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Bad mpg with quadzilla tune

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Mopar1973Man

Mopar1973Man

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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 by Mopar1973Man
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40 minutes ago, Evan said:

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.  

 

18 hours ago, Southpole560 said:

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.

My timing for 2k rpm is 17* on winter tune with 3* timing advance and light load throttle at 30% my boost is between 3-5 psi until hitting grades then it’ll reach about 12 my engine load will be at 16% cruising on pretty flat ground but will hit 26-28 depending on grade if hill

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Evan

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Just smarty.

Been running sw7 t4 timing 3 duration2

 

I usually cruise at 1800 that's about 75. Sometimes I cruise at 80.

I not really driving for mpg I'm burning a couple tanks  week and towing. 

 

I gave up trying to get better than 17 just not gonna happen at 10k with towing and stop and go mixed in with interstate. 

 

Towing significantly knocks me away from 17. I cruise at 80 while towing slurping the fuel 

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Mopar1973Man

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Smarty does not have enough top end timing to handle 80 MPH. Caps out way to early. Quadzilla I've done it multiple times but I was running around 23* cruise timing at 2,500 RPMs turning out 21 MPG at 80 MPH. Smarty I think caps out at 19* and that is it.

 

Remember Smarty has to play by the rules of the ECM and VP44. Quadzilla does not have to play by those rules completely. It highjacks the commands and send a priority message with the new timing and CAN Bus fuel message. So the problem is IAT drops below 80*F and the Smarty will have an extra +4* of timing where the Quadzilla doesn't use IAT temp. Again we don't have to play by all the rules just some...

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Mopar1973Man

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14 minutes ago, Evan said:

Your more than 500rpm higher than me at 80

 

Engine load is much lower than most. Typically empty truck is about 15 to 17% at 65 MPH. Even at 80 MPH at 2,500 RPM still only 20% to 22% engine load. Gear ratio is my good friend. Net gain is less fuel spent to keep rolling. Still doing long haul back and forth handling thing like medical appointments in Boise, picking up parts, getting Eileen's storage brought home, etc. 

 

Being 500 RPM lower would kill my city MPG performance because launch takes a lot of fuel from light to light. Give you an idea I'm in 4th gear 1:1 direct by 25 to 30 MPH. This would be your 3rd gear for that 47RE.

 

 

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5 minutes ago, Evan said:

Yeah thts 3rd. I dont go to 4th till 55-60

Top gear I'm in by 45 MPH. Puts me at 66 MPH at perfect 2,000 RPM.

 

Use that Quadzilla watch the engine load numbers. This is how much fuel is applied. Now change things like tires and watch. What you want is ultimately the lowest engine load at cruise state. As you reduce engine load then the EGT's follow too they will go down as well. Tuning it just part of it, the other half is to shed your drag, rolling resistance, rotational mass. Takes time to hunt down these small parasitic losses. 

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Evan

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If your going to delete replies send  a message say hey I deleted it didnt feel it was relevant.  I may not agree but ill be fine with it.

 

However I feel I asked good questions and brought up good points in that reply

 

Knowing how the quad handles heat in  heavy throttle towing situations with  a small turbo.

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