Hey fellas
I have an EL XR6 and i think that my Diff is a 3.45 LSD. Correct me if I am wrong.

So my question is, what are the pros and cons of changing the diff to a 3.7 or a 3.9?

the areas that I am concerned about are, acceleration, fuel, revs at cruising, things like that.

thanks

If you have an Auto, then there's heaps of difference, worth doing imo.
I doubt you'll notice any consumption difference.

iirc, 3.45:1 to 3.7 is around 200rpm @ 100?


In a manual you'll prolly notice the fuel side of things, and sure the take off, but I even think 3.45:1 is too low.

For what it's worth I went from 3.08 to 3.45 and it was a waste of time - a slight improvement was JUST noticeable but I should have gone to 3.73 to feel any decent improvement - so from 3.45 I'd personally go to 3.9 if you want to see a decent improvement - ie. off the line etc.

Also, as far as general driveability goes I was finding the original factory 3.08 diff and 4spd auto setup really bad - unless I was really just being really laid back - ie. in order to have sufficient instantaneous response/acceleration for normal driving - I had to manually run in 2rd around town at speeds below 60 - then go to 3rd if I was going to be able to stay above 60 - then only put it to drive somewhere between 70 and 80. The 3.45 diff made a tiny tiny difference to off the line and enabled me to generally not worry about manually using second below 60 unless I really needed to be able to make rapid squirts of acceleration - but I still found myself using 3rd below 70 a lot. I think if I'd gone to 3.73 I would have pretty much been able to leave it in Drive and not worry too much about manually downshifting - as well as having a decent off the line improvement.

You can work out rev differences with a bit of basic maths - ie. look at your current (with 3.45 diff) revs at say 100kph in top gear and multiply by 3.9/3.45 to work out what those revs will be with the 3.9 diff - ie. if you currently have 2000rpm at 100kph then the 3.9 diff will see you running something like 2260rpm.