How much Boost on Stock Internals?

[Isphius]

This is incorrect!! Fuel cut is the ECU slowing the fuel injectors to idle, To stop the car from breaking itself. It stops it when the AFM is reading higher than a predetermined frequency. That is why its a general range, because of air temp, humidity, barometric pressure, etc. It is not the fuel pump failing. If you hit fuel cut it feels like you just broke something, and the CEL will come on for a little while. And detonation happens because the inside of the motor is getting so hot when the piston is on the way up it detonates the fuel before the sparkplug does, also not because of fuel. It can detonate because of lean air/fuel, but thats not all that causes it. And not matter how much gas you have, the ecu will still cut it just the same. Its about air! not fuel. But of course they must match. All the lex afm does is let unmetered air go through, and the 550s to make up for it. which is basically a crap shoot with tuning.

Originally Posted by IHateHacks

Fuel cut is when the fuel pump can no longer flow enough fuel to supply what the injectors are demanding. Fuel pressure rises about 1 psi for every psi of boost. As fuel pressure rises, flow falls. Yes, I know that doesn't make sense but it is a proven fact. That 10-14psi range is just the general range that a stock fuel pumps' flow falls off. Now when that happens the air/fuel ratio becomes dangerously high and detonation is emminent. Thats when the ECU cuts the fuel entirely to prevent damage. You can raise the fuel cut boost range with mods like a walbro fuel pump, 550cc injectors and a lexus MAF but fuel cut will always be there. It's your engine's way of telling you you need more fuel.