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Originally Posted by pgfpro
3) "Engine efficiency" this is where the ecomodder's will say the racing performance crowd just want to burn more fuel to make more power and don't care how efficient the engine is. Not true at all!!! They both want the same thing... excellent BSFC numbers.
Engine weight plays a key role in all racing today. The best example is how the turbo charger and super charger racing engines today are down-sizing the engine to make the whole car lighter. There are mechanical advantages to running a smaller engine also. Small bore size just to name one, helps with detonation.
Next years F1 race cars is where Fast and Efficient are probably the best example of how these to words coincide. Major engine downsize with stringent fuel usage rules compare to 2013 rules.
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Ehhhh...
Forced induction often does not result in a lighter engine. Often times they throw in heavy iron blocks which ruins any sort of weight saving. For example the iron block 3S-GTE weighs more than a 3.5L 2GR-FE (with a cam swap easily makes well over 300hp). Turbo/supercharger hardware can add 100 pounds to an engine that was only 250 pounds to begin with.
To get a high power/weight ratio engine you first want a small stroke, maximum possible revs, and then very high boost (hey what do you know, F1 is running the smallest possible stroke, as many rpms as the regulations allow, and when turbos are around, as much boost as possible). With the <1 bar boost that most cars have the turbo barely adds to the power/weight ratio of the powertrain, especially because of the increased torque which needs a stronger transmission.
Now you can nitpick and say certain setups such as a centrifugal supercharger are extremely light, but forced induction is typically going to lower the engine's thermal efficiency under load.
Anyhow my point is naturally aspirated engines are used in racing for a reason.