Building high performance engines doesn’t come cheap. The components you use cost more, the time you take to build each motor is longer, and paying attention to detail is the name of the game.
High performance engines have a very small margin for error when it comes to tolerances and extreme loads, therefore the demand for lubrication is also much greater than in your typical production engine. So why would you entrust any off-the-shelf oil to protect those vital parts?
In a passenger car, parts typically wear out until eventually they give out all together. In a racing engine the smallest imperfection and subsequent build up of friction will cause catastrophic results, spreading bits and pieces of your prized powerplant – along with a bit of your reputation as well – all over the track. The needs are different, as the experts we spoke to will attest, and so is the need for a different type of oil for racing applications. We spoke to a number of niche manufacturers of racing oils to see what those needs were.
According to some experts, the oil you use can help your engine survive the race and make more power. “The main function of racing oil is to increase film strength and anti-wear protection, reduce the effects of fuel dilution, whether that be from gasoline, methanol or alcohol or what have you, and increase oxidation resistance as a whole,” says Royal Purple’s Jared Martin.
Amsoil’s Ed Newman agrees, “Most racing oils are formulated to provide better anti-wear protection and shear stability than standard American Petroleum Institute (API) quality oils on the shelf. Our racing oil was designed specifically with these two protection and performance characteristics in mind.”
API Oil
The American Petroleum Institute (API) is a trade association that promotes U.S. petroleum interests and encourages development of petroleum technology. The classifications and designations for lubricating oils for automotive engines was developed by API along with SAE, ASTM and also recently with ILSAC (International Lubricant Standardization and Approval Committee).
API used to be the standard by which oils were measured when some oils on the market weren’t up to par. Now, according to some experts, it’s a starting point, from which you can downgrade and make more profit.
API is a standard to which auto manufacturers and government along with oil companies agree to have certain drain intervals and additives to lower emissions and improve fuel economy. Although API oils may have many of the necessary ingredients a performance engine needs, there is a compromise due to the regulations.
However, API standards are not a requirement for racing oils. Some manufacturers are now more worried about meeting or exceeding the latest SL or SM (API standards for 2001 and newer vehicles) oil requirements than they are about meeting older API standards.
Most racing oil manufacturers develop oil for specific types of racing applications and therefore the additives needed vary. Racing oil can be more specifically modified and anti-wear ingredients such as zinc and phosphorous may be used in higher concentration levels than an API oil.
Cameron Evans of Red Line Oil says there are definitely differences to be aware of. “It may seem to be a pretty simple equation when you’re making a racing oil. Everyone knows that you change race oil frequently, so you don’t need detergents in racing oil. But blending oil is a bit like making a cake: you may have a quart’s worth of ingredients to blend into the batter, and if it didn’t need to be sweet then there would be more room to blend in something else. In passenger car oil the detergents allow the deposit to be either suspended in fluid or picked up by the oil filter. With race oil it’s a bit different because you don’t have that same ability. When you look at racing oil, you can remove the detergents that take up much of the room in the additive package of a passenger car oil. It leaves more room for lubricity additives this way.”
With the plethora of oil on the market today it may be difficult to distinguish differences between brands. Not all oil is the same, say experts. Racing oil, for the most part, is made up of synthetic base oil and the manufacturers’ blend of additives for that particular race application. The additive package is what separates the winners from the also-rans. One manufacturer said that a good additive package in mineral base oil will outperform a synthetic base oil with a poor additive package. It’s all in the mix, so to speak.
There’s a lot of confusion, according to some race oil manufacturers, between race oil and street oil. “For many of our customers there is confusion, and many race with our [API] 20W50. They’re getting the zinc and the phosphorous that they need but not some of the other additives in our race oil.”
Viscosity
Viscosity is the measure of the internal friction in a liquid or the resistance to flow. Low viscosity fluids flow easily such as water or alcohol. High viscosity fluids, on the other hand, pour slowly, such as molasses or cold honey.
The friction between a moving part and a surrounding liquid increases with velocity, so no matter how streamlined a part may be, eventually terminal velocity will be reached and therefore an object falling through water accelerated by gravitational pull, will eventually fall at a constant speed. In racing terms, a crank rotating in a bath of oil will experience a parasitic loss. Any object will sink much faster in a low viscosity fluid such as water, and will sink much more slowly in a high viscosity fluid such as oil. The viscosity of a fluid can therefore be measured by the time it takes for an object or part, such as a ball bearing for example, to fall to the bottom of a test tube filled with oil.
Viscosity has long been held as the most important quality of a lubricant. And the reason it is so important is that if the oil gets too thin it will be forced out from the bearing surface under pressure resulting in poor lubrication, which leads to bearing surface damage. If the oil is too viscous it either doesn’t flow into the bearing surface, resulting in oil starvation and bearing damage; or it consumes too much energy, which is then converted to heat and the bearing may be overheated, at which point it can seize due to loss of oil clearance.
The internal friction for any fluid is higher at low temperature and much lower at high temperatures. The proper viscosity for a given application is extremely important. After a just a few hours of operation the viscosity of pure petroleum oil will change due heat and combustion gases among other factors. Some oils will shear and thin out, while other oils will oxidize and sludge up to become much more viscous.
“Low viscosity oils can offer the same amount of wear protection as high viscosity oils, and they will produce less drag inside the engine,” says Amsoil’s Newman. “This can provide increases in horsepower and reductions in elapsed time.”
So no matter what oil you use for any application, the ideal viscosity that provides maximum lubrication, that is total bearing surface separation, and at minimum power that is consumed by the lubricant’s viscosity occurs at only one combination of speed, load and temperature, say experts.
Additives
Additives are materials that impart new properties to or enhance existing properties of the lubricant into which they are incorporated. Flow characteristics of oil largely depend on the choice of base oil, however, they can be improved through the use of pour point depressants and viscosity modifiers. Factors such as temperature, oxidation and contamination with water, unburned fuel fragments and corrosive acids limit the useful life of motor oil. In this area additives have had a major impact on the performance and life of oil.
Formulating oil is a balance, and, as Red Line’s Evans pointed out, many compare it to cooking. A little bit of cinnamon may taste good but a whole lot of it tastes terrible, so finding the right amount of spice requires a lot of skill.
“You have to find just the right amount of the various additives – friction modifiers, anti-wear agents, detergents and dispersants – all of this stuff the chemical engineers are playing with to get just the right mix for that particular application,” explains Joe Gibbs Racing Oil’s Lake Speed, Jr. “We have been playing around with our mix for some time and the oil we race with today is not the same thing we ran 6 years ago. We’ve perfected the recipe since then, and now we run a 5W20. But there are still some NASCAR NEXTEL Cup teams that run 15W50 motor oil because that’s what they’ve always run.”
Base oils are an important ingredient in motor oil but what sets one oil apart from another is the additives.
According to Royal Purple’s Martin, oil really doesn’t become what it is until you add the additives.
“All of the benefits are in the additives,” says Martin. “Even in terms of racing oils most oil companies purchase additive packages. There are only a handful of additive suppliers globally. So in many cases the oils are basically the same with the only differences being the marketing. We actually manufacture our own additives. We aren’t a refinery so we buy our base oil but that’s the flour in the cake. The two major characteristics of our additives is the film strength, which is the load carrying characteristics of the oil not just the wear, and the oxidation resistance.”
There are several type of additives and each are used like a different spice in a recipe. One of the most common types of additives used in oils are detergents, which can also be categorized as dispersants because of its ability to remove debris rather than to clean it. In racing applications detergents and dispersants are often not added at all or if so, in much smaller amounts than a street oil. However, detergents can reduce bearing corrosion by neutralizing the corrosive acids.
Oxidation inhibitors function to prevent deterioration of the oil associated with oxygen attack. The corrosion of bearing metal is generally considered to be due to the reaction of the acid with the oxides of the bearing metal. These acids either originate from incomplete combustion gases that find their way into the oil as blow-by gases or are produced from oil oxidation. Oxidation inhibitors significantly reduce this tendency.
Anti-wear additives are used to help prevent metal-to-metal contact by adding film-forming compounds that protect the surface either by absorption or chemical reaction. Some of the main factors causing wear are, of course, metal-to-metal contact, abrasive debris and attack of corrosive acids. Abrasive wear can be prevented by filtering the particles of debris.
Viscosity modifiers or viscosity index improvers as they used to be called, are materials that improve the viscosity/temperature characteristics of an oil. This additive increases the viscosity at higher temperatures, significantly improving the viscosity index of the lubricant. The higher the temperature and volume, the greater the “thickening” effect the additive has on the oil. Therefore, the oil tends to “thin” less when exposed to increased temperatures.
Base Oils
Base oil is what some experts refer to as the “flour” in the cake. It’s is the bulk of the ingredient and therefore quite an important component in making up the oil package. Many of the larger oil companies simply produce the base oils and buy an additive package to put on the shelf. The smaller niche players such as those in the racing oil market tend to pride themselves on the makeup of not only the selection of base oils but the additives as well.
Base oils are basically obtained from two main sources: oil refineries of petroleum products and the synthesis of relatively pure compounds with properties that are more suitable for lubricants. Mineral base oils are generally not the preferred base stock for racing oil because it is made of varying compounds and therefore less stable or predictable than a refined chemical compound found in synthetic base stock.
Among synthetic’s advantages over mineral base oil is improved thermal and oxidation stability, more desirable viscosity/temperature characteristics, improved low-temperature properties, superior volatility, and preferred frictional traits.
“There are several different types of base oils,” explains Royal Purple’s Martin. “In automotive applications there’s Group 2 and lower, then Group 3 and Group 4 (Group 4 being synthetics). Really, if you have a Group 4 from BP/Amoco vs. Exxon/Mobil there’s not going to be much of a difference. The refinement process is identical, and the tech specs will be virtually the same. Where you gain your benefit and tell the difference between any two branded oils is your additives. That’s how you enhance and tweak the performance of the oil. The base oil is only going to do so much, just like the flour in the cake.”
It has been said before many times, but a well-formulated mineral oil will outperform a poorly formulated synthetic. Synthetic is inherently better base oil vs. base oil but if you fall asleep on the additive end of it a mineral base oil could be tweaked enough to out perform in some applications.
Synthetic is a better starting point but it’s really what you do with it, say race oil manufacturers like Royal Purple, Amsoil, Red Line, Joe Gibbs Racing Oil and others.
|
David Vizard Dyno Tests Joe Gibbs Racing Oil –
In Joe Gibbs’ Racing Engine! Back in the spring of 2005 I received a call from Joe Gibbs Racing’s (JGR) Lake Speed, Jr. Lake had called to tell me about the new flat tappet racing oil that they had brewed and were running in Tony Stewart’s #20 car. He sent extensive test results (run on a Busch motor) and I had to admit, they looked good. The numbers Lake had sent were comparisons of a number of top, high quality racing oils, versus their new flat tappet XP2 oil. These results showed an improvement of about 1.68 hp increase over the next best oil. To maximize power from these engines it’s necessary to build an engine with low friction to start with. This means low tension rings, etc. Because these engines are inherently low friction units to start with showing any improvement is difficult, so, bearing that in mind, the gain shown looked good. The first engine I tested JGR’s XP2 oil in was a hydraulic flat tappet “cammed” 5.0L Ford motor making a nominal 350 hp. To get our baseline numbers, 10 pulls were made with all significant parameters held constant at the start of each run. The best and worst numbers were then thrown out and the remaining 8 averaged. Next a flushing oil/filter change was made using XP2. The engine was then run for about 5 minutes and a final oil/filter change made. Again 10 runs were done. After the best and worst were thrown out the average increase came to 5.86 hp! Although I was very sure of the test procedure I was far from happy about an increase this large. As soon as the opportunity arose I ran the same sort of test with my dirt car motor. This Super Street Stocker equipped with a 350 Chevy was sporting a solid flat tappet cam conforming to a .500? valve lift rule. This test showed XP2 to be 3.1 hp better than the Mobil 1 baseline oil. This looked a little more realistic but just to seal the deal I asked Lake Speed if I could come along and sit in on a re-run of their original tests. Please understand that although my dyno works well and is regularly calibrated it is hardly the million dollar plus deal that JGR’s #1 dyno is. With a restrictor plate motor on the JGR dyno, the same 10 runs were done. So you have an idea of the accuracy of this dyno the mean deviation of all 10 runs is contained within 0.3 hp. This gave me great confidence in the accuracy of the numbers delivered. The oil change, with flushing, involved the use of over 20 gallons of XP2. The results of subsequent tests showed an average of 1.88 hp increase. Although the foregoing looks much like a power test it should be remembered that NASCAR NEXTEL Cup car engines have to use flat tappet cams, which, in an effort to get power, are very hard on the valvetrain. Since JGR engines are not only showing good speed but also surviving, I made the assumption that this oil is up to the job of keeping the lifters and cam profiles in shape. As for the big increases on my tests, I’m assuming that in the first test the lifters were sealing up better, hence the relatively high number. In the second instance the dirt motor, being built all of cost-cutting parts, does not have the benefit of ultra low friction as a starting point.
|
