Sunday, December 27, 2009 - 05:15 pm, by: Bobby Green(Nash)
if we're talking 1.5j, then wiked(sp?) motorsport in brisbane made 900+ hp from theirs. I think its more interesting as to what stock bottom end 1j's can do with some bolt ons.
Tuesday, December 29, 2009 - 01:16 pm, by: Cihan Aday(Cihan)
Just depends how long you want it to last.
If you're after reasonable life at 600-700hp from 2500cc, the limit on good fuel is cylinder pressure (amongst other things!).
To mitigate, some of the obvious options are to use high temperature rated valves, valve seat inserts and a wider cut valve job for improved heat transfer.
Piston crown, cylinder head and valve coatings are also effective.
Then, tune for leaner AFR's and less ignition advance rather than richer with more ignition advance. The outcome is more power, less cylinder pressure and improved long motor longevity.
I don't know what standard valves are made of or rated for, so we can only assume. In this case I would only advise not to polish back the OEM valve face coatings and run a slightly richer mixture without additional advance.
Keep in mind, either way you will need a very good ignition system. There are cheap TSI options out there from BOSCH and the like that work with the standard igniter. For 400rwkw and above, i would consider upgrading the igniter.
The fact of the matter is, if a 1.5JZ can do 400rwkw - then a 1JZ of the same caliber will be close, but, with smaller displacement comes more stress and less service life (read : reliability) at a given output.
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