Plz help
#11
Originally Posted by cvcrcr99
The "stock" boost is something like 5 psi. My kit made 7.5 psi at WOT. They do sell smaller pulleys for boost at 9, or 11 psi.
With the Miatas, stock boost was 6psi, but later they were making big boost kits (with a smaller pulley) that went to 8psi. The stock fueling would handle it fine at 6psi, but when the boost was cranked, you needed to go with bigger injectors and a knock sensor. The ECU would handle it okay, but to gain full advantage, most guys went with the old TEC-2 ECU or later to JR's own Power Card setup, though there's lots of safely boosted Miatas with rising rate fuel pressure regulators that work just fine. However, Miatas tend to run rich anyway, and the compression is lower than the Civic at something like 9:1 (depending on which Miata BP engine we were using).
For cooling, there was an air-to-air intercooler, and later a water injection kit.
The crummy plastic pulley wheels they used to supply were awful, so the trick someone discovered was to shim the mounting plates (for alignment, which was always terrible), then replace the idler pulleys with metal ones that were used for timing belt tension on the engine. They really helped improve belt life.
I once ran into a guy at Carlisle with the M45 JR setup that was claiming a reliable 12psi that was pushing 240hp. I called BS instantly, and knowing the blower bearings wouldn't have handled that for the 50k miles he claimed he'd driven it.
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