Modest reliable upgrades for NHC-250?

[mdainsd]

What is/are some basic mods to improve the performance of the NHC250? I don't want to go crazy, I sure as heck don't want to "roll coal", but with 53" tires the ol girl is about as gutless as the day is long . I have read through the threads and see a moderate turbo with a modest bump in fuel seems to be a straight forward approach?

Thoughts?

 

[simp5782]

Plenty of threads on this.

You only need a dual fuel line and air intake upgrade. Thosemilitaryguys makes a air intake mod. There are a few others on cutting the inner ring from the intake. I myself made a sort of ram air system on the inner fender liner with a 1000cfm filter. It works. You can also have your pump button dropped to a #16 or 18 and some good metering done and you will get a benefit. The dual fuel line install is by far the most beneficial. You can give it as much fuel as you want as long as you give her some air to breathe.

Turbos are ok but that is personal choice and damage can occur over the long term if one is negligent. Any 5 ton regardless of engine with 1600s is going to gut gutless with the Allison. It only allows so much power to go thru it. And it's gearing just sucks in general. Even worse with a stock 8.3 vs the NHC250.

Is your transmission modulator cable properly adjusted? This can make a truck seem well pretty much like a sloth on getting up to speed if it is not adjusted right.

 

[mdainsd]

I will check the modulator cable adjustments first. Ive fallen prey to not doing the obvious first before (du-Ohh).

Are you saying the 8.3s (stock) are even worse?

Mark

 

[simp5782]

I will check the modulator cable adjustments first. Ive fallen prey to not doing the obvious first before (du-Ohh).

Are you saying the 8.3s (stock) are even worse?

Mark

Off the line yes. Especially with 1600s. They have turbo lag before they have power.

a dual fuel line mod will give you alot better throttle response off the get go.

 

[mdainsd]

I looked up the dual line mod, seems like a weekend job, very straight forward.

I have my baseline. My m37 kicks the 921s arse up to about 45. I know, that bar is pretty low ...

 

[74M35A2]

Most reliable upgrade for a 250 is to put an 8.3L in its place! Sorry, just had to say it....... Can't beat the sound or low speed torque of an 855 engine though, I will give it that, but they are thirsty and get asthma once you get close to a freeway.

Please post any changes you make, we are trying to get people to actually document improvements, such as a timed acceleration run before vs after, etc...

 

[mdainsd]

But I don't want a pickup truck engine in my 5 ton! Sorry, just had to say it. (Its all good).

I will try and be disciplined about making real measurements.

 

[74M35A2]

So glad you have good humor over it. Yes, you’re right, school bus to be even more accurate.

 

[porkysplace]

So glad you have good humor over it. Yes, you’re right, school bus to be even more accurate.

School buses get 5.9's around here.

 

[98G]

School buses get 5.9's around here.

Dare i say it?

TRASH TRUCK

Back on topic - dual fuel and call it done. Anything else has excessive risk.

 

[rhurey]

I looked up the dual line mod, seems like a weekend job, very straight forward.

Until you find the rust hole or something under the floor mat and have to re-weld 1/2 the cab floor.

Or I just have bad luck.
Other things if you're going to play with power are to get a pyro to measure exhaust temp.

While it's not performance, coolant filter.

 

[SyrionDeathvow]

https://youtu.be/wXwKa4PH2sQ