View Full Version : Smallest Inj

12-20-2004, 08:59 AM
I am going to convert a Hilborn BB stack unit - would like to put inj on inboard side of throttle bodies but I don't think there is enough room - unless I can find an injector small enough. Any ideas? Thanks. -Bob

Fuelie Fan
12-25-2004, 10:19 AM
We've got some pretty small injectors at work from Delphi, I forget which series multec they are but they are tiny. Message me after the first of the year and I can try to get you more info. Edelbrock also sells pico injectors, they are very compact as well.

12-25-2004, 03:37 PM
Thanks, I'll do that. -Bob

12-26-2004, 10:21 AM
I had the same problem with my SB conversion. Magneti Marelli makes some really small injectors. Mine are 44 lbs/hour. The cheapest way I've found to get them new is through Edelbrock. They use them on one of their systems and you can get the replacement part through Summit (Part Number: EDL-3684). They are also used on Ducati motorcycles. I got mine on ebay from a guy that was doing race bike engines and had a bunch left over because he changed the system. I haven't tested them yet, but the fact that Edelbrock uses them hopefully means they verified their reliability. The MSD fuel rail kit is pretty low profile also if you need even more.

Injector Info

Fuelie Fan
12-26-2004, 11:55 PM
I think the clue is not that edelbrock uses magnetti marelli, but that some formula 1 teams do. MM is high quality.

12-27-2004, 11:42 AM
Thanks for the link - I knew about the MM inj but didn't have any specs on them. -Bob

12-29-2004, 06:38 AM
Just because some Formula 1 teams use them on a limited life engine (not even these exact injectors) doesn't mean that they are suitable for street use. It is a whole different ballgame with duty cycles that are completely different. I just found it comforting that Edelbrock uses them because they would not release a system without some street testing.

Fuelie Fan
12-29-2004, 12:29 PM
My point was that Formula 1 teams don't run off-brand stuff, they buy from companies that have demonstrated expertise. I definitely did not mean to imply that you were getting the same part. I also didn't mean to imply that edelbrock's endorsement is worthless, they do maintain pretty high levels of quality. I jut meant that the endorsement of such an elite motorsport adds even more, in my eyes. Sometimes (though not in this circumstance) american aftermarket companies will use parts not becuase they are better, but becuase they are cheaper, and you have to be wary of that from time to time.

As a fuel injection engineer I am well aware the different requirements placed upon injectors.

12-30-2004, 11:16 AM
Fuelie Fan,

I would like to test these injectors to make sure they all work and have similar flow rates before I put them on the car. Would it burn them out if I applied a constant 12v source to open them? In other words, do they need to be pulsed to check them out? I have a spare fuel pump and regulator so I could rig up a little test.


12-30-2004, 07:24 PM
Tireman what did you use for fuel rail on your SBC Hilborn conversion? Thanks for any help.

12-31-2004, 09:32 AM
I made them using the MSD injector parts.


I just silver soldered the injector mounts (PN 2115) to the tubing. For the little injectors, I turned off about 0.050" from the ends so they would sit all the way down on the injector. I didn't use the clips because my rails are hard mounted.

Hope this helps...

12-31-2004, 06:56 PM
Tireman thanks for the reply I'd seen MSD's 55 in Super Chevy and noticed the rails on their project car seemed like the same ones or with the same style parts, the information you've provided has been very useful.

Fuelie Fan
01-03-2005, 10:20 AM
A basic flow rate test does basically what you describe: apply 12V for a set period of time (anywhere from 10-30 seconds) and measure the volume of fuel. You'd probably need a 500 or 1000 mL cylinder to do the test. Since we have a signal generator, we actually never go above 90% duty cycle, but for short periods you should be just fine.
We do a lot more than that, but for your purpose the other tests wouldn't be necessary. Most injectors are remarkably linear for 80-90% of their operating range. Also, if they are new, I expect they will be pretty closely matched. Most injectors that I've tested have been very consistent, usually better than their quoted tolerance (except those from Dana, they sucked)

Don't apply power without fuel, as it helps cool the coils.

Fuelie Fan
01-03-2005, 10:27 AM
Here's some compact injectors. Delphi's multec 2's are pretty common