This is my first post on this site, but I have spent a lot of time over the past few years over at 4BTswaps.com discussing the Cummins 4BT that I rebuilt and installed into a 1980 International Scout II. I do know a bit about diesels, but not as much as a few folks on here whose posts I've been reading.

I just bought a 1991 IH 4900 with a 185-HP DT466 (crew cab, 22 foot box truck).

I bought it to replace my 1985 Chevy Kodiak with a Cat 3208 non-turbo. One of the big reasons I wanted to replace the Chevy was because of the 7-8 MPG I've always gotten. I have always read that the DT466 does quite a bit better than that; something in the 10-12 MPG range.

I bought the International without ever seeing it or driving it. Yes, that's maybe a little bit of a risk, but the price was excellent for a crew cab with a long wheelbase, and only 146K miles.

The truck seems to suffer from low power (especially when it's hot outside) and also from low fuel mileage, like something in the 8 MPG range.

I'm not opposed to performing the fuel-screw and timing mods that nevrenufhp has discussed on here and video'd up on youtube to "wake up" the engine a little, but..... I don't think they are going to improve my mileage.

Any ideas where to start looking to address these issues?

Thanks,
Christian

 

The fueling mods do improve the mpg per tankful, just as long as you dont drive like a maniac. Hiking up the timing will bring it up some too. Then, with a little added power, you can go with better rear gears to slow the engine down on the highway. Even if you drop a half a point(like 4.78 to a 4.44), it'll help.

 

Thank you , Dale.

I was hoping that you would respond to my post. I've read much of what you have written on here, specifically about the DT466, and I really appreciate your knowledge.

I have also noticed that my brand new truck does not have an intercooler... I need to remedy that, pronto! I know an intercooler will help remedy the low power situation, as well as the "poor performance in hot weather" situation, but.... will it also help the mileage?

I am considering upgrading the turbo, as well. Any idea what would come stock on a 185HP 1991 DT? I've read elsewhere that an HX40 would be a good upgrade. Would that be a bolt-on?

Thanks again,
Christian

 

I try to throw in my 2 cents here & there.
Wow, being a 91, it should have an intercooler. You should easily be able to find all that stuff at a truck bone yard. Yep, it all helps the mpg. Think of all of it as teamwork to achieve power and mpg.
The work truck in my sig went from 3.7 to 5.5mpg just from the freebie mods.
The stocker is made by AiResearch, and is a little guy. The compressor on an HX35 is even bigger. There's a couple options for a turbo. The cheapest is an HX40 from a Cummins 8.3 and the other is the Garrett GT40 from a DT466/530E. Either isnt a total bolt on, but the GT40 would be easier to make fit...but not by a whole lot. A Schwitzer S300 is another good option.

 

Thanks, nevrenuf.

There aren't really any truck yards near me, so....
I spent a few minutes poking around on eBay.
I assume that the HX40s made for the 5.9 Cummins are too different to use in this application, correct? (They are plentiful.)
There are Garretts on there too, including one for $200 that needs a rebuild. Thinking about that.... BTW, what does A/R with a decimal after it (like A/R .72) mean in turbo designation?

There are intercoolers on there too.
When I built my 4BT Scout, I just bought a generic intercooler that would fit, and a piping kit, and got it in there. It did wonders for the EGTs and the power. I will do some calling around to parts yards down in Albuquerque on Monday to see if I can turn anything up especially for the IH, but if not I might just start hunting for a generic one.

Thanks again,
Christian

 

You can use the ones for the 6BT, but you'd need the T3-T4 adapter to mate it to the manifold. It's going to need to be a larger exhaust housing. In Holset terms, look for a 16-19 square cm housing. In most other cases, they list just the A/R(Area Ratio). That's just the relationship ratio referring to the size of the snail to the size of the piping inside it. Look for something in the 1.1-1.3 area. Go bigger if you're going past 300hp. If you want big towing power, an HX50 or Pro52 would be a nice kick in the fanny.

 

So, my turbo actually seems to be a Garrett, rather than an Airesearch....



With an A/R .60 Kinda small, I guess. It sure looks small.

Does anyone know what the solenoid tucked behind the IP does? It is connected to a lever-arm and shaft which appears to enter the pump...

 

The Garrett is a T04, which isnt anything special. A compressor in the 53mm range, where an HX35 is 56mm. The A/R you're looking for is actually on the exhaust side.
That solenoid is the shutoff sol.

 

OK... thanks.

I am used to the shutoff solenoid being internal, as it is in the VE pump.

Now I understand what is meant by "tie up the shutoff solenoid" as part of the fuel screw adjustment procedure.

My engine is set stock at the factory at 17 degrees timing (as indicated on a label affixed to the engine), and I have read elsewhere that with 17 degrees timing, you might not even feel the difference going up to 19 degrees. But my truck is pretty sluggish, so I think I'll do it anyway.

Gotta get EGT and boost gauges in there pretty soon. Speaking of which.... I was looking around the intake manifold for a convenient port to plumb in a boost gauge, and didn't see one, other than the little tube that goes into the injection pump. Should I TEE off of that one for the gauge? Or is there a port I am not seeing?

 

Shoot, 17 isnt too bad. You could even put it to 20 if you want.
There isnt but a couple places for the booost gauge. A Tee off the boost reference will do fine.