Hell, if you can get in the upper teens with a 1 ton 4x4 diesel you're ahead of most others. Big block would get what...10mpg while a small block might do 12 or so?
CK5
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CUCV Needs OD
- Thread starter CUCV2
- Start date
CUCV2
5/4 ton fun
I think the set-up will be on par with what a Dmax gets. At least mileage wise. 
After looking at your sig, it will also be on par with your tracker. LOL
After looking at your sig, it will also be on par with your tracker. LOL
Hahaha...be careful what you wish for. Sounds like a lot of the newer Duramax's (and PSD's and Cummins) aren't getting chit for mpg as they try to squeeze all that power out of them and now there's the new emissions and ULSD muddying everything up...
I'm pretty sure I don't have a ton of pressure blowing out the intake and air filter when I decel, and I'm pretty sure the intake and exhaust valves are still closed during the compression stroke while the pistons are trying to compress that air 2-3 times as much as a normal gas engine.
My DD gas truck has very little compression braking also, even if I put the auto down into 2 I still usually have to use the brakes quite a bit to control speed while hauling my 9,000 lb. trailer around.
I'm sure if gas engines were common in 80,000 lb. tractor-trailers they would have some type of engine brake on them also.
I never said that air was flowing backwards through the motor. You're misunderstanding what I'm saying.
The air that is compressed also helps push the piston back down on the power stroke, kinda like compressing a spring.
Without any restriction to in/out airflow in the engine, the only resistance to travel with diesels in coasting situations comes from internal engine friction and the gearing in use at the time - diesel engines don't have natural compression braking as do gas engines, and only addition of devises like exhaust brakes will deliver significant resistance to vehicle coasting on downgrades.
A gasoline engine provides braking because the closed throttle plate turns it into a vacuum pump - which produces negative (braking) horsepower.
Masiony
1/2 ton status
you mentioned needing a 32 spline t-case for the nv4500. do you know that the 4l80 is also 32 spline just like th400's?
Mikey von
1/2 ton status
I am in the same boat as far as need OD. My plan (after I finish my house) is to swap in a NV4500. I know it won't be simple, but it has been done. IIRC the th400 and the NV4500 are about the same length, so I believe a drive shaft swap is not needed.
CUCV2
5/4 ton fun
Yes, all three of those are 32 spline. I was referring to the 700R4 that he suggested building up not being 32 spline. I am not aware of any of those being 32 spline. There is probably a way to change that but it adds to the cost of building a 700R4. And if a 700R4 cost about the same as putting in a 4L80e, wouldn't it make more sense to put in the 4L80e. You could put in a matching tcase for the 700R4 but the 32 spline set up would be the stronger choice. Thanks for the clarification.
I did wake up thinking about the NV4500 and how much that would cost to install. What year and vehicle would be a good donor for that?
Masiony
1/2 ton status
93+ chevy IIRC
on a side note, my burb has a 4l80e, and i drive it everyday. its a nice auto dont get me wrong, i just dont think the OD is really giving me much of a break on the MPG's. if i had my way it would probably just have an old reliable sm465, but that would be a little odd for some people in a 94' (not too many manual burbs, especially in those years).
on a side note, my burb has a 4l80e, and i drive it everyday. its a nice auto dont get me wrong, i just dont think the OD is really giving me much of a break on the MPG's. if i had my way it would probably just have an old reliable sm465, but that would be a little odd for some people in a 94' (not too many manual burbs, especially in those years).
uao85
1/2 ton status
The reason you dont have much compression braking is bc your driving an auto, and even manually shifting down into a lower gear doesnt prevent the transmission from constantly slipping by way of the torque convertor to allow good driving characteristics/manners etc. Try driving a stick gasser and say there is no compression braking.
Remington
That's not really my point. There is some compression braking with an automatic, and I'm comparing an automatic gas vs. automatic diesel and to an auto gasser vs. manual diesel. In regards to compression braking my diesel seems to have more (at least when the two have been in the same situation). I test vehicles for a living, and I've driven other diesel trucks where you could lock up the rear tires by downshifting (compression breaking)...I know gearing multiplies compression breaking, but if diesels had no compression braking then it wouldn't do this ( zero x million = zero).
Its not zero, its just much less than a gas motor.
Maybe so but it is possible to get good compression braking form an auto.
I'm currently running a th-400 that would rival any standard out there for compression breaking.
CUCV2 - If a 700r seems like a reasonable option for you, I've got one you can have.
Was said to be good when I got it but I'd still rebuild it.
CUCV2
5/4 ton fun
Does that 700r happen to have a tcase? I'm starting to think 40" tires would be the best OD.
gm guy
1/2 ton status
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very good thread! I'm giving thought to the nv 4500 since I had great luck with a NV 3500 in the past.... Either that or the 4L80E with manual valvebody.
I am currently putting a 700R4 in my M1008.
It is a straight bolt-in so far concerning driveshaft lengths.
I needed a new flexplate, TC, and TV cable/rod/bracket.
I already had 36s on my and that was not enough OD to make me happy.
I am not done yet, so take what I am saying with a grain of salt.
adam
It is a straight bolt-in so far concerning driveshaft lengths.
I needed a new flexplate, TC, and TV cable/rod/bracket.
I already had 36s on my and that was not enough OD to make me happy.
I am not done yet, so take what I am saying with a grain of salt.
adam
CUCV2
5/4 ton fun
More details and pics would be awesome. Where are you at with it?
Not enough OD? Really?
According to the gear chart, a 700r, w/4:56 gears and 36" rubber should get you right around 1900rpm's on the highway @ 65mph but being a diesel maybe you want it lower still.
That combo will also get you out a 79:1 crawl ratio too.
with a diesel, peak mpg is around 1800rpm. i have 6.2/th400/205 4.56 and 42's (before that 4.10's and 39.5's) and it sucks in town. its got no balls off the line and going deeper gears puts it back in the same situation. i never realized how much of a difference overdrive makes until you dont have it. with overdrive you could easily run 4.88's/5.13s so youd have decent off the line and still have the lower rpms on the highway with the overdrive
i think he meant with the 400 in it still and 36's it was not enough overdrive. that combo would be 2766 rpm's to run 65.
i am looking at putting a 700 in my m1009 for sure with some 4.56 axles and running the 37 inch hummer tires, since i have a few sets.
same on my m1008, although i may just go with 3.73's in the axles.
