I'm currently working on an ls vtec build that will utilize itb's. They have 46mm butterflies and came off a BMW motor cycle. I also received the rail and injectors. Now the injectors are rated at 236cc at 43.5psi

I'm going to be running larger secondaries as shower injectors, these are rated at 510cc at 43.5psi

That being said, this is a street car, no drag racing, maybe the occasional mountain run or track day at road Atlanta or AMP. I'm centering my build around ,maximum torque production and driveability/ efficiency.

Both injectors state "for fuel systems up to 5bar", which is 72.something psi... now at this base pressure injector flow goes up dramatically, from 236 to 277 and from 510 to 658cc. Now I'm not looking for more than 400-425hp at the most and the two injectors at 43.5 give me plenty fuel but bumping the pressure to 72.5 would in theory give me much better atomization.

Given my pressure range will be in the 20-25psi range, this brings up fuel pressure a lot. At most 97psi... which I'm pretty sure will cause a bunch of issues.

So here's my question, run 43.5 base with a 1:1 regulator or run 72.5 with no pressure reference to the regulator. I'm just wondering what the regulator would do with no pressure signal?

Using 72.5 as a base would still provide plenty of fuel provided I don't give the regulator a pressure source. Because 43.5 base with my pressure goal will end up in the low to mid 70s with a 1:1 reference.

So is this a decent idea or am I better off running the standard base pressure? I was just thinking the higher base pressure would yield better atomization and lower injector pulse width.

 

No one?

 

pics or it isnt happening...

 

I already have the primaries and my itb's

The secondary shower injectors are retardedly expensive new like 511 each without the holder from Ducati... however not I only do I know a few Ducati WSB/MotoGP factory guys but I get a good discount at every dealer. Still cheap enough to get new? Doubtful... unless I can get Mondo to mail me a set from Italy.

I do have a few places that recycle motorcycles and they get a lot of new ducatis, they'll sell me 4 for 150, including the billet holders. Which is ironically the cheapest I've found a new injector without holder

There's a lot of work to get this project done.., and this is just a small part... there's managing 8 injectors, blending them while tuning, as well as a bunch of other hush hush things, including an LCD dash, etc.

 

The injectors in question




They are fairly small, 14mm diameter rail end and smaller than an ev14 injector but have an absolutely amazing spray pattern... even at 43.5 psi it looks like fog

 

To answer your q's I would say yes stick with base and a 1:1 regulator. This is kind of an interesting project.

Some questions I have though are what kind of pump were you planning on using at that high system pressure? What ECU do you have lined up?

Those injectors definitely look exotic but is there a special reason other than the fact that they came with the itb's you are using them? If they are 'worth' a lot of $ would it more practical and smarter to sell them, buy Injector Dynamic units, and simply shim the fuel rails for them to fit?

If the focus is on efficiency I would think that some ID injectors will probably yield higher cylinder consistency being a closely matched set.

Obviously just my outside perspective but definitely got me interested. Any more pics?

 

Either dual 044s or something else, at 72.5 psi, each set of injectors would really need its own pump. I'm using an AEM ems

They didn't come with my itbs, I'm getting them separately. The reason is standard injectors don't have the proper spray pattern for proper atomization when used as a shower injector.

The typical Bosch/ Rochester pintle and ball and seat style just spray the fuel in a stream.
The magnetti marelli injectors I posted above look like a fog. I've been building race bikes and have been on numerous factory and factory funded teams.. anytime we used shower injectors, magnetti was who we turned to...

The conical area after a 12 hole discharge insures the fuel atomizes in a 20* cone...


Same applies with ev14 injectors... spray pattern doesn't work for shower uses... using any other injector causes fuel to bead to the walls.

I have an injector guy I use locally, he can make me anything I want out of any current injector except these... however I will be letting him clean and balance them.

 

seems like to me your over complicating it IMO but thats fine do what you want, but whats the need of 8 injectors for 400hp?

 

I want the best in driveability and control, 400 is the lower end of what I want, and I've had issues with larger injectors having shitty part throttle drivability.

The goal is response and efficiency. We have a membership at AMP and are regulars at Road Atlanta, so I want to do some road racing. We also do a few mountain runs. I never drag race

My last build used a single set of 1000cc injectors, everything but wot sucked

And I can do an 8 injector setup cheaper than buying 4.

 

^^Agreed

 

With?

 

I can probably help a bit here, despite none of my 800+ injectors being magnetti marelli. Regardless, injectors are rated by differential pressure, not absolute. Just the pump has to deal with absolute pressures. The vacuum or boost in the manifold pushes against fuel pressure. With 20psi of boost and 72psi of base fuel pressure, the rail is at 92psi, but the injector is still at 72psi differential pressure.

One reason to NOT run a rising rate or static fuel pressure is because injector latency changes with base fuel pressure. If your ECU does not know what the fuel pressure is, your AFR's will be wacky when it has to add/remove fuel, say for high IAT's or low ECT's. S300 for instance can't adjust injector latency, but a newer Ford ecu can since it has a fuel pressure sensor and latencies/flow rates for various pressures.





The problem with that info is what type of ev14 you're dealing with - "decapped" vs the intended design that has atomizer plates. Most OEM injectors have one or two 20-24 degree cone(s) via the angles & placement the atomizer plate's holes are cut. To turn an injector into a monster ID1000 you remove that plate to expose the ball seat, which gives you a very narrow cone. They are still far better than a Lucas injector or a stock obd1 Keihin injector, but not as good as they started.

If the injectors were near the head, you'd have better options with Bosch. Many newer motors use injectors with 2 distinct cones to direct fuel right to the valve. I have 370cc and 550cc injectors that do this with 4 & 6 holes respectively, two 24* cones, and even aim them upwards towards the valve bases. I do know some 12-hole Denso's can let a GSR cruise at nearly 16:1 AFR's and idle almost up to 18:1 AFR's.




Regarding your pictured injectors, I don't think you really need them. Bike motors have insane specific outputs, and bike makers use every trick they have even on consumer models. Most bikes don't even activate the secondary injectors in the airbox til 5k.

Bike makers also design their ECU's to accomidate the slight differences in latencies, and use almost identical injectors (usually just 50% higher flow). Your primaries will invariably be quite different from those secondaries, and may create problems due to latency differences.

Lastly, the only time I'd want a shroud or cone near the outlet of my fuel injector is if the motor has some sort of manifold air injection type system like some VW's, Lexus, or newer Hondas. If air isn't being drawn around the injector tip from above, it is likely to gather onto the cone and come off in large droplets. There is a reason that Bosch, Keihin, Siemens, Denso, and Delpi no longer have conical shapes projecting past their atomizer plates. [ID2000's have shrouds but were designed for natural gas, not liquid gasoline]

If you do use them, this is my favorite idea: you use a multi-pole relay (solid-state or not) with a feedback to an ecu input to activate secondary maps. The ecu ativates the relay, then as soon as the injectors get power the ecu switches maps. You wire them in parallel to the primaries, and avoid spending >33% of each 5 minutes with them activated. Your stock injector drivers should handle the extra amp per transistor for a few minutes without issue. You can also wire your stock ecu's 4 outputs to the primaries and an injector driver feeding the secondaries - thus only a hair over 1 amp per ecu channel. The relay idea is used to turn on the driver as well as give the ecu the feedback signal to switch maps.


Anyways that's a lot of info to post, so I'm sorry for any errors that slipped in.

 

I'm not using a stock ecu, I'm using an AEM ems for this build, so I could automatically have the secondaries activate at a given rpm/load without issue.

My primaries are like you describe, each has 4 distinct cones to direct the fuel directly at the valve. Given their distance from the port, this works as the fuel/air mixture would atomize as the cylinder draws in air.

The secondary shower injectors literally create a fog. We've tuned multiple bikes with varying activation points, even run them entirely on secondary injectors, the atomization they provide make everything run better, smoother, more power, etc. Not to mention with their distance from the valve you can play around with dead times and such to perfectly control fuel delivery times, so there's no fuel polling in the ports, etc

Honestly I can get the 4 shower injectors cheaper than anything else. And since it hasn't been done a lot (except in high HP apps with huge injectors) I feel like being different, plus I feel I can tune this system to provide much better drivability, efficiency and overall power than a setup with 4 large injectors.

Hell if it doesn't work out I still have 4 high capacity injectors to use as primaries.