400 Cummins or 8.3 Cummins??

[wehring]

Thinking of swapping out my NHC 250 for a 400 Cummins or 8.3 Cummins... any opinions on this??

Justin Wehring
979 997 3112

 

[emr]

Yes there are alot, look thru past threads, and U will read for awhile.... wish i was doing it.

 

[armytruck63]

One possible concern, will the Cummins 400 turn as fast as the NHC 250? Just asking, I don't know.

 

[wehring]

Don't know

I assume that all 3 are limited to 2200rpm.

Justin

 

[bigjuice69]

what truck is it going in?? the 250 is 855 cubic inch as well as the 400. the 8.3 is 508 cubic inch some where in the ball park anyway.

 

[Trango]

Cubic inches only tell part of the story when comparing cummins of different generations, e.g. the NHC and 6CT series.

 

[Trailboss]

Thinking of swapping out my NHC 250 for a 400 Cummins or 8.3 Cummins... any opinions on this??

Dibs on your NHC - I can pick it up tonight!!

Actually, I really have been thinking I need a complete drop in NHC250 engine after all the trouble I had finding parts for my old one.

Assuming the 400 and 8.3 are otherwise equal as a replacement, you might also consider the availability and price of repair parts.

 

[m16ty]

Both the 250 and the 400 turn the same RPMs.

The 400 will bolt right in but you will have hood clearance issues to deal with because of turbo pipes.

 

[wehring]

Thanks

Thanks for the thoughts. It is going in a M925 that already has the MT654CR Allison.

Either one (8.3 or 400) should bolt in. The 8.3 I have is currently sitting in an M931 truck so I know there are no clearance issues.

Here is the drama... I bought a set of factory air locking differential 5 ton axles to put in the same truck but they have 5.81:1 gears in lieu of the 6:44.1 in the 5 ton. Looking for enough power to pull the higher gears with 14.00s

Justin Wehring
979 997 3112

 

[m16ty]

Thanks for the thoughts. It is going in a M925 that already has the MT654CR Allison.

Either one (8.3 or 400) should bolt in. The 8.3 I have is currently sitting in an M931 truck so I know there are no clearance issues.

Ok, I thought you were talking about a 800 series. Disregard what I said earlier (except about the 250 and 400 having the same RPM).

 

[LanceRobson]

Keep in mind that if you put in an NTC 400 and use the power for really fast acceleration as opposed to more gentle acceleration and maintaining highway speed you'll be twisting parts off the drivline in short order.

The injectors and turbo in the 400 will have a big effect on how the engine is going behave and what economy you'll get. there's a world of info on Cummins 855 engines at Pittsburgh Power's website on selection.

• View forum - Bruce's Articles

I'm jealous. Have fun.

Lance

 

[M1075]

Keep in mind that if you put in an NTC 400 and use the power for really fast acceleration as opposed to more gentle acceleration and maintaining highway speed you'll be twisting parts off the drivline in short order.

The injectors and turbo in the 400 will have a big effect on how the engine is going behave and what economy you'll get. there's a world of info on Cummins 855 engines at Pittsburgh Power's website on selection.

• View forum - Bruce's Articles

I'm jealous. Have fun.

Lance

Woo-hoo, air lockers! Nice! What is your intended application for the truck. I think the gear change might be very desirable, unless you will have a higher gross weight and/or operating off road.

 

[mudguppy]

depends on what you want to do w/ the truck. the 6CT is a medium duty motor and the 400 is a heavy duty motor. either will have more power than the 250. the 8.3 can be modified to turn higher rpms. the 400 will have more torque than the stock auto will be happy with it you get in a bind, so it will need adjusted/worked-over.

 

[wehring]

Uses

M1075,

I am purpose building a go-to recovery truck. I don't have anything but bobber deuces and I need a heavy tow rig to drag other treasures home. You of all people know how nasty Hooks can get!

The mid-axle power divider, air shift front axle and 5.81 gears will be a treat for on-road travels. The air lockers and hydro winch will cover the dirt. I am watching Adam's post about 5 ton locking hubs. These will complete the package.

On Road: power only to middle axle, front axle completely disabled.

Off Road: Power to all 3 axles with all 6 tires pulling.

Justin Wehring
979 997 3112

 

[M1075]

M1075,

I am purpose building a go-to recovery truck. I don't have anything but bobber deuces and I need a heavy tow rig to drag other treasures home. You of all people know how nasty Hooks can get!

The mid-axle power divider, air shift front axle and 5.81 gears will be a treat for on-road travels. The air lockers and hydro winch will cover the dirt. I am watching Adam's post about 5 ton locking hubs. These will complete the package.

On Road: power only to middle axle, front axle completely disabled.

Off Road: Power to all 3 axles with all 6 tires pulling.

Justin Wehring
979 997 3112

Sounds like a cool project. The stock 250 might meet your needs as-is. If you are planning to tow/haul big stuff, I would go for 400 hp.

 

[wehring]

Bruce

Yep, I just got off the phone with Bruce and he said the same thing. He gave me some pointers for flushing out the fuel system to wake the motor up.

Only time will tell. I have no experience with the 250s. I will get it home and hook up to another 5 ton and drag it around and see...

Justin Wehring
979 997 3112

 

[supermechanic]

One more vote for the 400 cummins.
I have years of experience with it ,I think you will like it.
Hard to improve upon a prover player.