For most people, the first time they pay any attention to the power-steering pump is when it either boils over or starts making a horrible howling noise, and this is often during the middle of an autocross or open-track day. LS1 powered F-bodies are notorious for burning up pumps. GM recognized this problem and started installing an oil-to-water power-steering cooler on the '98 SS and WS6 F-bodies, and also providing it as an option on all LS1-powered F-bodies. By 2000, the cooler was standard equipment on all LS1 F-bodies. While the cooler is a reasonable fix for most street and mild track use, it only treats the symptom.
Sports cars are almost never driven to their potential. Most people want the image without any of the sacrifices of a race car. Because of this, most will never experience the precise steering that is possible when pump volumes are not over boosted.
If you have ever driven a domestic car from the '70s, you probably remember being able to parallel park with one finger on the wheel. While Grandma probably saw this as a sign of quality, it can cost half a horsepower at low rpm and as much as 3 hp at 5,000 rpm. Over the past 20 years automakers started paying more attention to steering effort versus driver feedback, but they still have to compromise for parking-lot maneuvers. Stock pumps have relatively high flow rates at low rpm to allow for those low-effort maneuvers. Unfortunately, this extra flow manifests itself as a disconnected feel on the highway and boiled fluid at the autocross or road course.
Turn One, the largest supplier of steering pumps and gears to Nextel Cup, has the solution: Blueprinted, reduced-flow, 40-series power-steering pumps for all '93-02 F-bodies and '84-and-later Corvettes. Turn One claims its pump will reduce or eliminate power-steering overheating and may improve steering feedback.
Turn One's pumps and steering gears were under the hood of four Winston and Nextel Cup champs in the last five years, so I figured I was in pretty good hands, but I still wanted to do some testing. Follow along as I test Turn One's pump at the autocross with some help from Auto Meter.
Pump Chart From Turn One's Jeff Roethlisberger:
This graph represents pump flow (y axis) vs. pump rpm (x axis) of a stock production pump and a Turn One pump. Analyzing the solid line graph of the stock pump at approximately 900 rpm, the pump achieves flow control mode, which means the pump will deliver one constant flow to the steering box/rack at any rpm above 900. The 2.6-gpm flow control value is used here as an example. Depending on application, the actual flow control may vary.
Following the dashed line of the stock pump at 5,000 rpm, the pump delivery is 15 gpm. This is the total volume at 5,000 rpm, with 2.6 gpm being delivered to the box/rack. The other 12.4 gpm is being recirculated internal of the pump. This excess flow is what creates high fluid temperatures and robs horsepower.Analyzing the Turn One pump graph, it achieves 2.6-gpm flow control at 1,300 rpm. At 5,000 rpm, it's pumping a total of 10 gpm, recirculating only 7.4 gpm. That's 5 gpm less, resulting in lower fluid temperatures and less parasitic horsepower consumption.You may ask why the production pump is designed this way. The reason is to have more than adequate flow at low engine rpm. So, due to production variation, higher-than-average steering effort wouldn't be experienced during low-speed maneuvers.
ConclusionBased on the results of this testing, I think it pays to take a break from the constant search for the seat-of-the-pants improvement, and focus on the seat-of-the-palms. Based on Glenn's and my own driving experience with Turn One products, the full benefit of suspension mods and alignment changes will never be fully realized on most stock power-steering systems. A Turn One pump might be the best bang-for-the-buck suspension mod you can make.