Reply To J-Spec Engine Question
 

I have some knowledge on this subject becuase my best friend has a 93 MX6 (Mazda's version of the Probe) and his brother has a 92 240 SXSE. Anyway they are both comtimplating the J-Spec engine swap. They J-Spec engine have better air flow, better vavle timing, ususally a stronger crank for higher revs. The high grade octane level in Japan is 110 and this engines usually run on that grade. I know a guy personally that swapped a stock Probe engine for the J-spec one and ran 93 octane. He dynoed at 162 with everything stock beside the engine. Then a few months later he ran 100 octane for a few weeks and dynoed at 175. So go figure but everyone I know that talks about the J-Spec engine swap debates the fuel question.

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89' 5.0 GT Convertible Mustang and a 69' Mustang Mach 1 Fastback. If you want to know the rest, buy the rights.
AOL name: Woodnutz351

I assume he played with the timing too or was using the Japanese ECU. The US ecu won't adjust the timing for anything higher than 94 octane fuel so you really won't see any more hp. So basically he had the engine and a "chip". That goes along with what I said in the other post.

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90 Honda CRX aka Project Mongoose
Estimated Completion: 7/1/01
453 horses with a stock head...built head and LSD on the way

84 Toyota Supra
High flow cat, two chamber flowmaster, custom 2.5" piping, msd 8.5mm wires. Will have boost before 2002.
Have HKS turbo manifold for it:D.....T04e next week

Yep it was a full blown conversion after the chip was installed.