Lighting Larger Chargers

[SmokeShow]

In general, tuning wise, what do you adjust to help light a larger charger on a single CP3 LB7??? I seem to recall someone mentioning that the LB7 likes timing to do this but I can't find any threads on it again.

So, do you fuel aggresively or moderately down low?? What do you do with timing down low (staging and the initial WOT stab)?

 

[bullfrogjohnson]

How large of a charger Mitch?

 

[malibu795]

how big of a charger?

the converter loosed enough to allow the engine to spin?

scenario... say a charger starts spooling @ 2500rpm.. it a 42XX or 4094 with a 1.XX turbine housing..A5k and the like

i would start dumping fuel 2300-2400rpm and increase timing as needed starting with 9-11* at ~60mm3 and slowly work my way up couple degrees at a time till i was happy with the results.

2500rpm @ 100mm3 im floating 20* +/- 3-4 depending on the truck dont ahve my tunes on this PC to double check... that is with a stock and comparabel charger... the A5ks i have done basicly i moved the whole table to the right on the rpm till i was in the effeciency area of the a5k.

i was still running 30* +/- @ 3000-3200rpm depending on how fast they reved the motor. shift point and whatnot...

speculation im shure pats timing tables starte roughly 1000rpms latter then a stock/mild turbo setup

if the only thing changed is timing this is bassicly what you will find.
added timeing creates pressure and clears smoke, increases repsonsiveness of the said engine and too much breaks stuff.
IMO black smoke doesnt spool a charger 1/2 as well as hazzy to clear smoke does.

JMHO

 

[McRat]

Yup.

Your timing and fueling needs to be mapped into the boost curve of the charger.

The bigger the charger, the later you bring in the fuel and timing.

 

[SmokeShow]

How large of a charger Mitch?

Airflow should be equivalent to a run-of-the-mill 2.8 charger.

how big of a charger?
see above
the converter loosed enough to allow the engine to spin?
about as loose as can get... IIRC, stall is around 2500 though the truck begins lurching before that
scenario... say a charger starts spooling @ 2500rpm.. it a 42XX or 4094 with a 1.XX turbine housing..A5k and the like

i would start dumping fuel 2300-2400rpm and increase timing as needed starting with 9-11* at ~60mm3 and slowly work my way up couple degrees at a time till i was happy with the results.

2500rpm @ 100mm3 im floating 20* +/- 3-4 depending on the truck dont ahve my tunes on this PC to double check... that is with a stock and comparabel charger... the A5ks i have done basicly i moved the whole table to the right on the rpm till i was in the effeciency area of the a5k.

i was still running 30* +/- @ 3000-3200rpm depending on how fast they reved the motor. shift point and whatnot...

speculation im shure pats timing tables starte roughly 1000rpms latter then a stock/mild turbo setup

if the only thing changed is timing this is bassicly what you will find.
added timeing creates pressure and clears smoke, increases repsonsiveness of the said engine and too much breaks stuff.
IMO black smoke doesnt spool a charger 1/2 as well as hazzy to clear smoke does.

JMHO

thanks, we'll give 'er a whirl.

Yup.

Your timing and fueling needs to be mapped into the boost curve of the charger.
in general, how do you go about doing that???

The bigger the charger, the later you bring in the fuel and timing.

Thanks folks! :hug: :cool2: :beer

 

[05smoker]

Mitch,

PM Johnboy. He is wise in the ways of the LB7.

Ed

 

[bullfrogjohnson]

Back from the dead

I need to be able to lite my charger quicker than I am now. I am having to sit on the line for at least 30 seconds building heat. I think my timing is low enough but I think I need to add more fuel down low to bring the egts up faster.

 

[JOHNBOY]

What kind off EGTs are you getting before it lights? Try adding fuel to get it to around 800*. But becareful. If your really rolling coal to get the heat you might have to moch fuel.

 

[bullfrogjohnson]

I can get about 900* but it is still not on top of the charger when I come out of the hole

 

[bullfrogjohnson]

The pic in my avatar is coming out of the hole with the older 3.0 charger with an 83mm turbine and my new 3.0 has a 87mm and I am just scared I wont be able to lite it

 

[Stingpuller]

Big Chargers

I bet you mite be surprised how well the bigger exhaust wheel will spool. Think of it like a bigger lever. Jeff

 

[jckleewein]

I had this same problem this weekend. I could not get my turbo to spool on the line. It was taking me about 25 to 30 sec. to start to spool. It sounds like I might need to decrease fueling and timing until the turbo starts to light, and then start dumping more fuel and increase timing?