[az968]

That's roughly 27 mpg for highway and 19 mpg for city for us non-metric types.


I don't think I've ever driven any car to 160 kph, or 100 mph, officer.

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[J.Elenbaas]

That's the good thing of having Germany as next door neighbor 

They still have many roads without speedlimits.

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[jthomson]

Hey, all. Ever since I installed the RS1 chip my mileage has suffered. Before it was 17/27 ish. Now it's 14/23 ish. So, really ISH. Any ideas? 

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[Ernie]

Have you changed your driving style? I seem to find the chip, makes my right foot weigh more.

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[jthomson]

That's the thing. Before I chipped I got roughly the same mileage no matter how I drove. Given the chance, I like to get to 70 or 80 as fast as possible. So I'd say no, my driving has not changed. On another note, while the torque curve is smoother I'm not impressed with the chip in the least. I'll probably go back to the stock chip.

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[Ernie]

I wonder if other members feel the same about the RS Barn chip? I found that when I was swapping out the RS Barn chip, the PO had already had a Racer X chip installed by his mechanic (Flash probably has the stats). I don't really know how the stock chip performed, or gas milage differences. Heck, my DD is a 2000 Honda civic with 289,000 miles still getting @ 34 mpg. My Wrangler gets @15mpg. Give me whatever I get as far as mpg and peel the smile off my face in the 968! Just sayin! :-)

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[az968]

I installed an RS Barn chip a few years ago and found a Weltmeister chip in there.  i prefer the RS Barn chip but also can't compare to the stock chip. It's more responsive across the RPMs  .I think my gas mileage is decent compared with the fun i have driving the car.

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[MCL968]

With my RS Barn chip I calculated 30.7 mpg on an all freeway trip of over 120 miles. But, that was with clogged injectors. Now that the cleaned injectors are installed, I need to rerun the test and see what happens. I have a RS Barn exhaust and the airbox mod with a K&N filter. It seems that this tank is going faster, but that's just a feeling, not based on a fill-up and mileage check.

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[Kim]

keeping more horses in the barn always results in a larger hay bill.

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[94SilverCab]

I have had both Stage 1 and Stage 2 chips. The RS Barn Stage 1 chip, along with the air box mod, woke my car up. I don't recall that it lowered my gas mileage at all.

 

The stage 2 chip, when I upgraded to the RS Barn header, added considerable power, but yes, my mileage went down a bit.

 

I get about 18.5 MPG overall, but I am more interested in the smiles per gallon.

 

Jay 

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[Ernie]

Jay, may I ask what considerable power is? Without any superchargers left, it may be the only step to increase hp. Then you burn more gas (lol, staying on topic)!

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[ds968]

Actually with a supercharger you might get better gas mileage ; you don't have to plant your foot that hard on the gas pedal all the time to make the car go as fast as you would with a NA engine ; a lighter touch will achieve the same desired result . Of course, one ( me for example, lol ) may have a tendency to stomp on it more often for the thrill of it , so perhaps in reality the gas mileage is worse with the SC, but under mild-mannered driving, in theory, more power should yield better mileage . Flash, if you're reading this , any input ??

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[94SilverCab]

Jay, may I ask what considerable power is? Without any superchargers left, it may be the only step to increase hp. Then you burn more gas (lol, staying on topic)!

My 968 had significant modifications by RS Barn, while keeping it NA...I'm not at liberty to divulge all of the mods, but my car delivers to the wheels roughly what Porsche claimed was the crank HP.

 

Pete did post about some of his super engine modifications, you might start following the trail there.

 

Pete is welcome to weigh in to the extent that he wants to share 

 

Jay

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[Kim]

"but under mild-mannered driving, in theory, more power should yield better mileage ."

 

My understanding of basic physics is that more power is the result of more air allowing the use of more fuel making more power.  Even in mild mannered driving the supercharger is drawing engine power to turn, unlike a turbo that might return gas mileage equal to a non turbo engine of the same size when not spinning much (think  of a V8 Cayenne, it gets about the same mileage as a V8 turbo in the gov't tests, where "stepping on it" is not a component).  My guess would be that a supercharged car would always get a bit poorer mileage that a non-supercharged vehicle of the same displacement under all conditions, due if nothing more that to the parasitic nature of its operation.

 

Having said this, I will now retire to the drawing room to await the various and sundry reviews of my exuberant verbosity.

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[94SilverCab]

Sorry Kim, on this one I think you don't have it right. Having said this, I will now retire to the drawing room to await the various and sundry reviews of my minimalistic verbosity.

 

Jay

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[Waylander]

I think Mercedes gave superchargers a fair run, think they have gone turbo route only now

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[az968]

I would wager that Flash has written a 50 page engineering report on this posted somewhere on this site, hee hee

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[ds968]

I would wager that Flash has written a 50 page engineering report on this posted somewhere on this site, hee hee

I think you're probably right and I vaguely recall somewhere here that he also mentioned you " should " be getting better mileage with the SC, all else being equal and of course same driving m.o. as before-SC. But I could be wrong, I qualified that with " vaguely ". :-)

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[MCL968]

I believe the existing data shows that an SC can marginally improve mileage in the manner that they are used in the 968, but there are different ways to employ a SC on an internal combustion engine. The old 671 GMC blowers used by hot-rodders back in the 60s to the 80s could (believe it or not) improve mileage substantially because they are located between the fuel source (carbs) and the intake valves. Such a location served to homogenize the air fuel mixture, which improved efficiency and decreased the fuel precipitation on the walls of the cylinder prior to combustion.

 

If you remember the name Smokey Yunick, he experimented with an adiabatic motor that had something akin to superchargers on each bank of the flat 4 (I think he used a Subaru motor). It made crazy horsepower and produced surprising MPG for the displacement. Problem was, the motor eventually expired because of the heat soak caused by the reuse of the heat generated by the design. It all was for naught because shortly afterward port fuel injection became the norm and there was no way to fit a homogenizer between the injector and the cylinder.

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[ds968]

So on my Tiptronic it looks like I'm averaging 12 mpg ( 20% highway-80% street combo based on the most recent 100 miles drive test ). No idea about the six speed car's mileage , but for the Tip, I guess that's way too much fuel consumption, and not sure what to look for ...

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