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Choosing The Right Injector For Your 7.3

128K views 225 replies 71 participants last post by  Sbluke55 
#1 ·
The most common question I see for guys wanting to pick injectors is what to get and why.

There is a general formula I like to use that is 2.3HP for every CC of fuel that you can use effectively. Do these numbers jive with what everyone is seeing in the real world?

So figuring RWHP with an automatic trans. This takes into account horsepower peak happening between 2600-3000RPMs. All numbers based on single shots.

Here are some common injector combinations and the power level they usually accomodate. This also assumes you can maintain proper HPOP pressure.

I am also using common street nozzles 30% EH, 80% and 100% EDM nozzles. The larger nozzles allow you to push the power peak up into the higher rpms and make more HP. These are typical fuel only numbers because nitrous oxide allows you to peak the power lower in the RPM scale and make more peak torque and therefore more HP. There are so many variables that these are merely general guidlines.

General Rule of Thumb max power with no nitrous (but a properly matched turbo):

90cc stock nozzle 225HP
130cc stock nozzle 260-290HP
160cc stock nozzle 325-345HP
160cc 30% nozzle 350-360HP
180cc stock nozzle 300-350HP
180cc 30% nozzle 370-390HP
180cc 80% nozzle 400-425HP
200cc 30% nozzle 385-410HP
200cc 80% nozzle 400-440HP
200cc 100% nozzle 420-460HP

238cc 30% nozzle 440-475HP
(depends on air flow in lower rpms can make 550HP with nitrous for example)

238cc 80% nozzle 450-520HP
238cc 100% nozzle 465-550HP
250cc 30% not much gain over 238cc with 30%
250cc 80% nozzle 460-530HP
250cc 100% nozzle 470-575HP

It gets sketchy above that number due to the other variables that are involved with HP levels much above 550. Also remember that RPM can play a major factor. Somebody have corrections or want to add anything?
 
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#11 ·
That's enough fuel and enough nozzle to really make some stupid power....750 should be possible.... hell the 6 liter guys can make 1000 with nitrous... The only impediment I would think is injection quality. The bigger nozzles seem to be dirty for some reason and it may not be the size of the holes. It's just something that I'm sure the big guys like Swamps are working on.
 
#16 · (Edited)
I'd think those are in the ballpark, like you said, there are alot of variables in there but I'd think they're pretty close. Some old numbers from mine from a couple yrs ago.
160cc/Stock Nozzle/15*/Stock Charger-326
Fuel System Added
160cc/.007EH Nozzle/17*/Stock H2E-388
160cc/100%EDM Nozzle/17*/Stock H2E-418
238cc/100%EDM Nozzle/17*/ 66mm/76mm H2E-538
Hadnt got on a dyno with new stuff yet.
 
#17 ·
so how big of an injector could you safely run on a stock hpop with a gtp38r turbo
 
#19 ·
so does it make much diff between bcodes and hybirds
or pretty much cc's and nozzle? ie 250 etc..
 
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#21 ·
I don't want to get into that discussion because I know what the flowbench says, but a specially modded B code has potential to do some stupid fuel per time but we aren't there yet.

Just look at the ranges of HP..... a bad 250cc is on the low end and a good 250cc (fast) is going to be on the high end.
 
#20 ·
so matt have you ever run into the industrial injection phat stroker turbo and if so what does it run compared to the gtp38r and also what kind of tuning on a set up like that
 
#24 ·
Good info Matt. I think you posted good ballpark figures.
My setup when I dynoed last Fall was Swamps 200cc hybrids 30% nozzle Stealth stage II hpop TN/jb DP tunes and was 408hp/850tq. I have swapped out the TN for a 38R/1.15 and changed from DP tunes to Swamps and am interested in seeing some change.
 
#25 ·
Jason, justin- 76mm S400, T6

Swamp redid the injectors, put all their little secrets in them.

They were labeled 325cc, but..

2.0ms, 2800psi ICP @ 4000 rpm, netted 160-190cc before they did their work
2.5ms, 2800psi ICP @ 4000 rom, netted 210-240cc before.....
Even 4.0ms under the same circumstance only got out 210-300

After...

2.0ms, 3000psi ICP @ 4000 rpm -- 290-300cc, almost doubling the flow,
2.5ms same conditions 310-320, damn near empty.
 
#31 ·
Fun thread Matt! Please tell though which is faster on the bench, Hybrids or B codes? Swamp says Hybrids, others seem to say B-codes. Geoff found it was highly dependent on your nozzle size. B-codes won out w/ small nozzles where-as Hybrids won out w/ big nozzles. I guess the internal flow limitations on the B-code don't become an issue until you are REALLY trying to move some fuel/ time? I think Dock's excellent #'s back in the day on stock B-codes w/ stock smallish 5 holer nozzles underscore this fact.





PSJunkie, that's pretty cool that Jon and Dave got your injectors so much faster. Although I'm not sure what RPMs has to do w/ it? Should just be per 1000 shots right?

Obvoiusly you kept the same nozzle size? Are they small nozzles? They just seemed slow, similiar in speed to mine actually. Also, why didn't you get any more fuel out as pw increased before they were modified? Never seen that before.

Thanks!
 
#26 ·
I find your 2.3hp per cc rule of thumb to be strikingly familiar. A few months back I did a similar study on my own results with various injectors on an otherwise identical setup and actually came up with 2.35hp/cc.

:eek:


Did I mention that to you by chance? Or did we nearly hit the exact same value independently?
 
#36 ·
In the example given above, the swamp "f*ck mini-mes" as they were called were 250cc.

A bone stock set of B-codes flow somewhere between 239-244cc in my experience.

So yes basially the same cc injectors w/ the same small nozzles, the B-codes would whip the Hybrids pretty handily.

I don't think Nitrous, tq, or RPM are really relavent to this discussion as are assumming applicable supporting mods for each set of injectors.
 
#37 ·
RPM is very relavent to the discussion. I was witness to testing using some "hot" b-codes and some "hot" hybrids on the bench at the exact same time (one of each for comparison purposes). Both injectors were heavily modified and at say 2800-3400 flowed nearly identical (off the top of my head..) but as the RPMs on the bench was continually turned up the hybrids not only flowed more fuel, but by the time it got to 5500-6000 RPMs the hybrids were kicking ass and taking names. All the tests were at real world PW and ICP and as the RPMs climbed the PW dropped inversly since that is the only way a factory IDM can do it.

Now take off the shelf hybrids and b-codes with just a tip change and I bet the difference is even more dramatic.
 
#39 ·
I remember now that Geoff saw something like this as well.

He said the advantage of the B-codes (w/ small nozzles) depended on requested ICP and pw.

I guess as more RPMs are requested the flow limitations of the B-codes come into effect more. Still dependent on the specific nozzle size being used and in the example given using 'hot' injectors w/ large nozzles we would expect to see that crossover point come sooner.
 
#40 ·
Well the hybrids were an older version of "hot" not like today's standards. The b-codes were a newer model of "hot" but still not like what is possible today. When they were thrown on the bench the first trial run was made and I don't remember the exact settings, but you would have almost thought the two injectors were identical.

This was a good case of pulling competitors coming together to get them both further down the track ;) We were certain that we were similar in HP on the track, but we knew that both of our sets of injectors were very different so we wanted to know how we stacked up in the flow department.
 
#41 ·
90cc stock nozzle 225HP
130cc stock nozzle 260-290HP
160cc stock nozzle 325-345HP
160cc 30% nozzle 350-360HP
180cc stock nozzle 300-350HP
180cc 30% nozzle 370-390HP
What kind of a 30% nozzle are you talking about here?
 
#56 ·
I was told me hybrids are 100% over. I was also told they were .009''.

Is this all correct, do the numbers jive?

And a better Q....how will they perform (how many cc's) at 2800psi in 2ms window.

I am asking because I am making north of 500 at 2400r's. I want to know how much fuel I am pushing through at that icp and pulsewidth to base sizing my next injectors on.

Thanks guys.
 
#57 ·
Whats your ICP and PW at 2700 RPMs at WOT? You know your HP number at that level and can then divide that by "2.3" (close enough for a guess) to know roughly how many CCs you are injecting then in that particular window. If its all of them more volume would be good. If its close to all of them then you need more volume and larger tips. If its no where near empty you will need to start with bigger tips.

My guess is, depending on your goals that is, you'll need bigger tips and more volume.

Personally I wouldn't ever do hybrids with anything less than a 200% tip (roughly 7x 0.0115"). They can be controlled very well in tuning so that is where I would start.
 
#58 ·
Thanks Jason!

No I do not know all of those answers fo so. I do know I can hold 2800 psi with the hybrids and stock 17* pump with 300K on it.

I have not scoped the truck, I was just wanting to know from others using similar inj's if I was close to using the 238cc in the correct window or if I could get more out of them with 200% tips.

I guess I need to talk to David in more detail and get a scope on it to be sure.

Thanks
 
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