1jz , r154, gearing and mpg ?

[525gte]

as my 1jz swap is still new to me, i have noticed that my mpg are not that good, granted i am not pa pa driving it yet, still heavy footed due to the newness of the power.

my stock set up out of the bmw was a 5 speed , 5th gear was 1:1 no overdrive, and rear diff was 323s. and doing 60 mph i would turn about 3krpm. the bimmer motor loved it and got about 25mpg hwy

the 1j swap has a r154 and i swapped out the bmw diff for a 410lsd , in 5th gear witch is overdriven i think .74 :1 . the motor is almost the same. 3k to do 60 mph+-100rpm
so i guess i am wondering what a stock supra is turning at 60 and what kind of mpg should io expect.?

i love the way the car handles with the 410 rear diff lots of fun and power in the taller gears, but should i possible look into 373s?.. bmw also makes a 391 but its a larger diff and axles , and driveline, very hard to find and prob out of the question. so 373s is the next closest gear ratio..

my 1st tank of gas i got 9.9 mpg,,lol lots of foot ,mostly in town, and had a very bad rich idle condition. that has since been fixed. but still not seeing much inprovment,

 

[xzeror]

iirc i would be around 2.5-3k crusing at 70-75 with my r154 im not sure which diff i have exactly its either the 3.9 or 3.7 :/

This was on a 7mge and i would get like 20 hw mpg

 

[destrux]

Check your speedometer to make sure you're not driving faster than it's showing. Mine is off by 7mph at 75 with my swap. Use a GPS or a stopwatch between milemarkers on the highway to check it.

The 1JZ should get about 17 mpg combined during normal driving. Maybe 20-23 highway, but people have claimed up to 27 with a really good tune and a light foot. 10mpg when you're racing around is pretty good. For comparison, my friend's new hemi charger gets 5mpg when he drives fast.

 

[525gte]

Check your speedometer to make sure you're not driving faster than it's showing. Mine is off by 7mph at 75 with my swap. Use a GPS or a stopwatch between milemarkers on the highway to check it.

The 1JZ should get about 17 mpg combined during normal driving. Maybe 20-23 highway, but people have claimed up to 27 with a really good tune and a light foot. 10mpg when you're racing around is pretty good. For comparison, my friend's new hemi charger gets 5mpg when he drives fast.

spedo is all good. it its all standalone off the bmw rear diff. all stock bmw set up. i am going on a longer drive tomorrow so ill double ck it