The turbo system upgrade is completed with a Tial 50mm blow off valve. Doug's Dynopower reports the turbo comes on so smooth and strong and doesn't stop pulling until 7600 rpm, and even then, it's still making excellent power. Although peak torque numbers are decreasing as horsepower numbers increase, the engine's broad torque range is still substantial. Output only increased 10 horses at peak with the GT turbo at the same boost level, but this increase is over a 4000-rpm span. The old turbo had little lag; this unit has no lag.
Add in the increased durability of a true ball bearing design and the GT is a worthwhile investment. Having used the old turbo on a few other cars and made 440-450 hp at the wheels at 22-23 psi, Doug's Dynopower hopes the GT will make 480-500 hp at the same or slightly higher boost levels.
Tuning has been relatively straightforward, so far, although the injectors are pretty much beyond their capacity with duty cycles at 100 percent. Compensating with increased fuel pressure via an SX regulator has helped somewhat, so it's time to increase their size from 550cc to 620cc or larger.
An often overlooked key to making any 4G63 DSM run to its fullest potential is guarding against detonation or knock. Ask anyone that has dyno'd their car how much power timing is responsible for and their response will include numbers varying from 50-80 hp -substantial power to sacrifice.
Some engine designs like more timing than others. The Mitsubishi engine seems to be happy with a fair amount. The Technomotive Datalogger easily traces the timing and monitors knock under boost. The goal is to keep the timing above 15 degrees at WOT and the knock sum below a value of 5.
The Doug's Dynopower engine doesn't like to make consistent power on 91-octane, regardless of the ambient air temperature. Although 100-octane unleaded is for sale at the pump, Doug's Dynopower was looking for a booster that could be added at any time.
Nitrous Express developed just such a product. Designed to be used in N/A, turbo and all-nitrous applications, Nitrous Express' fuel booster has its largest power effect when used in conjunction with nitrous. Doug's Dynopower used it with 91-octane pump gas with profound effects. Timing increased to 20 plus degrees at WOT; knock sum was zero. The ECU didn't have to pull a crazy amount of timing out due to knock.
Some will argue to simply add more fuel to combat knock. Sure, more fuel will cool the combustion chamber, but it reduces power output at the same time. Maintaining an O2 reading of .85-.90 volts has produced the best results so far.
The intercooler used on the car is a Spearco air-to-air unit that flows over 1000 cfm in a top-to-bottom core arrangement. While it has done an admirable job thus far, Doug's Dynopower needs more area and it plans to upgrade to an APEXi Skyline side-to-side core arrangement.
In the meantime, Nitrous Express has developed a new intercooler sprayer system that uses either nitrous or CO2. It douses the intercooler core with an extremely cold charge of gas. What a difference-the Galant runs like it's 40-50 degrees cooler outside with the system on and spraying.
There is a side effect; boost increases slightly from the cooler and denser air. It also leans the engine out at higher engine speeds, but larger injectors will cure that. For anyone in a high-heat climate or with a seriously undersized intercooler this is a product worth looking at.