'm not sure if this is accurate but isn't dropping pulse the same as adding timing and fuel pressure. If you drop pulse you have to run higher MM3 to maintain speed. The ECM just picks from the next cell up to get the fuel that's required to run. That and you will be running more pilot.
On my LMM with 100 overs I could add pilot, reduce pilot, raise or lower pilot timing and it wouldn't make a difference, at least one I didn't notice.
I dropped PW 50us and running timing around 8* and bumped the fuel pressure up at cruising speeds and got 20.5mpgs this last weekend in my LLY. Better then the 16-17 I was getting lol
My city driving mileage hasn't really changed much, around that 13-14 mpg but the cruising mileage is 16-17 at best. I miss the 20-21mpg I could get fairly easily out of the stock turbo/injectors.
Don't recall towing mileage being any worse, maybe better actually.
I drive 50-150 miles a day so it is adding up for sure. I should probably be driving something different but I love my truck too much! :thumb:
No clue how the tune is set up, that's all in the Doc's department.. When JoshH modified tunes it was strictly for driveability. He nailed that part! Responsive and a blast to drive now! :thumb: I guess fuel mileage is a by product that we haven't discussed much.
Don't recall towing mileage being any worse, maybe better actually.
I drive 50-150 miles a day so it is adding up for sure. I should probably be driving something different but I love my truck too much! :thumb:
No clue how the tune is set up, that's all in the Doc's department.
. When JoshH modified tunes it was strictly for driveability. He nailed that part! Responsive and a blast to drive now! :thumb: I guess fuel mileage is a by product that we haven't discussed much.
See i tend to agree with anthony about dropping pw in the cruise area, not about increasing it but how it would react decreasing it. Just adding more pressure, you could see MM3 drop to a lower amount but increasing pressure also increases the amount of fuel put into the cylinder.
im so use to how quite my truck use to be, any little rattle sounds like a lot. maybe i should hop in a stock LB7 and see how they sound again
thats for damn sure for me as well!
im so use to how quite my truck use to be, any little rattle sounds like a lot. maybe i should hop in a stock LB7 and see how they sound again
thats for damn sure for me as well!
Say it takes 20 horsepower to idle the engine at 600rpm.
Once you set the pressure and timing, the engine will only use as many mm3's as it needs to keep it there. Efficiency and mileage is the true mm3's needed to make the needed power.
Ditto is true for freeway cruise. Your goal is to get the true mm3's to their lowest point. You don't need to monitor mileage. You need a stretch of flat road and no wind (morning runs). You make an adjustment and see how many mm3's it takes by averaging a large identical sample (say 5 miles).
Once you set the pressure and timing, the engine will only use as many mm3's as it needs to keep it there. Efficiency and mileage is the true mm3's needed to make the needed power.
Ditto is true for freeway cruise. Your goal is to get the true mm3's to their lowest point. You don't need to monitor mileage. You need a stretch of flat road and no wind (morning runs). You make an adjustment and see how many mm3's it takes by averaging a large identical sample (say 5 miles).
See i tend to agree with anthony about dropping pw in the cruise area, not about increasing it but how it would react decreasing it. Just adding more pressure, you could see MM3 drop to a lower amount but increasing pressure also increases the amount of fuel put into the cylinder.
im so use to how quite my truck use to be, any little rattle sounds like a lot. maybe i should hop in a stock LB7 and see how they sound again
thats for damn sure for me as well!
I had that same problem when I was tuning my moms LLY, I couldn't get the rattle to go away. I put the stock tune back in and realized how loud that it was.