SUFFERING FROM IMPROVEMENT
For Richer Or Pourer...
By Oscar Jackson
Posted on Jan 3, 2006
I was perusing my local auto parts store recently, trying to buy some hand cleaner when one of my readers spotted me. He started with the normal chit-chat — “Nice to meet you...etc.” — but with very short notice his demeanor changed and he moved in for the kill. “Which one of these oil additives will give me the most horsepower?” was his first blow to come my way. Then, “If I put this other additive in my crankcase, will it reduce the clanking sound in my engine?” was the second of the two-punch combination.
Additives, be them oil, gas, or coolant, all have their own story. Each story has way too much information to include on these pages — in fact, the Society of Automotive Engineers has volumes on any one subject alone. I’d like to pass a few tidbits that may help my readers when they pass by that part of the auto parts store that’s so irresistible to us motor heads, the chemical additive department.
You pass down that additive aisle and you can’t help but ask yourself, “Wouldn’t 20 percent more horsepower from that octane booster be nice?” And then you remind yourself about the ads that you’ve seen where a very overweight guy turns into Mr. Olympia in six short weeks just by taking a pill once a day. Yeah, right!
Having said that, there are some additives that are beneficial to our cars. Let’s start with fuel/octane additives. Today’s fuels aren’t nearly as bad on our engines as fuels in the past. Just 10 years ago, fuels didn’t have the additive package to keep fuel injectors and fuel rails clean if the car had sat for any length of time. Today’s fuel has been reformulated to stay healthy longer so that fuel injectors and their pumping system won’t clog up if they are not driven for an extended length of time, but the pump octane for us high performance drivers has gone down. While our current late model turbo, supercharged, or high rpm variable camshaft engines are designed for these lower octane fuels, a little bit of help in the octane department is always useful. Most of the well-known brands of octane boost will increase your pump octane 2-4 points if used near, or slightly above, the recommended ratios. But be warned — if you dramatically over treat your fuel be prepared for a rust color coming from your tail pipe and on your spark plugs. Oh, and don’t be surprised if the engine starts running poorly and misfiring. Remember, if a little is good, a lot is probably overkill.
The reason that these octane boosters increase horsepower in our late-model, high-compression, supercharged/turbocharged engines is simple. By improving the octane of the fuel, we raise the detonation threshold of the fuel. In basic speak, we prevent “knock.” All late-model, high-performance engines use a “knock sensor” of some sort to “listen” for engine “knock.” Pump gasoline today usually has a pump octane rating of 91-93 octane, depending on what state you live in and what altitude you live at. Octane is simply the ability to resist “knock.” Octane doesn’t have any ability to produce more BTU’s (British Thermal Units) of energy, and, thus, cannot produce horsepower from raising the octane rating. It’s simply a measure of how much pressure/stress the fuel can take before it explodes uncontrollably. Uncontrollable explosions inside an engine produce what we hear as “knock.” It’s also the moment in time when pressure on the pistons, rings, rods, etc. rises from around 1000 psi of pressure to 5000 psi of pressure. So, controlling knock is very important. And the manufacturers of our cars know that. So the engine computer is programmed to look for knock and to retard ignition timing if it sees any signs of knock. Retarded ignition timing also retards horsepower. So, if we can raise the detonation threshold of the fuel we can effectively raise the ignition timing tables in the engine computer without touching the computer.
I believe that pump gas fuel is great for daily driving, but when your thoughts turn to the quarter mile or the local Autocross on the weekend you’re no longer driving the car as it was intended. So, if you go racing I recommend racing gas or at least some octane booster.
While we’re on the subject of hydrocarbon additives, let me address oil additives. I can make this one short and sweet. If you buy quality oil, you do not need any additives. How did you like that answer? OK, let me get a little more in-depth. There are many additives that are already in your can of oil. Modern oils all start with a base stock of refined oil from crude. To that, the oil manufacturers add ingredients like viscosity modifiers, detergents, antiwear (AW) agents, oxidation inhibitors, rust inhibitors, pour point modifiers, and antifoam agents. Each of these additives performs an important function. The viscosity modifiers allow good cold start performance and then change with temperature to maintain good performance as the engine heats up. Detergents are added to keep all the nasty sludge and carbon deposits suspended IN the oil to be removed during your oil changes instead of sticking to the inside of your engine block. Antiwear agents form a protective film on moving engine parts to prevent galling under cold start and high load conditions. You may remember some oil additive companies telling you about how their antiwear packages help provide a protective film on engine parts. Well, the truth is most quality oils already have the AW agents in the oil. Most of the other additives are just to keep oxidation and rust in check. The pour point modifier is used to keep oil flowing in cold weather. There is nothing worse that trying to start a car in very cold weather only to find that you’ve got an oil that has nearly converted itself into one solid block of crude.
Now let’s talk about synthetics. Synthetics are one giant step above good, conventional, hydrocarbon oils in quality and price. This is not to say that quality hydrocarbon oil isn’t good enough — I’m just saying that for that extra protection in high load conditions, synthetic oil is what you need. Mobil 1 was the first mass produced production synthetic oil sold in the U.S. in, or around, 1976 (if my memory is correct). Today, almost all of the major brands produce full or partial synthetic oil. The reason synthetics are better is simply the ingredients used to produce them. They have to blend more of each ingredient that’s used in conventional oils and then add some very expensive additives to make the synthetic last longer. Synthetic oils will start better in colder weather due to their lower pour point. Most synthetics have a minus 60F pour point. Conventional oils generally have a pour point of minus 40F. And synthetic oils resist “thermal breakdown” (those words you hear on the TV adds, but they are true) better than conventional hydrocarbon oils. This is why I use synthetics in all of my cars and almost every race engine builder I know recommends synthetics in their racing engines, but for a daily drive I don’t think an expensive synthetic is required. Normal oil changes on time will give your car the protection it requires.
Until next time, stand on the loud pedal. It’s the first one on your right. <<