250hp vs 275hp calibration

[Outlaw Bill]

This has been eating at me for years. What is the difference between the two?. Only the 6 speed had this cal, I keep hearing its the same as the 250hp, but the 6 speed eats less power, which I don't believe for one minute. I hate having smoke blown up my behind.

[Power Hungry]

Okay, so we won't blow smoke up your behind, but how about out your tailpipe? (Sorry... I couldn't resist.)

The manual transmission trucks have always had a higher power output rating than the automatics because Ford felt the ZF6 could handle the power and wanted to prevent automatic transmission failures to a minimum.

To answer your question quite simply, the manuals have some moderate tuning changes to make more power in the RPM range in which the engines are rated:

A/T - 250 HP @ 2600 RPM, 505 Ft./Lbs. @ 1600 RPM
M/T - 275 HP @ 2800 RPM, 525 Ft./Lbs. @ 1600 RPM

Two significant changes are:

Mass Fuel Limit vs. RPM

(Click to Enlarge)

Start of Injection (Main)

(Click to Enlarge)

As you can see, Ford specifically modified these table to achieve another 25 HP out of the engine in the higher RPM range. They raised the Fuel Limit on the M/T trucks and also added about 3º of timing starting at about 2600 RPM.

Ford didn't do anything special really... just did what the chip manufacturers had been doing already.

Take care.

[Outlaw Bill]

Thank you Bill.