I’ve been getting about 13mpg on highway with speed steady at 70mph. I’ve been seeing/ hearing people talk about getting 20mpg and wondering if I can achieve that here is the tune I’m cut using 

Tune

Tune

Rpm timing

Fuel

Fuel

Data log a highway run and post it. 

 

What tires and gears and lift?  

33 minutes ago, Me78569 said:

Data log a highway run and post it. 

 

What tires and gears and lift?  

I will give a data log on Friday. As for lift 4in, tires are 35s and gearing is 3.55

Edited February 5, 20205 yr by Voltronics

4 minutes ago, Voltronics said:

I will give a data log on Friday. As for lift 4in, tires are 35s and gearing is 3.55

Ooohh wee, Quadzilla ain't going to fix that. @Evan might though  seems the set up you got is up his alley.

You are working the truck pretty hard at 70 with that setup.  

 

The guys getting 20 mpg have stock height stock tires and are typically doing under 65.  

11 minutes ago, Me78569 said:

You are working the truck pretty hard at 70 with that setup.  

 

The guys getting 20 mpg have stock height stock tires and are typically doing under 65.  

That makes sense I just wasn’t sure if my tuning was messed up or what 

I can 19.5 at 75 on 265 75 16 and no lift. You are turning a lot of rotational mass and way up in the wind. @Evan would be the man on your set up.

you might not be in the cruise timing area of the map depending on engine load at 70 mph.  editing the tune might help some, but we will need to see a data log.

For my tune to work for you... You would have to be on...

• 30" inch tires (245/75 R16) - your final ratio is too low. 
• No lift, stock rake. - Your frontal area is too big.

The whole problem is your final gear ratio is too low. Then with 4 inch lift you standing up in the wind too high. Like myself my final gear ratio to the ground is 3.69:1 vs your 3.21:1 this will add engine load considerably. Then the 4 inch lift will add to you frontal area drag calc. II have been twisting out 19 to 20 MPG at 80 MPH on the interstate twisting nearly a perfect 2,500 RPM's. I can typically keep my engine load below 25%. EGT's typically are about 600*F.

On 2/6/2020 at 7:19 AM, Mopar1973Man said:

For my tune to work for you... You would have to be on...

• 30" inch tires (245/75 R16) - your final ratio is too low. 
• No lift, stock rake. - Your frontal area is too big.

The whole problem is your final gear ratio is too low. Then with 4 inch lift you standing up in the wind too high. Like myself my final gear ratio to the ground is 3.69:1 vs your 3.21:1 this will add engine load considerably. Then the 4 inch lift will add to you frontal area drag calc. II have been twisting out 19 to 20 MPG at 80 MPH on the interstate twisting nearly a perfect 2,500 RPM's. I can typically keep my engine load below 25%. EGT's typically are about 600*F.

Here’s my data log from a 30 min highway run cruising up hills egts won’t go past 1000 I don’t have my quad egt gauge hooked up.

http://s000.tinyupload.com/index.php?file_id=90586236393748262639

On 2/5/2020 at 6:43 PM, Me78569 said:

you might not be in the cruise timing area of the map depending on engine load at 70 mph.  editing the tune might help some, but we will need to see a data log.

http://s000.tinyupload.com/index.php?file_id=90586236393748262639

it looks like you are not getting into cruise timing reliably at your cruise state.

 

Whats your current cruise timing limit % set at?  What does your load report at your typical cruise speed / state?

51 minutes ago, Me78569 said:

it looks like you are not getting into cruise timing reliably at your cruise state.

 

Whats your current cruise timing limit % set at?  What does your load report at your typical cruise speed / state?

22% cruise and load is typically around 15/17 at about 70mph I drive where it’s very hilly 

increase light load limit to %30

 

that tells the quad if you are under %30 load then use cruise timing otherwise use tow / performance timing.  

 

Then watch your cruise % and see if you are jumping above that %30 mark. 

 

Rolling over hill it should just jump out of cruise timing then come back quickly.  I think mike says %5 over your desired cruise load.

1 hour ago, Me78569 said:

increase light load limit to %30

 

that tells the quad if you are under %30 load then use cruise timing otherwise use tow / performance timing.  

 

Then watch your cruise % and see if you are jumping above that %30 mark. 

 

Rolling over hill it should just jump out of cruise timing then come back quickly.  I think mike says %5 over your desired cruise load.

Ok I’ll change it to 30% and see what’s she does. Should I worry about cylinder pressure my timing is about 21.3* when running at 70mph. If I increase the light load limit that higher timing will still be there when pushing about 10-15psi. And is that timing to high for winter in Wisconsin rn we averaging 30* and my iat doesn’t go above 70 when I drive on the high for 40 min coming back from school

There is a breaking point to cruise timing too. More focus you build to a set speed the better. Sometimes though building to high speed like 70 and 80 MPH just are not reachable with cruise timing. Say you build a tune around 80 MPH you can get 20 to 21 MPH but now the lower speed typically will be poor like my 65 MPH will be 18 MPG. So its best to build around like 60 or 65 MPH for cruise timing. This way the middle ground speeds tend to be better for MPG.

On 2/11/2020 at 5:07 AM, Mopar1973Man said:

There is a breaking point to cruise timing too. More focus you build to a set speed the better. Sometimes though building to high speed like 70 and 80 MPH just are not reachable with cruise timing. Say you build a tune around 80 MPH you can get 20 to 21 MPH but now the lower speed typically will be poor like my 65 MPH will be 18 MPG. So its best to build around like 60 or 65 MPH for cruise timing. This way the middle ground speeds tend to be better for MPG.

If you don't mind me asking, what cruise timing do you run with your mpg tune when you go 70-80? Maybe I can try experiment with a higher speed to see if my mpg can increase. Thanks!

11 hours ago, Southpole560 said:

If you don't mind me asking, what cruise timing do you run with your mpg tune when you go 70-80? Maybe I can try experiment with a higher speed to see if my mpg can increase. Thanks!

My running about 20* sometimes 21* when I hit cruise and my egts are at about 700

Try setting the light throttle advancement to 2°. I personally have my light throttle load limit set to 33% and have seen alright results. Last trip I took I got 18.9mpg tank average going from Portland to Pendleton, OR and had cruise set at 65. I also slowed down on the grades and let the momentum bring the truck up a bit until my speed got down to 55 then slowly increased when it was flat again. My 35 inch tires are like 33.5 now.

What's your pressure gauge reading at 70mph. Hopefully 5-8psi 

 

Maybe bump speed to 75 . Youl find a sweet spot with those tires.

 

Dont be afraid to see it hazing cruising at freeway speeds.  

Holding cruise timing too long will hurt MPG's. I'm only running 20% with 4* of cruise timing. You can run more cruise timing on lower percentage of loads. Being my normal cruise load is 17% at 65 MPH I get to keep the cruise timing quite a bit. My base timing is retarded for local high cetane fuel which will shortly start to be reduced soon. 

 

3.55 gears with 35 inch tires are not going to work. That puts your final ratio to the ground too low. 3.21:1 to the ground is your final ratio this will add enough drag to equal towing my 31 foot RV. Optimal final ratio is 3.55 to 3.73. I reverse my setup dropped the 265's and went to 245/75 R16 which is 3.69:1 to the ground, my cruising RPM is optimal at 2.500 RPM at 82 MPH. This has been twisting out 20 to 21 MPG for the last 2 years at 80 MPH tested many times even datalogged.

 

Edited February 24, 20205 yr by Mopar1973Man