Every time you drive, gasoline and air mix it up in your engine. Whether you get a rumble or the roar of power you want depends on whether it’s a good, clean fight – and you can stack the odds in your favor with AMSOIL PI.

Gasoline and air must be mixed at about a 15:1 ratio for complete combustion. Automotive engines rely on fuel injectors or carburetors for mixing fuel and air.

Carburetors first appeared at the end of the nineteenth century. Early ones simply drew air over the surface of liquid gasoline to make a combustible air-fuel mixture which was fed into the engine. They were replaced by
wick carburetors and, later, jetted carburetors.

Jetted carburetors work on the principle that nature abhors a vacuum. (It’s the same principle that enables you to drink through a straw.) Air rushes from the outside, where it is at atmospheric pressure, into the
lower-than-atmospheric-pressure partial vacuum inside the carburetor. As air rushes past the fuel jet, the air’s low pressure draws gasoline vapors into its stream. Ultimately, the gasoline vapor and air reach the combustion chamber where the mixture is burned for energy to drive the engine.

Carburetors have largely given way to fuel injectors, which meter a controlled amount of fuel into the fuel-air mixing area. Most automotive fuel injection systems today are computerized, and the precise measure of fuel meted out for combustion is electronically controlled.

Fuel Injectors Before And After Treatment With AMSOIL P.I.

Compared to carburetors, injector systems allow much more precise control of fuel delivery, which in turn, benefits fuel economy, emissions output and drivability.

Throttle body fuel injector systems deliver fuel through one injector into a fuel-air mixing area, located in the manifold, and each cylinder is fed the fuel-air mixture from that common location.

AMSOIL P.I. 1995

Port injector systems deliver fuel to a fuel-air mixing area near the cylinders. Port injectors usually serve one or two cylinders each.

The throttle body system offers the advantage of lower cost while the port system offers the advantage of more precise control.

While fuel injectors are extremely dependable, they do benefit from proper fuel system maintenance, including regular fuel filter changes and the use of high quality gasoline and AMSOIL Performance Improver.

For example, deposits impair the ability of fuel injectors to deliver the right quantity of fuel in a fine, easy-to-burn spray at the precise moment it’s needed for efficient combustion.

Port injectors, because they are nearer the source of combustion, may be somewhat more prone to deposits as the liquid gasoline in them deteriorates from heat exposure. But throttle body injectors cause more havoc when deposit-ridden, since one injector controls the delivery of fuel to all the cylinders.

AMSOIL PI removes fuel injector (and carburetor) deposits, and its regular use keeps new ones from forming. That optimizes fuel-air mixing for maximum power and fuel efficiency.

Regular use of PI also keeps intake valves clean, so they seat securely, which helps preserve compression and power. Its regular use also prevents rust, which helps keep fuel lines free of obstruction. AMSOIL PI also helps gasoline resist high temperature deterioration and consequent deposit formation.

PI may be used at six oz. per ten gallons of gas for a single-tank clean-up treatment and at one oz. per ten gallons of gas for maintenance.

SLS Note: Since 1995 engines and fuel injector systems have changed and more and more vehicles are incorporating gasoline direct injection (GDI) into the cylinders. While this allows even finer control of the fuel air mixture and the combustion process, it also adds several problems.

For years vehicles have had PCV and EGR valves. These valves recirculated crankcase and exhaust vapors into the intake manifold which brought them into contact with the back side of the intake valve. Until recently that wasn’t a major problem because the fuel air mixture also made contact with the valves and tended to keep carbon buildup to a minimum.

With the introduction of GDI, the fuel now goes directly into the combustion chamber and doesn’t touch the back side of the intake valves which allows carbon buildup which can hurt performance.

Direct injection now exposes the tip of the injector to the intense heat and pressures of the combustion chamber which can cause poor injector spray patterns from carbon buildup.

Because of this, AMSOIL P.I. has been reformulated to better clean direct injectors and the combustion chamber which also means it does a great job cleaning valves in throttle body and port injector engines.

Recommended treat rate is now 1 bottle for up to 30 gallons of fuel every 4,000 miles. No need for a maintenance dose every tank full.

AMSOIL P.I. is not for use in diesel, E85 or 2-Stroke engines.

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