what diff ratio??
11-22-2011, 06:26 AM
#1
what diff ratio?? I am going to be installing a 99 ls1 and t56 into an 85 BMW 5 series. I am looking to get the best mpg I can get when cruising in 6th on the xway. What is a good rear end ratio ? Where does the ls1 like to be in the rpm range on the xway?
Is there anything in the tune that can help gas mileage?
Is there anything in the tune that can help gas mileage?
11-22-2011, 02:42 PM
#2
I am going to be installing a 99 ls1 and t56 into an 85 BMW 5 series. I am looking to get the best mpg I can get when cruising in 6th on the xway. What is a good rear end ratio ? Where does the ls1 like to be in the rpm range on the xway?
Is there anything in the tune that can help gas mileage?
Is there anything in the tune that can help gas mileage?
There are variables, such as tire size and engine power.
For best mpg, I wouldn't go beyond a 3.23 or 3.42
For rpm range, it depends on how much power you have, and how you will be driving the car.
After all, no one I know just cruises around at 1800rpm all day...
....even this old guy.
Is your a stock engine?
11-22-2011, 04:20 PM
#3
The engine will be mostly stock, some bolt ons, intake, bigger throttle body.
haha yeah I don't plan to just cruise at 1800rpm all day. I don't want it to be a dog off the line.
A 3.25 is no problem to get, as well as a 3.73 is pretty easy (both in a lsd). I will have to see if I can get something around a 3.4x...
haha yeah I don't plan to just cruise at 1800rpm all day. I don't want it to be a dog off the line.
A 3.25 is no problem to get, as well as a 3.73 is pretty easy (both in a lsd). I will have to see if I can get something around a 3.4x...
11-22-2011, 05:01 PM
#6
wow...35mpg. What car was that in? How heavy? I should be around 3600lbs or less
cruising around 75? That would be excellent, not sure if I want a complete dog in both 5th and 6th tho....hmmm
The tire will be a 225/45/17 if it makes a difference
cruising around 75? That would be excellent, not sure if I want a complete dog in both 5th and 6th tho....hmmm
The tire will be a 225/45/17 if it makes a difference
11-22-2011, 06:28 PM
#7
There was another thread here not too long ago about engine speeds at given rpms.
My car will do 2050rpm @ 70mph, in 5th (my only OD gear-.064). This is with a 3.70 rear & 28 inch tires/approx 380hp.
In 5th, there isn't much pull until about 3500. But, who doesn't down shift anyway when you're really looking for some speed.
So, if you're only looking for mpg, I would stick with 3.42 max.
From your stated mods, with 6 gears, and your intention to tap some power, I would go for at least a 3.73 rear, as Andrew said.
You can still cruise the highway at low engine rpm.
My car will do 2050rpm @ 70mph, in 5th (my only OD gear-.064). This is with a 3.70 rear & 28 inch tires/approx 380hp.
In 5th, there isn't much pull until about 3500. But, who doesn't down shift anyway when you're really looking for some speed.
So, if you're only looking for mpg, I would stick with 3.42 max.
From your stated mods, with 6 gears, and your intention to tap some power, I would go for at least a 3.73 rear, as Andrew said.
You can still cruise the highway at low engine rpm.
