I'm kinda wanting to ditch the FMU, and run bigger injectors. I'm thinking of 42# or even 55# with a 255lph in tank fuel pump. I'm just curious to see who's running what, and if it's enough for your setup

 

I am running 55's with a DFI and big aeromotive external pump. Enough for my end goal of 700HP at the crank

 

36# injectors.. 55psi wot pressure. $58 ecm.. somewhere around 500-550hp..

-- Joe

 

24 lbs @ 55-60 psi

Stock pump and ATI inline.

Haven't put a wideband on there yet or really pushed the RPMs but it seems alright.

EDIT:
Did some WOT runs with the wideband.
It doesn't seem alright, ~4000 rpm the A/F goes bye bye, ~14:1 and 16:1+ and rising by 4500 rpm.

I'll add injectors next to a new clutch and tires on the list of supercharger headaches.

 

what about driving those injectors? Isn't there some issues with making injectors that big idle?

and another question, will using a 749 which has the two injector drivers, can i run bigger injectors that will still idle properly?

These all relate heh and they're tidbits of information i've picked up which could be answered/dispelled.

thanks

 

I was running 55# injectors last two years with good results, was running out of fuel around 650hp(100% duty cycle)but then I only have 6 injectors. 8 of them should support around 880hp at 100%(750ish at 85% duty cycle).

Went to 83# injectors this year, they run real nice just had to bring the idle up a bit and the fuel pressure up too or it would foul plugs when cold. These should more than meet my goals of between 700-750hp without needing to go over 75% duty cycle And that is again with 6 injectors, 8 of them should support just over 1300hp at 100%(1120ish at 85%).

I think if your gonna go 55# injectors or bigger and plan on really using them(75% duty cycle or more)then your intank pump and stock fuel lines are gonna be a restriction. I know many have used the stock fuel lines and make big power but fuel is never something you can have too much of(in the rails at least)and would always rather go a little overkill than come up short.

HTH,
Steve

 

Thanks for the replies guys. I don't wanna give away all the details (prying eyes from my home town), but basically I've got a 383 block with all the goodies, and plan to run a good amount of boost. I can get a really good deal on 42's but I'm just contemplating if that will be enough. I think it should.


nightrider87
I don't see why running bigger injectors would give you any problems at idle as long as you have a good tune. Stang guys do it all the time with no problems, so we shouldn't either

 

Hey nightrider87, I found this for ya.

Sure it's a Mustang board (and no I'm not swinging to the "other side" lol), but a lot of it applies to our cars too. We get virtually no coverage in magazines (nothing hardcore anyway) and never really did. The only place to get useful information about buildups is on this website, and most of the guys doing anything interesting are being pioneers in the field! Just look at some of the combos from people in this post!

Sometimes when I can't find any, or much, information that I need here, I peruse over the Mustang stuff and pick out the pieces of info that are relevent to our cars. You can find just about every possible buildup there ever was or can be over on the corral site.

42# injectors, driveability, fuel consumption questions...