Is the 8.3L Turbo Cummins the " best " engine ?

[PoppinZombies]

Hey Guys , thinking of picking up an M932A2, to add a shorty bed to. Or an M923A2. Which engine is more reliable ? The NHC 250 or the 8.3L Turbo ? Either one have any real drawbacks or benefits ? The gist I'm getting is that the 8.3L Turbo gets better mpg and has more power on hills ? Is that right ? I'll just be driving for fun and occasionally be pulling a toy hauler.

Thanks.

 

[BKubu]

I've had trucks with both engines that I felt were really powerful. The point is, if you find a good running NHC250 or 6CTA8.3, you will be happy. I have an M925A2 that has serious power; many others I've had were slugs. I have an M934 that will kick your a** back in the seat when you hit the pedal; I've had others that were not as powerful. The key, to me, would be condition, price, and proximity to me (in that order). The 6CTA does seem to have more top-end power. The NHC250 has more power from a dead stop. I feel that the A2s really don't want to move from a dead stop...then, as the tires start to turn and the turbo spools up, the truck pulls nicely.

 

[PoppinZombies]

Thanks. Is one more reliable than the other ?

 

[porkysplace]

Thanks. Is one more reliable than the other ?

It depends on how they are taken care of.

 

[trooper632]

Might be easier to get parts for the 8.3 just because its a newer engine, but I'm not 100 percent sure on it, 8.3 is quieter which is nice

 

[Scott88M]

With so many variables I'd look more into quality/price of the truck first and engine second. For what you want it for either one would probably be fine.

 

[Gunzy]

If you can test drive both it's best. that way you can make your own decision. The 8.3 is supposed to get better mileage, but the NHC250 has better bottom end.

 

[chess]

If your only comparing the 250 and 8.3 there's plenty of downs for the 250 like it's heavier, less power, cylinders liners go bad more frequently, too many belts on it, Noiser, less fuel efficient. Has canister filter element for the oil, harder to start when cold also needs more battery power, there is no downsides to the 8.3 and the a2 900 series 5 tons is a better truck. Stronger front axle. And outbore brakes.

 

[1 Patriot-of-many]

If your only comparing the 250 and 8.3 there's plenty of downs for the 250 like it's heavier, less power, cylinders liners go bad more frequently, too many belts on it, Noiser, less fuel efficient. Has canister filter element for the oil, harder to start when cold also needs more battery power, there is no downsides to the 8.3 and the a2 900 series 5 tons is a better truck. Stronger front axle. And outbore brakes.

The downside is you can't buy just one.

 

[chess]

i knew i forgot something hahahah.

 

[armytruck63]

If you were planning to operate the truck at high elevations, then the 8.3 with turbo would be a better choice. Obviously, not a concern in Florida.

I love my NHC250, but I haven't had it up in the mountains yet. It has a definite happy spot at 1900 RPM.

 

[PoppinZombies]

That's the info I needed guys. Thanks.

 

[porkysplace]

If your only comparing the 250 and 8.3 there's plenty of downs for the 250 like it's heavier, less power, cylinders liners go bad more frequently, too many belts on it, Noiser, less fuel efficient. Has canister filter element for the oil, harder to start when cold also needs more battery power, there is no downsides to the 8.3 and the a2 900 series 5 tons is a better truck. Stronger front axle. And outbore brakes.

You forgot the A2's are known the split the transfer cases when reverse is used in low range.

 

[RustyM923]

You forgot the A2's are known the split the transfer cases when reverse is used in low range.

I thought the A0, A1, and A2 used the same transfer case?

 

[Scott88M]

I believe it has some to do with the big tires too I don't think the problem was as prevalent with duals

 

[BKubu]

You forgot the A2's are known the split the transfer cases when reverse is used in low range.

That is not a problem that is specific to the A2s. The entire series suffers from what I believe was a failure in engineering. Check out the data plates on any M939 series truck...they will direct you NOT to use reverse in low range.

 

[Nasty610]

I've been doing a lot of research on these engines recently. Both engine produce roughly the same power if left stock. The 6CTA can be turned up a lot further than a NHC250 though. Either engine can be turned up far enough to destroy the transmission.

The 6CTA was produced in power levels up around 450 HP and can built/tuned to over 1000 HP. They can also turn 3000 RPMs safely. These engines are widely used so parts are readily available.

The NHC250 is a Cummins Small Cam engine that was produced in the 70s. The Small Cams were produced with power levels up to 335hp. There was a "smoke kit", which was mainly a turbo, available for the non-turbo engine to reduce engine smoke. With the addition of the smoke kit you should bs somewhere in the 270-290 HP range. You can add the turbo and pump off a Cummins Big Cam for more power. The block may or may not have provisions for oil squirters so you'll need to watch EGTs to keep the engine safe. The Big or Small Cam engines will turn 2350 RPMs safely under load.

Either engine is a great choice. If youre worried about mileage the 6CTA is a much better choice and should give around 10 mpg while the NHC250 is only going to get 5ish mpg. If you're looking for big power and RPMs the 6CTA is also a much better choice. About the only real advantages the NHC250 has is lower price and it sounds amazing.

There's a lot in favour of the 6CTA but there's something about the old 250. Personally I'm more interested in the NHC250. I'm not sure which engine would be the "best" though. Like everyone else said if you can drive both that will help your decision. Another thing you should consider is repairs. If you aren't able to work on it yourself there will be more shops able to work on the 6CTA then the NHC250.

 

[RustyM923]

That is not a problem that is specific to the A2s. The entire series suffers from what I believe was a failure in engineering. Check out the data plates on any M939 series truck...they will direct you NOT to use reverse in low range.

Reverse is just over 10:1 ratio (DEEP). So, basically, engaging the transfer case in reverse is SUPER STEEP (over 18:1). It's a good way to tear apart your transfer case on any of the versions. Floor your truck in reverse (high range) and you'll see what I mean...you'll be going sloooowwww.

 

[chess]

When I convert my 5 tons to water trucks I have my allison trans guy put the first and reverse gear pack from a 653 on this 654. Which makes it a 8:1 low first and a 5.67 reverse. Perfect for going quicker in reverse and slowwwww in first.