EngineLabs: X16 is billed as a lower-cost alternative to C16. Where did the motivation to develop X16 come from?
Jason Rueckert: We’ve always had C16 as our 116 octane fuel, but the issue with C16 is that it’s not a good naturally-aspirated fuel as it has a very low Reid Vapor Pressure – the Reid scale goes from 0-10 and C16 has a 1.85 RVP. More pressure helps to turn fuel into vapor at lower temperatures. That’s why C16 is so killer for non-intercooled blower and turbo combinations, because it stays as a liquid longer under heat. But in a naturally-aspirated application, you want the fuel to turn to vapor as soon as it gets to the back of the intake valve, and C16 doesn’t do that. We had a lot of customers coming to us, for example, with a 565-cubic inch bracket car and looking for a 116 octane fuel. C16 would actually run slower than our competition’s fuels in those applications, because the competing fuel had a better vapor pressure and was designed more for a naturally-aspirated application. We were using C14 and C15 to make up the difference, but we were losing a lot of business due to the competitor’s fuel being less expensive. We went back to the drawing board and formulated X16 to work best for those competitors – it has a Reid pressure of 6 RVP. It also comes out at about $11.00-$12.00 per gallon in a drum, where C16 is about $15.00-$17.00 per gallon and not optimized for those applications.
EL: What types of applications is X16 best suited for?
Rueckert: It’s great for Super Comp, Super Gas, and bracket-type applications. It seems as if everyone is running 500-plus cubic inches with 14.0-15.0:1 compression, and X16 suits those applications perfectly. We’ve got Tracy Dennis at Sunset Racecraft and Jim Hughes using it in all of their cars, and they’ve had great success with the fuel so far. You can spray 2-300 horsepower of nitrous on top of it, but it’s not a fuel I’d recommend for any more nitrous than that. It’s a killer 116 octane fuel for a good price. You don’t want to put much boost on it – that’s the reason we make C16 and Q16.
TYPICAL VALUES OF X16
• Color: Red
• Motor Octane 114
• Research Octane: 118
• R M/2: 116
• Specific Gravity: .710 at 60° F
EL: Where is the breaking point for a racer to switch to X16 from, say, C12?
Rueckert: Once you get above 14.5:1 compression or 8,000-plus rpm, I would switch it to X16. If the engine only has 12.0:1 compression but is spinning 9,500 rpm, I would also want to see them on X16. If they’ve got a big-block only turning 6,800 rpm but pushing 16.0:1 compression, X16 is still the answer because there’s a lot of cylinder pressure. I even think it would be a great tractor and truck-pull fuel in a naturally-aspirated combination.
EL: What role does the fuel play in engine tuning?
Rueckert: The specific gravity of X16 is .710 at 60 degrees Fahrenheit, so it’s a little bit of a lighter fuel. Let’s say you’re on C12, which has .717 specific gravity. If you swap in X16, you’d have to jet up probably one jet number. It’s non-oxygenated, so it’s basically throw it in and go. It’ll be very consistent for bracket racing, but it’s not a replacement for C16, but it’ll be a couple hundred dollars a drum cheaper for the applications that can make use of it.
EL: What makes up the difference between particular types of fuel in terms of cost?
Rueckert: It’s the chemicals that are added to the fuel. Once you get above C12, all of the fuels are chemical-based, where we have to buy the chemicals and blend them together to make the fuel. Everything comes from oil, so it’s a petroleum product, but the chemicals we use in the higher-end fuels come from the plastics and rubber industry, and that follows a completely different pricing market than the fuel industry does. That’s why sometimes you’ll see a price increase in our fuels even though the cost of pump fuel hasn’t changed, and on the flip side, when pump fuel becomes more expensive, our cost will go a little bit lower on some of these fuels.