Originally Posted by
Jim P
To the original question, if running stock truck, majority of the duration table you can leave alone. Messing with the duration table really depends on your ultimate goals. Sure you could tweak the table throughout its entirety to match it to your injectors actual flow rate, can send your injectors in to be mapped out but with stock injectors it?s pretty much fine as is. If you got high mileage injectors, about a 3% increase in duration across the board can ?restore? responsiveness and power.
Can increase duration in the upper mm3 and rail pressure range for higher torque output, 70mm3 and up and 120MPa and up, this can increase responsiveness. You?ll have to play around with rail pressure, timing, etc in the spots you want better response in to find what your truck likes and what works well for you.
Getting these truck to put out 20-23mpg every day of the year with custom tuning isn?t overly daunting or trivial and doesn?t require light weight pulleys, electric fans, wheel well ducts or any other gizmo when working with custom tuning, whether stock engine or a 700hp twin turbo engine or stock tires or 33? tires which are barely larger than stock. All it takes is time getting your truck dialed in through custom tuning.
Most add-ons that claim +1-3mpg are nothing but marketing hype, even going as far as installing manual locking hubs to keep the front drivetrain from rotating when not being used. I never seen any discernible difference it ECM output in data logs showing that free spin hub kits put less load on the engine to reduce fuel output. They have high upfront cost for cheaper bearing replacement down the road is all.
Electric fans and such just move load to the alternator which is pulley driven by the engine, more electrical load puts more work load on the engine to create the current needed to drive electrical components. The stock fan will flow more air when needed compared to electric fan and it is duty cycle driven, using an electric pulse to control the engagement of the fan from basically free spin to full locked, kind of like an electronically controlled torque converter in an automatic transmission.
Cold air intakes really do nothing for you below 550hp or so, stock air filter flows more than enough air to push a stock turbo to its extreme limits. Ultimately just make small changes in your tuning till you find the feel you like and get the results you like. Your duration, rail pressure and timing are all going to play an effect in achieving your end game.