Need to know the best differential to use

Hey fellas need some.advice I recently put a 1 jz engine in my hiace how ever I am not getting the full power because of the differential ratio I need recommendation on which differential would be suitable the bus drive ok but am not getting enough power

Hello Daneleung123 and welcome to the forum

I’m sorry but I can’t directly address your question but I can point you to resources that might help a bit, but probably not fully.

I’m not familiar with the 1JZ engines. Wikipedia has this info about them: https://en.wikipedia.org/wiki/Toyota_JZ_engine

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The Toyota JZ engine family is a series of inline-6 automobile engines produced by Toyota Motor Corporation. As a replacement for the M-series inline-6 engines, the JZ engines were 24-valve DOHC engines in 2.5- and 3.0-litre versions.

1JZ
The 2,492 cc (2.5 L; 152.1 cu in) 1JZ version was produced from 1990 to 2007 (last sold in the Mark II Blit Wagon and Crown Athlete). Cylinder bore and stroke is 86 mm × 71.5 mm (3.39 in × 2.81 in).[1] It is a 24-valve DOHC engine with two belt-driven camshafts and a dual-stage intake manifold.
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This seems to be a close cut and paste from:
https://www.autospeed.com.au/cms/a_2750/article

The first sentence describes this as:
“One of the most potent engine designs in recent years has come from Toyota - the JZ-series in-line six. Released as successor to the smooth and faithful M-series six, the JZ engine has a DOHC 4-valve-per-cylinder head and comes in 2.5 and 3-litre capacities.”

I didn’t see power and torque values for the non-turbo variants but the turbo ones seem very adequate.

Anyway that wasn’t your question.

Hiacesoutheast shows details and ratios for the common gearbox and diff variants, so that could be your first resource to scour to understand what you currently have and what might be the next step up/down for off the shelf options. I’ve never re-geared a vehicle but a good transmission company might also be well worth sounding out, also for creating something specific. Wheels and tyres will also play a part.

https://www.blocklayer.com/rpm-gear seem a handy site for plugging in your current setup and possible options.

From the little I know it seems there are all sorts of compromises when gearing a vehicle so it’s driveable.

Good luck and do report back!!

Thanks a lot I will let you know