2JZ conversion experts - your insight please!

[pwpanas]

Originally Posted by Johnny A

We have 99ron pump gas here is the UK But to be honest I plan to run this all the time anyways as it's a JDM import. If that's not enough I could put a little methanol in there too, I am a fan of water/meth injection.

RON is not MON. You need to find out the MON of that 99RON gas...I'd guess that it's about 89MON. This is only good for about 16psi of boost, max, using the oem Mkiv ecu. In other words, yes, you'll definitely need to supplement with methanol injection to make 400+rwhp. To make 600rwhp, you'll need a very heavy shot of methanol - the biggest kit you can find should do the trick.

Originally Posted by Johnny A

...I am still confused as to why a manual gearbox has it's own ECU though

Sigh. The manual gearbox does not have its own ECU. There's a different ECU for the MKIV Supra Turbo depending upon which transmission it has. Hypothetically speaking, if you already owned an Mkiv Supra Turbo with an auto tranny and you decided to convert it to a 6spd, you'd have to swap out the primary ECU. Make sense?

To make 600rwhp+, you'll need an aftermarket fuel controller (eg. an A'PEXI AFC Neo), and a small-medium single turbo kit (eg. 57+mm inducer). The oem twins can't make 600rwhp. Be sure you're running Toyota's 550cc injectors (your j-spec 2jz-gte probably came with 440s, so you'll have to swap them out). Together with the meth kit, you'll have enough fuel for 600rwhp, but just barely. For additional safety, I'd recommend an aftermarket fuel pressure regulator, and bump it up to about 50psi base.