[stillsearching]

I will clarify - everything i'm referring to refers to gas engines in this instance.

Originally Posted by oil pan 4

They do have a bypass for the exhaust, its called a waste gate.

I haven't seen ones you can set to 0psi yet though. :-/ Maybe they're out there though. Just if it's in the exhaust path, it's acting as a restriction.

Originally Posted by thomason2wheels

Not to puttoo fine a. Point on it but there is a bypass of sorts.....your right foot.

See points above and below.

Originally Posted by Diesel_Dave

I'm more familliar with the diesel world, but I can't recall the last time I heard about a turbo hurting fuel economy (assuming the turbo match has been done properly).

Can you find me even one vehicle on fueleconomy.gov that shows the same MPG figure for a turbo engine vs a nonturbo engine if gas powered? Those are being driven about as easily as possible in the mileage loop. The mileage drop is often about the same as a bigger engine producing the same power without the turbo.


Out of order response:

Originally Posted by Vekke

Some of the time turbo helps to lower fuel consumption like when accelerating etc.

I don't know that it lowers it, it might let you accelerate in a higher gear though, or give you power without the drawbacks of larger displacement carried around all the rest of the time. But that seems to be the case for "normal" drivers. What i'm wondering with all the ecomodders already lowering axle ratios, lowering aerodynamic load, driving slower and swapping in smaller engines if there's even a point to the turbo... wondering whether a total bypass for 0psi and no exhaust restriction would work better under many conditions of cruise, short of pulling a hill that would normally require you to downshift. (and maybe you could throw the bypass off/turbo back in with a little switch on the shifter or something then)

All I know is that i've never seen a turbocharger added to a gas engine which didn't take away 1-2mpg under steady state low load conditions.