I don't post here often but I'd like to give you a bit of help.
 

Sometimes thinking outside of the box is useful.

For all of you who are struggling with FI due to fueling, I have a suggestion to make.

Add port fueling...

There is going to be a lot of conjecture and theories, but from experience with adding port fuel on top of a stock DI vehicle, it works, and works just fine.

Just make sure that you are hitting the back of the valves with your injector. How to do this?

I'd suggest looking into an LY7 Lower intake manifold, it'll likely bolt right up. It'll already have the correct bosses in there, and if the fuel rail doesn't fit with the LLT upper, run the LY7 upper.

This could be interesting. :popcorn:

I'm confused. Arent' they port fueled anyway? You talking about spraying along with FI?

No, the LLT is a DI motor. I'm talking about adding port fueling on top of this. This is the best solution. The LLT already has a 4 lobe cam for the pump (so we can't add another lobe with a custom cam)(im almost 100% positive).

People need to be logging rail pressure though. If you guys are really running out of fuel due to the mechanical limits of the pump a couple of things will happen.

#1 Fuel pressure will drop off.
#2 As RPMs climb the amount of fuel that the pump will support will also climb.

If neither is the case, you're likely running out of pressure or volume in the tank pump, or you're running out of injector (which I don't think is the case)

Ok. I get that but most of them would measure rail pressure. And upgrading the fuel pumping system.

So you mean instead of BAP, duel pump, bigger pump etc ....... ???

Are you doing it now?


I had to change my post. I didnt realize you were talking about the LLT. LMAO

Forced Induction - V6 V6 Supercharger, turbo, nitrous discussions

It is one of the things we are looking at. However, if we can keep it all DI then we can maintain the cooling benefits that comes with it.

You still retain all of the cooling effects of the DI even though you are adding port fuel, and you can stage the system if you wish as well.

What is your response on my comment about measuring rail pressure? What have you found?

There are many cars that use both today, including the Lexus IS-F.

Save yourself the trouble, and add port fuel on top of it, you'll be just fine. Direct injection works more like port fueling at high RPM's anyways due to the volume and injection duration. It doesn't atomize quite the same as low rpm. You'll notice a lot of DI cars running 14.5 A/F usually up to around 5000 rpm, after that A/F ratio will drop significantly to around normal port fuel levels.

Seriously. Go on ebaymotors, pick up a LY7 Lower intake manifold, Upper intake manifold, and fuel rail. Heck you could even use stock injectors if you want to start - you'll get them for a song. The issue will be in mating up a simple stand-alone for the fuel trigger and injector control. Problems solved.

We've seen two things happen with the rail pressure. The first is just like all the others that the tuner has seen...at middle RPMs the fuel pressure drops too low. The second scenario happens when he tries to compenstate for that...we see the overall flow drop to low at the higher RPMs.

:rolleyes: I know, I know. I was browsing the 'New Post' page and didn't look at what section it was in.

Ok well that settles it then. You're running out of volume on the high pressure pump. They can be modified, check out what the 2.0FSI guys were doing with them.

However I think it's better to run the port fuel on top of it for many many reasons, namely improved upgrade path, and reliability. Even if it complicates things a bit.

:popcorn:subscribed

It's okay. You learned something new about the LLT and now that you are thinking about it something may come to you.

Port fueling sound interesting. maybe you should bring this up to tracy and see what his response is gretch. does anyone know how adkin did with their turbo build? I wonder how they got around the fueling issue even if they got around it:iono::iono: