So let say you car on a 300 mile trip. One is a 350z with a supercharger and another with a turbocharged motor (exhaust powered). Which one would get the best mileage assumung weight, driver habits, traffic, other variables are held constant other than the difference of the type of forced induction?

how are they driving? normal take off speeds at lighs? launching at lights? are they stopping at lights? if they're not and they're just cruising, i don't think it would make any difference. they're not in spool so it's not going to matter.

edit- unless like dino said, they are in high rpms.

The turbo car.

Superchargers make boost based on RPM, as they are directly driven from the engine. They will make boost under a cruise condition if the RPM is high enough. More air always requires more fuel. More fuel means less milage.

A turbo car would function as a NA car in a cruise condition, as the exhaust energy is insufficient under a low throttle cruise to achieve turbine speeds capable of creating positive pressure on the compressor side.

Originally posted by 420a-Tnthewerks
edit- unless like dino said, they are in high rpms.

Doesn't even have to be high. Superchargers don't "spool" like a turbo. Roots type blowers will even make boost at IDLE. Centrifical types are essentially a turbo on a stick (shaft) and do share spool characteristics of turbochargers, but as they are engine RPM dependant, can make boost under cruise situations depending on how they are sized and geared to the shaft.

Originally posted by DarkOne

Originally posted by 420a-Tnthewerks edit- unless like dino said, they are in high rpms.

Doesn't even have to be high. Superchargers don't "spool" like a turbo. Roots type blowers will even make boost at IDLE. Centrifical types are essentially a turbo on a stick (shaft) and do share spool characteristics of turbochargers, but as they are engine RPM dependant, can make boost under cruise situations depending on how they are sized and geared to the shaft.

aw. i was thinking that if the supercharger car didn't press on the gas and just left in one place while cruising, it would not create boost. but thanx for the info.

but it would definatly be the turbo car becuase you can even accelerate without boosting with a turbo.

Yeah that's what I was guessing. I just wanted to here from the gurus.

well when you think about it turbochargers are more conservative cuz they use up gases that aren't being used by the engine anymore where'as the supercharger will put some parasitic drag on the engine. But then again you got a big ass obstruction in your exhuast with a turbo.

but generally turbo cars have better freeway mileage just because you can spool up to whatever speed you want then just cruise, the engine doesn't have to work so hard.

Originally posted by 420a-Tnthewerks
but it would definatly be the turbo car becuase you can even accelerate without boosting with a turbo.

Not if you drive an SRT-4. An SRT off any throttle is like driving a 3 cylinder metro with the A/C on. I get about 15 mpg on a good tank.

just hope you get 10mph on your next tank after you let me drive it :evil

Originally posted by 420a-Tnthewerks

Originally posted by DarkOne

Originally posted by 420a-Tnthewerks edit- unless like dino said, they are in high rpms.

Doesn't even have to be high. Superchargers don't "spool" like a turbo. Roots type blowers will even make boost at IDLE. Centrifical types are essentially a turbo on a stick (shaft) and do share spool characteristics of turbochargers, but as they are engine RPM dependant, can make boost under cruise situations depending on how they are sized and geared to the shaft.

aw. i was thinking that if the supercharger car didn't press on the gas and just left in one place while cruising, it would not create boost. but thanx for the info. but it would definatly be the turbo car becuase you can even accelerate without boosting with a turbo.

It does create boost, but that boost does not make it past the bypass valve if the throttle plate is creating a difference in pressure in the intake manifold.

Originally posted by etx
It does create boost, but that boost does not make it past the bypass valve if the throttle plate is creating a difference in pressure in the intake manifold.

you know what i mean ;) . with it still being in vaccum, it's going to act like a n/a car. thus, letting you get better gas mileage :thumbsup yay!!

I believe the SRT-4 gas mileage sucks because it has a very "safe" rich tune from the factory. They dont want lean situations and blown motors for the warranty i would suspect.


1997 Silver RS
Built
T3/T4 BB Turbo
20psi
Most current 1/8th mile time: 8.1@93mph 2.015 60'
1996 Black Supra TT
2004 Silver Snake