diff ratios gq

[gdjenna]

currently have a 95 gq efi 4in lift 31in tyres and believe the diffs a 4.1 i am after more grunt when towing my caravan if i put in the 4.3 diff centers is it going to help me of not

[5inchgq]

Better take off speed but top end speed will suffer.

[hokey]

what do you mean by top end suffering? it'll acclerate harder all over the rev range but will obviously rev harder at 100kmh when towing and could use more fuel.

look at how many revs you're doing now and if going up 3-500rpm (at a guess) would bother you then might not be the right way for you

[MyGQ]

i love this mis-conception about Diff ratios

Your engine won't be working any hader or reving any more with lower diff ratios and big tires than it would if it had standard ratio and standard tires.

Lower ratios/Bigger tires makes the engine "think" its back on standard rubber. so if you had 31" Tires and 4.11:1 diffs and it takes 2400rpm to do 110K's on the Freeway then with say 4.625:1 diffs and 35" tires you will be doing the same RPM to do 110K's.

People who say you use less RPM's with taller diff ratios are talking GPS/Real world speed vs. Speedo rated speed, yes you are doing less RPM's but your engine has to work harder to get it there cause its turning bigger tires on a higher ratio diff.

If You have 4.11:1 and looking for a slight boost in power/torque and have 33" tires or larger then 4.375:1 will be good. If you have 35's or more, 4.625:1 are what you want.

[351ciofgrunt]

i love this mis-conception about Diff ratios

Your engine won't be working any hader or reving any more with lower diff ratios and big tires than it would if it had standard ratio and standard tires.

Lower ratios/Bigger tires makes the engine "think" its back on standard rubber. so if you had 31" Tires and 4.11:1 diffs and it takes 2400rpm to do 110K's on the Freeway then with say 4.625:1 diffs and 35" tires you will be doing the same RPM to do 110K's.

People who say you use less RPM's with taller diff ratios are talking GPS/Real world speed vs. Speedo rated speed, yes you are doing less RPM's but your engine has to work harder to get it there cause its turning bigger tires on a higher ratio diff.

If You have 4.11:1 and looking for a slight boost in power/torque and have 33" tires or larger then 4.375:1 will be good. If you have 35's or more, 4.625:1 are what you want.

Yes but if you read the original post he is only running 31's. So he is not running big tyres and going to a lower ratio to bring it back to 'standard' he is already at standard and going lower.

Anyway going from 4.1 to 4.3 will make for easier towing but it is an expensive mod for a small gain, if you can afford it then go for it.

[5inchgq]

what do you mean by top end suffering? it'll acclerate harder all over the rev range but will obviously rev harder at 100kmh when towing and could use more fuel.

look at how many revs you're doing now and if going up 3-500rpm (at a guess) would bother you then might not be the right way for you

This is basically what I meant less economy and more revs at 100-110kph.

[PacMan]

4 inch lift with 31 inch tyres? What is that for?

[351ciofgrunt]

4 inch lift with 31 inch tyres? What is that for?

For the Hektic Flex?

[hokey]

4 inch lift with 31 inch tyres? What is that for?

For the Hektic Flex?

heavy caravan more likely haha

[gdjenna]

thanks guys
the 4in lift was for the 34jts that i used to run but at the time couldnt afford to replace them hence the 31s i am going to get some 33s for offroad but tend to do more touring hence the toeing a van