Detuning large injector nozzles - How to pick injector size for upgrades!

[Derek@Vision Diesel]

I think I have a pretty good understanding of the concept we are trying to accomplish, though I do appreciate the further explanation. Where I don't understand is what part of the equation is lacking. Whether there isn't enough resolution to accomplish this on the tuning side, or if it comes down to the probably "sloppiest" part of the injector, which IMO should be in the in the solenoid.

While I think there is good info for to be had in this thread, I think there are two trains of thoughts on "oversizing" injectors.

For me, when someone says they want a hybrid 200cc, 80% nozzle I think to myself, why oh why wouldn't you just get a 238 or 250 with the same size nozzle, and run a tune that only uses ~200cc and have a future if you decide later "D@mn, I wish I had more fuel to play with" They are basically the same price(if not exactly), and since the 238 or 250 can be limited on pulse width to ~200cc of fuel, why wouldnt you do that?

Can you see a reason why that thought process is foolish?
(Or does that thought process go back to the user ending up running too hot of a file and complaining about EGTs?)

If all of those injectors are using the same 80% nozzle you are completely right.
200cc of fuel from a 250cc injector
200cc of fuel from a 200cc injector

both through an 80% nozzle....

Those scenarios are exactly the same, so yes it is a no brainer to go with the larger one if you have larger goals in the future.

 

[mikeeg02]

Well now I feel stupid. The thread is called "Detuning large injector nozzles....." not "Detuning large injectors....."

 

[Chatham036]

I think I have a pretty good understanding of the concept we are trying to accomplish, though I do appreciate the further explanation. Where I don't understand is what part of the equation is lacking. Whether there isn't enough resolution to accomplish this on the tuning side, or if it comes down to the probably "sloppiest" part of the injector, which IMO should be in the in the solenoid.

It is a combination of things IMO. Consistency between injector builders is huge. Some use EDM nozzles vs extruded, although the same percent over stock, they flow entirely different. Used solenoids operate differently than new. Then you have the solenoids that are slap worn out or the poppet in the injector that simply cant hold the ICP needed. Which will cause the ICP to bleed off.
These problems are not as common with guys running smaller injectors which ultimately contributes to them being satisfied with their purchase. Customer satisfaction being my main concern for any recommendation on products.

Through tuning, we have a lot of control on a 7.3L . What gets us is that you put 300cc/200% injectors (different manufacturers) in three different trucks with the same tuning and I can promise each truck will run differently. This can cause very large fluctuations in the tuning.

For me, when someone says they want a hybrid 200cc, 80% nozzle I think to myself, why oh why wouldn't you just get a 238 or 250 with the same size nozzle, and run a tune that only uses ~200cc and have a future if you decide later "D@mn, I wish I had more fuel to play with" They are basically the same price(if not exactly), and since the 238 or 250 can be limited on pulse width to ~200cc of fuel, why wouldnt you do that?

Can you see a reason why that thought process is foolish?
(Or does that thought process go back to the user ending up running too hot of a file and complaining about EGTs?)

To an extent, you absolutely can do that and I will recommend that to some customers.
The people that I recommend that to are the ones who want 600 hp and dont haul more than a utility trailer. They just cant afford to go with the proper sized turbo at the same time as upgrading the injectors.

In this situation, I would recommend sticking to a file with lower pulsewidth commanded to prevent over fueling the factory charger thus blacking out a street. Once the proper sized turbo(s) are installed, turn that bitch up and let it eat.

 

[Derek@Vision Diesel]

Well now I feel stupid. The thread is called "Detuning large injector nozzles....." not "Detuning large injectors....."

No need to feel stupid at all. Jay made this thread to educate! We all have questions for the people more intelligent and I have learned a ton from reading posts of tuners and injector builders, its awesome!

 

[superpsd]

I think if 200% nozzles were so poor at atomization they would not run well on stock calibration. My tune for 200% nozzles has idle mapping areas that are unchanged from a stock program. If you toggle from my tune to a stock AA calibration it's seemlesss and idles purfect.

The other side of it is pressure drop behind the Intensifier piston. An A code 6.0mm plunger has to stroke further to inject the same amount of fuel than a 7.1mm B code or Hydrid plunger will have to stroke. One reason why the large A codes are so oil hungry and you don't see any talk about huge A codes with 200% nozzles much.

I have my daily tune for 200% nozzles set to 1.8ms and max of 3000 ICP. Drives and idles very nice. Only issue I have is the touchy pedal due to ICP rate. I may play with it more to tackle a happy medium as I finish all the other upgrades.

 

[Chatham036]

It is very uncommon for a 200% nozzle to run well on OE tuning but I can see it being feasible since your OE tuning is set up for AA code injectors. Most get at minimum a fuel haze with that large of a nozzle. I am curious to know if the fact your truck idles at 2 psi boost has anything to do with the equation.

Were you running the same injectors prior to the super charger? How did they idle on a factory configuration?
Did you change your pistons when you built the engine? What compression are you running?
Also, what do you have your idle RPM set at?

I am asking these questions to help me get an understanding for why your truck is an anomaly.

 

[superpsd]

Engine is completely stock. No studs. No springs. 300K miles. Never done a compression check. Mechanical fuel pump with a spin on filter and aeromotive regulator.

I have been running the supercharger for 2 years now back to when I had stock injectors. I do have a haze at idle so light that I can only visibly see it on bright blinding sunny days. My timing is untouched from the PHP canned performance tune. Idle is set to the factory 650 although I did build a tune that is the same as my daily but bumped the idle 100 rpm higher for when and if I get stuck in traffic jams to make it easier on working the ceramic clutch easing thru traffic.

I also built B code injectors which have the 3600 VOP springs which may account for a cleaner burn. The injectors are split shots that I took and TIG welded the spill port shut. Injectors were old cores that have never been flow tested. I had to grind the back of two of the armatures to allow the injectors to light off cold as they have worn poppet valve seats. They run well and feel balanced wish I will put that all on being lucky and not my injector building skills.

I think it was Charles on here who said they played around with different VOP and found that overall the higher VOP made for a cleaner burn but power had dropped up top. My idle pressure may help a little I would have to remove the belt and start it up and see.

 

[TyCorr]

My nvk 4 pcm idles my pis 250/200s just fine also. I dont see a haze either.

 

[CSIPSD]

Here is what I posted on Facebook just last night when this thread came up...

Here is the deal...

You can tow all day long with 400/400's. Its going to take LOADS of live tuning, a near perfect turbo set up, perfect gearing set up, perfect HPO system and set up. Perfect.

Well boys and girls 99.95% of our trucks are not perfect. Most never will be. It takes loads of money to make them, and keep them perfect.

I am a vendor that sells these parts. I want happy customers, that enjoy there trucks. I offer and sell packages I know will make the customers happy and let them enjoy there trucks.

400/400's and a 38R will NOT tow easy. It will NOT tune easy.

250/200's were a bitch to tow with, did I do it, sure. But I spent hours and hours driving with my eyes glued to the EGT gauge, watching the loads on the trans, hoping I didnt miss and let it downshift loaded (which would spike the boost to 60, go from 250-300hp to almost 600 and break ****)...

I recommend packages that work.

I'll sell you what ever you want, but yall need to understand what your getting into.

Now I am not a vendor here, cant afford it! LOL

But just my take on injector sizing and people screaming that you can tow "just fine" with 300cc injectors.

 

[CSIPSD]

IMHO...

Perfect "working mans" set up...

Normal supporting mods.
Tuning
160/30's
Billet wheel or 38R like turbo...

Enjoy.

 

[FlatbedCowboy]

The people that I recommend that to are the ones who want 600 hp and dont haul more than a utility trailer. They just cant afford to go with the proper sized turbo at the same time as upgrading the injectors.

In this situation, I would recommend sticking to a file with lower pulsewidth commanded to prevent over fueling the factory charger thus blacking out a street. Once the proper sized turbo(s) are installed, turn that bitch up and let it eat.

So if you wanna tow (20,000 lbs) with hybrids (200/30) you just needs to properly match with a turbo and supporting mods, is what your getting at?

Or are you saying a person would be better off sticking with 160/0 to get the maximum horse and torque for pulling that much weight?

 

[CSIPSD]

I've towed with 230/100's for a long time now, over 100,000 miles.

Works fine, but it takes a near perfect tuning, and turbo, and oil, and air set up.

 

[NyCowboy87]

Supporting mods make or break a setup. Back 5 or 6 years ago I had my obs set up with 400/200's 66/88mm twins (with big exhaust wheels, not no baby s300/400 stuff) as it was just a fun bad a$$ street truck. There were a few times I had to pull a trailer loaded with concrete forms which weighted in the neighborhood of 8k lbs. In a tune that made roughly 500hp, I pulled the same hills on the same stretch of road, that can burry the pyro on my superduty with 200/30's and a 38r, yet my obs truck wouldn't break 1100*. The tunes in my superduty are not 100% spot on by any means as the injectors and tunes have only been in for 2 weeks. I received some new programs that seem a lot better but havnt loaded the trailer up with the horses yet to really see.
Was I lucky for that obs to run the way it did, yeah probably given I had no intentions of towing with it, however I had a ton of air to give it and the tuner gave me a couple tunes that were super clean running.


Sent from my iPhone using Tapatalk

 

[TyCorr]

The company that posted this tuned my setup of 250/200s, 38r, srp, twisted stg 2 4r100, irate fuel system, and all the other crap to hold it together. Right after Jason Seay did 547, then 563, then with a billet wheel-603rwhp.

I gotta say despite the warnings, it was as close to perfect as you can get. People always said a 38r is too small but I don't do a lot of sledpulls on the street lol

I dont want a larger turbo that moves more air up top and needs 2k rpm to tow on anything but flat ground. I agree you need to match the turbo to the injectors and also what its doing. To tow and with extra fuel, you need a smaller turbo that responds quicker to the fuel. The 38r is close to perfect considering its a 15 year old turbo design.

The only way to have it better with todays technology, up to the minute, is a 364.5sxe which on paper moves more lb/min than a 38r or a set of compounds.

I dont disagree with anyones sizing thus far but my personal choice would be a s362 sxe and an s488....for injectors from 200-200 to 300-300.

 

[Countrycar]

opcorn: Very Interesting read.

 

[Chatham036]

The only way to have it better with todays technology, up to the minute, is a 364.5sxe which on paper moves more lb/min than a 38r or a set of compounds.

I dont disagree with anyones sizing thus far but my personal choice would be a s362 sxe and an s488....for injectors from 200-200 to 300-300.

I very much so agree. My only concern would be that the s362 would be too constrictive for the amount of air a 7.3 requires. I know the six liter guys love that compound setup.

 

[TyCorr]

I very much so agree. My only concern would be that the s362 would be too constrictive for the amount of air a 7.3 requires. I know the six liter guys love that compound setup.

I think a 66mm charger would be just on the left side of its meat in terms of compressor map in a 200-250/200% nozzled setup with a s488 feeding it. Again, how much WOT scenarios are there on a street truck running a setup like this?

The only reason i say it is look how little a 38r flows ,supposedly, 79lb/min and its design flaw is the exhaust side is too small. So an s364.5 actually flows a good deal more and you aren't given a small turbine wheel. That 362 sxe might be close in terms of flow to the 38r which us considered to be a good compound anchor on a 7.3 setup. Throw gt4718 in there (88mm) and let it loose.

That guy from tsd had a 300/200 setup with a 38r/gt4718 . Charles did as well. Charles was on the dyno list for making 644 with that and 300/300 hybrids.

But as for use and manners, which correlates to street driving Id be trying that 362sxe if i was running anything under a 300/200 for injectors. If it didn't work it'd be easy to throw a 364.5 in it. The 88mm is a given lol.

 

[Luke@MillerPerformance]

I very much so agree. My only concern would be that the s362 would be too constrictive for the amount of air a 7.3 requires. I know the six liter guys love that compound setup.

I put an s366sxe on a guys stick shift 7.3 with 160/30s and that thing is a towing machine. 65 mph up hill with 15k lbs and his egts won't go over 1150.

 

[Hotrodtractor]

ICP psi: 3,000
Injection ratio: 7:1 (A code intensifier piston)
Final pressure at the nozzle: 21,000 psi

When you switch over to a hybrid style injector, your injection ratio decreases down closer to 5:1

ICP psi: 3,000
Injection ratio: 5:1 (Hybrid injector)
Final pressure at the nozzle: 15,000 psi

Hybrids just allow a greater fuel capacity without a need for high pressure oil volume.

The biggest issue with the above is the pressure drop across the poppet is not taken into account - as ICP goes up or nozzle size increases the pressure drop across the nozzle poppet for the oil increases dramatically. It doesn't take long before that 5:1 hybrid actually has MORE fuel pressure at the tip than the 7:1 A-code. While its not cheap and easy to measure the actual pressure at the tip - it can be demonstrated on a bench pretty easily - take two injectors that are identical with the exception of the injection ratio and map the flow rates - you will see the injector with the lower injection ratio actually inject more fuel per time at higher ICP pressures - that means that it has a higher injection pressure (remember everything is identical including the tip). Granted at lower ICP pressures the higher injection ratio has the advantage. This like all things is a balancing act between parts and the requirements for the task at hand.

I had a rather complicated mathematical model that I created 10 years or so ago that showed this very clearly - sadly it was lost about 4 years ago on a computer that died. Such is life.

I do however still have some of the graphs made from actual flow bench data taken during some development I was working on at the time that while not 100% in alignment with the discussion it is pertinent and should be of interest to tuners in the group.

Here is a 238cc hybrid with 80% tips:

Not much to talk about without something to compare it to - so we will just call this injector a 238cc "FAST" Injector with undisclosed tips (mostly because I don't recall the specifics of the test off my head and all I have at the moment are graphs, but lets just call then stupid big and exaggerated for effect in this discussion)

These two graphs show the exact issue that Jay has with larger tips - they are a pain in the ass to control lower ICP and shorter PW occur. They aren't EASILY friendly to drive day in day out or tow because of this. I totally agree no problem.

Now comes the magic. Here is the actual flow rate data for a 238cc injector with the same tip as the stupid one above.... but pay attention to the ramping on the graph.

Its ALMOST as controllable as the 80% tip down low at the minor sacrifice of softening some flow rate at the high end with plenty more area to inject 238cc in a shorter window than the 80% tip. Now - granted a lot of what was done internally on the injector to produce this graph hasn't ever went into production injectors for customers (that I am aware of), but it goes to show you that you can have identical volumes, tips, and injection ratios and still have a wide variety of flow characteristics based on what is done internally - THIS is the issue with trying to tune the "same" injector but built by a different manufacturer and is the crux of the issue with producing tunes that operate the same from truck to truck with the "same" injectors but built by different people.

In conclusion - I totally understand why tuners recommend small nozzles - they are easier and far less variability from injector shop to injector shop. Its basically the only way to guarantee the customer has a good experience without putting together a complete known package for them. I disagree that a 200% can't be a towing nozzle in the right package - the issue however is for the layman (and even the experienced tuner) to know how each shop builds their injectors and modifies them to either increase/decrease control resolution.

 

[TyCorr]

Jason, hrt, that was going to be my next comment was that MANY consumers are fast finding out that a single shot injector many times WILL overtax the hpo system despite what the interwebz say. Should it? Maybe not in a perfect world but many times on the street under load or in a hotter tune, those a codes start dropping icp. In fact that was what lead me to hybrids. I learned that those injectors are quite limited. If you dont have all the hpo in the world available they start to drop out and the reuck gets hot and smoky as hell. So what do tuners do? Well, lets draw that pw out to 3.5 or 40 ms...which holds it open longer and exacerbates the issue. Smoke, smoke, smoke...

This issue is more common on 175/80s or 175/100 it seems. Hardly enough injector worth all the fuss over. Pull pw way back to about 400hp and live with it or step up to a hybrid. Preferably with a 200% nozzle.

I can overfuel my charger if i try but not in normal use areas where the a codes were crapping the bed and trying to ghetto fog the cylinder into making hp above 2800 rpm.

For me, your information is dead on. That hybrid will play so nicely at over 400hp working that you'd have to be crazy to try to get a tiny ac injector and nozzle to do the same job.

And maybe I got lucky but Bill@php sent me similar tunes to the ones I mentioned before and there was no trouble. I had one tow tunes shift points stretched out but I dont believe that's relevant to this thread topic.