So I am still a ways off from getting a pyrometer; I need to do steering shaft and wheels/tires more urgently, but I am itching to bump the timing a little, if only to see if I can get a little better mileage.

I just ran almost pure biodiesel through the truck for 300 miles of mostly short trip and non-freeway driving and got 16.3 MPG, which I know can be improved on. I have been wanting to try the 1/8" bump, but have been reluctant to without gauges. Is that much timing advance going to:

a) help my mileage at all?

and

b) run any risk of increased EGT related problems?

I have the factory "lagmaster" 21 cm housing, so at least it's not too restrictive. At the rate I'm going now, it will be late summer before I can afford any gauges..

 

Timing will generally increase mileage by around 1mpg, depending on how advanced you run. It will also decrease EGT's.

 

You may find the lag unbearable with that 21 cm housing. The retarded timing helps the turbo spool.

 

Oh. Well, maybe that one will have to wait a while too, until I can switch to a 14 or 16 cm housing, which I definitely don't want to do without gauges.

 

I didn't say not to try it - you can always put it back if you don't like it.

 

true enough. And I am not out drag racing or anything either. What about the retarded timing makes the big turbo housing work better?

 

As you advance the timing, fuel is injected into the cylinder earlier. This earlier injection means the fuel is being more efficiently used (more completely burned). This leaves less heat energy in the exhaust gases, because more is being used to drive the piston downward. With less heat energy in the exhaust gases, the turbocharger isn't driven as hard, and will take longer to spool up and produce less boost.

Also, you'll see a slight decrease in torque with advanced timing.

 

In theory, yes, but retarded timing also leads to higher EGTs, even if the turbo does light sooner.

edit: got a pyro?

 

Not yet. That's part of my concern.