Fuel injectors size and Boost

peter551984

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Aug 16, 2008
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If I have a apexi neo, a PTE6265, 3inch exhaust, Lexus MAF, FCD, walbro 255lph High presure for 600HP, hks MHG, ARP studs, FX500 clutch master and stock ECU and not planing on using another ecu or stand alone or engine management ecu...
Can I use 680cc injectors?
How much boost it will increase?:icon_bigg
 

GrimJack

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Dec 31, 1969
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idriders.com
Well, you certainly can. How much extra power (notice I didn't say boost, as that's literally impossible to calculate beyond a wild stab in the dark) you will be able to run is difficult to say.

Typically I'd tell someone to put it on the dyno with a set of electric ears, and keep turning it up until you start to knock, then turn it down a bit.

The problem with this is that you don't list any forged internals, which means the knock you hear might be your piston ringlands shattering under the knock.

You need to keep in mind that the stock ECU doesn't have fuel or timing maps for 500+ horsepower. Using the Lexus AFM and Apexi Neo to get around that will work, but what it's doing is scaling the inputs to the ECU so it thinks it's running inside the stock 230hp envelope. The only reason this works is because Toyota put a huge safety margin around the ECU parameters in the first place - but at the levels you are talking about, those safety margins are very likely expended. And if you go over, bad things will happen.