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Discussion Starter #1
I know that 24 lb injectors handle 380 hp but does that calculation change when nitrous is implemented? Should I step up to 30 lbs? I am looking into the long run after heads, pistons, cam setup with 100 shot. I do not want to buy a different MAF and injectors later. Thank you.:)
 

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Brian, nitrous kits usually introduce fuel separate from the injectors.... If you install a wet kit, it comes with it's own "injector" of sorts; the gas solenoid. It introduces fuel into the intake sepatare from the injectors via the nozzle/solenoid. Same with dry systems- They raise fuel pressure when under the spray, which has the effect of having a larger injector. What you want to be sure of when adding N20, it that fuel VOLUME is sufficient in the way of pump delivery. You do this by adding a larger capacity fuel pump, be it a 190 or 255 in-tank or perhaps via a in-line pump like a T-Rex...

Hope this helps.
 

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Brian95GT said:
Should I step up to 30 lbs? I am looking into the long run after heads, pistons, cam setup with 100 shot. I do not want to buy a different MAF and injectors later. Thank you.:)
That's the reason I bought my 30#'ers. They cost almost the same as 24's, and since I bought my MAF at the same time, I figured I would do it all at once.
 

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If you went with larger injectors for nitrous, but did not increase pump capacity, how would this be of benefit to you? I'm not flaming, just wondering what that would do for you? Rememeber- when you use nitrous oxide, you use much more fuel in the way of volume. This means that you can have large injectors, but you could still go lean by taxing the fuel delivery system. Leaning out on the juice is how you end up with a meltdown. It would be money better spent to increase pump capacity rather then injector size.
 

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If you went with larger injectors for nitrous, but did not increase pump capacity, how would this be of benefit to you? I'm not flaming, just wondering what that would do for you? Rememeber- when you use nitrous oxide, you use much more fuel in the way of volume. This means that you can have large injectors, but you could still go lean by taxing the fuel delivery system. Leaning out on the juice is how you end up with a meltdown. It would be money better spent to increase pump capacity rather then injector size.
The 255 lph pump will be installed soon (definitely BEFORE I do nitrous)
 

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Ok, just making sure you understood what I was trying to say. :)
 

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Discussion Starter #8 (Edited)
The reason I ask is that I do not want to run lean when the car is finished. Are there any problems with running 30lb injectors? I have seen a couple replies that 30lb are bad with our computer. Is that correct? I will be going Pro-M 77or 80, Kirban AFPR, Walbro 190 with T-Rex 190, but which injectors would be great for my plans and current mods? Future: Fuel, nitrous, AFR 185's, Forged pistons, and I do not know which cam yet. I am basically asking someone to tell me which injectors would perform great for me.

Edit: Basically, do you factor the shot size into the injector capability? For example, If I am running say 275hp at the crank right now and dropped in a 100 shot. That is almost maxing the 24 lb injectors. Is that the way nitrous is calculated into injector size? Or do you just ignore it when shopping for injectors and look for hp capabilities N/A? With this idea, I would be hurting my engine with a heads and cam mod.
 

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That formula you are refering to does not apply here- remember Brian, like i said: With a nitrous system, you are introducing fuel into the engine in a different configuration then injector supplied. With a wet system it would make no difference whatsoever, and with a dry system it would be negligable. The size of the fuel pump capacity is what matters with nitrous.
30 lb injectors work fine, as long as you have a properly calibrated mass-air meter. I have used them for years, they work great.

Once again, think this thru for a moment-
if you have a WET nitrous system, you are tapping in to the fuel rail and supplying additional fuel for the added horsepower thru the nitrous/fuel nozzle. The fuel is metered by the fuel jet in the nozzle and is supplied by pressure from the fuel pump/delivery system. With a DRY system, there is a small line that will cause the fuel pressure to rise dramatically, just like an FMU on a blower system, so the injectors will "act" much bigger by spraying harder due to the rise in fuel pressure. The horsepower vs injector size is in reference to an injector spraying at the "stock" fuel pressure and not an elevated level. For example, by using an FMU on a blower car, this will cause a 24 LB injector to act laike a much parger injector, simply because the pressure applied to the injector is much higher, hence, more fuel is supplied to the engine then a 24 Lb injector could normally supply.

Do you follow me here? maybe I am doing a poor job of explaining things? Somebody help me out here....
 

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Discussion Starter #10
Now I gotcha. I will be going with a dry kit because of the whole puddling exploding MAF thing with wet kits. I guess I am a little worried about nitrous. Thank you very much Greg.
 

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Ok here is my .02

I have a 95 gt with afr 165's (box stock), stock camshaft, 1.7 rockers, uported cobra intake, 65mm throttle body, mac equal length shorties, off road h pipe, mac mufflers (i am a mac dealer), precision industries stallion convertor(3200) , bauman shift kit, stock 3.27 gears.. 110k on stock short block, NOS dry nitrous kit,, with the stock 19lb injectors and a C & L 76mm meter with the aluminum elbow etc.. (nice piece and i am now set up as a dealer for them as well) ,msd 6 al , and a retard box (cause i am lazy and do not want to have to adjust timing all the time.. ),, adjustable fuel pressure regulator....rich lean guage, etc..

Now for the et's and combo..

I am pushing the 19 lb injectors pretty hard..

With the 100 shot in the sytem and draglites with 275/50/15 's on the back last night i went [email protected] mph with a 1.77 sixty foot backed it up with a [email protected] (bumped the rev limiter hard ) witha 1.71 sixty foot and the car still has the factory 5500 rpm rev limiter.. I was shifting the car right at the rev limiter and actually bumped it on every run just a little.. I am fixing to put it on the chassis dyno and put the 24 lb injectors in (along with correct sample tube) and rejet the nos (so it works with the bigger injectors) then retard the timing some more and add the 150 shot in.. Keep in mind this is a full weight car with nothing removed but the front sway bar and completly stock suspension.. (pretty impressive for a auto car if i do say so..:) )
I am also a pretty healthy driver..lol 358lbs and 6 ft 7.. once iget it tuned in i will get my wife to make a few passes and i believe it will run in the 11's... Fixing to put some gears in it and see if it will go 11's with me in it... Car is presently bogging a good bit ...

ONE NOTE.. i will NEVER buy another pro m meter ... I installed a pro m calibrated for 19 lb injectors when the car was stock .. It would barely idle.. (sounded like it had a huge cam in it when cold) and it would set a ck engine lite on a long drive (cruise rich limit exceeded) i sent it back (i bought it new) and they recaled it and it was just as bad.. stuck the stock meter back on and it ran perfect.. the c & l is working pretty good.. it has a very light surge if you let it idle for a long period but other than that it is working very well..
 

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oh,, btw,

I think personally that 24's are plenty for your combo.. the 94/95 computers are finicky enough without pushing them hard (that is why i kept the stock camshaft).. I think without some custom dyno chip tuning 30 lb'ers are going to be bad driveability wise.. You can call nos tech and they can give you a baseling jetting with larger than stock injectors.. but you may have to play with the fuel side on the dyno with a air fuel meter to get optimum power as every fuel pressure regulator will react differently to the pressure from the dry kit..(some will add more fuel pressure than others ,, at least my adjustable added way more fuel pressure than with the stock regulator)
 
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