robox

I'm interested in mods that will increase the amount of power getting to the ground, even if the increases are only modest, but will NOT decrease my fuel mileage and may even increase it. I have been reading the forum here for a while and I think I have a pretty good idea what those mods would be. I'm interested, however, in whether anyone has anymore to add to the list or any additional info/opinions about the ones I've already compiled.

Here's what I've put together so far:
1) Bigger exhaust (a 4" system is near the top of my wish list... might try to fashion one myself, if I'm feeling adventurous)

2) BHAF

3) New injectors (I remember reading a thread indicating that new ones use fuel more efficiently. Could I get the same results by taking mine out and cleaning them? Bigger injectors would just use more fuel, right? So if I replaced them, I'd want to go with the same size, right?)

4) Modest boost in pump timing (Due to my driving "profile," I don't want to lose too much low end, so I'm gonna be sparing with this one)

5) Stiffer torque converter in the A518

6) A shift kit in the A518 (what the hell is a "shift kit?")

All pump mods are great for adding power, but do so by adding more fuel, correct?

So, anything else that will help accomplish these goals?

Thanks,
CR


(P.S., If anyone saw Monster Garage last night, I was the guy who fell at the end and gashed my arm open... Good times!)

wannadiesel

The list looks good. New injectors you could skip, just get your old ones cleaned and repopped unless you are looking for more power.

A shift kit is a group of parts with instructions. If you install the parts (typically springs and spacers that are installed in the valve body and other accessible places on the trans) and follow the procedures in the instructions, you will be rewarded with a snappier shifting trans. Not really a fuel mileage mod, but it will help the trans live longer. Smooth shifts = slippage = heat = toasted trans (eventually).

The only pump mods that will hurt mpg (assuming you aren't driving around WFO using all the power all the time) are mods that cause lots of smoke at light load. Running your star wheel and smoke screw all the way down or grinding the AFC lever will hurt your around town mileage unless you drive very carefully.

What type of driving do you do mostly? If you are stuck in L.A. traffic a lot, you should consider a 12 cm wastegated housing. The quicker spoolup gives more power at low RPM and helps fuel economy. This will also allow you to run more timing - which will help even more. If most of your driving is between L.A. and Taos and you tend to run over 70 mph a lot, stick with the stock 18.5 cm.

robox

What I'm thinking of primarily when I refer to my "driving profile" is long hauls with moderate to heavy loads. That's why I'm so interested in mpg.

Also, I've got a 3200 rpm spring sitting here (along with a new pump top from PDR) which I haven't installed yet. What kind of effect, if any, will the spring have on mpg?

Thanks, CR

wannadiesel

Definitely stick with a larger housing then, 16 cm at the smallest.

The 3200 RPM spring won't hurt your mileage. The thing to remember about diesels is that it doesn't really matter how much power the engine is capable of making, what matters is how much of that power you are using. This is why my truck continues to get the same highway mileage that it did when I bought it. It doesn't take any more power to push the 7,500 lb. brick down the road at 70 mph now than it did then - so the highway mileage is the same. Every time I get on the throttle hard I can see where the in-town mileage went.

"Stupid" mods like running the smoke screw down all the way just so it smokes on take-off will hurt the mileage due to wasted fuel. But grinding the fuel pin or turning the power screw will have no effect on mileage assuming two things - that you tune the truck for minimal smoke on take-off and that you don't use the extra power all the time. If you add power but continue to drive as you do now, you will not lose mpg.