Mileage numbers for c6 to e4od swap?

[jayro88]

Hello,
Does anyone who has done a c6 to e4od swap have any mileage data? I have searched and found varying information about the increase from a c6+aux O/D to an e4od. Some say they have seen a 1-2mpg increase while others say the locking torque converter would only make a 1mpg difference at most. I track each tank on my e250 and was hoping someone did something similar on theirs before and after the swap.

I believe I have figured out a way to use my aux O/D with the e4od so I could end up with double O/D. This would be nice since because it would give me the option of swapping out my 3.54's for 4.10's (or even 4.56's) for added towing ability and still have lower hwy cruising rpms than I have now. I run higher rpm's than a truck since I don't have the ability to increase my tire size that much on a van due to clearance issues.

The van is my DD and I plan on running it for another 300k miles so I don't mind investing some money as long as the benefits are worth it. Gotta decide if I want to start digging into the details of this swap. Thanks

 

[FarmerFrank]

If I remember correct, and if my math was correct a double o/d and 4:56 gears would give you a 2:70 rear in high gear. That's a zf5 and a dne2 box. To me that would be so ideal

 

[franklin2]

How does a zf 5 speed compare to a e4OD? Would it be close to the same if the e4od is locked up and in overdrive? I gained 3 mpg when I swapped from a c6 to a zf 5 speed, changing nothing else.

 

[lindstromjd]

How does a zf 5 speed compare to a e4OD? Would it be close to the same if the e4od is locked up and in overdrive? I gained 3 mpg when I swapped from a c6 to a zf 5 speed, changing nothing else.

E4od has a better overdrive than the ZF, but you have to compensate for the parasitic power drain from the torque converter. So the ZF should actually get about 1mpg better than the E4.

 

[jayro88]

If I remember correct, and if my math was correct a double o/d and 4:56 gears would give you a 2:70 rear in high gear. That's a zf5 and a dne2 box. To me that would be so ideal

Your math sounds about right.

I would be all about a zf5, but it is a little more involved to do the swap in a van. I haven't looked into it too much, but I know a 3 peddle set up fort an Econoline can be found but are fairly rare. Past that I am not sure. I think IDIJohn was putting together parts for a zf5 swap in one of his vans but I don't think anything ever came of it.

 

[jaluhn83]

Doubt the lockup converter would make more than a 1 mpg difference.

C6 / T-19 to E4OD / ZF is adding an od and lockup converter, so it would be different numbers. OP is asking about C6 + DNE vs E4OD, where the only real difference is lockup vs non.

Honestly I doubt it's economically worth much, more a question of what you like best.

 

[FarmerFrank]

I think he's asking more about c6 + dne2 to e4od+dne2.

I did some more thinking about this.... At your current gear and tire size I feel a double overdrive would be about worthless. In high gear high range you'd be working the engine out of its efficiency range.

BUT
Can you imagine e4od and a dne box with 4:56 gears??? You'd be a monster off the lights and pull houses down (with the garage) and when on long trips be mild mannered, fuel sippin big ass heavy van.

 

[typ4]

If your c-6 convertor is loose , like the one in the dually, you will see a bigger improvement with the lockup. If convertor is "tight" you will gain less going lockup. If the dually would have been an e4od truck I would have put one behind the diesel, I still might but not till I could afford a BTS trans and standalone controller.

 

[jayro88]

I think he's asking more about c6 + dne2 to e4od+dne2.

I did some more thinking about this.... At your current gear and tire size I feel a double overdrive would be about worthless. In high gear high range you'd be working the engine out of its efficiency range.

BUT
Can you imagine e4od and a dne box with 4:56 gears??? You'd be a monster off the lights and pull houses down (with the garage) and when on long trips be mild mannered, fuel sippin big ass heavy van.

You are correct. I would be able to keep my DNE2 and swap the c6 for an e4od. As far as rpm, this is what I have figured.
1. If I stayed with my current 3.54's. I am at about 2100rpms at 65mph. With the e4od+dne2 I would be at 1500rpm. This calculates the e4od O/D at .71 and the DNE2 at .8.
2. If I went to 4.10's I would currently be at about 2400rpms at 65mph. With the e40d+dne2 I would be at 1700rpms.
3. If I went with 4.56's I would currently be at 2700rpms at 65mph. With the e4od+dne2 I would be at 1900rpms.

So even with 4.56's I would be at a lower rpm on the hwy and gain the locking torque converter. My torque peak, since I am currently N/A, is 1800rpms. Am I incorrect in thinking that I want to stay near my torque peak since that is where my engine is most efficient? Both 4.10's and 4.56's put me within 100rpms of my torque peak at 65mph. A slight increase in tire size could put the 4.56 right at it. Since I have a van I cannot upsize my tires nearly as much as I could on a truck. I am currently running 225/75r16. The largest I can go without rubbing is 235/85r16.

If I didn't use my DNE2 the benefit would be a deeper OD (.71 vs .8) and the locking torque converter....although I don't see why I wouldnt use my DNE2 since I already have it and it just bolts up.

 

[FarmerFrank]

Your running 225's?!? I thought you'd at least have 245/75's. 235/85 is stock size tire on my truck and I'm happy enough with how they handle and look.

 

[jayro88]

If your c-6 convertor is loose , like the one in the dually, you will see a bigger improvement with the lockup. If convertor is "tight" you will gain less going lockup. If the dually would have been an e4od truck I would have put one behind the diesel, I still might but not till I could afford a BTS trans and standalone controller.

The converter is tight. Last summer I installed a new Hughes low stall diesel towing converter. I don't have a lot of "Torque converter upgrade only" data since I did other upgrades fairly soon afterwards, but from what I have it looks like I gained about 1-1.5mpg average increase with the new converter. I used the Towing converter instead of the Fuel Miser one since I wanted to have the option to tow heaver if I wanted. Another member was also told that the Fuel Miser one wouldn't fit our setup even though it is listed as an option on multiple sites......not sure about that one.

I would definitly go the stand alone controller route. A BTS trans is probably overkill for my use and they are mighty pricey. I think a newly rebuilt one with all the updates and medium upgrades would work for me. If I towed heavy on a consistent basis and had more hp/tq I may choose the BTS route. Adding a turbo is on my upgrade list (though a ways down), but the max boost I would be running would be in the 10-12psi range. The van chassis makes finding a spot for an inter-cooler challenging and installing head studs a pain.

 

[jayro88]

Your running 225's?!? I thought you'd at least have 245/75's. 235/85 is stock size tire on my truck and I'm happy enough with how they handle and look.

Yep. I was looking at my options when I purchased new tires. I think stock for the van are right in the 225/75, 215/85 range. Talking to other e250 van members confirmed that anything more than 235/85's will rub an unacceptable amount.

General Tire has some 235/85 LT LRR tires that have gotten good reviews and are priced well. I will probably try those next.

 

[jaluhn83]

Go for it. May as well if you already have everything.

One thing to keep in mind is that there's going to be losses associated with all the gearing - that is, a direct drive high geared rear will be more efficient than a double od low gear since you're having to run through 2 od gearsets and then turn right around and drop it back down again. Also worth looking at what the rpm of the driveshaft will be and possibly getting it balanced. Chances are good that it's designed with a max rpm around what you'd get with a single overdrive and highway speed, and you'd be going 20-30% above that. This means that vibration and acceleration forces on the driveline/u-joints will be around 50% greater. Not much to be done about u-joints other than be aware that they may wear out significantly faster, but balancing I think would be wise to make sure everything is a spot on as you can get.