Part VI - Tech - Power Trip - 559 HP 550 TQ

When the engine is cold, Hartline tunes the coolant temp correction table (View-Temperature Correction Tables-CTS Correction). This is the Warm-Up Enrichment vs. Coolant Temperature screen, which adds extra fuel based on the coolant temperature-as you can see, a cold motor needs more fuel.

Now it's time for some VE performance/drivability tuning, the most time-consuming part of tuning. (View-Fuel Tables-Base VE Table, or F3 shortcut). This can be done on the street and on the dyno; WOT is easier and safer to do on a dyno, but street tuning needs to be done as well. It's very straightforward: with the floating green ball, you can highlight the in-use cell in white (arrow keys, or space bar to choose current highlighted cell). A beginner can use page up/page down to change values one digit at a time. There's also Shift-8 which will allow you to trim the cell by percentage. Shift-arrow keys will allow multiple cells to be highlighted and changed simultaneously. Even more, the I key will interpolate-smooth out the map by averaging cells from corner to corner. This is a very advanced function; be careful using it.

While Cal does idle and drivability in real-time, he prefers to use the log feature for WOT tuning. This not only allows him to view the log after a track run or dyno pull, he can hit F3 with a log open, click Window-Tile Vertically to put the log and recorded VE table side by side, and replay the log. While the log runs, he can view the cells in use over on the VE table, making fuel adjustments a cinch....

...When he is tuning the VE tables, the closed loop correction limits (View-Closed Loop Parameters-Correction Limits) are brought in closer and closer to 0 each time. For instance, the initial program that we played with would correct plus and minus 25 percent; here you can see that there's 2.4 percent of O2 correction. Anything under +/-3 percent is stellar. Note the fuel pressure readout thanks to the logging kit.

Another cool XFI function is the 3D mapping (hit letter G). This makes it easier to see a value that perhaps isn't in line with the surrounding cells.

A tip regarding the Closed Loop Positive Correction Limit vs. rpm & MAP table: since I have a double-pumper setup, Cal left the positive O2 correction at the 25 percent max in the upper right-hand cells as a safety net-if one fuel pump quit at WOT, XFI could throw in a ton of fuel and save the motor. Pretty slick, huh?

Hartline thinks that one of the most overlooked parts of the tuning is the five additional enrichment (AE) fueling tables. (View-Fuel Tables). These tables are what make the car responsive and driveable (AE Fuel vs. MAP Rate of Change shown). "The two most important are TPS and MAP enrichment," Cal states. "TPS enrichment looks at the TPS rate of change, and is just like an accelerator pump in a carb. If you have 0 TPS enrichment, when you go to give it gas it only goes off of the VE table's squares-and moving the throttle quick means more air and not enough fuel. TPS enrichment gives it an additional shot of fuel (additional enrichment) to prevent a stumble." The MAP AE works similar to the TPS AE, except it's looking at the change in manifold pressure.

An afternoon of XFI setup and Hartline Performance tuning has resulted in a smooth-driving Turbo Buick. Even better, trips down long straightaways in Toms River, New Jersey, reveal that the power on pump gas and 17 psi of boost feels like the old race gas/24-psi setup! Putting a foot to the floor reveals a bit of turbo lag before the hides start boiling-and they don't stop until well into third gear. The SLP dyno session is now only a day away, but feels like forever. With the ratty paint and 1980s rims, this thing is way faster than it looks!

SLP Performance Parts was good enough to have us over to its chassis dyno the next morning to tune the Hartline Turbo V-6 with race gas. SLP uses a high-tech Superflow dual eddy-current brake dyno that works well with turbo/converter cars.