Fuel rail pressure

Hi..

In this tutorial (tuning 2005 LLY Duramax), I don’t see you make any adjustment in the fuel rail pressure table..why is that? ..and in what circumstances (when is it necessary) that we have to adjust the fuel rail pressure table?

Best regards.

Mio,

In general we can max out the factory turbochargers by only adding fuel via injector duration (widening the injector pulsewidth or on-time). However, at some point we'll reach a pulsewidth/RPM where the injector is spraying fuel deep into the engine's power stroke.

Evidence of this scenario includes the following:

-Smoke that doesn't clear up regardless of boost/airflow

-EGT out of control

-Truck fails to pick up HP on the dyno despite additional fuel and plenty of air

Each platform/injector style is different but on the LLY DMAX anything over 2500-3000us PW is really diminishing returns, and anything over 3000us is a smoky mess. At this point you can usually net an additional 40-75HP by raising the fuel pressure from 23k psi to 28K psi at peak load. By doing this you'll be injecting much more fuel where it can be efficiently used in the combustion process.

More good info here -> https://www.youtube.com/watch?v=vlZ6oau3oSM&t=122s

-Nick

Nick,

Thanks a lot for your time and superb explanation..

Thank you again Guru! 🙏🏼

Mio