Introduction

Hondata has undertaken a study of the fueling and ignition or the boosted tunes in the tunes library. This information has been averaged and applied to the boost section (columns b11-b16) of the fuel and ignition maps. The result is an improved set of base maps and a further reduction in tuning time. All the Hondata base maps in the tunes library and those supplied with Hondata will be updated and made available to stage 4 owners (soon).

When tuning your choices will be to either modify an existing tune from the library, or to start from one of the improved base maps, utilizing some of the changes documented here.

Creating forced induction tables

This is found under the Edit menu, and can be applied to any base map or tune from the tunes library.

Ignition

Hondata was conservative in the amount of ignition retard under boost in the base maps. By default the ignition was set to retard 1.5 degrees per lb of boost. 0.75 degrees per lb of boost is more appropriate (and still probably a little conservative). Generally after 11.4 lb of boost, the ignition values should level out. However it up to the tuner to decide what is the best ignition advance. All tuning should be done with the distributor set to the Honda's recommended setting.

The default boost ignition maps previously looked like this for a B18c GSR:

After applying the 0.75 retard per lb of boost and manually editing the ignition values after 11.4 lb of boost, the ignition timing should level out and look something like this: (changes start from column B11)

Fueling

The default Hondata fueling maps are set to deliver fuel with a turbocharger efficiency of 75%. What this did not take into account was the increase in brake specific fuel consumption characteristic (drop in fuel efficiency of the engine) with forced induction. A value of 120% is much closer to the mark, giving the engine much more fuel under boost.

Before, (note the 1500 value on the y axis) :

After (note the 2000 value on the y axis) :

As the base fuel maps given here are for stock injectors, and as you will not be running stock injectors with boost, more changes are necessary. The shapes of these fuel maps in columns 1-6 at part throttle will be further altered by characteristics of larger injectors (Fuel will need to be added). The larger the injectors the greater the change. This is covered in a further article on injector sizing, and is a necessary follow on from this article.

These changes detailed above will be soon applied to all existing base maps supplied with ROM Editor and where appropriate, to the tunes in the library.