Administrators BRAAP Posted October 9, 2006 Administrators Share Posted October 9, 2006 While in the middle of building another custom N-42 intake, I thought I'd take a few pics and document some of the differences between injector styles when used on an OE L-series EFI intake manifold. The OE Datsun/Hitachi/Bosch barbed style injectors vs the 14mm O-ring style which seems to be the predominate aftermarket and OEM late model car/truck injector style available currently.These pictures are two NON EGR N-42 intakes, one that is totally stock/unmolested, and the other is in the rough-in stage of customization, (getting Lokar throttle cable actuation, 60mm throttle valve, O-ring style injectors, and ceramic coated).These 2 shots below show the intakes and injector mounting region. The O-ring style intake is still being massaged so I apologize for its very rough appearance.These two shots below show the injectors as installed. It is quite clear how much cleaner the overall appearance and mounting of the O ring style is vs. the OE Barbed style. Also, with the O-ring style injectors, there are WAY more options when considering other injectors. Pretty much any flow rate and flow style style can be had in the 14mm O-ring type injectors. My race car is using Pencil beam spray pattern 21 lb/hr injectors for a C-4 Vette. The yellow injectors in these pics are Ford 19 lb/hr fine mist cone pattern injectors, same flow rate as the OE N/A Datsun injectors.The mounts for this in process custom intake will look just like these as used on my personal N-42 intake. Instead of going up to catch and retain the fuel rail as would be needed for the Barbed style injectors, the mounts are flat and go forward towards the engine.One issue with the lower profile fuel rail is that the front of the rail itself will hit the thermostat housing if it is too long, i.e. more than 1 3/8" inch from the centerline of the #1 injector to the end of the fuel rail. If one is dead set on running the fuel rail as a flow through fuel rail design, attaching a fitting on the front of the fuel rail could be quite tricky due to the very limited space, but it probably could be done, though where to route the fuel line to clear the exhaust manifold, thermostat housing, throttle valve, etc and NOT look awkward is another trick. My solution was to use my Mallory Fuel Pressure regulator as a tee. Instead of running my fuel rail between the fuel pump and the fuel pressure regulator in flow through manner ads most of us have done in the past, I used my pressure regulator as a "T" utilizing one of the available ports in the regulator to feed the fuel rail with pressure regulated fuel, and I plugged the other end of the fuel rail. In essence, the fuel rail itself, is returnless. (see sketch below for a visual representation of this set up). I could've just as easily mounted the fuel pressure regulator right after the fuel pump in the back of the car so there would be only one fuel line running to the front of the car, but I'd would've also had to run the vacuum line back to the regulator for manifold pressure compensation, 6 one, half dozen the other. Quote Link to comment Share on other sites More sharing options...
340ZXTTAZ Posted October 9, 2006 Share Posted October 9, 2006 Nice intakes and rails! do you sell these peices? If so how much? Quote Link to comment Share on other sites More sharing options...
aarang Posted October 9, 2006 Share Posted October 9, 2006 I was going to try that type of return system with my Aeromotive regulator. Less fuel lines on top of the manifold is always a plus. Do you think there would be any pressure fluctuations with that setup? Quote Link to comment Share on other sites More sharing options...
nismofiend Posted October 9, 2006 Share Posted October 9, 2006 That looks great and the fab work is incredible, very informative as well. I too would like to know how much one of these setups would cost or how difficult it would be to diy all this. I was going to go with the pallnet fuel rail but it would be nice to get rid of the OE injector type. I guess my overall goal is to just clean up the engine bay as much as possible by getting rid of anything unnecessary and rearranging the stuff that is needed. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 10, 2006 Author Administrators Share Posted October 10, 2006 Thanks for the compliments guys.We are currently working on adding this service to our list of services, i.e. converting OE EFI intakes to accept the 14mm O-ring style injectors and including a matching 20" long fuel rail, (just like pictured). Nothing set in stone as of yet. Lots of details to work out first.As for doing this DIY, the clean up of the intake manifold itself is mostly time. LOTS of time with a die grinder. One could easily spend over 15-20 hours just cutting, grinding, carving, and sanding to get the intake to level worthy the effort put forth.To do the O-ring conversion, that operation is best left to a competent machinist/machine shop. Do not use a drill press. A drill press does NOT have the tolerances and/or accuracy to perform the O-ring conversion as the bore finish is very critical. The wall finish in the bore for the O-rings has to be perfectly round and with an almost mirror like finish or it WILL leak. A fuel leak at the rail is DANGEROUS as the fuel will drip onto the hot exhaust manifold, FIRE, and the manifold portion of the O-ring conversions has to seal against manifold vacuum or you will have a vacuum leak in that cylinder.Hope that helps. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 10, 2006 Author Administrators Share Posted October 10, 2006 I was going to try that type of return system with my Aeromotive regulator. Less fuel lines on top of the manifold is always a plus. Do you think there would be any pressure fluctuations with that setup? In using the returnless style depicted above, there really should be no added or induced pressure fluctuations above and beyond what would be present in the fuel system if it were a flow through style. This set up is currently running on my car and it runs great. Just make sure you have adequate fuel supply, i.e. as long as your fuel pump is capable of meeting the demands that your injectors are capable of flowing at the max fuel pressure you intend to run.HTH. Quote Link to comment Share on other sites More sharing options...
DemonZ Posted October 10, 2006 Share Posted October 10, 2006 ...A drill press does NOT have the tolerances and/or accuracy to perform the O-ring conversion as the bore finish is very critical. The wall finish in the bore for the O-rings has to be perfectly round and with an almost mirror like finish or it WILL leak. A fuel leak at the rail is DANGEROUS as the fuel will drip onto the hot exhaust manifold, “FIREâ€, and the manifold portion of the O-ring conversions has to seal against manifold vacuum or you will have a vacuum leak in that cylinder. Hope that helps. Isn't the bore finish determined more by the kind of cutter (bit/reamer) and speed rather than the machine? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 10, 2006 Author Administrators Share Posted October 10, 2006 Isn't the bore finish determined more by the kind of cutter (bit/reamer) and speed rather than the machine? Yes, you are absolutely correct. The finish is determined by the cutter and its speed. But also of importance is that the hole being bored is truly round, not oblong. The O-ring will conform to minor shape irregularities, but not always and in the situation of an L-series fuel injector, if it leaks, it will leak fuel onto a hot exhaust manifold. The spindle/quill in a drill press has slop radially, side to side, and even just a couple thousands of an inch slop in the spindle/quill/chuck could cause the hole that is bored, drilled, or reamed, to come out oblong. Generally speaking, this would not be the case if done on a mill. A drill press is engineered and built to drill holes, not perform precision boring. In the design and manufacture of drill presses, there is not as much consideration placed on its ability to keep the quill/chuck exactly true or take side loads, where as a mill, this is a very critical and important aspect of its design and function. In short, you can pretty much trust that a milling machine will deliver a quality hole that is not only smooth, but truly round and exactly where you want it. With a drill press, I personally wouldn't trust its more lax tolerances, though that is not to say it can't work, it's just not a chance I would be willing to take myself.I look at machining O-ring bores as requiring the same attention to detail as a valve seat in a cylinder head would require.I apologize if I went too far off on a tangent there¦ Quote Link to comment Share on other sites More sharing options...
TimZ Posted October 10, 2006 Share Posted October 10, 2006 One issue with the lower profile fuel rail is that the front of the rail itself will hit the thermostat housing if it is too long, i.e. more than 1 3/8†inch from the centerline of the #1 injector to the end of the fuel rail. If one is dead set on running the fuel rail as a â€flow through†fuel rail design, attaching a fitting on the front of the fuel rail could be quite tricky due to the very limited space, but it probably could be done, though where to route the fuel line to clear the exhaust manifold, thermostat housing, throttle valve, etc and NOT look awkward is another trick. Here was how I solved that problem on one of my old setups... Basically, I used a straight -6 fitting on the end of the rail and a 180 deg -6 hose end, running back to the FPR which was mounted on the firewall. I used firesleeving to keep the braided hose from destroying everything around it. The only advantage that I know of (aside from not having to continually explain why it doesn't matter ) for the flow-through setup is that it will self-purge any trapped air out of the rail without having to do anything special. That said, I think the non flow-through setup will probably do the same within a minute or so after the first startup. Quote Link to comment Share on other sites More sharing options...
CarJway Posted October 11, 2006 Share Posted October 11, 2006 Showing a little from my build... I was a little anal and used the factory hold downs also. The fuel rail does come close to the thermostat housing, but a 45* turn solved that for me... Braap - I really like the looks of the quality from the rails shown. My rail took quite a bit of massaging... looking towards your rail if do begin to produce. (For another build) Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted October 11, 2006 Share Posted October 11, 2006 hey guys, are the mkIII supra turbo 440cc injectors 14mm o-ring? If not what are they and what kind of mods to the intake are nessary to make them work. As always thanks for the info. Quote Link to comment Share on other sites More sharing options...
veritech-z Posted October 11, 2006 Share Posted October 11, 2006 I decided to feed my rail from both sides, with the regulator being fed towards the middle...I haven't actually run the car this way yet, I'll be sure and let you know how it works out. This isn't the O-ring rail, it's just another picture of the barbed rail installed to show that you don't have the problem with thermostat clearance you have on the other type. Quote Link to comment Share on other sites More sharing options...
340ZXTTAZ Posted October 11, 2006 Share Posted October 11, 2006 Well Braap, You can put me on the list for both an intake and a rail. I know that it could be done with a little time and determination but i would rather hust pay someone with the experience to do it. Quote Link to comment Share on other sites More sharing options...
240hoke Posted October 11, 2006 Share Posted October 11, 2006 I run my lines like Tim, There is a thread here about why you shouldnt run the returnless style. I like it its very clean but it doesnt seem to work well for some reason, lemme see if i can find it. Anyway here is how i ran mine, Its tight but it works great.. Its a Pallnet rail BTW. Quote Link to comment Share on other sites More sharing options...
240hoke Posted October 11, 2006 Share Posted October 11, 2006 Here you go: http://forums.hybridz.org/showthread.php?t=105219 Quote Link to comment Share on other sites More sharing options...
rztmartini Posted October 11, 2006 Share Posted October 11, 2006 supra 440cc injectors are 11mm i believe. they do not require any modification to fit the intake manifold but you will need to get an o-ring fuel rail... Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted October 14, 2006 Author Administrators Share Posted October 14, 2006 Here you go:http://forums.hybridz.org/showthread.php?t=105219 240hoke,Ok, I'm struggling with this one. Below is how I perceive both of these fuel supply scenarios. If I am missing something or completely off base, please let me know shoe me how and why so that I can get on track and not lead anyone else astray. Nice induction system by the ay.For starters, if the fuel pump is unable to keep up, it wouldn't matter what system you are using, flow through or a returnless fuel rail, there will be fuel starvation issues. Now if the fuel pump is up to the task, then I would think there should be no issue with using either system for the following reasons.If the ID of the fuel rail, (cross sectional area), is able to flow enough fuel at the given fuel pressure to keep up with the demands of the engine, (which is typically larger than the fuel line supplying the fuel), then it shouldn't matter if the fuel rail is a flow through or returnless style in regards to getting enough fuel to ALL of the injectors. Now if the if there is an issue with the returnless fuel rail not allowing fuel to get to the last injector, that would mean there is pressure drop because either the fuel pump can't keep up or the fuel rail ID is too small and if this same fuel rail was a flow through style, that same issue would still exist and there would be fuel starvation issues. Most fuel rails have way more cross-sectional area than the fuel line supplying it. Based on that, I would think fuel flow to all the injectors should be adequate. I.e. if the fuel system is sized appropriately for the application, and the fuel rail is at least, to some extent, larger in cross sectional area compared to the fuel lines supplying it, then all the injectors should receive adequate fuel qty/pressure whether it is flow through style or returnless style.FWIW, the current production GM Vette is using returnless fuel system which is a much more exaggerated returnless system than that depicted here.Am I missing anything here?Paul Quote Link to comment Share on other sites More sharing options...
dave280zxt Posted January 17, 2009 Share Posted January 17, 2009 what type of barbed injectors are pictured? (size? brand?) (The green ones) thanks Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted May 7, 2009 Author Administrators Share Posted May 7, 2009 (edited) what type of barbed injectors are pictured? (size? brand?) (The green ones) thanks O-ring injectors are Factory Chev '85 Corvette C-4 injectors. I think they were either 19 or 21 lb/hr, I don't recall. The Barbed injectors? I don't recall, sorry. Edited May 7, 2009 by BRAAP Quote Link to comment Share on other sites More sharing options...
neotech84 Posted May 7, 2009 Share Posted May 7, 2009 LOL thats a great way to revive a DEAD thread! FWIW I like the look of a clean intake...... good job Braap Quote Link to comment Share on other sites More sharing options...
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