Fuel Injection vs. Carburetors
In the past, carburetors ruled the track, but made tuning difficult with often substandard results. Fuel injection is the perfect solution to the “carburetor headache” that we’ve become so accustomed to. With the appropriate knowledge and a good technical support team, even the novice racer can find great success with fuel injection.
There are several fundamental differences between carburetors and fuel injection. Though both may be capable of similar peak horsepower numbers, actual “on-track” performance characteristics vary greatly. On track performance begins with a strong tuning program. When tuning carburetors, there are very limited tuning opportunities for wide-open-throttle adjustments, mostly limited to main jet changes. Conversely, fuel injection allows a tuner to make adjustments at every 250 RPM’s in addition to 10 throttle positions. Successful fuel injection tuning requires little or no compromise. Carburetors force you to compromise between reach and lean areas in the fuel curve to find that “happy medium”. In order to make some areas run at optimum performance, it causes the tuner to compromise the fuel curve with other areas being too rich and/or too lean. A fuel injection system allows the tuner to make far fewer compromises due to the highly increased adjustment capabilities.
Fuel Injection vs. Carburetors on the Dyno
Note that the dotted green line (fuel injected air/fuel curve) remains virtually constant from the beginning of the pull to the end. The solid green line (the carbureted air/fuel curve) starts out overly rich, quickly falls to the lean side, and then ends the pull balanced.
Now compare the dotted blue line (fuel injected torque) with the solid blue line (carbureted torque). The torque curve on the injected engine is much broader which leads to superior performance on the track.
Carburetors must be re-jetted for altitude and atmospheric changes. This includes adjusting air/fuel for simple changes in the weather. Properly tuned fuel injection systems have sensors that direct the computer to automatically adjust for these changes with no need to retune at all. Fuel injection systems have the ability to “self-preserve”, meaning that if something happens to cause the engine to overheat, the system will detect this condition, it will automatically make changes, like add additional fuel and retard the timing to preserve the engine for as long as possible. Carbureted systems have no ability to “self-preserve”.
