Hello...I do not own a Cummins powered Dodge truck....yet. Checking classifieds local to me I repeatedly see different ads wanting 1st and early 2nd Gen trucks with the Cummins engine and specifically 12 valve engines. I am not trying to start a war but IMHO electronic controls should give better fuel economy and easier HP/Torque via tuning. Is this a nostalgia thing or maybe a reliability issue?
I have been centering my search (but not limiting it) to pre 24 valve trucks. I do not have a large budget so I am interested in slight mods maybe doing things that are not too expensive and do not affect drivability, fuel economy or reliability

 

It is a reliability issue more than anything. As for MPG, you would think the space shuttle trucks would get you better, but the reality is the first gen trucks are the MPG kings.

As for ease of HP? Yea, flipping a switch is much easier......

 

How about boosting available HP and torque without affecting fuel economy?

 

Fuel economy is controlled by your right foot, hp mods make no difference except turning up the timing which increases both hp and mpg.

 

We have a few VW TDI's in our household. Timing is set mechanically via rotating the injection pump in very small ammounts. After a change the result is checked via a software program running on a laptop using a cable plugged into the OBD port and is checked at idle only. If you are within factory recommended parameters you are good to go. After that fueling and timing are modified by the tune you have which is setup according to what modifications you have nozzle size, turbo size and how good your clutch is. Some guys do away with the drive by wire setup in order to have a direct injected engine in a different vehicle however they are not able to reproduce both the fuel economy and hp/torque characteristics of the electronically controlled setup.

 

Maybe the results are a lot easier to verify on these VW engines because the fuel economy is higher and a change is easier to verify ex my 97Passat averages 800miles/tank when I pull a 1800lb trailer it drops to about 550 on a similar fillup so I really notice this

 

I own a 1985 vw golf with the mechanical bosch pump And I got 64mpg on one trip with a light foot and turning the key off on long downhill's (shuts the fuel off 100% rather than always feeding in idle fuel) tires @ 50psi and rear drums adjusted to zero drag.
The 24 valve electronic Cummins do great, with MPG as well as the mechanical 12 valve ones. the electronic ones idle higher and have a higher redline thus they "can" use more fuel than a stock 12 valve mechanical.
My 12 valve gets 19-22mpg with cruse on at 70mph highway
my old 24 valve with a stock VP44 pump got 18
my 2006 duramax chev (lost during recession) got 20MPG but I account that to the stock knife blade tires and the 6th gear.

 

That is exellent fuel enonomy particularily for an older IDI. My VW TDI economy would be about 52 mpg (US gal) in the summer averaging 60-65mph with AC on. I have upgraded my nozzles by one size from stock and they have a coating that helps atomize the fuel better improving both economy and performance (win/win). I have never tried any of the hypermiling tricks. but have read about guys using them and getting up into the mpg that you have achieved. as for myself I like having the use of the powersteering and brakes at all times.
I have also owned a 96 F250,PSD,excab,LB,4x4 it did about 15-17mpg hwy (US gal) empty which was a bit better than my 84 F250 6.9l ex cab,4x4. The 96 was a much nicer truck and had lots more power.
I am hoping to find a retired 2500 2x4 with a 5 speed and hwy gearing

 

One of the things I liked best about my 1992 12 valve truck was the higher compression ratio vs. my current 2000 truck. That old 1st gen would start in subzero temps without needing to be plugged in, where my 2nd gen turns over a couple of times and then laughs at me if I don't plug in below about 20 deg. F.

That higher compression ratio is probably helping fuel mileage as well for the 1st gens, but there's so many other things that factor into mileage that it's almost impossible to say. Like Infidel says, the right foot is about the only real constant.

Mike

 

LOL. my right foot always seems to be getting me in trouble!

 

Is there be much difference between the 89-93 and the 94-98 12 valve engines other than the injection pump and if there is an IC?

 

Not much at all................

 

i believe there is also a simplicity factor as well. the early 2nd gen trucks had AT's that were 95% hydraulic as well. thats what i like about mine. in the event of a catastrophic electrical system failure you're still mobile. my engine and 1-3 gears require no electricity to operate

 

I should also ask if fuel economy is the same between 1st and early 2nd Gen (all things being equal)

 

Pretty close, the VE ( first gen ) had timing advance, the P7100 doesn't.

Probably 1 MPG or less difference.