Turn One's Power-Steering Pump - Low Flow For More Go

Turn One's New Power-Steering Pump Gives F-Bodies A New Feel, and Frees Up As Much As 3 Horses

From the July, 2009 issue of GM High-Tech Performance

By John Ulaszek

Photography by Glenn Estelle, John Ulaszek

Turn-One chose GM High-Tech...

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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.

Unlike the LS1's pump, the... read full caption Unlike the LS1's pump, the LT1 has a detached reservoir that allows it to run cooler than the LS1 F-bodies. Except for the pulley, the Turn One pump looks like a stock part that could have come off the shelf from the local parts house. Don't be fooled, Turn One starts with brand-new pumps, and the internals are extensively reworked. While Turn One asked us not to photograph its process, I can assure you it is not just changing springs or drilling bigger holes.	Pumps purchased from Turn... read full caption Pumps purchased from Turn One with a pulley come assembled. If you buy just the pump or pulley you will need to get your hands on a power-steering pump pulley puller or you will have to get awfully creative to get it off the pump.	I recruited Glenn Estelle... read full caption I recruited Glenn Estelle and his '92 LT1 Camaro as a test bed for the Turn One pump testing. Glenn's car is a daily driver that he autocrosses on a regular basis. Since Glenn had about a dozen autocrosses in his car before the pump change, I figured he would notice if the pump changed the steering effort and feedback.
Jeff Roethlisberger, the owner... read full caption Jeff Roethlisberger, the owner of Turn One, took time out from building steering gears for Nextel Cup cars to explain the inner workings of his company's pumps and steering gears. Jeff spent 16 years at Saginaw Gear, GM's steering division, as a ride and handling engineer before striking out on his own and starting Turn One. Jeff also managed to bring his father on to help out after he retired as the Chief Engineer of steering systems at Saginaw steering division. Between Jeff and his father, there is about 50 years of power-steering experience.	Not only does Turn One use... read full caption Not only does Turn One use its pump dyno to verify the quality of every pump, it shows a Turn One pump will free up about half a horsepower. While not a huge gain, it is a side benefit of the improved feel and lower fluid temps.	To determine PS fluid temps,... read full caption To determine PS fluid temps, I tapped into the return line coming from the steering gear. Ideally, I would have tapped into the output of the pump, but the high pressure complicated the plumbing. I conned my friend Paul Ruggles into fabricating a small T-block, which allowed plumbing an Auto Meter oil temp gauge probe directly inline with the fluid path. Paul drilled the block's bore diameter oversize such that flow was not impeded by the sender probe.
Since Jeff had so many years... read full caption Since Jeff had so many years of experience as a test driver, I wanted his thoughts on what he looked for in a well sorted out steering system. This is what he had to say: "When I evaluate steering performance I look for two things: The first is on-center feel. This is evaluated by small steering inputs, such as highway lane changes. The steering should feel crisp and precise, giving the driver a very 'connected to the road feeling.' The second is high-speed connectivity. As the vehicle generates lateral acceleration, the steering wheel torque should increase proportionally. This tells the driver the front wheels are turning. Most street-car steering is over boosted during this type of maneuver, leaving the driver with very little directional sense."After autocrossing with the Turn One pump, Glenn found the change to steering input to match Jeff's definition of a well sorted out steering system. He also found he could actually feel the difference camber and caster changes were making at the autocross. As predicted, Glenn found increased steering effort required in low-speed parking lot maneuvers, but he felt the tradeoff was worth it for the improved steering response.	At the autocross, Glenn documented... read full caption At the autocross, Glenn documented the peak temperatures at the end of each run. Throwing out the highest and lowest temps from the day, the average temperature with the stock pump was about 175 F. The following week, with almost identical weather, the average temps were down a solid 10 degrees to 165 F. At 275 F, the seals in the power-steering system begin to deteriorate; while the LT1's OEM pump never got this hot, it proved the Turn One pump could reduce temps on an already-cool-running setup. In city and highway driving situations, Glenn consistently observed anywhere from 5- to 10- degree lower temperatures than the OEM pump. While our testing methods could have been more scientific, I feel the across-the-board temperature drops with the Turn One pump validate Turn One's claims.

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