WATER INJECTIONYou may have noticed that our 440 combination was running high boost, without the aid of an intercooler. It's a fact of physics that compressing a gas (air in this case) produces heat. In practical terms, that means more boost equals more heat in the incoming charge. It's well known that high inlet air temperature saps power and encourages detonation, hence the need for a means of charge cooling, especially with lots of boost. Cooling the air/fuel charge is typically accomplished by employing a heat-exchanging unit known as an intercooler. Essentially, an intercooler is a radiator through which the induction charge is passed and cooled by the temperature differential between the high-temperature inlet air and the cooling medium--ambient air in an air-to-air intercooler.
The system favored by The Supercharger Store is a departure from a conventional intercooler, and actually borrows from technology employed in supercharged WWII fighter aircraft--water injection. Water injection provides a cooling effect to the charge through another effect of physics, the latent heat of vaporization. As a highly atomized liquid changes state to vapor, the process consumes heat. The Supercharger Store's system provides a high-pressure pump that is triggered by a pressure switch, which in turn is referenced to boost. When the boost hits the prescribed pressure level, the pump sends high-pressure water to a fine-atomizing nozzle aimed at the blower intake. Water provides the cooling, and also acts as a detonation suppressant. The kit is complete, with all of the fittings, tubes, an anti-siphon valve, and a fuel cell to serve as the holding tank.
With the water injection properly set up, Bob Woods of The Supercharger Store reports phenomenal power output on pump gas. Various kits are sized with nozzles designed to differ the fluid flow rate for different output levels, with some of the higher horsepower kits featuring two stages of injection, for outputs of up to 2,000 hp. The system can be used with straight water, or various concentrations of water/methanol mix. Bob recommends common windshield washer solution, which contains up to 25 percent methanol. Water injection is far from a new idea, but with the output capabilities of modern supercharger systems, it's an innovative solution for power on pump gas.
Our own observations on the system brought out some aspects that may warrant further investigation. The water/methanol mix is injected into the blower intake, which serves to cool the blower, however, our observation was that the impeller had a tendency to centrifuge the atomized liquid in the blower housing. Injection at the discharge side of the blower may be an alternative worth exploring; in fact we had done some experimentation with such a setup on a pure methanol injection arrangement in a very high output blown Bonneville car. It seemed to work better.
875 HP TIME BOMB?Reading through our adventures here, it is readily apparent that our 440 is nothing more than a stock Chrysler engine, with some "old-school" high-compression SpeedPro forged pistons, basically the old TRW 440 Sixpack replacement street forgings, for those of you who can remember these from back in the day. Our goal was to explore the power potential of the blower system, and in doing this we adapted it to an existing test engine. We made close to 900 hp, with basically all stock bottom-end parts: the block, crank, main caps, and standard 440 connecting rods. We know the factory Mopar stuff is fairly robust, and making power on the blower isn't as hard on the bottom as some other forms of power enhancement, or even making significantly less power normally aspirated. That said, we knew it would work on the dyno and probably not blow up, especially since we would be extremely careful not to detonate it, or lean it out under the controlled dyno conditions. However, it was a calculated risk, and one that you, your machinist, or your engine builder might not want to make.
Would we run exactly this combination on the street, or duplicate it in detail for even a drag racing project? No way. We'd definitely look to build a dedicated blower engine with a host of durability mods. Frankly, we'd consider a partial fill on the block, with aftermarket main caps, preferably with a girdle system, or better yet an aftermarket block. We'd buy the best forged-steel crankshaft we could afford, and the same goes for the rods. We cheated with the head spacers and gasket stack to get the compression ratio down, but for a real world application like this you'd better be thinking about a nice set of custom forged dished blower pistons in the high strength alloy. We'd also be looking really hard at a set of steel rings like the Hell-Fires. Making big power with stock factory components is not the formula for a happy long-term marriage. Sure, some of these kits can work just fine at lower boost on a relatively stock engine, but longevity is a dangerous roll of the dice with anywhere near these boost or power levels.