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How Gauges Can Save Your Engine

By: · August 17, 2009

The average driver could really care less about what’s going on under the hood of whatever they’re driving. Around they drive, oblivious to their engine’s operation. Enthusiast drivers, however, want to squeeze as much reliable power out of the engine as possible. So if performance is your game, then learning to improve upon your engine’s fuel and air delivery systems should be as well. S quality set of automotive gauges is, therefore, the first step on the path to more horsepower…

Knowing what’s going on inside the engine can mean the difference between making reliable power, or turning the powerplant into an oily heap of really expensive scrap metal. In the case of forced induction by way of turbocharging, one quick way to put holes in the side of an engine block is to let boost levels run away from the ability of the fuel system to feed the engine enough fuel. A lean condition with the addition of forced induction is a sure-fire recipe for a terminal case of engine detonation, quickly followed by a heaping helping of collapsed ring lands, blown head gaskets, melted pistons, dropped valves, and a new picture window in the side of the block courtesy of broken connecting rods.

Level Headed

Before installing a manual boost controller, messing with the fuel pump, goofing around with the injectors, or spending all sorts of time getting a blow-off valve bolted up and attracting the police, it’s a good idea to determine where turbo boost levels are at in the first place. This is especially true if using a manual boost controller to override factory boost levels. Since the turbo wastegate is essentially an exhaust bleed valve whose purpose is to prevent runaway boost, fooling it into thinking there is no reason to open with a manual boost controller is a game best played only with an accurate boost gauge installed.

There are more than a few types of boost gauges but they all more or less accomplish the same tasks: displaying how much boost the turbocharger is forcing into the engine and at what point in the RPM range this is occurring. Installing a manual boost gauge couldn’t be simpler. Run a line from a boost-vacuum source by way of a T-adapter to the gauge and be done with it. The only power required for a manual boost gauge is for lighting. Electronic boost gauges offer a bit more complexity, but they can bring improved accuracy along with added features such as warning levels, peak recording, and playback. Another advantage is that the boost line itself is not required to run into the cabin, but only to a metering block or sensor unit. Although manual gauges are usually less expensive than their electronic counterparts, both will do the job of reading boost levels.

Lean or Fat?

Putting fuel and air into the engine isn’t very tricky, getting the right mixture of fuel and air into the engine is however. Too much fuel over air and the engine will run rich, or fat and lose power—much the same way you will run if you put too much butter on your bagel. Too much air and not enough fuel, and the engine will run lean, starve for fuel and burn up—just like you would if you tried to run a few miles after not eating anything all day. The best place to be when it comes to fuel and air ratios is a theoretical spot where all the fuel and air is completely burned. This ideal air ratio, known as the stoichiometric ratio, is a ratio of 14:7:1. Think of it as the point right in the middle of too much butter and not enough.

Most engines are set up to run with a little extra butter so they don’t run the risk of starving, and running lean. An air-fuel ratio gauge monitors the oxygen sensor output and visually converts the ratio into light ranges on the gauge. A narrow-band air fuel gauge runs off the stock oxygen sensor, and is a decent indicator of what’s going on at WOT, or wide-open throttle. While a narrow band gauge is not really a tuning device, it can quickly alert you to a lean condition at wide open throttle before pistons start melting and valves start dropping. Driving around without any gauges at all is a dangerous decision to make if performance is in the plan.


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