The Power Is In Your Hands

Track Days and Autocross Events Demand A Customized Power Steering System

Words And Photos: Jeff Smith

Autocross racing and track days at road courses have become the new fun ways to abuse a Pro Touring car. With fat tires, big brakes and a great suspension, you can have a ton of fun in an afternoon chasing the clock for a quicker lap time. It is addicting fun and all you want to do is make another lap. Frankly, it beats sitting in the staging lanes at the drag strip waiting for two hours to make a single 10-second run down the track. But all this corner-turning fun can also cause havoc with certain systems.

The more knowledgeable racers with lots of runs under their belt know that engine oil and automatic transmission fluid coolers are essential to manage heat for extended lap sessions. But few, if any, pay attention to that high-pressure power steering system that is among the hardest working systems on the car during even short autocross jaunts. We’ve raced in and attended hundreds of autocross and Pro Touring events including all the prestigious Optima Ultimate Street Car Challenge races and power steering pump problems are among the most common mechanical failures. The most common solution is to replace a failed pump with another stock unit with the same shortcomings. But there are solutions if you know where to look.

There are several reasons for power steering pump failures, but the most common culprit is excessive fluid temperatures caused by a combination of high pressure demands and high engine speeds. A stock factory LS accessory system, for example, pushes the power steering pump 15 percent faster than crank speed. This ensures that the pump can generate sufficient pressure and volume at idle when power assist is in greatest demand. This also means the pump spins at peak engine speeds. At 6,500 rpm, this pushes the power steering pump to nearly 7,500 rpm.

These higher pump speeds also push the fluid temperatures higher. As fluid temperatures increase, replacement auto parts store power steering fluids cannot handle these elevated temperatures and pressures. Power steering fluid is a basic hydraulic pump fluid – but high performance power steering fluids also include additives intended to reduce aeration and improve the fluid’s ability to release air from suspension quicker. This improves the fluid’s ability to resist cavitation. Pump cavitation can be created by several different conditions but often the issue is caused by a combination of high fluid temperatures and inlet side restrictions. When this happens, the suction side of the pump creates high vacuum levels. If the inlet side hose is not designed to resist collapse under vacuum, this vacuum can collapse the hose, causing an inlet side restriction that creates cavitation. For this reason KRC recommends using no less than a ¾-inch inner diameter hose that is rated to withstand at least 28 inches Hg of vacuum without collapsing.

Higher fluid temperatures can also be the cause for cavitation because as temperature rises, the fluid’s ability to minimize air entrapment is reduced. This is why using a dedicated power steering fluid is so important and why using ATF in a high performance power steering system is not recommended. High quality power steering fluids include dedicated anti-foaming and anti-aeration additives that minimize the air trapped in the fluid. High fluid temperature is a serious issue as even a stock system will operate at temperatures above 225 degrees F. In autocross and track day situations, it would not be uncommon to see power steering fluid temps as high as 300 degrees F. KRC’s Cody Haskins says that they see temperatures with NASCAR pumps as high as 350 degrees. He also says that KRC’s pumps are rated to a maximum temperature of 400 degrees F but KRC prefers to see fluid temperatures roughly equal to engine coolant temperature – or 200 degrees F.

A great way to achieve lower temperatures is to use a more efficient pump. For GM cars, the older Saginaw pumps were originally designed with high volume flow to create minimal effort steering. High performance steering boxes and rack and pinion steering require far less volume. There are several different Saginaw pumps produced but most produce volumes of 2.4 to 3.5 gallons per minute (gpm) at 1,100 to 1,400 psi. Newer Type II pumps produce slightly less volume – around 2.4 to 2.8 gpm at similar pressures. This reduced volume means the pump is not working as hard so less power is required to drive the pump. Perhaps more importantly, with reduced volume, these smaller pumps do not bypass as much fluid which dramatically reduces fluid temperature. The key is reducing the operating temperature.

There is much more to the entire story on pumps, speeds, and operating characteristic than we can squeeze into this short story, but the key is to create a package that reduces fluid temperature. Combine Type II pump advantages with a reduced pulley ratio of 1:1 and a high quality fluid that is designed to withstand increased temperatures without breaking down and losing viscosity and you have created a power steering system that can be abused on a road course or autocross without failing. It’s always a plus when at the end of a fun day at the track that all the systems on your car still function normally and you can drive it home!

10 Tips to Improve Power Steering System Performance

Reduce pump speed – KRC recommends 1:1 with crank rpm.
Use a high quality power steering fluid. Do not use ATF.
KRC remote aluminum reservoirs use a non-vented cap to improve pump performance. Race system use mild pressure of 25 psi.
Always use a quality, 20” Hg rated ¾-inch pump return hose to ensure it does not collapse under high vacuum.
Make sure that the fluid level is 2-3 inches higher than the pump and all hoses.
Do not install a filter or cooler on the return side of the system.
Wider front tires and more caster demand increase pump flow.
Ensure system fittings do not restrict fluid flow.
Fluid should always return below the fluid level in the reservoir.
Always completely remove all air by bleeding before starting engine with a new pump or hoses.

Pulley Ratios

When it comes to power steering pulley ratios, it’s all about being bigger in the right place. Pulley ratios affect both pump shaft speeds and belt speeds. Both of these are important. KRC tells us they don’t recommend spinning the typical Type II iron power steering pump more than 5,000 rpm. But that’s exactly what happens with a production power steering system on a typical Pro Touring car with roughly a 15 percent overdriven power steering pump. Let’s look at an example.

We measured the stock pulley sizes on a 2000 LS1 Camaro system. The crank pulley measures 7.5 inches while the power steering pump pulley is 6.5 inches. This means that at 6,500 rpm engine speed, the power steering pump is spinning 15 percent faster at 7,500 rpm. At this speed, the belt is travelling at over 2,500 feet per minute!

The formula for calculating pulley ratio looks like this:

(Drive Pulley Dia. X Engine rpm) / Power Steering Pulley Dia.
(7.5 x 6,500) / 6.5 = 7,500 rpm

The formula for belt speed in feet-per-minute (fpm) is:

Belt Speed = Pulley Diameter X Pi X rpm / 12
Belt Speed = 7.5 x 3.1417 X 6,500 = 153,158 / 12 = 12,763 fpm

To reduce power steering pump speed, there are two routes. Either increase the diameter of the power steering pump pulley versus the crank pulley or make the crank pulley smaller – at least equal to the size of the power steering pulley to make the pump speed 1:1. Unfortunately, reducing the crankshaft pulley size also slows all the other accessories driven by the crank such as the alternator and the water pump, which may not be desirable.

We tried reducing the crank pulley diameter from the original 7.5 to 6 inches, which is a 20 percent reduction in diameter. If we leave the power steering pulley at 6 inches, this automatically reduces the pump rpm by 15 percent and cuts the belt speed by 20 percent.

6” x 3.1417 = 18.85” x 6,500 rpm = 122,526 / 60 = 2,042 fpm belt speed.
2,042 / 2,552 = 80 percent belt speed – or a reduction in speed of 20 percent.

Description	PN	Source	Price
KRC F-car accessory drive kit, alt /P.S.	KIT76315811	Jegs	$1,419.00
KRC Y-car accessory drive kit, alt/P.S.	KIT76315000	Jegs	$1,235.99
KRC LS truck power steering pump kit	KIT76327000	Jegs	$364.57
KRC Power steering cooler	95120606	KRC	$171.45
KRC 63512000 alum. Pump, 17-spline	63512000	Jegs	$456.86
KRC Power steering fluid	10032001	KRC	$14.95
Driven power steering fluid	01306	Jegs	$19.99