On average do supercharges and turbocharges increase fuel consumption, if so how much? Thanks.

 

When I had just my cai/tune I got 14 city mpg. I now get 17 city and 28 highway since my supercharger and new tune. I think its the tune or my upgraded fuel pumps or something. IDK but I think its weird how I gained mpg after a s/c

 

I read somewhere that they actually make it more efficient IF you do NOT get on it. But who the hell is gonna do that??

 

You mean you wouldn't get a S/C for the added fuel ecomony?

 

Turbo's will generally give better mpg since they are 'recycling' some of that energy of the exahaust flow. Some car manufactures (BMW for one) are designing cars with smaller engines with dual turbos to give more horsepower and better mpg than their larger displacement counterparts. But I've heard several turbo S197 guys say they get better mpg on the highway. Most twin screws usually loose a couple mpg's on the highway due to the drag of the supercharger on the crank. Since it's not adding any boost (usually) at highway cruise, I'm actually wasting horsepower/mpgs turning the screws, such as a huge accessory like a giant a/c compressor. But, since it's not building boost at highway cruise, I'm basically just turning the screws, not enough to help the engine and make boost, but actually a drag on the crank.

All that being said, I only lost about 2mpg, and can still get 25 mpg at 55mph, so can't really complaign. I think trading 2 mpg for 150rwhp is worth it.

 

Will have my s/c two years this July. At highway/interstate speeds (75 mph +/-), my mpg went up 1.8 when cruising. When really enjoying myself, thats a different story...

 

Normal cruising , the mpg is about the same. Getting on it , priceless ...