MPG

[Masshole]

This is my first post, since I found tons of great info and knowledgeable people on here figured I should join the fun. I got a 98.5 24v going to be heading on a 400 mile  drive, half of the drive will include steep terrain. I would like some guidance on timing and mpg. I see lots of different mpg tunes here but do not know which is right for me. Just trying to run the most timing with minimal risk of popping the head gasket. I do not have head studs nor have I retorqued the stock bolts. Mods are quad adrenaline, rv275, cold air and 4” straight, 6” lift with 22.5 wheels and 37s (dually). Also has stock hx35, airdog, and a southbend to transfer all that extra power. If requested I can put up my current mpg tune for reference and adjustments to all of the different timing parameters.

Thanks in advance

[Me78569]

post your current tune.

[Ed ke6bnl]

Is there a tune for towing, that would be my main goal for the Quadzilla other than a milage economy when running around town. although the truck is 90% use to tow or haul something. Will purchase one when I sell a transmission or old truck I have for sale.

Edited August 27, 2020 by Ed ke6bnl

[Mopar1973Man]

Very difficult to do with 37 inch tires and a 6 inch lift and most likely will not happen. 

 

My first question is what gears are in the axles? If you have 3.55 gear this will make your final ratio 3.07:1 to the ground too low of ratio. If you have 4.10 gear different story this would be 3.51 ratio which is good. Good final ratio to the ground is 3.55 to 3.73 for these truck. 

 

With RV275 injectors not really pushing the stock envelope. +40 HP isn't really all that big and won't require a lot of timing but with bigger tires your going to need a good amount of retard to get it to spool with 37 inch tires. Bigger tires typically on 3.55 gear places the cruise RPM too low at road speed and causes more excessive engine load. 

 

Watch your engine load on flat ground. When you hit the best timing your engine load will drop. Like Even @Me78569 will suggest 19° to 20° for cruise timing at 2K RPM. That bring me back around to the Ratio. Which is why I gotta ask optimal I'm finding is about 2K at 66 MPH or 82 MPH at 2,500 RPM. Engine loads are super low but this is a 3.69:1 ratio to the ground. Even towing my EGT's never got out of control and was very capable of holding 65 MPH speed limit and towing 17,300 gross combined weight. 

 

Like most of us have jumped towards 100 HP to 150 HP injectors. Now bigger injectors typically can take much more timing. In the winter (sub zero) my truck likes a 23° to 24° cruise timing now with summer time is 21° to 22°. For you with a mere RV275 injector I would say stick around 19° as a starting point. 14, 17, 20, 23... (+3 steeps between bands)Then +2° for cruise timing will give you roughly 19°. Load based timing set for 3°.

 

Just for example my own tune I'm +4.5° between bands. 15, 19.5, 24.0, 28.5. Then +1° to cruise give me ~21° cruise timing at 2k.

 

Our truck can take quite a wide range of timings without issues it a matter of paying attention to engine load. Engine load is the amount of fuel your dumping in to keep rolling. This why you should test out on true flat ground with cruise set. Then as you adjust timing you can see if the engine load rises (going away from good timing) or lowers engine load (heading towards optimal timing).

 

Resent screen capture cruising at 65 MPH. 

 

• +150 HP Injectors (7 x 0.010) @ 320 bar
• Quadzilla Adrenaline (Economy Tune)
• HX35/40 Hybrid (60/60/12)
• 245/75 R16 tires (30.5 Inches) 3.69:1 ratio final. 
• 5 Speed NV4500
• 3.55 Gears

Edited August 27, 2020 by Mopar1973Man

[Masshole]

Power Levels: 8

 

Fuel Load Timing: 2

Low PSI Timing Reduct: 2.5

Timing Reduct Scaling: 100

Light Throttle Timing Adv:2

Light Throttle Timing Load Limit: 34

 

Timing vs rpm

1500: 16

2000: 18

2500: 23

3000: 25

Timing Max: 26

Fuel Stretch: 1200

TPS Pump max: 100

TPS Pump Min 45

Minimum Pump Tap Fueling Percentage:0

Pump Low Boost Scale PSI: 12

 

Boost Scaling: 36

 

RPM Limit: 3200

 

Power Reduction: 50

 

0 PSI %:95

1 PSI %:95

2 PSI %:95

3 PSI %:95

4 PSI %:95

5 PSI %:95

6 PSI %:95

7 PSI %:95

8 PSI %:95

9 PSI %:96

10 PSI %:97

11 PSI %:98

12 PSI %:98

13 PSI %:99

14 PSI %:100

15 PSI %:101

16 PSI %:102

18 PSI %:105

20 PSI %:108

22 PSI %:111

24 PSI %:115

26 PSI %:120

28 PSI %:125

30 PSI %:132

 

 

Thank you for all of the quick responses. I have already made the trip and took into consideration the recommendations that you guys provided. I did log some data when I was in the steep hills of Maine, I went 50 miles (according to mile markers, not odometer) and used the quad’s flow meter. at 66mph on cruise control with 1700lb payload i was getting 17.5mpg, I was impressed, hopefully someone can chime in and make it even better. To reply to your comment I do have 4.10 gears (4x4 as well). I would also like to add I was around 3-5 psi while on relatively flat ground. It felt like a few more microseconds on the fuel stretch would help a bit, correct me if I’m wrong. Thanks again

[LorenS]

I'm rather surprised someone hasn't chimed in since Friday!  I'm not the expert in this matter, so consider this a post to Bump the topic back to the top!  I'm still trying to learn my Quad tuning, so love reading others' experiences.

[Me78569]

with 4.10's i'd say your doing good.   

 

might throw another * of timing at your 2500 rpm slot.

[Threadzy]

I’m not a tuning guru like Mike and Nick are but here is what I would try. 
Low psi timing reduction 5.0

low psi scale 50% 

your 1500 timing try dropping to 15* possibly 14*
and like Nick said raise your 2500 rpm timing to 24*.  
Just my .02. 

[Mopar1973Man]

On 8/28/2020 at 5:38 PM, Masshole said:

at 66mph on cruise control with 1700lb payload i was getting 17.5mpg, I was impressed, hopefully someone can chime in and make it even better.

 

65 MPH you should be closer to 2,000 RPM.  Its the lower band like 1,500 and 2,000 that build MPG. You starting too high and not enough spread. With those big tires you should be starting out at 13° or 14° you need to be able to spool the turbo quickly. Then the low timing reduct should be like @Threadzy said but I would try the 50% but raise it next time to 60%. Need more retard for large tires. Take lot of energy to move large flywheels (37 inch tires).The 4.10 gears are optimal. 

 

Remember for every ONE pound of rotational mass you ditch is like EIGHT pounds off the frame. Hence why lot of guys went towards the single piece aluminum driveshaft. Shed the rotational mass weight to gain more to the ground. 

 

I work at removing as much rotational drag and weight drag to gain the most power. Then when you do add power to already reduced drag truck more power comes out with little need for big fuel. Then the economy comes out like it should. There is only so much tuning your going to be able to cover up the big tires and will always come at the price of lower MPG. The higher you stand in the wind more drag there is above 55 MPH. Above 55 MPH is all about aerodynamics. So with your setup I would reduce your driving speed a bit more if you can. 

 

Even my economy tune is more about the 1,500 and 2,000 bands where you spend the most time. Like Myself I would start you at 13° and step up +4 which would give 17° then cruise timing of +2° which would be 19° at 2,000 RPM. Starting at 16° you can't get spooled at all that high. Make sure to set the load based timing for 3°. I never really study the 2,500 or 3,000 because so little time is spent there. 99% at 1,500 to 2,000 is cruise state typically. Unless I84 at 80 MPH now I consider the 2,500 RPM band but rare at best for me now. 

 

[dripley]

@Mopar1973Man I respect the hell out you. You and the members here have helped me thru many issues over the past eleven years. I dont dispute the technical info on the 245's at all. So I say this with all due respect, we dont all want the 245 tires. I am very happy with the 265's and if I ever do step up to the quad the 265's are coming with me. I like turning 2000 rpm at 70, always have always will. The Comp gives me darn good power at that speed. With the versatility of the Quad good results should obtainable. Lord knows if I make the step, I will need a lot of help.

 

Love ya, mean it,     

 

The Chickenator 

[Mopar1973Man]

Oh... He's on track...

On 8/28/2020 at 5:38 PM, Masshole said:

To reply to your comment I do have 4.10 gears (4x4 as well).

 

As I replied...

8 hours ago, Mopar1973Man said:

The 4.10 gears are optimal. 

 

Not the tires... The final ratio. That the only way I can explain it is use the math I figure out on my own truck. But people with extremely low ratios are not going to gain anything. I've worked with several locally to fix oversized tires (low ratio). Too many are trying to build a lifted truck on 3.55 gears. Won't work. 4.10 gears is great for 35 or 37 inch tires. Problem as you add tires your adding rotational mass so asking for high MPG with heavy tires is impossible, won't happen. There will always be some loss to having larger tires. Another common mistake is thinking the odometer is still right after changing tires. (only if you had your ABS recalibrated). 

 

When you start mathing out 32" (285's) and above tires and looking at final ratios and wonder how to fix this problem. There is only 2 ways. Have the correct gears in the axles to build your big tire rig (4.10) or return to the proper ratio by coming back to stockish 31 inch tires. (265's or 285's - OK)

 

Now the few that actually listened and tired a set of stock tires again find out the power is much better and pull strong again. Put oversize tires back on and BAM! MPG down, EGT up, and then lack of power comes again. I tried it on a few trucks Fords, Dodge and Chevy's too. I've seen truck run the rollers (dyno) and traded tires down and always had a improvement of HP/TQ to the dyno. I can care less about the size of tire really, It's the proper final ratio I try to get people back to. 

 

I'm actually looking to go a bit wider in tire but stay around the 30 inch. I'm trying to keep my final ratio but... I looking to enhance traction a bit more since I did improve power I've been loosing traction really easy.  Snap 47 to 49 PSI of boost quick enough the rear tires can start slipping. 

 

Bad final ratio (only fix is to change tires back or change axle(s) to 4.10 gears)

37" tire on 3.55 is a final of 3.07

35" tire on 3.55 is a final of 3.21

 

Good final ratio

37" tire on 4.10 is a final of 3.71

35" tire on 4.10 is a final of 3.51

285/75 R16 on 4.10 is a final of 3.91

285/75 R16 on 3.55 is a final of 3.42 (bit low but OK!)

 

A good 3.55 to 3.73 ratio not a problem easy to build good solid power and usable all the way up the RPM's. Quick to spool little smoke. So again its not the tires, I don't care... But if you asking to build clean power, lower EGT's, and good high MPG with big tires not that easy. You have to get the final ratio straighten out, then it will happen. I've been confronted with lots of 35's and 37's on 3.55 and just doesn't work...

 

Edited September 1, 2020 by Mopar1973Man

[LorenS]

@Mopar1973Man thanks to your preaching on the small diameter tire, today I ordered a set of LT265/65/17 tires, around 30.7" diameter. Not easy to find!

[Mopar1973Man]

Yup your hung with 17's... Very tough size to get tires for. One of the reasons I've not opted towards 17's because of that tread puts you in wider and taller tires typically. 16's are more common place and have wider range of sizes yet. Just wheel selection can be limited too.

 

should be 245/70 R17 vs 245/75 R16

[That Guy]

Aluminium is lighter than more steel belts and rubber. It is obscenely lighter than steelies of the same size. I don't miss hauling steel rims around. Al is much lighter (and much more profitable). 

 

My 12v with 4.10's on 285's is ~59mph at 2k and is why we ordered the 2012 with 3.73's. I wish the 12v sat lower, but the 6.7 with stock tires sits higher than the 12v on 285's.

 

Still, the 12v gets 19.5mpg at 75 and the 6.7 gets 16.5 at 75. 

I have managed 26 with the 12v and 285's, but that was doing 45-50 the whole way. 

 

 

2 hours ago, dripley said:

I like turning 2000 rpm at 70, always have always will. 

 

Though, pulling 21k with 4.10's is nice. Neighbors with 3.55's dog slow.

[dripley]

5 hours ago, That Guy said:

 

Though, pulling 21k with 4.10's is nice. Neighbors with 3.55's dog slow

My 5th wheel weighs in at 15k plus 8k for the truck left me with 23k total. Even in 6th i coul pull it on 2% grade witn the comp on level 2 or 3. Empty at that speed and the with the Comp on level 5 she was plenty quick enough for me. This on 3:55's.

[NIsaacs]

7 hours ago, That Guy said:

 

Though, pulling 21k with 4.10's is nice. Neighbors with 3.55's dog slow.

 

Without knowing truck specifics this doesn't mean much. My '01 with 400hp/900tq, 3.55's, 285's and 6spd, is not slow.

 

For three years in a row, I followed the truck pull circuit in the Rocky Mountain states towing my sled puller (19k gcw) 12k miles per year. My three year average mpg is 12.5 mpg. 5th gear (direct) will pull a house.

 

Yesterday, I hauled 4 heavy loads of cinders, 8 hours and never got out of 5th, all local slow roads. Not using overdrive (6th) my tranny never got over 160*, plus any overdrive uses more fuel in any given towing distance v/s direct drive if all is equal.

 

When my truck was a daily driver for work (8years) 4.10's would have drove me crazy. NVH at 75 mph w/4.10's is real with these old trucks. With 3.55's I have good freeway gears and good off highway gears, that's what the transmission is for, changing ratios. The 6spd shines here v/s 5spd's or 4spd autos. The upshift gap with a 5spd and heavy load sucks (4.10's help) with a 6spd the gap is way less so (3.55's) work.

 

Why run 2600 rpm when 2100 will do the same job? Less NVH, better fuel economy, less wear and tear and the Cummins likes it.

 

And, the gear ratio debate lives on, if I have seen one thread, I have seen a thousand, Lol 

[dripley]

I would like to have the 5 speed for daily driving and the 6 speed for towing. But you cant. My 96 had the 5 speed and it always tickled how often on the I would pull it out of 5th then remember 5th was all I had. Then when I got 6 speed I figured that was over. Wrong, cant say how many times I have gone for 7th on the highway. Pretty cured of it now after almost 19 years. I am glad they did not bring up 4:10's when I bought it. Probably would have done it just from the towing aspect. But would not be happy DD'ing.

[That Guy]

5 hours ago, dripley said:

My 5th wheel weighs in at 15k plus 8k for the truck left me with 23k total. Even in 6th i coul pull it on 2% grade witn the comp on level 2 or 3. Empty at that speed and the with the Comp on level 5 she was plenty quick enough for me. This on 3:55's.

I was saying 21+ the truck(7300ish). A friend bought a 2wd dually 5spd with 3.55's. Compare to him, I can get to highway speed about 15 seconds faster. Same 35ft trailer, same 17 roles of hay. 

 

Still, I want his gears (or yours). Just add some more go pedal, when you smell clutch, back it off a 1/4 turn.

 

My top speed is currently 95. I want more like 110.

Edited September 1, 2020 by That Guy

[That Guy]

3 hours ago, NIsaacs said:

 

Without knowing truck specifics this doesn't mean much. My '01 with 400hp/900tq, 3.55's, 285's and 6spd, is not slow.

 

Neighbor bought a 3.55 truck in late 96 and a 4.10 truck (mine) in early 97. They were identical other than color, they both even had a Banks Get Kit installed with the different turbine housing and fuel plate. The 4.10 would outpull the 3.55, no surprises there. Once you got above about 25k, the difference really started to show. My neighbor finally just stopped using the 96 for towing. It would consistently show up 3-5 minutes later every trip, and he was doing about 4,000 round bales a year. Said he has crossed scales at 33k with pecans and (educated guessing) got closer to 40k hauling hay on a 40' trailer(~10k trailer, 21x round bales @ 1200 each, and truck). Hauling 23 bales has happened, he says he doesn't like doing that. Iirc, the B series Cummins is rated for 35k max. Higher than that, they want to sell you a C series. If there is a limit, I think my neighbor has found it.

 

He hauls with a 2013 3500 mega cab auto now..... or the 03 CR.

[LorenS]

3 hours ago, That Guy said:

got closer to 40k hauling hay

So at what point do normal people decide "this is why they make 5500 series trucks"?

16 hours ago, Mopar1973Man said:

puts you in wider and taller tires typically

Yes.  If the truck hadn't come with 17s and I hadn't already purchased the brake components for 17s, I may have found a used set of 16s the first time I needed tires.  Since I have the 8" wide wheels, I didn't want the LT245/70/17 tires, since that's the max wheel width.  Strangely, an 8" wheel is the minimum wheel width for the 265/65/17 - but that's easier to seat the bead when I mount them ;)

Yesterday I got a set of used steel wheels pretty cheap, so if I hate the setup hopefully I can sell as a package and not be out much money.

Edited September 1, 2020 by LorenS