View Full Version : Who has maxed out their 17# injectors?
Has anyone tried to richen their mixture at WOT after modding and been unable to because the stock 17lbers are maxed out? I'm getting ready to add the apexi AFC and I really don't want to get it all wired up and on the dyno to find out that I can't richen my mixture far enough. If I need the 19's I'd rather get them first. At this point, I have no plans to do any more engine mods than what I've got (perhaps the 75mm MAF, but that would be with the 19lbers I think).
My current engine mods are (SCA CAI [KKM], SVT TB&IM, MSDS, Borla).
mcon99
03-24-2002, 02:38 PM
get 19lb injectors. I have a similar setup and although I am not sure I am hitting 100% on the 17lb injectors at WOT, I am having a bit of a fuel delivery issue. I am going with 19lb injectors + a C&L 73mm calibrated for them. Butt dyno test on puck's car says "yes" this is a good thing (and he doesn't even have the SVT UIM)
l8r
What the heck....it's only money. 8)
mello88
03-25-2002, 05:18 AM
From the looks of things (your mods) I'd say you're under the 220ish hp mark for 17pph run out. In some other thread there was a bunch of math that showed 17pph injectors are maxxed (at stock rail psi) around 200-220hp. If I were you, I'd take the car+afc assembly to the dyno, and try to tune it as much as possible. If the injectors are holding you back, then leave it tuned as aggressively as you can get it, order some 19pph injectors and a new MAF, wait a few weeks to get that stuff in, then hit the dyno again.
mcon99
03-25-2002, 11:01 AM
the way I figure it is:
Ford choose to put 19lb injectors into the first (192HP) and second (205HP) 2.5L SVT engines. Why did they do that? They probably cost more so there must have been some compelling information on Ford's dyno testing that 19lb injectors were required for higher HP. Ford does not spend money needlessly and complicate the supply chain (remember these engines were built in batches on the same lines)
Now with the simple bolts on you can get for a 2.5L (intake, exhaust, headers/no-precats, UIM, TB, LIM, MAF) you will easily peak at least 192HP if not real close. Thats without some external tuning such as an ApexI or a Greddy-Emange. Both of those are probably worth at least 15HP with those bolts ons.
So 19lb injectors seem to be a requirement. I believe over at CEG some people doing a 3.0L conversion are actually using 24lb injectors (over-sized) and are having great success.
mello88
03-25-2002, 01:34 PM
According to Maximum Boost by Corky Bell, the way to figure out aproximately which injectors you need is like this:
lb/hr injectors =est. bhp * .55 / # cylinders...
For our car, you get inj = 170*.55/6, or inj = 15.8. The 19s were not needed on our car from the lot, and no, Ford does not anticipate that you're going to mod your car beyond the capabilities of their stock injectors... They used the 17s because there was no need for the 19s..
If you figure that you're putting 200hp or so at the crank, you should be requiring ~18pph, 225hp =~ 20pph injectors.
This is why I said that you MIGHT not need them, and that it's worth a try to tune the engine without them. Installing the AFC has nothing to do with installing the injector -- you won't save any installation time (as opposed to installing new springs when you install the struts) now, or in the future. If the thought of buying a new MAF + injectors sounds expensive/time consuming, then I'd suggest you try to hit the dyno with your current setup; you'll most likely have no problem getting it to where you want it. If you're looking to upgrade the injectors/maf anyways (why wouldn't you?), then buy them and get everything tuned. I'd still stick to my original plan, get it tuned well enough with the 17s, then later upgrade to a bigger maf and the 19s at the same time.
It's not the expense that scares me (I've spent enough on it already to be immune tho this. ;) ), it's the total inconvenience of getting to a dyno. There's slim pickings where I am.
mello88
03-25-2002, 08:38 PM
It's not the expense that scares me (I've spent enough on it already to be immune tho this. ;) ), it's the total inconvenience of getting to a dyno. There's slim pickings where I am.
www.dynojet.com has a list of some dynos in the area, but I guess you probably knew that already.
Yup, and it shows nothing valid for my entire state. Took me 6 months of searching to find one 2 1/2 hours away.