Injector Swap

[TXPony]

Sorry if this question has already been asked, but I looked and didn't see a thread addressing this question. So I just saw that Livernois recently released a High Pressure Fuel pump. I know this has been talked about and sought after in a few threads before, but my question is; even though the kit comes with new fuel line and pump, wouldn't you need bigger injectors to utilize the upgraded fuel delivery system? Or even better fuel rails? I'm no car engine mechanic, but I know when I owned mustangs those items were available everywhere and seemed to be equally as important as the pump for obvious reasons. Seems that we would need the other supporting components to be upgraded to me. I'm not quite at this step in my mods yet, but I am putting together a pretty nice Christmas list and this may very well go on it! Can someone clear this up for me? Much thanks!

 

[TXPony]

As luck would have it, I actually did find some bigger injectors available through a couple of online stores. I'm still interested whether a high performance in-tank pump would need to be run with the pump LMS is selling and if any other components would need upgraded as well.

 

[Johnbigdog]

Not really. It depends on the injector and the pressure. Pressure and volume are directly related. Pressure just come from a restriction to flow or heat. If the injector is open 1 millisecond and you have 1 psi vs 10000 psi one will flow more fuel vs the other.

If you don't increase pressure, say 50 psi you can flow more fuel by creating a larger leak. So instead of 1 millisecond we open it 2 milliseconds.

Say the the fuel needs at 2 milliseconds are too long though because of valve timing. To get the necessary fuel delivered the engine we can only have the injector open 1.5 seconds. Well now we make the hole bigger in the injector so that 50 psi can leak out faster.

So take a garden hose. Stock injector is one multi nozzle things. Say a stock injector is the jet stream. That's good. But say you want to water the lawn faster so you need more water. You turn it to the stream/rinse. Same pressure more volume right?

Well say you only have the multi nozzle thing and you want to water the lawn faster. Now you need something that can provide your garden hose with more volume. Since pressure is caused by a restriction to flow if you have more flow with the same nozzle you great more pressure until that restriction is removed.

With the O.E.M.pump it just can't keep up with the volume of fuel needed.

A pressure washer is high pressure low volume. A small piston increases the pressure greatly, but once the restriction is gone there is low volume. If I'm undersanimg the stuff right, we are getting a pump that moves more fuel (water) so we can open the injector longer so the more fuel is added to the motor. Since the engine is direct injected intake valve timing is not a factor so you don't really need a larger hole, you just need more time but the factory pump just can't keep up.

So the pressure washer that powers one nozzle? We just bolted on a pump that can supply 2 nozzles and not skip a beat all day.

This is as simple is I can come up with.

Are my hrdrolic theory sound? I'm a simple guy.

 

[TXPony]

Thanks for the explanation Bigdog! I couldn't begin to tell you if your theory is correct, but sounds legit and certainly helps explain a lot.

 

[BamSHO]

If you are planning to go full E85 on your 2010-12 SHO, you will need to buy injectors. They can't get them to cycle long enough for enough fuel. The 2013+ cars, it shouldn't be an issue. That's what I have been told from my friend who just did this upgrade.