fuel mag

[scuba_sean]

ive got an old turbo for my 1990 KA24E, and my welder friend is making me a manifold\headers, but im worried about fuel delivery. ive been told i need to get new injectors, but since the stock clutch in the 240 slips over 5psi, im gonna be running about 4psi to begin with. Do i need the new injectors at this pressure?? also, how do i regulate the pressure the turbo delivers? is a BOV the only way? where can i get a fuel pump with enough capacity? and how many psi can i run before i need to upgrade the mass air flow sensor? thanks guys, youve all been a lot of help.

[sapix @ RHIT]

well, at 4 psi your not going to notice a lot of difference. You should be fine on the stock injectors, but not positive. A BOV doesn't regulate pressure, it helps extend the life of the turbo by preventing compressor surge. At 4 psi you don't need one. To regulate the boost you'll either need a boost controller, or get the spring in the internal (assuming its internal) wastegate change. If you want to go cheap, get a manual boost controller. I'd say get a Walbro fuel pump, these seem to be the best units you can get, I think the fuel pump from a 300zx TT will also fit. I've heard the MAF can let you hit something like 260 hp or there abouts.

But even with all this, you'll still need a way to get more fuel to the engine. Your going to have to get something to control it. Fuel control is the most important aspect of tuning.

[scuba_sean]

ok, how does a boost controller work, where can i get one, and how much are they? also, what does a wastegate do, and where is it located? one more thing, is this fuel pump in the tank? right at the end, you said even with this, i'll need to get more fuel to the engine. isnt this what a bigger fuel pump does?

[C-Kwik]

Boost controllers can not lower the boost any lower than the wastegate is set at. The boost controller just fools the wastegate. This can be done either by bleeding out a small amount of air so the pressure in the signal line to the wastegate is slightly lower than in the manifold, or with electronic systems, it basically cuts the signal until your desired boost is reached. Electronic ones spool the turbo slightly faster since the wastegate won't creep open as early.

[sapix @ RHIT]

The walbro fuel pump does go in the tank. Just because the pump can pump more doesn't mean it will, you've got to have something that tells pump to pump more.

[huguetpj]

actually sapix, I believe the fuel pump doesn't pump more or less since there is nothing to control it, it's just turned on. The fuel regulator regulates the fuel pressure in the fuel rail so more pressure means more fuel injected.

scuba_sean, the two best ways to get more fuel is either by adding fuel pressure (regulator) or bigger injectors. I personally prefer the last one, and thus keeping fuel pressure stock (less potential problems). In either case it's best to have a fuel controller or ECU retune to control the injectors so you can fine tune the fuel system.

When going turbo don't go cheap on the fuel delivery. And before going turbo I would recommend reading up a bit and getting more knowledge so you don't screw something up.

[ziggy682]

The bigger Walbro fuel pump will pump more fuel through the system, but you won't get anymore fuel coming out of your injectors with just a bigger fuel pump. The fuel pressure regulator allows the pressure in the fuel rail to build up to a certain fuel pressure(usually something like 36 psi) and lets all the extra fuel go back into the fuel tank. With a bigger fuel pump, you are flowing more fuel, but it is flowing at the same pressure in the fuel rail.

To get more fuel out of the injectors you can do three things. Make the injectors stay open longer. Get bigger injectors so they flow more fuel every time they open. Or increase the pressure in the rail so more fuel flows out of the injectors.

Of those three, I think the best is to get bigger injectors, and then tune them to deliver the right amount of fuel. Easier said than done.