5.7 vortec mpg

[Awest623]

Give these values a run. Just bump up the timing where you are in lean cruise. 2* at lower rpm and 4 where it is leanest then back down to 2 where it is richer at 2,400 rpm.

Ok, guess I had the spark add table backwards. How's this look?

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[L31MaxExpress]

Ok, guess I had the spark add table backwards. How's this look?

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Give her a run. How did it feel previously in lean cruise? Still running smoothly?

 

[Awest623]

Give her a run. How did it feel previously in lean cruise? Still running smoothly?

Perfectly smooth, measured 0 knock retard.

 

[Awest623]

Give her a run. How did it feel previously in lean cruise? Still running smoothly?

That worked pretty good. Thanks for the help. I'll definitely see how much I can bump it up after I get my VE and spark dialed in.

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[L31MaxExpress]

That worked pretty good. Thanks for the help. I'll definitely see how much I can bump it up after I get my VE and spark dialed in.

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I generally go until I feel its no longer happy then richen it up a half point. Lean combustion limit varies a bit. Generally the more EGR dilution either from a functional EGR or cam overlap the richer it will have to run. Tiny cams can get away running leanest especially if the vehicle is over geared.

 

[PlayingWithTBI]

I've been thinking about how to calculate your MPG with HLC. What if you take your highway MPG, let's say 18MPG, when running without HLC and your stoich AFR, let's say 14.1, then divide your HLC AFR, let's say 16.5, by stoich, and then multiply that by your MPG? So, it'll be 16.5/14.1X18=21.06MPG with HLC enabled, a 3MPG gain?

As @L31MaxExpress said, you'll see higher MAF but, the engine will run at the same RPM and the same power needed to maintain your speed, right? Or am I over simplifying it too much?

 

[Awest623]

I've been thinking about how to calculate your MPG with HLC. What if you take your highway MPG, let's say 18MPG, when running without HLC and your stoich AFR, let's say 14.1, then divide your HLC AFR, let's say 16.5, by stoich, and then multiply that by your MPG? So, it'll be 16.5/14.1X18=21.06MPG with HLC enabled, a 3MPG gain?

As @L31MaxExpress said, you'll see higher MAF but, the engine will run at the same RPM and the same power needed to maintain your speed, right? Or am I over simplifying it too much?

Ehhhhhh. I'm pretty sure that wouldn't work. Too many other variables. I think the best way to do it would be to log injector puldwidthes, rpm, maybe duty cycle (but that's just a math function of pulsewidth), and speed. If you know the fuel pressure and injector flow rate you should be able to deduce how much fuel you're burning at any given time. Then it's just a matter of taking that number, and popping it into an equation of (x)/(y). With (x) being your instantaneous speed (distance over time) and (y) being the inverse of your flow rate (time over volume). Should give you your instantaneous (distance per volume) measurement and you could average that and use whatever units you want.

I'll see if I could work out a custom math in HPT to give me that.

 

[Awest623]

Dashcommand gives me a mpg number. But I don't know what values it uses so don't know how trustworthy it is.

 

[Christian Steffen]

Ehhhhhh. I'm pretty sure that wouldn't work. Too many other variables. I think the best way to do it would be to log injector puldwidthes, rpm, maybe duty cycle (but that's just a math function of pulsewidth), and speed. If you know the fuel pressure and injector flow rate you should be able to deduce how much fuel you're burning at any given time. Then it's just a matter of taking that number, and popping it into an equation of (x)/(y). With (x) being your instantaneous speed (distance over time) and (y) being the inverse of your flow rate (time over volume). Should give you your instantaneous (distance per volume) measurement and you could average that and use whatever units you want.

I'll see if I could work out a custom math in HPT to give me that.

PM me your email and i can send you the mpg PID i made if you want. You can watch the mpg increase with LC coming on.

Does the Lean Cruise have a big impact on mileage? I tried researching it on other forums but couldn't find anything other than speculation and failed attempts at running in HLC mode.

I only ran to 15.7:1 afr, so there was probably more to be had, but generally i saw ~1 mpg immediate increase on my mpg PID. When in really light cruising, or sorta coasting the mileage increase was probably better.

I never did test this on a long drive though so take it with a grain of salt. I currently have it shut off, my drives with this truck are short enough it doesn't really matter if i get 13 instead of 14 on the highway. If I was going to drive it 500 miles I'd probably turn it back on.

 

[Awest623]

PM me your email and i can send you the mpg PID i made if you want. You can watch the mpg increase with LC coming on.




I only ran to 15.7:1 afr, so there was probably more to be had, but generally i saw ~1 mpg immediate increase on my mpg PID. When in really light cruising, or sorta coasting the mileage increase was probably better.

I never did test this on a long drive though so take it with a grain of salt. I currently have it shut off, my drives with this truck are short enough it doesn't really matter if i get 13 instead of 14 on the highway. If I was going to drive it 500 miles I'd probably turn it back on.

PM sent