How to build L28E / L28ET 14mm o-ring fuel rail on the cheap!
08-29-2012, 09:12 PM
#1
How to build L28E / L28ET 14mm o-ring fuel rail on the cheap!
As always, I'm on the lookout for interchangeable parts while at the junk yards. Recently I've been wanting to run 300cc o-ring injectors, but don't really want to spend $120-$200 for a custom cnc machined rail. So after looking at MANY o-ring rails, I found that the Jeep 4L inline six fuel rail would work with some "modification" (which is my middle name). I bought this rail for $9 from the local Pick n Pull.
Let's skip to the chase. This is a budget "how to" adapt domestic 14mm o-ring injectors to the L28E / L28ET. As far as I can tell, any EFI Jeep 4L rail should work.
The rail needs to be sectioned 3 times:
-0.75" between ports 2 & 3
-1.00" between ports 3 & 4
-0.75" between ports 4 & 5
I marked out the cut line with a pencil, and used an electric grinder with a thin cutting disc. I clamped the rail in a vice (rail wrapped in a rag), and had to flip the whole thing over to get all the way around. I did one section at a time. I cleaned the edges with a file & then hit them with a wire wheel on the drill. Then used a set of strong magnets to hold the sections in place while tack welding. Removed magnets and cris-cross welded the joint to keep it from burning through. Lastly I cut a 25mm diameter sheet metal plate to weld closed the fuel pressure regulator port (I will be using an external one).
I still need to weld on two manifold mount brackets, and pressure test it. I may source another and try things a little differently (mainly use my band saw instead of a grinder). I spent a total of about 4hrs working on this one, but I could probably do a second one in 2hrs now.
Let's skip to the chase. This is a budget "how to" adapt domestic 14mm o-ring injectors to the L28E / L28ET. As far as I can tell, any EFI Jeep 4L rail should work.
The rail needs to be sectioned 3 times:
-0.75" between ports 2 & 3
-1.00" between ports 3 & 4
-0.75" between ports 4 & 5
I marked out the cut line with a pencil, and used an electric grinder with a thin cutting disc. I clamped the rail in a vice (rail wrapped in a rag), and had to flip the whole thing over to get all the way around. I did one section at a time. I cleaned the edges with a file & then hit them with a wire wheel on the drill. Then used a set of strong magnets to hold the sections in place while tack welding. Removed magnets and cris-cross welded the joint to keep it from burning through. Lastly I cut a 25mm diameter sheet metal plate to weld closed the fuel pressure regulator port (I will be using an external one).
I still need to weld on two manifold mount brackets, and pressure test it. I may source another and try things a little differently (mainly use my band saw instead of a grinder). I spent a total of about 4hrs working on this one, but I could probably do a second one in 2hrs now.
09-05-2012, 09:08 PM
#4
After doing tons of injector research, I'm actually pondering the use of 11mm o-ring import injectors. 99% of the domestic 14mm injectors are high impedance (saturated), which are less effective for boosted applications than low impedance (peak and hold). Low impedance actually kick back the needle, creating a more effective and accurately timed spray. There are more 11mm low impedance injector options, but I gotta go back to the drawing board to find import rails to modify. 
09-06-2012, 02:51 PM
#5
Mr Z++ Wiki
Join Date: Sep 2009
Location: Victoria, BC
Posts: 2,195
After doing tons of injector research, I'm actually pondering the use of 11mm o-ring import injectors. 99% of the domestic 14mm injectors are high impedance (saturated), which are less effective for boosted applications than low impedance (peak and hold). Low impedance actually kick back the needle, creating a more effective and accurately timed spray. There are more 11mm low impedance injector options, but I gotta go back to the drawing board to find import rails to modify.
Mega Squirt allows for adjustment on the peak and the time to turn the injector on fully, PWM, etc so it's all there you just need to add the info. I actually "tuned" my injectors PWM by ear with the MS test mode and it was within 0.1ms of the measured current draw with an O-Scope one of the HybridZ members did.
I've found the after market 14mm are low impedance from 550cc and above but we are typically looking for 330cc or 440cc injectors...
Last edited by FricFrac; 09-06-2012 at 02:59 PM.
09-08-2012, 06:37 AM
#6
Big Poppa
Join Date: Jan 2005
Location: Mission, British Columbia
Posts: 4,499
nice work, i like where your headed. ill take that barbed rail off your hands when your done. my "big" upgrade is to turbo injectors for the na and there still barbed. lol. you could just go on ebay and buy rail blems for 2 bux a foot or something and then just properly bore the holes for injectors tho.
09-08-2012, 08:27 PM
#7
I'm keeping the barbed rail around to pass emissions. 
I did mull over the idea of building my own billet rail, but the cheapest price online that I could find is $10/ft, most are $15 - $20/ft for billet rail stock. An old neighbor kid I know is now a cnc machinist. I talked to him about it, and even grabbed a stock GM rail from the junk yard as an example, but it would still probably be $100-$200 in labor.
I did mull over the idea of building my own billet rail, but the cheapest price online that I could find is $10/ft, most are $15 - $20/ft for billet rail stock. An old neighbor kid I know is now a cnc machinist. I talked to him about it, and even grabbed a stock GM rail from the junk yard as an example, but it would still probably be $100-$200 in labor.
09-08-2012, 10:13 PM
#9
Mr Z++ Wiki
Join Date: Sep 2009
Location: Victoria, BC
Posts: 2,195
nice work, i like where your headed. ill take that barbed rail off your hands when your done. my "big" upgrade is to turbo injectors for the na and there still barbed. lol. you could just go on ebay and buy rail blems for 2 bux a foot or something and then just properly bore the holes for injectors tho.
09-10-2012, 05:33 AM
#10
Big Poppa
Join Date: Jan 2005
Location: Mission, British Columbia
Posts: 4,499
yeah i have the taps and a drill press, plus a tig if i need to mount any brackets. plus taps arent that expensive if i need a bigger one for the ends. rossmachining sells there blem rails at super cheap prices to recover some of there cost on there website and ebay sometimes. all you need to build a o-ring rail is a drill press and the correct bits or reamers. prolly not that expensive.
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