The ZF Helps with MPG here is the proof

[Cincinnati Guy]

I been using fuelfrog for a long while, When I had the C6 I was getting 11-13 MPG, only one time did I get 19 but only because I was traveling I-75. The last two readings show the average of where I am at now with the ZF5. I plan on keeping up again with the tracking of my mileage, I just kind of slacked because it wasto depressing.

http://fuelfrog.com/users/rmalott/fuels/records

 

[dakotajeep]

I am a mileage nerd too. I have every fillup I have ever made with my truck. Its nice when the mileage is up so high...

I would love a ZF 5....I wonder if its better to swap one in or buy a whole new truck.....

 

[punkmechanic]

swap one in. You get to know your truck and all its ups and downs, buying a new one is nice for a bit, then you find the flaws and start to think about your old one. vicious cycle.

punk

a zf swap isnt too bad if you have the parts ready.

 

[dakotajeep]

I meant "new" as in different IDI with a 5 spd.....but I understand. I just lack the time and ability to put a 5 spd in myself. Unless you want to volunteer your time and come to Kansas.....please?

Thad

 

[subway]

you can do like my brother in law did with me. we found a idi truck for cheep with a connecting rod hanging out the side of the block. he needed the 5 speed i needed a turbo. we grabbed some other misc stuff and parted the rest. after all was said and done i think we about broke even not including labor.

 

[dakotajeep]

The biggest problem is that I lack the time, tools and know how to complete the process efficiently....

 

[gonecrazyi]

Heck, half the things that I do I had no Idea how to do them before I jumped in and tore things apart.

I can put anything back together that I can take a part.

In reality, putting a 5 sp in is far easier then putting in the automatic. The only thing to deal with would be the rear driveshaft.

 

[Sycostang67]

Hey Ryan, nice to see a familiar truck. Glad to see your liking that 5spd swap. I bought my IDI with a 5spd so I wouldn't have to do it again. I still picked up 4.5mpg with my 460 by ditching that C6. I'm still getting better mpg with the diesel though.

 

[david85]

If there is a MPG difference between an E4OD and a ZF5, I haven't seen it. The E4OD has a little more losses, but has a taller overdrive ratio. Once you are up to cruising speed, I would be very suprised if the losses would be much different between the two transmissions.

I suppose it you simply don't like the E4OD and prefer stick shift, then that could be reason enough to swap to a 5 speed, but you will NOT see the kind of gain as going from a C6 to a 5 speed. The C6 is a great transmission for anything other than cruising/economy .

I was able to keep my truck between 19 and 24.9 MPG highway last june when fuel prices were going ape sh*t. Averaged about 4 fillups between those numbers but the average is lower since I usually drive with an eye on the clock lately instead of the fuel gauge. That will probably change by mid summer with fuel prices drifting up already.

 

[Shadetreemechanic]

If there is a MPG difference between an E4OD and a ZF5, I haven't seen it. The E4OD has a little more losses, but has a taller overdrive ratio. Once you are up to cruising speed, I would be very suprised if the losses would be much different between the two transmissions.

I suppose it you simply don't like the E4OD and prefer stick shift, then that could be reason enough to swap to a 5 speed, but you will NOT see the kind of gain as going from a C6 to a 5 speed. The C6 is a great transmission for anything other than cruising/economy .

I was able to keep my truck between 19 and 24.9 MPG highway last june when fuel prices were going ape sh*t. Averaged about 4 fillups between those numbers but the average is lower since I usually drive with an eye on the clock lately instead of the fuel gauge. That will probably change by mid summer with fuel prices drifting up already.

I agree with above.
I recently traded IDIs and went from an e40d to a zf, both with 3.55s. I have picked up a mpg or two in around town driving, but I lost it on the interstate. The taller OD on the e40d really makes a difference. Before I could travel about 72mph without breaking 2krpms. With the zf I approach 2k just a hair above 65.

 

[Brutis]

I hit 2k at about 53mph with the E40D. I have the 4:10s though. Does that sound normal?

I was thinking about swapping in a manual trans until I read this thread. My torque converter is going out and I'm not sure if I want to just replace it or put in a manual. I thought I might increase mpg. I get 12-13 currently.

Anybody have a thought on this?

 

[6 Nebraska IDIs]

I hit 3400rpm at about 60mph in my brown truck, but it still has the T19 and a 4:10 locker in the back.
Think i got about 7-8mpg in that thing. lol

 

[Brutis]

I see you're going to swap trannys and put in an ATS non-wg. That should bring your 7-8 up! I'd like to do that myself.

 

[6 Nebraska IDIs]

Check it again, had to edit it.

 

[crashnzuk]

Speaking of MPGs, what RPM does a 6.9 return best mileage. It really seems to like 2300
Travis..