I’ve been working on a setup to test injectors. Haven’t finished it by a long shot, but as 3 of my ebay auctions arrived today, I just had to do a bit of a flow test :)

Just a small intro on the test setup. It consist of my netbook running a simple C program based on libftdi. It is using bitbang mode through a Sparkfun ft232r FTDI adapter to a driver board (thanks Peter!!).

Next is the injector setup. I made a small rig holding a slightly modified Z22SE fuelrail. It has the middle pipe removed and a damper fitted at the side. So it basically is a dead end fuel rail. For injectors the 2 on the left are the standard 2.2 injectors, the right 2 are the standard LSJ injectors. None of the injectors have been cleaned, just stock second hand :)

On the gas tank I fitted a fuel pressure regulator. It is set at 3.8 bar for this test as that is the standard fuel pressure on the Speedster. As this is a flow test at 100% dutycycle there is no point increasing the pressure to compensate for manifold vacuum.

As a fuel I used white spirits, which seems to be a pretty standard fluid to use when testing injectors. I tested the injectors 5 seconds a piece at 100% dutycycle. I didn’t test them simultaneously to prevent any problems in pressure drop.

After the test I read the scales on the measure cylinders.

Injector 1 (standard z22se)

Injector 2 (standard z22se)

Injector 3 (standard LSJ)

Injector 4 (standard LSJ)

For this test the number of ml per injector were:

• injector 1: 20ml
• injector 2: 20.5ml
• injector 3: 34ml
• injector 4: 33ml

I ran the same test again, just to verify and it gave the exact same results. So based on these 5 second flow results, the per minute flows are:

• injector 1: 20cc * 12 = 240cc/min @ 3.8bar
• injector 2: 20.5cc * 12 = 246cc/min @ 3.8bar
• injector 3: 34cc * 12 = 408cc/min @ 3.8bar
• injector 4: 33cc * 12 = 396cc/min @ 3.8bar

So, based on the information I gathered on the internet, the results seem to be pretty close:

Injectors

One uncertainty has always been the 352cc/min the LSJ’s are rated for. Some sites say it is at 3.0 bar some at 3.8 bar. It looks like it is 352cc/min @ 3.0bar.