So he's probably comparing apples and oranges and then saying the SC gets better millage. Since he mentioned the 4.56 in the 2nd vehicle I can only assume the SC has some stock ratio.

 

a buddy of mine averages 30mpg in his 800hp dodge srt4... when he drives like a grandma but when he spools the turbo and really gives it gas or floors it... goodbye gas and whoever hes racing haha

in his situation, more horsepower is deff helping his mpg because the engine burns very efficiently. but some things need to be tuned and replaced over a certain amount of hours being driven because it is pretty much a race car..

hes actually taking it off the road soon and making it a dedicated track car

 

It is surprising how little, time wise, you are actually spending in boost. Start, idle, stop, deceleration, idling, cruising, etc, boost. Maybe only 5% of the time is in boost.
So for example, in a 60 minute drive, 18MPG x 57minutes + 6MPG x 3 minutes = 17.4MPG. 18 vs. 17.4 with boost.
Even if 10% of the time is in boost, which is way high, in 60 minutes, 18MPGx57minutes + 6MPGx6minutes = 16.8MPG
With the S/C or Turbo you will see 3-7% (0.6-1.2MPG) drop in MPG. That's it.

With the S/C parasitic loss and the turbos restriction on the exhaust and long tubing, Forced Induction will never see better mileage than naturally aspirated.

 

I am comparing- both are 1998 XJ's 2 doors, both autos, 150k and 160k miles, nearly same mods and weight.
S/C'ed one has stock 3.55 gears and 32"MTR's. The N/A'ed one has 4.56 gears and 33"MTR's.

 

O.o

Doubtful, but I'm not going to argue those pointless details.

You want mileage? Dont drive an XJ.

 

The variables your leaving out are numerous.

A bigger turbo will require more fuel at the same boost level as a smaller turbo due to effeciency. Since turbos are not directly driven by the crank there is a huge variable during the rpm and throttle position range. Nit to mention driving style and heaviness of foot.

Nearly impossible to simplify the MPG estimates like this.

 

I am telling you real world numbers from my 2 XJ's, one supercharged and one not.
Like it or not, they are real.

 

http://www.youtube.com/watch?feature...&v=cQ2_VtMB6AI

Wait for the last part of the video... I WANT THIS KIT!!!!

 

one benifit to a turbo setup however si that u most likely wouldnt need to regear as a turbo works better with a sort of load so the lower gears are actually better such as astock gears will help it build boost better

 

Sorry. No.

 

Real? Two different XJs with one bias driver. And if they are geared differently, the numbers will be nowhere near accurate.

Like it or not.

 

actually yes look up anythign about turbo theory and any turbo car the same math theory applies no matter the vehicle and honestly i wont get into this as their is way to much about turbos that it would take days to explain..... go to the turboforums or somethign and start reading before you just shout out no.... also if u can fab turbos can be done on the cheap plenty of junkyard setups ive seen run 10s all day with like 1k into it

 

I was building a turbo car long before the Jeep.

There is plenty of load on the motor just by the vehicle itself.

What your trying to say is by making the wheels harder to spin it makes the turbo better and the vehilce more powerful/faster.

Just think about that a bit.

 

Agree, even superchargers benefit.

 

turbos like a load. This is fact.... also yes superchargers work of the same theory in some ways so think about how much a full regear etc costs and take that away from a turbo/supercharger setup and if u were into turbo cars u should know this .......