Stock GTP, combined city and highway. Quite a difference in fuel mileage. When I bury it every time I can in town, and cruise the highway at ~100mph, I get only 15.5 mpg after 200 miles. When I take off sedately and let the Yugo's pass me and keep it from indicating any boost on the DIC(giggle snort), I get 23 mpg after 100 more miles. Anybody ever wire a switch into their system so the supercharger never builds boost, no matter what the throttle position, unless the switch is thrown--like Mad Max? Or maybe adjust the bleed off system to engage even later, like almost full throttle? I was thinking it might allow greater throttle input(more normal driving) without the mileage hit until you needed it, or hit the dragstrip. These motors seem to be pretty torquey even without boost.

So far I love my new car, just gotta get used to paying the price at the pump. I'm used to raising hell every time I got into my Civic and it would still give great mileage, just not the performance of the GTP. I suppose I shouldn't complain as it only had 1.6l and I could get it down to 24mpg if I raced it allot.

Did I mention I love my new car?

Doug
Mansfield, TX.

Hello,

I may be wrong, but, the blower only pushes air in....It doesn't affect the fuel input. Unless you take into the case the fact that it takes more throttle to get going without the S/C. That being said, the blower actually gets you better gas mileage. I've seen one thread where someone actually disconnected the Super Charger. The only way they were saving money, is the fact they weren't having to run premium fuel. Even on that note, the performance was obviously not there, and the mileage didn't change enough to make me want to go there, and I don't recall anyone else heading down that road either. You can look through the archives...it's there.
Bottom line....It takes more fuel to get you going faster. When you want to go faster, you're going to want the SC pumpin'. When you don't want to go faster, it takes that much less throttle to get you going w/ the SC turning.
Later now,
Clint

I agree that I have heard using a SC will reduce your MPG on heavily loaded applications that are underpowered, like pulling a trailer. Keeps you from having to plant your foot in it to maintain speed. There was an earlier thread concerning adjutment of the boost valve to get it to build boost earlier, and someone said doing so would REDUCE mpg so I thought it might be interesting to go the other way. Like I said, these engines seem to have more than enough torque for daily driving without the SC.

Doug
'99 Black GTP Coupe

If you plan on pulling a trailer or whatnot you can always just pull the belt off of your SC. Granted you should get better mpg's with your SC, but if you want to do a test or whatever, you can run without your SC belt without hurting your car. See if your mpg's go up, if they dont, then there might be something else not right with your car.

Doug-

Your mpg difference that you've noticed isn't directly related to the amount of boost. When you increase your throttle, more fuel gets put in. At wide open throttle, a LOT of fuel is dumped in. You probably noticed a higher mpg when you kept boost low just because you stayed out of the throttle.

Yes you are probably right. And as far as my previous post, I meant to say using a supercharger under a loaded condition improves MPG not reduces it due to the fact that you don't have to keep your foot in it so much. That's why I was wondering if having the supercharger build boost at a lower throttle input might actually help our MPG. I'm guessing the only reason bleeding off the boost at idle and part throttle helps MPG is due to the reduced resistance felt by the SC and therefore the motor. Don't most aftermarket SC kits build boost all the time? Or do they all bleed the boost off when not needed?

Doug