Injector sizes

[radrangerXLT]

Was doing a little reading and found some info for people doing this swap and looking to run stock boost levels.

The 1997 and later SOHC 4.0 Rangers come stock with 24lb injectors. These can be had at a bone yard for relatively cheap $$$

IIRC the formula to figure out how much HP an injector will support is;

injector size x number of injectors being used x 2

24 x 4 x 2 = 192 HP

This should be plenty for someone only looking to push about 7psi. Or if you were just trying to get your project up and running so you could work out all the little bugs before you start pushing more boost (such as myself).




The X-cal 2 has a setting for 24lb injectors doesn't it?

[fordnut71]

you can also find 24#s on 4.6 dohc motors like the cobra an markviii
but stock ranger are #35

[radrangerXLT]

but stock ranger are #35


I thought all 2.3/2.5/3.0/ and 4.0 OHV engines came from the factory with 19lb injectors?

[flyin]

3.0 uses 14lb for sure unless it is a flex fuel then I believe it to have 24lbs.
the 2.3 has 14 (pretty sure)

[Touring23]

To muddy the picture further, I have the impression it's 14's up through 1994, then 19's from 95 on. My '93 absolutely positively had 14's (and a 60lph pump), which is just enough horsepower for idling in the driveway. :prrr:

A word of caution about those numbers, Rad: Injector #/hr ratings are for a given pressure across the injector. The injectors have to push against manifold pressure. So to be accurate you either need to compensate for the boost pressure with additional fuel pressure or de-rate the injector like this:
(24#/hr) * square root of { (43psi-7psi)/43psi } = 22#/hr (~176HP)

Then, turning up the rail pressure decreases your fuel pump capacity, so be careful with these calcs, guys. There's just enough info in that calculation to be dangerous.

[fordnut71]

my understanding that the stock 97 2.3 injector was #35. so i may have been told wrong.

[flyin]

I think that Jess ran into that with a 255lph pump and had to go to a 255 hp pump designed to run at higher pressures