Tech Talk #76 – The Titanium Solution

DavidTechArticlesBy David Reher, Reher-Morrison Racing Engines

“Installing titanium valves is simply the best way to improve a racing engine.”

The same properties that made titanium the metal of choice for nuclear submarines and high-altitude spy planes during the Cold War also make titanium an ideal material for engine valves. Depending on its alloy, titanium is 45 percent lighter than steel and twice as strong as 6061-T6 aluminum. Replacing steel valves with titanium is simply the best way to improve a racing engine.

Titanium was once regarded as a state secret by the Russians and classified as a strategic material by the U.S. government. Commercial development of titanium has made this amazing metal both more affordable and more widely available. Today it’s commonly used in products ranging from tennis rackets to mountain bikes. Compared to the cost of steel valves, a set of titanium valves for a big-block Chevy V8 is an upgrade of approximately $1500. Yes, that is a big-ticket item, but the benefits of titanium valves more than justify the additional expense.

Reducing valve weight has a tremendous impact on an engine’s reliability, longevity, and performance. When we test a sportsman engine on the dyno, I can literally hear the difference between steel and titanium valves – an engine with titanium valves accelerates more smoothly, the result of the valve springs’ ability to keep the valvetrain under control.

Here are the numbers: A typical 2.300-inch diameter steel intake valve with an 11/32-inch stem for a conventional big-block Chevrolet weighs 142 grams. A titanium replacement with the same head diameter and stem diameters weighs about 90 grams. (Differences in the margin thickness and head shape account for the fact that the titanium valve is slightly more than 60 percent of the weight of the steel valve.) Now consider that loads increase exponentially with rpm: Double the engine speed and the forces are quadrupled. The 52-gram reduction in static valve weight offered by titanium becomes much greater when the valve is opening and closing thousands of times every minute. Consequently the valve spring can control the valve motion more accurately in a dynamic state.

The effects of reducing valve weight become apparent throughout the engine. Valve springs last longer, and lifters are more reliable. When we overhaul an engine with titanium valves, the guides and seats invariably look better than comparable parts in a steel-valve motor. The benefits of lightweight valves are even visible in less wear and tear on the camshaft drive, whether it’s a chain, belt, or gears.

The usual motivation for installing titanium valves is to increase maximum rpm. More than 30 years ago, when we put a set of titanium valves in a 287-cubic-inch Modified Production small-block, the elapsed time immediately dropped two tenths of a second. It was a revelation then, and the same technology still works today. Swap the steel valves in one of our Reher-Morrison Super Series sportsman big-blocks to titanium and the peak engine speed will increase instantly by 400-500 rpm with no other changes.

However, the key point for a sportsman racer is that it’s not necessary to turn the engine faster to realize the benefits of titanium valves. By maintaining the same redline as with steel valves, an engine with titanium valves will operate with less stress, less wear, and better reliability over the long haul.

Many sportsman racers regard titanium valves as an expensive luxury, but I think titanium is a good investment. As consumers, we often focus on the sticker price, not the overall cost of ownership. I’m reminded of that fact every time I take the lowest bid on a home repair, and then live to regret my decision. If I’d considered quality as well as price, I would be better off in the long run.

Another myth is that titanium valves aren’t durable. I remind racers that the production Corvette Z06 and ZR1 have titanium valves, as do several other high-end sports cars. If Chevrolet is willing to put a warranty on a street motor that’s designed to last 100,000 miles with titanium valves, I don’t think that racers need to worry about the longevity of titanium valves. If I had a hot street motor, I’d run titanium valves without hesitation.

As with most products, there are differences in the quality of titanium valves on the market. Without going into specifics, I’ll just note that you usually get what you pay for. It’s my strong belief that valves are not the place to try to save a few dollars in a racing engine.

My philosophy of engine building is always to try to make the product better. I’ve written previously about the improvements we’ve made in wet-sump oiling systems, and I’ve made the decision to put bronze lifter bushings in all of our racing engines because it’s the right thing to do. I know that titanium valves aren’t the answer for every drag racer, but when I know in my heart that a part is better, I certainly hope to see it widely used.