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Just a heads up that may save you some R&D/fab time.... The LY7 lower intake manifold off of the 04-07 3.6 platforms were PFI. You will only need to make a small adapter plate on your mill to clean up a few areas between it and the LFX heads and you will have the injector placement and fuel rail sorted out. The extra length should also boost TQ a bit too. Machine a few plugs for the GDI injector holes in the heads and you are off to the races.
Also, just as a heads up, the throttle body GM used on the LFX is TERRIBLY noisy. The feedback from the internal blade motor leaks to the TPS so badly that the ECU will think the blade is out of position and try to adjust. The end result is a throttle blade that just sits there and flutters. I ended up having to go to a Bosch 82mm off of a GT3, only $120 brand new, just to get the DBW to work properly with an aftermarket ECU. Two of the mounting holes line up perfectly so the adapter was super easy to make.
Happy to answer any questions you may have on all the standalone stuff bud. It is a hell of a tough road for the GDI LFX and you are for sure making the right call to switch over to PFI for simplicity and standalone options. Not sure what the performance end will look like, but I can't imagine you will lose anything on the top end going that route.
I have the LY7 lower manifold and fuel rail here One of a few things I picked up to mess with mock ups and figure out the PFI intake manifold puzzle.
View looking down one of the ports. It's off by a good bit. Doable, but need some thickness to the adapter flange to do a good blend, that blend can't be done in a slim 1/4" for example:
Height is the main problem; the LFX manifold is suuuper slim, realistically it's lower profile than anything that we will make for the PFI, and the LFX manifold already sticks out of the hood. The LY7 lower offers the convenience of the bolt pattern lining up and providing injector ports, but it's tall.. and that's before adding a 3/4" thick or so adapter plate between the head and manifold to blend between the two port shapes. Then add, oh, at least 2.5" of height for an upper manifold. That is going to be sticking wayyy out of the hood.
Good to know about the throttle body. Sounds like I should plan on a non-LFX TB when building the intake manifold and do a different TB flange for a more ideal unit right off the bat.
It is from a natural gas LFX impala with additional injectors in the lower manifold. Some other 5th gen camaro guys found this and were using it for methanol injection. Overkill is now using this for their new port injection fuel system.
https://www.rockauto.com/en/parts/gm...+manifold,5536
The part number doesn't show as attached to any car, so it doesn't even show up properly on most sites. On Rockauto, you have to click the search by part number tab to find it.
Iiiiiinteresting. That may even work with the LFX upper manifold. Keen to confirm that matches up to the LFX ports, and see how the injector placement/dimensions look. Hopefully it takes a 14mm injector o-ring, already have a set of ID1300-XDS here for the project.
Iiiiiinteresting. That may even work with the LFX upper manifold. Keen to confirm that matches up to the LFX ports, and see how the injector placement/dimensions look. Hopefully it takes a 14mm injector o-ring, already have a set of ID1300-XDS here for the project.
I'm hoping the same Ryan. With any luck, I can drill and tap the manifold to take the tops of these mini injector holders I bought. Then there is no need for an additional fuel rail under the LFX manifold. Looking pretty promising though because the PN for the CNG injectors are the standard Bosch pico injectors like I already have but with a CNG tip:
Genuine Bosch 0280158843 fuel injector CNG
These are the injectors and holders I picked up to develop a staged injection with the standalone to get enough e85 to play in the the 15psi ranges with the help of some Boostane.
If this doesn't pan out, another option for you Ryan since you are ditching the GDI would be to use these and weld them directly into the head like so while you are sealing up the GDI port:
Great fit and aims the injector right at the intake valves with plenty of room for good atomization with quality injectors like ID injectors.
I have very similar mini injector holders here for 34mm long injector and 14mm o-rings. Also have extruded aluminum fuel rail raw stock for if it looks like a rail would be a better solution for packaging.
That's an interesting idea as well to put them in the head. Welding that top seam below the overhang would be tricky but it's an idea. Not sure if there's room for the injector length plus the height of the aluminum cap and fitting with the injector horizontal there.
Just ordered the Bosch 82mm throttle body from a Porsche 997 GT3 since that seems to be the well documented DBW option that will give a clean signal to the standalone.
Rear brakes needed some changes to accommodate the 5x114 change as well. First, new hat was obviously needed with the new lug pattern. V8Roadster's front hats for their NC floating BBKs had the bolt pattern I needed, and after much comparing of measurements, the other dimensions were close enough that they'd work on the car with some adjustments to surrounding bits.
Bonus is these are designed to use the same StopTech 8mm floating hardware as the new front brakes, so same hardware all around.
The 5 lug hats have a slightly different offset than the previous NA/NB sport rotor hats, so a correction was made to the brackets to account for that:
The 5 lug hats are also slightly larger in total diameter than 4x100 hats, which caused an interference with the caliper. So rotor friction ring ID and OD were increased slightly to get the clearance needed. Then I fired up the lathe for my first real project with that machine and made small radial spacers to move the caliper for the larger diameter. The finish on them could be better, learning as I go, but paired with longer bolts they'll work perfectly:
Finally, the 5 lug hats have a center register hole for an NC hub, but my rear 5 lug Miatahubs were made with a center to match NA/NB specs. So project #2 with the lathe was a set of hubcentric adapter rings for the rear rotors.
Started with this:
Progress shot, this is after all the forming operations, just starting to part off the individual pieces:
And individual rings finished and back from anodizing. Two for the car, one for the spares box:
Centering ring mounted up with the new rotor on the 5 lug Miatahub, carnage in the background
Looks like your lathe uses the same parts as the one we have where I work (ours is the grizly version). It's a good machine, can reliably shave 0.002mm on the diameter if I need it to, and I have zero problems holding tolerances to within 0.01mm. I am impressed at how good these cheapish import lathes are.
Should have the CNG manifold in tomorrow and will provide an update and analysis on its viability as a PFI option under a camaro intake real soon. If it works, I am going to go ahead and seal up the GDI ports in the heads of my spare motor since this will make the calibration of the standalone MUCH easier.
Mind sharing your ideas on sealing up the GDI ports on your heads? I thought about either using a fine thread set screw and tapping the holes (no different than a spark plug for sealing the chamber) or making alu inserts and welding them in. Set screws just seemed like an easier operation overall but would love to hear your ideas. Papadakis racing just machined some plugs and then heated the head and put the plugs in nitrogen and pressed them in when they removed the GDI on their supra, but that and welding just sounds like a recipe for a warped head to me.
I think I am going to go grab a few 5/16-24 grub ended set screws and tap the GDI port on my spare head and see how it goes. I will not tap it all the way into the combustion chamber so that the set screw can never work its way down and use some red locktight.
Hmm it's a good question. My preliminary plan, without having a chance to really look at the head and think about it much yet, has been to turn some aluminum plugs on the lathe to a press-fit, and then weld over the top of them so they can't go anywhere. Benefit there is same expansion/contraction as the surrounding head material. Chilling the plug and just relying on it holding after expansion might be sufficient if the tolerances are really dialed in, but I just don't know that I could ever feel completely at ease with that solution. If welding, I wouldn't be too worried about warping the head as it's such a large chunk of aluminum and a relatively small/fast plug weld. I'd leave the head bolted to the block if possible so the block serves as a fixture to help prevent any warping.
I like the simplicity of tapping the port and just doing a set screw and loctite. Just not sure about that method with different material expansion/contraction.
Yea I'm researching that very thought now actually. Looking at the hole/thread comparison, it may be better to use coarse threads. I figured it couldn't be too different that a spark plug.
Good news:
The CNG lower manifold (92264709) will 100% fit a LFX upper manifold and allow the use of 6 Bosch 14mm pico injectors!
Bad news:
It is 2.4" overall compared to the LFX lower manifold at 1.1" so your intake will sit 1.3" taller with this manifold.
Here are a few pics to show how it lines up with a single pico injector and a sample injector holder with a barb fitting attached. You can see that the direction of injectors to the valves is great and there is a ton of room under this thing for fuel lines to the injectors even with the GDI system still in place. This means that with an aftermarket you could convert to PFI or keep the GDI and make a sequential system.
It just sandwiches between the heads and the camaro upper manifold so you will just need to replace the LFX bolts with ones that are 1.3" longer and you are in business.
Nice find LukeG!
GM makes a PRICY fuel rail ($750+) shown here, but I think I will just make my own with the pico injector holders I have.
Nice! Injector placement is great. Just confirming, the ports match the head on the bottom and IM on the top 100%?
Wow $750 for a rail. Heck, make a rail or weld tabs to the lower manifold to bolt the upper half of the pico injector caps to. Could be done either way.
12-31-2020, 11:00 AM
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One of a few things I picked up to mess with mock ups and figure out the PFI intake manifold puzzle.
