Hughes Performance has taken torque converter tune-ability to a new level with its own approach to converter charge dumping with the venerable GM Powerglide through the use of its Pro Series Dump Valve System. The first stage dumps converter charge oil, effectively reducing the amount of oil in the converter, thereby affecting stall speed and other attributes. The second stage exhausts cooler discharge oil — oil that’s being discharged from the converter out into the cooling system.
“This is a two-stage system — one works by taking oil from the converter feed circuit and is completely internal: this is the most effective, giving you anywhere from 200-800 rpm,” Hughes’ Tony Kane explains. “An external stage then interferes with the cooler flow, restricting flow back to a jet orifice and into the pan; this is good for anywhere from 200-400 rpm, depending on the circumstance. This of course varies depending on the car, the efficiency, and how tight the converter is. But between the two of them, you have flexibility from about 200-800 rpm, they can be run in series, and they’re adjustable from that range with the different orifices that come with them.”
“Generally, if you have too tight of a converter, it will loosen it up; if you have a turbo converter and trouble with the stall, we’ve had racers knock off from 1- to 2.5-seconds off their stall time to get right up on the converter right where it needs to be,” Kane goes on to explain. “And on the street, when the road is marginal, they can take some of the aggressiveness out of the converter by cavitating it a little bit by releasing the fluid, and it also softens the hit without having to adjust engine timing or some other parameters. It’s like being able to tune your converter without actually taking the converter out of the car and opening it up.”
Relatively basic for the mechanically-inclined, the dump valves can generally be installed be the end-user.
Hughes’ Dump Valve Systems can aid in reducing engine thrust bearing wear and tear, increase stall speed while staging in addition to faster engine engine response upon staging, faster boost response with turbos and centrifugal superchargers, reduce engine load in nitrous cars, exhibit less RPM drop on gear changes, can be used to manage wheel speed, and are fully tunable using a variety of jetting sizes.
Hughes’ Pete Nichols has produced in-depth technical looks at the Dump Valve System that explains their operation in great detail, which you can view below.