High performance engines deserve a set of high performance valves, and because we’re in the business of squeezing the most performance possible out of any engine combination, valves are very much an important aspect to focus upon. And why not? There’s plenty of horsepower to be made from a good set of valves and a proper valve job. Everything from the material selection, the valve and stem sizes, and the back cuts play a significant role in mating valves to your engine that not only meet the needs of your specific application, but make the most of it with great flow that leads to increased horsepower and efficiency.
In this guide to performance valves, we’ll take a look at variables like valve and stem sizing, materials, backcuts, and the technology that exists behind racing valves with one of the historic names in the industry, Ferrea Racing Components. Founded in the late 1960′s in Argentina by Dan Urrutia and Horacio Ferrea, the valvetrain manufacturer has remained at the forefront of cutting edge valve technology for more than 40 years. Today, the business remains with the Ferrea and Urrutia families, and we sat down with Director of Marketing and the third generation figure behind the renowned business, Zeke Urrutia, to gain some insight on valve technology and proper valve selection from the perspective of an industry leader.
Selecting The Proper Valve Material
When discussing the material for your valve selection, it generally comes down to a choice between several variations of stainless steel, which are most common in performance street and light duty racing applications for their durability and price, various forms of alloys, and the high-end, lightweight, titanium valves that are typically found in racing engines that receive regular maintenance.
“One of the primary decisions to take into account when selecting a valve is to determine the material for the specific application, be it stainless steel – which there are basically seven to eight different stainless materials – and then the other option, which would be titanium,” said Urrutia. “In some applications, you can get involved in using titanium, but in others, such as streets cars that are driven regularly, gas-driven cars, and anything that has very high temperatures, then steel is preferred.”
Titanium – When Nothing Less Will Do
Titanium valves are the material of choice in professional drag racing, oval track, road racing, and other venues where winning often outweighs the cost, due to their light weight and strength along with the allowance for more radical cam profiles and added power potential. With a price tag that is often two to three times that of the highest-quality stainless steel valves on the market, they aren’t for the faint of heart, nor the weekend warrior trying to race on the cheap.
“With titanium, there is only a certain market that we and our competitors dabble with, and that’s the high end,” says Urrutia. “There is titanium that we manufacture for the OEM’s though; primarily for the ‘Big Three.’ Titanium really involves a whole different process for these OEM-built engines. An example would be the popular GM LS line of engines, and specifically the Corvette LS7, which usually falls into a certain criteria where those are very low mileage cars. The cycle life of titanium valves is very marginal – you don’t get much time out of them. And if you do, you’re getting involved with some pretty exotic coatings and maybe put another 20-30 percent more life on them, but it’s marginal for what it’s worth.”
As such, the use of titanium is mostly limited to serious, cost-is-no-option racing teams that typically change out the valvetrain components on a regular basis. Urrutia explains that NHRA Pro Stock teams, for example, will often swap out the valves at least every other race and replace them and other drag racing applications might see between three and fives races before the valves are swapped out. While the valves still have a limited amount of life in them after that short time of use, for these teams it’s more of a security thing to keep their engines alive and in contention. Truth be told, not even the manufacturers can give an approximate timetable of just how long a titanium valve will last and when to replace them.
Stainless Steel Valves
When looking at the category of stainless steel valves, the primary advantage is the ability to not only withstand higher levels of heat and the strain that accompanies that heat, but also includes the tensile strength that the valve can handle as well. The materials or blends that are included in stainless, such as alloys comprised of nickel, chromium, and other materials will allow for a specific temperature on the valves, as well as a certain tensile strength. Both of these factors favor applications like large cubic inch naturally aspirated engines, or with the use of power adders including superchargers, turbochargers, and nitrous oxide. As such, the selection of the blends of the stainless material becomes important to getting the most from your engine.
“Stainless steel is a material as an identity for longevity. It holds itself very well, has properties that last very, very long, and you can get into very high temperature environments; especially on the exhaust side,” says Urrutia. “Stainless has become somewhat of an identity for guys that are building an engine, running it maybe at weekly circle track or drag race events, and depending on the build, can get very long durations out of them.”
Ferrea offers three different primary product lines of stainless steel and alloy valves: the Competition Plus Series, the 6000 Series, and the 5000 Series. Urrutia points out that within the Competition Plus line, there are four to five different stainless materials to choose from. “It mainly entails the exhaust valve side, because what really perturbs any valve is the heat and spring pressure. Those are really the two main factors that you have a big area of weakness on an exhaust valve. Bang for the buck, it’s an area where most engine builders venture first, and then see if there’s a possibility for titanium if their pockets are that deep.”
The 5000 Series is more performance oriented toward street rods, muscle cars, and similar applications that are often cruised on the weekends or driven for extended periods of time. The 6000 Series represents the middle ground between the other two lines, which is aimed at the cost-conscious bracket racer or weekly oval and dirt track racer with engines that often utilize high spring pressure, big roller camshafts, and large compression ratios that lack the use of power adders. Both of these lines are available only in stainless steel, and once you evolve to the Competition Plus series, there are four to five variations of stainless steel that utilize exotic alloys.
Ferrea utilizes three to four differing blends of stainless steel that make up a particular valve. The differences between the differing blends is primarily the heat range to which they can withstand.
The first among those is what’s known as an EV8, which Urrutia describes as being incredibly strong with great memory and because of it’s wide use in all forms of manufacturing, is a common blend in foundries around the world and quite popular for valves – especially on the intake side. EV8 is comprised of chromium and nickel and Ferrea adds tungsten to the mix to make it suitable as an exhaust valve, as well. Also on the intake side is IN751 – an inconel -
From there you get into some more exotic materials and alloys involving exhaust valves. These include VB54, a high-heat stainless steel blend with a high nickel base that’s used exclusively for exhaust valves for combinations composed of forced induction and nitrous oxide. Also on the exhaust side is Nickelvac N80 that sports nickel and tungsten for handling even higher temperatures – upwards of 1,850 degrees fahrenheit. And finally, you have what Urrutia calls the ultimate of their stainless steel exhaust valve blends; Nickelvac 800. These are used in large diesel engines, Top Fuel Dragsters and Funny Cars, and turbocharged road racing vehicles where the most extreme of valvetrain environments and heat exist.
Inconel and Sodium-Filled Valves
A blend that Ferrea uses on both the intake and exhaust side is IN751, which is an inconel material. Used in an engine that sees high heat on the intake side, this material will hold its memory and integrity quite well and is rather flexible. The term “memory” refers to the valve’s ability to shift and move in different positions under extreme loads without encountering fatigue issues.
“Inconel in this day and age is used a lo in our industry; almost as much as titanium. Inconel was brought on by the avionics industry and has made it’s way to the racing, as may things do. Inconel is categorized under our Super Alloys, but we actually create our own blends to that make it handle high temperatures that much better. so instead of handling in the neighborhood of 1,800 degrees, we’re looking at about 2,400 degrees.
Ferrea also manufactures sodium-filled valves, albeit on their OEM side where these valves are primarily limited to. Sodium bases used in these valves are only tested to around 1,600 degrees, which most racing and high performance engines exceed. The liquid sodium travels up and down the stem of the valve, and at the boiling point, the liquid turns to gas. You then essentially have a valve with a hollow neck and excessively high temperatures, the chance of failure is very high.
However, the benefit of the sodium-filled valve comes in the form of added longevity due to the cooling properties of the sodium, and in street cars where temperatures are kept in check and hundreds of thousands of miles are expected, these are key.
Hollow Stem Valves
“Something that we’ve enhanced in the last four to five years is the hollow-stem stainless valve, which we’ve been continuing to move in the direction of lighter and lighter valvetrain mass as a whole,” explains Urrutia.
The components related to the valve such as retainers, lifters, the camshaft, and the valvetrain as a whole as a mass adapt to the lighter valve – such as titanium or the lighter hollow stem stainless – much better harmonically. And thus component-wise, from a harmonics standpoint, the result is an engine that is far more stable. In that same regard, the power band becomes much smoother.
Says Urrutia “if you look at the durations of the power bands, whether it’s on a dyno or a spintron, the windows are shortened up a lot closer because you’re getting to that point that much faster with the lighter valves. If you take just the valve spring for example combined with a titanium or light stainless valve, the spring would see a lot more life because the mass driving the spring is the valve and it’s that much lighter. Thus, the spring doesn’t have to work itself as hard.”
Ferrea equates their hollow stem valves at about 22% lighter than a standard stainless steel valve, and while not as light and therefore not as easy on the correlating valvetrain components as the expensive titanium, the advantages are certainly present. At present, Ferrea produces only stainless steel valves in the hollow stem variety, but Urrutia indicates that he and his team are working to develop them in titanium, as well.
An element of a valve design that is commonly overlooked and rarely discussed are locks the varying styles of locks. The locks hold the retainer in place and come in various designs including standard, radius, square, and double locking mechanisms. The locks are two-piece and while a very small component itself, represents a rather important role in the overall picture of a valvetrain as it holds the valve in place. The valve designs are specifically designed based on the style of lock being used.
“We got into radius grooves nine to ten years ago and what amazes us is that they haven’t become all that popular, but they are much, much better than a square groove. Anything that is round and has round edges is always stronger on a material base, and thus you can prolong the life of the part longer than one that is square,” explains Urrutia.
Ferrea finds there to be about 30% more life in a radius lock compared alongside a square lock.
“Our square lock has been enhanced the last several years to where if you look at it, it’s not a true square lock. It has small radius corner edges on the top and bottom.
So What Are The Differences?
The information above can be best summed up by saying that the specific use of the various materials that valves are manufactured from is a game of tradeoffs. For the high-end racing applications where the ultimate in performance is key and maintenance is consistently performed, titanium valves are preferable. These come at a twofold cost, however. Due to their naturally shorter lifespan, you’re looking at not only the high one-time cost of a set, but the repeated cost of replacing them on a regular basis as needed. For those that can get away with the slightly lesser performing steel and alloy valves, the costs are significantly reduces and longevity is considerably longer; perhaps anywhere from one to three seasons of continual use.
“Selecting materials really comes down to the three main categories. The first is the application, the second being the fuel that you intend to use in the engine, and three is the duration of that application, or the longevity that the valvetrain is expected or desired to live,” explains Urrutia.
Properly Sizing The Valves And Stems
There are two main factors that need to be kept in mind when discussing sizing of both the intake and exhaust valves for a specific engine. Cylinder head manufacturers typically design an industry standard size for valves, which entails the OEM engines with a standard size for small blocks, big blocks, and smaller sport compact engines. All of that obviously involves it being just that: a standard. On the second point, according to Urrutia, “You open yourself up to a pretty sizable window, where the sizes can vary drastically for each typical cylinder head, depending on how far and between someone is willing to go with the port work on the head and flow enhancements.”
Urrutia continued, “A standard intake valve for a small block Chevrolet is 2.020-inches and the exhaust is 1.600. But, you can get in there and open up that area on the intake – for example to 2.050, 2.080. 2.100, 2.125 and even as large as 2.200. You open yourself up to where you can expand that much more in sizing depending upon how much you’re going to modify that head and whether it’s being placed on a mild race engine, full out race engine, or something completely hot rod performance-oriented.”
Valve Stems – Size Does Matter
Likewise, valve stem sizes are dictated by what is being looked at in todays world as a standard of 11/32-inch. Stem sizes, however, are becoming much smaller today due to the materials and processed used in their design, allowing manufacturers to not only produce valves with stems that are not only smaller, but lighter in that same regard.
“I would say that the two main sizes that have become very, very popular in this day and age would be 11/32 being one, and 5/16 being another, explained Urrutia. “Those are really two of the pivot points that still drive our market. And then you obviously get into some smaller ones, found in some foreign engines. Some of the LS engines have also gone to 8mm, which is just a tad bit larger in size than a 5/16, so it’s relatively close in the range that they’ve really looked at and determined for use in OEM engines. If you look back ten to fifteen years ago, everything was pretty much still 11/32 somewhat, and 3/8 was still very popular back then. Today, 3/8 is starting to become a little less popular and common.”
The stem of the valve has to be in proportion to the head size of the valve, meaning that if the stem is a specific size, the head can only be designed to a certain size as well. For example, a valve with an 11/32 and a 2.800 or larger head diameter would incur issues of what is known as deflection, in which abnormal areas of the valve experience more flex than usual with smaller head diameters relative to the proportionate size of the stem. Essentially, the size of both coincides with one another. And it’s these two elements of the design of a valve that play a large role in the lasting survival or failure of the valve over a period of time.
Some manufacturers on the market offer valves that are longer than stock, and others offer valves with undercut stems that leads to increased flow. One point important to note is that nearly all factory replacement and aftermarket valves have a .001-inch taper down the length of the valve – narrower at the base of the head – to accommodate expansion created by the heat that that would otherwise cause galling, or wear due to friction between the metals.
The one aspect of a valve that plays the biggest role in improved flow and horsepower is the backside of the valve, which can be modified – to an extent, obviously – through a process known as backcutting. This extra machining of the valve correspondent to the angles around the valve seat makes for a smoother transition and increased airflow. Many of the high performance and high-end racing valves on the market already incorporate back cuts into their design, and other valves, such as OEM replacements, can benefit from the process. In doing so, you prevent flow separation from the valve as air flows over them. Flow separation causes turbulence and therefore less-than-stellar flow.
“Back cuts are very relative to port design,” explained Urrutia. “Both the port design and the back cut coincide with one another. Multiple angles on the port, particularly on the seat, typically enhance and improve back cuts on valves. In this industry, some do a three-angle, and some do as much as a five-angle valve job on the initial seat on the port. That would typically determine at that point what angle to adjust on the valve itself for a back cut. Back cuts can be as minimum as half a degree or can be as large as one-degree difference.” This can be very critical when you get into multiple seat angles that are done on the cylinder head port, and falls into mostly the higher-end racing engines that are looked upon in very fine detail and gaining as little as one or two horsepower can be a monumental achievement.
Additional Considerations For Optimal Valve Performance
Finding performance in valves typically comes from a couple of different factors. The first, as with virtually any internal component, is weight. For example, hollow stem valves, which have been on the market for several years now, have proven to offer a great deal of increased performance due to their lighter weight. The second factor comes in the form of multiple enhancements, such as undercut stems and altered profiles that correspond to the particular port design of the cylinder head. In addition to automotive valves and valvetrain components, Ferrea produces or has played a role in the design of poppet valves for natural gas engines, tank valves, the aviation industry, oil pump engines, unmanned vehicle for the miliatry, and virtually any other type of internal combustion engine that uses valves.
Custom Valve Ordering
In addition to their wide and varying selection of valves, Ferrea can produce a custom set of valves for your application and per your specifications, so long as the desired valve conforms to the parameters of the blanks valves off the shelf. “We can custom make just about any valve, on any stem size relative to what we have available,” says Urrutia. “Today, we can make valves with 4mm stems up to 3/8-inch, and we can usually get them done within a two week span. We also do short production runs on any valve that we have readily available as a blank form.”
On the Ferrea website, under the “Custom Valves” tab, one can utilize the supplied custom order form to order a set of valves specifically catered to their design specifications. Customers check intake or exhaust, the material (titanium, stainless, alloy) and the application. The full valve specifications, from length, tip length, seat widths and angles, head diameter, and the like can all be specified. For reference, Ferrea has supplied a diagram pinpointing each attribute of a valve.
While valves may seem like a fairly simple and basic internal component on the surface, as you’ve read, there is a lot to making to choosing a valve and pairing the set appropriately with a specific cylinder head casting. From the materials to the stem and head sizes, and the modifications that can be made for added performance. And like any other component, it’s really all a matter of how much you want to spend and how fast you want to go. Because there’s certainly a lot of performance to be had in a good set of valves.