* Spirit Garage is selling an Nismo LSD for H145
* Traction Concepts sells LSD for H145
* Occasionally, Nismo units are seen on Yahoo Auctions

For better availability I'd go with a 1980s 1200 ute rear assembly (H165) and a Toyota GTS LSD. Toyota no longer sells them but aftermarket companies still do

You need to divide the RPM not Multiply, to get the output shaft speed. Unless you are in 5th gear which is an overdrive gear in most boxes.

So in any gear lower than 4th gear, the output shaft will be slower than engine speed.

The H145 will handle the torque of half a 13B.

No but revving to 9,000rpm+ could cause bearing issues or at least more heat the diff/seals may not be able to handle. Plus you have the extra torque also creating more heat, and I do plan on tracking the car, so the diff will get a bit of a flogging (rotaries are meant to be hard on gearboxes and diffs).

3.757 (standard 1st with 4 speed) x 6,500rpm = 24,420rpm (aprox max input speed using a10 and 4 speed)
3.67 (rx7 gearbox) x 9,000rpm = 33,030rpm (35% increase in speed)
3.815 (rx8 gearbox) x 9,000rpm = 34,335rpm (40% increase in speed)

I have a feeling that the friction (ie heat) isn't directly proportional to rpm, but a square of it. I wish I remembered more from uni...

I'd rather get the lightest available that will handle the torque (ie H145), but I don't want to be changing it every few months due to bearing failures, etc.

Also is a LSD still available for a H145? If so where (quick google search wasn't helpful)

For 1/2 a 13B, the reliable one is the H145. Use a Datsun 1000 wagon diff (4.3) or ute (4.6)

Later when you port it to raise the power band ... making more HP above 5,250 RPM does not increase torque

100ft/lbs is not so high - you could stay with Datsun and just use a H165 out of a 1200 ute,
Standard ratio is 4.1:1 lSD can be bought out of Japan

Hey All,
First off i have read through the diff/axle tech section and know i'll need a diff that can handle around 100ftlbs of torque (i'd rather something bigger then a H145 for reliability), what i can't seem to find though is the availability of LSD's for these diffs.

I would ideally like to run a ratio between 4.3-4.8 : 1 but may want to run a taller (numerically) diff in the future if i port the motor (half a 13b na) which will raise the power band.

BTW the axles are for a datto 1000 so I'll likely have to get it cut down no matter what, but want something as light as possible (attempting to get the car under 550kg).

cheers
Luke