Ok...so I have been so frustrated getting over 400rwhp..I may just go for 500. Howto?
- Thread starter Pokageek
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str8stang036
New Member
Check this place out, this is where I got my 96lb injectors. http://www.fiveomotorsport.com/Injector_SetsMODS.asp#cng150, the ones in the center of the page.
BlackVert
15 Year Member
http://www.injector.com/injectorselection.php
i tried this ... it assumes a fuel pressure of 43.5 psi (ours is usually around 40) and an 80% duty cycle. you don't want to go above 80%
it says for 550 horses (at the crank, not the wheels) with a 80% duty cycle, 42.97 injectors should be ok.
personally, i think you'd be fine with 42#ers. 36#ers might run a little lean at the top end
i tried this ... it assumes a fuel pressure of 43.5 psi (ours is usually around 40) and an 80% duty cycle. you don't want to go above 80%
it says for 550 horses (at the crank, not the wheels) with a 80% duty cycle, 42.97 injectors should be ok.
personally, i think you'd be fine with 42#ers. 36#ers might run a little lean at the top end
Thanks for the link, it gave me a fuel injector size of 34 and I plan on stepping up to#36 with the new mods. With the power out put now w/ the current mods it said I should be running #30's but I have #24's in
I just guessed at what my new HP will be with the new mods and I put it a little high and I still came below #36's so I should be fine.
I just guessed at what my new HP will be with the new mods and I put it a little high and I still came below #36's so I should be fine.
I don't believe that calculator. I'm making 380rwhp with 24lb injectors at 45lbs of FP and a MAX (and it only hits this number for a millisecond) duty cycle of 89%. I'm putting 30's in it and I'm not going to worry about a thing, and I expect to make >400rwhp when all is said and done NA.
well thats good. I didnt think #24's would be enough w/ the new parts but I didnt want to go as high as #42 so I figured #36's would be the sweet spot. I expect to be making in the ball park of 380 as well once its dyno tuned and the parts are installed.
rj95svt
Member
I was just wondering why go with just 30's if you you could pick up a set of 39lb 03-04 cobra injectors for around the same price. When you start going over 400rwhp will you not still be over 80% duty cycle with the 30's? This is just me but I would think that since you already have to buy injectors why not get injectors that you know will be plenty enough?
The reason is two fold. One, I'm getting a set of 30's with 7K miles on them for $100, and secondly these are just temporary until I put the turbo on, at which point I'll need 60's at a minimum. 30's should not be over 85% duty cycle at 45lbs of fuel pressure at 400rwhp, and although 45 is slightly higher than stock, its no where near anything to worry about and if need be I'll bump it to 50lbs of FP. Either way, it'll work (or I'll make it work) for the time being for what I'm doing.
The other problem with the '03-'04 injectors is that in addition to the injector cost, I'd need the adapters, at which point I'd be getting very close to what a new set of 60's cost (they can be had for ~$300 now).
rj95svt
Member
No way!
I am 100% maxed out with my 30's and i'm estimating around 400rwhp. 36's will not handle that.
It is amazing what those little 24 lb injectors can handle with some accurate duty cycle numbers.
I was way overinjected with mey 30 lb injectors on my 302. I should have went with 24 lb injectors.
I wish my little 30's could handle my power. I'm @ 96% duty cycle before my shift pointGood thing I just cruise and don't beat on the car much.
Mike, why do you think that is? What fuel pressure are you running?
BlackVert
15 Year Member
Paul,
An 89% duty cycle means that the injectors are on for 89% of the time, doesn't it?
If so, then that means that they start squirting pretty much right after the intake valve closes. I would also think the fuel would pool on the back of the intake valve and you'd get a bunch of fuel spilling into the valve when it opens.
While it might be able to deliver enough fuel that way, it seems like a "less than ideal" situation. I know you said it is a temporary setup for you until the turbo goes on, I'm just thinking out loud ...
Suppose you were staying NA ... what size injectors would you go with then?
An 89% duty cycle means that the injectors are on for 89% of the time, doesn't it?
If so, then that means that they start squirting pretty much right after the intake valve closes. I would also think the fuel would pool on the back of the intake valve and you'd get a bunch of fuel spilling into the valve when it opens.
While it might be able to deliver enough fuel that way, it seems like a "less than ideal" situation. I know you said it is a temporary setup for you until the turbo goes on, I'm just thinking out loud ...
Suppose you were staying NA ... what size injectors would you go with then?
The fuel is at 40-41psi.
My guess is because the cam is kinda aggressive and I spin to almost 7,000 rpm.
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