Because diesels “throttle-push” the amount of fuel injected into the engine rather than limiting the amount of air entering the engine, notable power gains can be achieved by just increasing the amount of fuel delivered. All that’s required is the aforementioned electronics box to alter the signals from the onboard computer that controls the timing and length of the fuel injector pulse and the fuel pressure. There are all sorts of diesel tuner boxes on the market that promise plenty of big power.
While you can make more power with more fuel, if you don’t do it right, exhaust gas temperatures can go out of sight. This can spell eventual death for the diesel engine or turbocharger. Many diesel racers and pullers are unfortunately unaware of such potential engine damage. They love to increase power and are willing to assume some ownership of the risk, and that’s just what you do when you over-fuel a diesel.
It is only after getting more airflow into, and out of, a diesel engine that max-power can be achieved safely. These enhancements include a bigger or less restrictive intake path, inducting cooler air, bigger valves or different camshaft timing, a less restrictive exhaust system, increasing cylinder head flow through porting, turbocharging, or supercharging.
It’s no secret that max-power increases happen when you control both fuel and the airflow. If you don’t burn the extra fuel, then you’re increasing the exhaust gas temperature of a diesel engine If the exhaust temperature isn’t too excessive, and if it occurs for only for a matter of a few seconds at a time, most diesel engines can withstand the abuse without incurring permanent damage, but there is always that risk.
The telltale sign of over-fueling and lack of a balanced air flow strategy is excessive thick black smoke coming out of the exhaust pipe.
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