Auto Parts: engine, wheel disc brakes, internal combustion 4

Question
1:does a GT engine consume more fuel than an ordinary engine?
2:having big mufflers,does it increase fuel consumption?
3:does a turbocharger increase fuel consumption?
thank u!

Answer
Hi George,

Well, the 'GT' badge is an option package. The Grand Touring option may add things like A/C, a roadster top, louder stereo, 4-wheel disc brakes and other non-performance upgrades. So, I'd have to say that 90% of the time a base model car will perform/run as good and as efficiently as it's GT counterpart.

Good question regarding the 'fart-can' mufflers import tuners use on their cars. Without a doubt they reduce the efficiency of an engine. An engine requires a certain level of back-pressure in the exhaust system. The wide-open, baffle-type mufflers reduce the amount of back-pressure to allow the engine to 'breathe' a little better which in turn allows the engine to produce more power. How? Pretty simple. An internal combustion, 4-cycle engine has to 'waste' a piston movement to remove the burnt fuel the cylinder just used for power. In a normal engine, when the piston is evacuating the used mixture into the exhaust, as it reaches the top of the stroke, the exhaust valve(s) closes trapping a small amount of the used mixture in the cylinder. This mixture may be used, but there is still quite a bit of fuel left in it and the heat it still has quickly warms the next intaked mixture allowing it to expand slightly causing a minute increase in cylinder pressure before being compressed. On an engine that uses an open exhaust (baffle-muffler), there is no back-pressure to keep that small amount of used mixture in the cylinder which allows more room for the next, clean mixture. The clean mixture is heavy with fuel because the O2 sensor is not getting a correct reading from the super-hot exhaust flowing passed it thinking it is lean so it pumps more fuel into the intake to attempt to compensate. When this mixture reaches the hot exhaust, it still has a pretty good amount of unburnt fuel in it and as it is sucked-out of the cylinder because of the lack of back-pressure, it explodes, in the exhaust manifold. That is the 'popping' sound you hear coming out of the muffler. These constant explosions are not healthy for any of the vital exhaust components like the manifold(s), the O2 sensor(s) and converter(s).

Do turbo engines use more fuel than their normally aspirated counterparts? Are you kidding me? A turbo-charger FORCES the air-fuel mixture into the cylinder under pressure usually between 2 and 14 PSI when active. Typically, the cylinder is fitted with almost twice the mixture a normally aspirated engine would have and it goes without saying that twice the mixture will produce twice the bang and therefore, nearly twice the power.

It should be noted that you can't have both. You can either have power or you can have fuel economy. There really is no comfortable medium. An engine designed to make power will never be efficient no matter the modification externally and as such, engines designed for economy will be power deprived.

Thanks for the question, I hope this information was helpful to you.
Fred
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