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c6 to e4od swap. Worth it?

Discussion in '6.9L IH & 7.3L IDI Diesels' started by jayro88, Mar 16, 2019.

  1. jayro88

    jayro88 Full Access Member

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    So here is the situation. I have an '88 e250 with a c6 and 3.54's. I also have added a DNE2 aux O/D. I currently have a Banks turbo kit sitting in my garage that will be added this year as well. I currently have 260K o on the clock and plan on driving the van until at-least 500K. I am thinking about an e4od swap.If I did it I would keep the aux O/D and use a stand alone e4od controller. So I am wondering id it is worth it. Here are some key facts:
    1. I do tow with it. I pull a 30ft TT multiple times a year, plus I tow my car to the track with it. I am thinking the addition of a turbo would make power a non issue, but with an e4od swap I could switch to 4.10's (or even 5.13's) and still have lower hwy rpms in double O/D than I do now. So better towing ability and better in town mileage.
    2. I put on a lot of mileage with my 3 boys playing travel soccer. This can mean 2000-3000 a month. Plus a lot of miles for a vacation in the summer. I live in Indiana and visit family in south Texas. So basically , I could put a lot of miles on so my mpg could help money wise.

    I know that the e4od had some issues when it first came out. Mostly it was related to original weak components that have been fixed since and faulty electronics they I would fix by using a stand alone controller.

    So do ya'll think it would be worth it for the drive-ability and the increased mpg?
     
  2. Cubey

    Cubey Full Access Member

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    I'd say it's not unless your c6 dies. You're losing money by replacing a good trans. Unless you do all the work yourself and keep the c6 as a spare. But unless you expect your new e4od to not last long, why bother?
     
  3. compressionignitionrules

    compressionignitionrules Full Access Member

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    I think you will notice a lot less rpms wasted with the lock up convertor. I don't think you will need your auxillary overdrive. but put a quality TC into the E4OD and while its out, get soem of the upgrades done like they did in the 4R100. I had a 6.9 C6 in my 88 Bronco, and both were rebuilt, it was great but needed a lock up and an E4OD > I would probably still own/drive it.
     
  4. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    I'll preface by saying I don't do slushboxes... :D

    What MPGs are you getting now? Adding a double OD would certainly help if you have the needed power down that low. I don't know what the DNE2 makes your final drive but I'm sure it's going to be smack in the heart of our VE on these engines(1800ish rpms at 65?) That'll net some nice gains; but switching back to steeper axle gears will move that around. No way in heck you need taller than 4.10s especially with a slushbox, IMHO.
    How heavy is the trailer? I would not build the drivetrain for just 1-3 heavy trips in the summer, but rather aim for the bulk of your workload.

    I'd say E4OD+DNE2 and lots of travel = win.
    Especially since you plan to run it another 250k.
    Maybe @genscripter or @david85 will come by and give an expert opinion, both have done extensive efficiency mods. Or ask @Thewespaul what his magic potion is! He says he got upper teens on a 500 mile trip passing everyone lol.

    Edit: as stated above, build the E4OD up a bit to whatever makes sense. May as well be little monkeys inside them to me so I'm of no help there. cookoo
     
    Last edited: Mar 17, 2019
  5. jayro88

    jayro88 Full Access Member

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    With the cruise set at 65mph I have gotten 19mpg under perfect conditions. My average all hwy is probably about 17mpg. Mixed is 15-16mpg.

    Good though about cruising at the rpm with the greatest VE. Would that be right about the torque peak?

    With the TT I gross just over 14k lbs (van and trailer combines). Tow it 10-15 times a summer. Sometimes 15 minutes and sometimes 4-5 hours. Loads with my utility trailer are probably in the 10k-12k lbs gross weight. That would be another 10-15 times a year.

    I have been kicking around this idea for a while now. Not sure if it will ever happen though.


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  6. The_Josh_Bear

    The_Josh_Bear Full Access Member

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    Wow I've never even sniffed 19! Sounds like you are doing really well to start with.

    Honestly 17mpgs average highway is good for any IDI these days. The gurus should chime in but my guess is you would only raise about 2 mpgs average with double OD.

    Yeah @Thewespaul mentioned getting cruising RPMs down near VE(which is typically around peak torque) in another thread. I thought that was a smart way to think of it, since with a turbo peak torque will change a bit with spool up. But anyway 1600rpm is N/A peak torque, with 1800 for the turbo. I suspect those of us running more fuel will move the peak torque further still-- I'm guessing mine is around 2k. But you get the idea!

    If'n you're towing that weight so often, now I see why you are thinking of changing gears. 4.10s will pull better than 3.55 for sure. However a tuned banks setup will work better than just the gears, so you might consider doing the Banks>E4OD>gears last if you still need them. Especially since you already have the Banks.
     
  7. jayro88

    jayro88 Full Access Member

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    It is fairly flat around here, but either this summer or next summer I am planning on taking 2-3 weeks off work, hooking up the trailer and making a big road trip.

    Rushmore, Yellowstone, the Rockies, Grand Canyon etc. I want to make sure I do okay towing in the mountains.


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  8. Eli

    Eli Full Access Member

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    It'll cost at least $3,000 to do what you're trying to do, and there isn't much advantage for your purposes. I'd put a 4R100 wide-ratio gearset in the C6, but without any OD that truck ought to be right in the sweet spot about 65 MPH.

    Eli
     
  9. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    You really can’t have too much gearing but I would wait to make any decisions until you get the turbo in, and then see how it pulls. If it feels like you could really benefit from an extra gear and lockup pulling the camper so you can cruise at a bit more speed at lower rpm then go for an e40d. If it feels like the van is happy at the same speed as before and you just use less effort to maintain the speed, then maybe don’t change it. I like the c6 better than the e40d, but with no lockup the more power/load/gearing you put through the trans the more slip you will get, which leads to more heat and wear.
     
  10. david85

    david85 Full Access Member

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    Many thought I was nuts to ditch a C6 in favor of an E4OD.

    After running it for several years I'm at the point where even if it was as unreliable as many seem to think, I would still use it over the C6. I did all the work myself, however, so it only cost me parts and my time. The wide ratio gearset won't make much difference. A low stall converter will, however. I believe Gary (Icanfixall) runs an E4OD combined with an overdrive/gear splitter and is able to cruise in double overdrive with 3.55 axle ratio. To my knowledge, he's the only one around with taller final drive ratio than me. We're talking less than 2:1 here!:eek:

    If you are able to meet your towing needs right now with N/A, 3.54 gears and a 3 speed slushbox, you will only do better with ANY of the combinations mentioned so far. It really comes down to how much you're willing to spend on the truck (I consider Econolines to be trucks due to the body on frame construction). As Paul mentioned, heat might be an issue so a good cooler and temp gauge is worth having.

    For regearing, I would be cautious about that. 65MPH with 3.54 is just about ideal for towing. Adding 4.10 gears means your RPM will be near redline if you have to gear down at freeway speed. If you want every last ounce of power available then this could be an advantage. If you'd rather not wind out out like that, then it would be a disadvantage. You could unlock the torque converter while staying in 4th, but I've found it doesn't gain you much once your're on the hill and bogged down. A gear splitter solves this dilemma, but you're looking at a pretty big drivetrain upgrade at this point.

    The advantage of a having 4x2=8 forward gears is obvious though.

    One caution of the E4OD is the reverse ratio is too tall in my opinion. I've reached the torque limit in reverse on rare occasions when trying to push a heavy trailer backward up a ramp. 3.08 gears make my set up uniquely vulnerable to this but I have fitted a transfer case that eliminates the problem. You have 3.54 which is already lower ratio. Going to 4.10 means you may never reach the limit of the E4OD's reverse ratio even with that 30' travel trailer

    If you can afford the time and money of a project like this, then I'd say go for it. The only other caution is to ask how good your head gaskets are. I realize the 7.3 has better head bolts than the 6.9, but your engine does have a fair amount of miles on it so it may be worth refreshing them before getting too deep. Any way you slice it, this is going to be a major powertrain overhaul.

    Just for reference, I've attached two charts to compare 3.54 to 4.10 gears. These assume zero slip, stock tires and 3000 RPM redline. I don't have a gear splitter built into the spreadsheet but may decide to add that some day.

    3.54 E4OD Stock Tires.JPG

    4.10 E4OD Stock Tires.JPG
     
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  11. jayro88

    jayro88 Full Access Member

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    Thanks for the input and the charts. I replaced my stock torque converter a while back with a low stall diesel towing converter to try and reduce slip at lower rpms. I also have a 6.0 auxiliary trans cooler installed with a thermostat block to control flow to it to control extra heat.

    I have thought about the head gasket thing, but doing head gaskets on a van is a lot more of a pain. I know a couple of people have done it, but it didn’t sound like fun at all.

    I am thinking that I will see where I am at performance wise after the turbo install. Currently I can’t really use 4th (3rd plus my DNE2 engaged) while towing. I am hoping that I will be able to with the turbo. At least on fairly flat areas.

    At some point it will probably come down to the choice of either putting a substantial amount of money into the van and driving it for many more years, or deciding to move on from it and use the money for a new to me vehicle.......but the way I see it is that decision is about 200k miles away.


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  12. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    If you put the E4OD in it, you'll basically be at the same place as with your current set up without the aux OD engaged. If you go this way, you won't need the aux OD to be engaged while towing, but you can still use it empty. This is all assuming that you put the turbo on. Plus it will make for an interesting read for the rest of us. I think it's a win all the way around with the turbo and E4OD.
     
  13. genscripter

    genscripter Full Access Member

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    I don't know enough about the DNE2 (I have the GVOD), but I'd be worried about sourcing a tailshaft housing adapter for the E4OD. They are usually the thing that junkyards don't include when they sell the OD. I know that I'd never switch to the E4OD, because with my 3.55's and GVOD, I'm pretty comfortable with the RPM's and highway speed. Also, we haul a lot on our trips, and never had any issues with the tranny and gearing.

    Another thing I'd be worried about is EGT's with double OD's, and also, I'd be worried about high-end speeds in these vans. Running double OD's with a low gear ratio could easily get you over 75mph at under 2100 rpms. While that kind of sounds interesting and efficient, you gotta wonder how appropriate it is to take a van designed to top out at around 3000rpms/60mph on a 3-speed C6, and push that steering and suspension up to 80mph. I have replaced my tie rod ends, steering links, put in bilstein HD shocks, installed a steering stabilizer, and some of the best coils I could buy, so that my steering could be the least sloppy that I could make it, but even with all that, whenever I get up to 80mph, it's like driving one of those bumper cars from a crappy carnival. I'd hate to get my 8'6" tall van sloppy at 83mph with a cross wind. As I get older, I find myself cruising a bit slower on road trips, not just for fuel efficiency but also I'm thinking the Ford engineers never really wanted these vans to go over 70mph.

    Ultimately, the E4OD is up to you. I wouldn't, but that's just me.

    As for the ecomods, I've detailed all my stuff on my site. I think running a double OD won't give you better fuel economy. Just because you're running lower RPM's doesn't mean that you are using less fuel. Depending on the grade, headwind, and other factors, the extra gearing might force you to use more throttle to keep the vehicle up to the higher speed. Also, your Banks upgrade is probably going to cost you a few MPG as well. Once you go turbo, you won't go back to the days of creeping up to speed on the on-ramp, stoplight, and passing lane. You'll hammer down and love every second of it. :thumbsup:
     
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  14. raydav

    raydav Full Access Member

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    I started with a 1984 E350/460/C6/3.04 rear. Replaced the C6 with an E4OD/Baumman. Replaced the 460 with an 89 IDI/diesel E4OD. Replaced the 3.04 rear with a 3.5 dually. Added a remote turbo that was intended for a 2001 PSD. Replaced the 89 IDI with a 93 turbo IDI.

    The current E4OD I built to 97 specs. It has a triple disk, billet, low stall converter. One toggle switch drops out OD. Another toggle switch selects one of two trans profiles; primary difference is I have one that locks the converter in OD only and the other will also lock in direct drive. I put LEDs on all the solenoids so I know what the trans is trying to do.

    The van now weighs 9K#. It carries seventy gallons of fuel. I get fifteen MPG on open road. I sometimes pull a two axle box trailer and a three axle car trailer.

    All is well.
     
    Last edited: Mar 18, 2019
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  15. jayro88

    jayro88 Full Access Member

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    That sounds like quite the setup. Do the 3.5 gears tow well with the turbo setup?
     

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