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Old 04-08-2013, 07:16 PM   #8
Scooby Specialist
Member#: 119958
Join Date: Jul 2006
Location: (IA) flyover cornfield country
1992 SVX LS-L


Originally Posted by SCRAPPYDO View Post
More MPGeebus's
It always strikes me that in order to get higher miles per gallon, they try to employ turbochargers, which by definition, pressurize the engine, requiring and allowing more fuel to be burned.

They arrange mpg tests to maximize low-load driving cycles, (usually when turbos are not spooled) to make the numbers look good, then when people normally drive, and actually USE the throttle, observed fuel economy isn't what the 'official' ratings promised.

Direct injection helps to not require pig-rich mixtures, like EJ Subaru turbos use, to avoid detonation, and also allow the use of higher static compression ratios, which help an engine run more like a good atmospheric engine when the turbo isn't pressurizing the intake above ambient air pressure, but it isn't flouting the laws of chemistry or thermodynamics. Energy out requires that energy to be put in first, which is stored in the fuel, not in the air.

As much as I like the rush of turbos, there is still something sublime about a well tuned, responsive, atmospheric engine, and Porsche builds some beauties.

C'mon... 991 GT3-RS is rumored to make ~450-460-475 naturally aspirated horsepower out of 3.8-4 liters, on an M97-derived block, not the previous metzger block, which had it's sunset with the 997 GT3-RS 4.0 this last year.

The far side of 450 naturally aspirated horsepower out of 3.8 liters... that is amazing stuff.
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