How to calculate flow rate of injectors

Len · April 4, 2002

To clear up some confusion (I guess really my own!);

To Calculate Correct Flow....You flow the injectors for 60 seconds at 43PSI multply by 4. That's the flow rate in CC's or ML's (both the same). To find lbs. you then divide by 10.5

For example my 370cc. Mustang SVO/Mercur I flow tested at 93ML. at 39lbs. X 4 = 372cc. (or ml.) then divide by 10.5 = 35.42 lbs. (or 35lbs.).

My injectors were alright, I was confused. I thought my cutting out was due to lean. Because my Dawes Air/Fuel Gauge showed lean(Along with my misconception on how to calculate flow rate).My Gauge was wrong (or not very accurate) and I was wrong.

My spark plugs (when I regapped them from .44 to .39 I noticed showed rich). My fuel economy (100 miles on 1/2 tank). My stock FPR was running higher pressure ( 40lbs. at idle I replaced with a 78 280z FPR I had laying around now 36lbs.).

The Big difference was adjusting my AFM cog nearly 200 degrees clockwise. Now car runs great at WOT.

To really improve operation I feel a 240SX TB along with a adjustable FPR like maybe Aeromotive (adjustable from 30lbs. up) or AEM adjustable from 20lbs. up). Both FPR are 1 to 1 indexed. If you lower your base pressure to much you could lose effiency of injectors spray pattern.

These improvments are along with the need to eventually install 2 3/4" DP (I got faith in you Scottie) 3" exaust and I/C.

I realize ideal situation is to buy SDS systum or some type of EFI controller systum to really fine tune things. I'm just trying to work cheaply as possible.

I want to save my money for the SDS systum for my Lt-1 T-56 into 240Z install. But want to play in the meantime.

SleeperZ · April 5, 2002

I'm sorry, I really do not understand. Where does this factor of 4 come in? I have over 2 dozen of these "brown tops" on my bench, and I have flow tested them. I hold them open for a minute over a graduated cylinder, and they put out 370cc - it's that simple. I can see opening the injector for 15 seconds, measuring and then multiplying by 4 - is that what you mean?

Len · April 5, 2002

No that's not what I came up with. I called over 12 different injector shops from FL. to CA. Got a hold of a guy at Dr. Injector in washington He gave me the formula. Verfied by 3 other outfits Those 370's I had ran 93ml. for 60sec. at 39lbs. I installed them, ran fine after adjusted AFM.

I Even spent 12 bucks and flow tested my new stock 260cc. turbo injectors they flowed 65ml. per min. times 4 = 260cc (or ml) divided by 10.5= 24.76 or 25lbs.