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The Hummer Knowledge Base

Turbocharging vs. Supercharging:

OK, to increase power & torque we need to provide the engine with a better flow of fuel & air and to make sure that the fuel is actually burnt or combusted. The two common, bolt on options are super & turbo chargers. When too much fuel is sent to the combustion chamber it causes excessive heat build up and subsequent possible piston and exhaust valve damage. When too much boost is applied it can cause crankshaft, piston rod & head/gasket failure. So, this is the reason that observers have fixed opinions one way or the other. If you act in a conservative way you are unlikely to cause damage to engine components but you should not attempt to extract every ounce of performance from the engine.

Intercoolers cool air intake & provide more air but are usually used on high performance engines running high boost (over say 10lbs, usually 14-15lbs). They offer virtually no benefit at all to conservatively modified engines. A pyrometer (heat) sensor is fitted just below the header pipes at the top of the collected exhaust, to monitor heat & a boost gauge is used to monitor the boost of air that the engine is getting. The engine can then be tuned on these two devices alone. Keep the exhaust temp. to the recommended level or below and keep the boost to the expert's recommended level. You should have no trouble with the engine or driveline. Make sure that you monitor the radiator temp. because boosted power can cause higher operating temperatures. By the way, modern turbos have virtually no "lag" and begin to operate at low (800 approx.) revs for 4x4 use. Turbos fitted to gas engines on performance machines do come in at much higher revs but they are designed to do that. It's horses for courses.

Ralph


Well put. I take a very conservative approach and I drive by the gauges. When installing the supercharger the fuel delivery is increased. Your comment about increasing fuel temps, etc., are also very good, however with a diesel it is possible to deliver more fuel than can be combusted. This results in dense clouds of black smoke and no appreciable increase in temps. I had an experience with this just before installing the supercharger when my family and I visited the bristlecone pine tree forest in Bishop CA. This road exceeds 12,000' if I remember correctly. Needless to say the truck was putting way more fuel in a NA diesel than was necessary for the given amount of O2. After that experience I can really appreciate an O2 sensor.


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