The following is intended to give some background on my comments regarding the FGT air temperature sensitivity in the OEM tire article. I have tried not to get too technical here, but show some fundamentals on the differences causing the FGT to be more weather sensitive than turbocharged (or normally aspirated) counterparts. I will not try to discuss other tradeoffs between turbocharging and supercharging like lag versus instant power from low RPM upward.
The GT engine performance sensitivity to weather/air temperature I mentioned are due to efficiencies as some posts mention. Engine architecture, cooling system and intercooler efficiency primarily. Engine system inefficiency means lost energy typically in the form of heat. Heat is obviously bad for performance. An engine system that has more waste energy benefits most or is penalized the most by weather conditions that help or hurt the performance. This is the case of the supercharged FGT and supercharged engines in general versus turbo charged (or naturally aspirated).
A supercharger is a lot less efficient than a turbocharged or naturally aspirated system. A turbocharged system utilizes waste energy/exhaust to turn the compressor for higher density intake air. EcoBoost’s (turbocharger) advantage is real. A supercharged engine runs directly off of the crankshaft. The FGT creates about 650 HP in the combustion chamber, but it takes about 100 HP to drive the supercharger, for a net gain of 550 BHP at the crankshaft. The FGT has to cool for 650 HP while the same BHP naturally aspirated engine has to cool for only 550 HP and the turbo charged engine is similar. So the FGT engine has to cool for nearly 20% more power it cannot use.
Forced induction engines (turbo and super chargers) use intercoolers (now mostly “aftercoolers”) to cool the intake charge because higher density air heats more when compressed, so the intercooler attempts to maintain the gains of the increased air intake density. As discussed by a few here, intercooler efficiencies can vary a lot and are critical to performance and efficiency. The FGT cooling pack with intercooler is at a big disadvantage to an equally rated turbocharged system because of the extra 100 HP the supercharged engine has to cool.
Exterior air of 75 deg F plus and the FGT cooling system and intercooler are far more taxed than equally rated turbocharged or naturally aspirated engine in which the FGT performance drops from “ideal” quickly. Many here have experienced the very noticeable power drops with a little heat soak at the mile events or spirited driving on the road course as you watch the engine water temp reach 225 deg F+ quickly.
However, the FGT cooling and intercooler perform well when it is cold out and the car is just being driven slowly on the street with short bursts of acceleration. The FGT engine benefits greatly from this cold air and sauntering pace to reach its “full potential” plus with the cold dense air.
The FGT cooling pack (radiator, A/C condenser and intercooler) up front is challenged to maintain cooler intake and engine temperatures on a warm day, but has little trouble on a 40 deg F day on the street. So engine architecture (supercharged) and intercooler inefficiencies cause the FGT to have much wider swings in performance due to weather conditions than its turbo charged and naturally aspirated counterparts of similar BHP.
Scott
The GT engine performance sensitivity to weather/air temperature I mentioned are due to efficiencies as some posts mention. Engine architecture, cooling system and intercooler efficiency primarily. Engine system inefficiency means lost energy typically in the form of heat. Heat is obviously bad for performance. An engine system that has more waste energy benefits most or is penalized the most by weather conditions that help or hurt the performance. This is the case of the supercharged FGT and supercharged engines in general versus turbo charged (or naturally aspirated).
A supercharger is a lot less efficient than a turbocharged or naturally aspirated system. A turbocharged system utilizes waste energy/exhaust to turn the compressor for higher density intake air. EcoBoost’s (turbocharger) advantage is real. A supercharged engine runs directly off of the crankshaft. The FGT creates about 650 HP in the combustion chamber, but it takes about 100 HP to drive the supercharger, for a net gain of 550 BHP at the crankshaft. The FGT has to cool for 650 HP while the same BHP naturally aspirated engine has to cool for only 550 HP and the turbo charged engine is similar. So the FGT engine has to cool for nearly 20% more power it cannot use.
Forced induction engines (turbo and super chargers) use intercoolers (now mostly “aftercoolers”) to cool the intake charge because higher density air heats more when compressed, so the intercooler attempts to maintain the gains of the increased air intake density. As discussed by a few here, intercooler efficiencies can vary a lot and are critical to performance and efficiency. The FGT cooling pack with intercooler is at a big disadvantage to an equally rated turbocharged system because of the extra 100 HP the supercharged engine has to cool.
Exterior air of 75 deg F plus and the FGT cooling system and intercooler are far more taxed than equally rated turbocharged or naturally aspirated engine in which the FGT performance drops from “ideal” quickly. Many here have experienced the very noticeable power drops with a little heat soak at the mile events or spirited driving on the road course as you watch the engine water temp reach 225 deg F+ quickly.
However, the FGT cooling and intercooler perform well when it is cold out and the car is just being driven slowly on the street with short bursts of acceleration. The FGT engine benefits greatly from this cold air and sauntering pace to reach its “full potential” plus with the cold dense air.
The FGT cooling pack (radiator, A/C condenser and intercooler) up front is challenged to maintain cooler intake and engine temperatures on a warm day, but has little trouble on a 40 deg F day on the street. So engine architecture (supercharged) and intercooler inefficiencies cause the FGT to have much wider swings in performance due to weather conditions than its turbo charged and naturally aspirated counterparts of similar BHP.
Scott
