High ratio LSD needed for cam?

[Jesterarts]

Ok, bit of a weird one.

Currently running a 23*/23* cam... pretty sure it's about a 233/233 but it's a custom grind so not 100% sure.

Anyway, i was looking on the camtech site and they say that pretty much with anything 233/233 onwards you need 3.91 gears.

Now, I currently have 4.11 gears but want to put in 3.73.

Can I run 3.73's or am I going to have issues?

[Boonz]

theres going to be very little difference between the 3.91 and 3.73's, only thing its going to affect is your revs at cruising speed, might put it into a bit of a rough patch at about 1600-1800 revs, mates vx ss had that problem at 110 km/h after he put in a similar size cam, was like it would cough every now and then like it was fueling up

[Jesterarts]

Yeah... there is like 80RPM between 3.91 and 4.11. Thus why I want to go 3.73... should drop my cruising @ 100kmph RPM from 1950 to about 1700.

I've noticed that if I cruise at around 1400RPM I get a surge now and then... but 1700RPM should be sweet.

Just looking to find out why they would say a 233/233 cam needs a 3.91 Diff.

[dijm8]

you can get any diff you want really ive got 231/236 in my ls3 with 3.08 will be going a 3.7's no need for 3.9's very little difference as said above

[Boonz]

Just looking to find out why they would say a 233/233 cam needs a 3.91 Diff.

probably cos it makes the dyno figures look better haha nah who knows... should be fine running that 3.73 diff ratio tho

[rhysdalegend]

Hey guys, just curious. Why is it recommended to change diff gears when camming an engine?

[hsv453]

^^ The cam is a decent size with more top end power so replacing diff gears with higher ones will give you more use of acceleration.. CSV told me 3.73's are the best to run with my 232/234 112 selection, however my clubby has 3.46's according to the stamp on the diff! i could only see them saying 3.9's to get the most out of the engine before the cam kicks in

[hsv453]

ohhh and jesterats your clubby with 4.11's must be so F**KING amazing from 0-100!!!

[Jesterarts]

Yeah, 0-100kmph pretty much doesn't exist with the 4.11's lol.

Wish I had my gtech now to get an accurate reading!

[Jesterarts]

^^ The cam is a decent size with more top end power so replacing diff gears with higher ones will give you more use of acceleration.. CSV told me 3.73's are the best to run with my 232/234 112 selection, however my clubby has 3.46's according to the stamp on the diff! i could only see them saying 3.9's to get the most out of the engine before the cam kicks in

I think 3.73 in a clubby is fine but 3.91 for non clubby.

We have the t56-m12 box over the regular t56 so a couple ratios are a bit different.

[hsv453]

I think 3.73 in a clubby is fine but 3.91 for non clubby.

We have the t56-m12 box over the regular t56 so a couple ratios are a bit different.

More then likely is the case, im suprised of my accel with standard 3.46's, but 4.11's must just be pure wheelspin up until 4th gear haha