Galant 4G63 Power Tuning

In the last "Dyno Cell" installment for the Galant VR-4, we tested an upgraded 16g turbo, A'pexi AFC and Turbo XS boost controller. Observing TMO datalogger info, it was clear the stock injectors were maxed out and then some.

Duty cycle sat at 100 percent but, fortunately, the in-tank ND pump used on the car flowed a substantial amount of fuel and did, in fact, bump the fuel pressure up 4-5 psi at idle. This helped suppress detonation, keeping the fuel curve linear across the range. The A'pexi AFC also did an excellent job of wringing every last cc of fuel out of the stock injectors.

One item of concern since the last article is the octane rating of premium fuel. Not long after the last dyno session, the octane of premium pump gas in this western region was dropped to a paltry 91 octane. Those who live where you can purchase 92 or 93 octane, consider yourself lucky. Every little bit helps.

In this installment, we installed a set of RC Engineering 550cc injectors to cure the fueling blues. These are brand-new units, flow tested by RC and shipped with the flow sheet. We made a few dyno passes with just the injectors installed to see what kind of a difference could be seen. Also of note, the stock ECU was swapped for a TMO unit with the 8,000-rpm rev limit and fuel cut removed.

This, coupled with the new injectors, resulted in clean runs with no cutting or misfires. Overall adjustments with the AFC were minimal. With roughly 100cc more fuel capacity than the stock units, the low-rpm range wasn't affected much, while the upper ranges required a little leaning of the percentage of fuel being added.

Power increased slightly, partially because of the ignition timing being a little more stable due to the injectors keeping the A/F ratio constant. O2 voltage was kept at .90 for safety; again, octane concerns.

Now it's time for camshafts--frequently talked about and promoted, but not always understood. Wanting more power and increased flow, especially when the Garrett turbo kit is added to the mix, Dougs Dynopower opted for a set of Crower cams constructed from brand-new billets. Crower's 414 grind is touted as more of a race version of the four versions currently offered by the company. We wanted to see how they would behave on the street.

Seeing how many consumers purchase and try to use race parts on the street, this would be a test to see if these cams could cut it. After installation and break in, idle wasn't that bad at all, more than 14 inches of vacuum was registered and the idle was set at 900 rpm. The real surprise was the power curve. Torque was abundant from 2000 rpm up.

Going in, we thought the engine would lose out down low, but this wasn't the case. All the way to the rev limiter, where the stock cams would taper off above 5000 rpm in terms of torque, the Crowers were still singing. Power increased about 12 hp at the same boost level as the stock cams.

Of more importance, however, is the horsepower curve from 5500 to 7500 rpm, where about 35 hp was realized compared with the stock cams. Even more impressive is the torque level, where the 4G63 was pumping out more than an additional 50 lb-ft when the engine was shut down at 7500 rpm.

Having an engine which makes power down low is usually not analogous with one that makes power up top; there's usually a compromise working. In this case, the 4G63 makes power across the range, which is vitally important for a street car. The cams should continue to pay dividends with the larger turbo, intake manifold, etc. Because of the cams, these components will generate more power. This is a good illustration of parts performing together in the real world.

Next up was the ignition. Having a few choices with Mitsubishi engines, we decided to use a Crane HI6-DI2 set-up. Trying to push this much fuel and air through a turbo engine puts enough demands on the stock ignition. Even with Magnecor 8.5mm plug wires and fresh NGK BPR7ES spark plugs, there comes a time when cylinder pressures demand more.

The Crane system is very modern, complete with weatherpack connections, and an electronic trigger tach adapter. It utilizes a multi-spark system, which sparks up to 12 times per cylinder firing, which cleans up the cylinders slightly by burning all of the fuel present at lower engine speeds. It also delivers a powerful spark in the upper ranges where the engine is under load and at full boost.

Added bonuses include two different rev limiters that adjust with switches and timing retard that's adjustable from 0-20 degrees.

Power increased slightly to a peak of 3 hp and torque 3 lbs-ft of torque, but the smoothness of the engine would lead you to believe otherwise. Installation wasn't difficult and the engine starts faster with the Hi-DI2. Fuel efficiency should increase as well. This is another mod that will pay bigger and bigger benefits as the build-up rolls along.

The 16g turbo was pretty maxed out at the end of the last article. However, it has performed admirably. The 4G63 is ready for more airflow and our Garrett set-up is primed. But they'll have to wait. The turbo will be joined by a sheetmetal intake, upgraded fuel rail and fuel pressure regulator. Also on the coming-soon list are a Nitrous Express single-nozzle nitrous system. The drivetrain will no doubt be calling for attention and we plan to quell it with a Centerforce clutch, Fidenza flywheel and possibly a stronger rear axle assembly from a '91-'94 AWD DSM. Stay tuned to the "Cell."