7.3 HEUI nozzles

Tim @ P.I.S. said:

All i am going to say is nozzles are not the direction to look at for furthering 7.3 performance.

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I have to disagree. Not necessarily the number of holes but the spray angle is a big factor depending on your rpms, piston bowl design, quench, etc

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Sorry to revive a 5 year old thread but I started a discussion about this on PSN years ago and never got any answers. My direction of inquiry was for efficiency and MPG.
Stock nozzle is 7 hole at .0065" orifice so theoretically dropping the diameter and increasing the number of holes will improve atomization and require less fuel to get the same amount of "work" out of the piston.

I.E. Stock nozzle hole area (just at the injector tip, I do not know the column length for the nozzle bore) is .14294" for all 7 holes
So 8 holes at .0056"
or 9 at .0051" to match the "total area" of the stock nozzle....

Now seeing as these holes are ridiculously close at the tip on the inside of the bore I am sure there is a limit to how many holes can be placed due to them crossing on the inside of the nozzle. Also dealing with these miniscule bores in a hardened material it has to be machined using a sinker EDM, 4 or 5 axis at that. Not a cheap prospect to get done... and without a prospectively profit generating market no one will do any research to see if it is viable.

But you could potentially see an increase in power/efficiency using smaller orifices and equal/less fuel.

Honestly it would be a waste of time going down that road. 7. 3 market has shrank considerably. Very little gain if any. From my experience I say no gain. You can buy a set of nozzles from Redat for about 250$. They mass produce them. Even a 200% nozzle when dialed in can deliver amazing results as long as the injector is in tolerance and not a clapped out rebuild full of shims. Timing a 7.3 thru the calibration will have greater effects on effeciency and power than expensive nozzle experiments. The nozzles are available to get the job done and the understanding of tuning a 7.3 has advanced. They now can tune to keep stock bottom for ge fb engines alive near 1000hp. My 200% nozzles are pretty effecient and clean. I spent alot of time playing with the tune. For an experiment here is a cold engine idling at 400rpms with 200% nozzles.
https://youtu.be/e_xCe2caUY4

Yes I see that the market has shrank, but the fact that I still have mine and this idea still rattles around in my head without an answer bothers me a bit, Kind of like actually seeing a small block ford shortblock running with LS head on it. seen mock up photo's but never seen video of one running.....

I have a couple of small block ford shortblocks, but can not justify the $800 cam cost along with the time and material expense for the sheetmetal intake, along with all the extra incidentals I am going to need to make it run.

Yes I see that the market has shrank, but the fact that I still have mine and this idea still rattles around in my head without an answer bothers me a bit, Kind of like actually seeing a small block ford shortblock running with LS head on it. seen mock up photo's but never seen video of one running.....

I have a couple of small block ford shortblocks, but can not justify the $800 cam cost along with the time and material expense for the sheetmetal intake, along with all the extra incidentals I am going to need to make it run.

I have thought about this as well, as my neighboring shop has a few wire EDMs, but never have persued anything due to lack of time.

I have plenty of I wonder if projects. But the reality is I am not retired. Can't finish all the projects I have already taken on and don't have endless funds to burn. The off the shelf performance nozzles are hard to beat for the price. Lot of guys over the years experimented with custom heui injector parts but most never showed any potential or had negative side effects. At the end of the day a well balanced set of injectors, plenty of oil to fire them and good tuning go the distance for effeciency and power. One way to overcome loss of pressure with larger nozzles is higher VOP and B code springs are off the shelf oem parts that can make that happen. Some have experienced little gains.

I have always wondered about those B code springs but the more I researched the more confused I got. Most responses were you lose power, driveabilty, and etc, very confusing.

I “retired” from the military, and work 50-100 hours a week at my next career. So i have limited time, like most everyone else. But unlike most i have a personal manual machine shop to dick around in when i find the time. And after i build my 4 car garage i am buying my neighbors VMC.

Vertical machining center. Not sure of it is 4/5 axis capable yet..... i am going to find out though......


Greater atomization of fuel is possible then what is currently generated with available nozzles. But i lack the blanks as well as a good editable 3d model to try and play around with my idea. I wanted to do these on single shot BA’s(i have 11 in hand from running engines) but now i would like to do this with BI’s and a good upgraded HPOP on a stock tune. Baselined with my 191k stock injectors first of course, followed by the hpop, then with the modified BI’s, and after i have any gains or losses documented with the B codes get it live tuned for max effect. And scale it back for daily driving/towing.

Whenever i have inquired with injector overhaulers or builders where to get blanks the response was always, “ I don’t know but if you find a source let me know too”

I got to play with some LM2500 (jet engine) fuel nozzles on deployment. Made a some prototypes and got a 2% reduction in fuel consumption.(when the engine burns 5500 gallons of fuel an hour at WOT 2% adds up) Could have been better but I only had so much of that material with a Taiwan mill drill and old colchester lathe on the Destroyer.


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Keep us updated i'm curious if more efficiency and power can be gained.

Heres the thing though as far as better atomization. Due to the heui design there will be compromises. The faster you can actuate an injector the higher the pressure will be at the nozzle. This is where a hybrid shines at higher ICP. B codes take much more HPO to actuate the injector. The BI codes are split shots. I run BI codes but I tig welded the spill ports shut to covert them to a single shot and run 200% nozzles. They run very clean with dialing in tuning and fuel economy when daily driven is about the same as the truck when it was completely stock. B code springs are 3600psi VOP vs the A code 2750 psi. If I recall the numbers correctly. A higher VOP will create better atomization and drivability at the expense of lower power numbers up top. Or so some have found. A higher VOP also creates more initial delay which retards the SOI if you make no tuning changes as the actual PW will be shorter with the same commanded PW due to mechanical delay.

That is good info, using the split shot b’s means I can theoretically run them without any special tuning....... so it would be a get them swapped to t444e nozzles, verify the rest of the specs, get some fresh o rings and send em.


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Well as long as it is a split shot truck the BIs should run ok. Dialing in a tune is going to have great effects on driveability and effeciency. Take SOI or timing. You advance timing, cylinder pressure increases, torque goes up and fuel effeciency goes up. EGTs go down which hurt spool. The reason they are not advanced so much from the factory is long term wear and tear and as cylinder pressure goes up temperature spikes and NOX production goes way up. Also increase in CP increases knock. You can run the BIs in split form but split shots have performance downsides. Reason why many go with single shots to replace splits and usually see slight fuel economy increases. Split shots also require more HPO.

I can see your points. I have heard good/bad things regarding running single shots in a splitshot truck. Tuning is everything. And trying to get a builder to "rebuild" my BA's into stage 2's is a pain in the ass.
So take the improvements in tuning to get efficiency and power, and add in the increased atomization from smaller orifices and get even more MPG and power from less fuel.

This idea/experiment (if I can get a set made) will not be for all out power builds. More for drivers like me. I like to surprise the fart can mafia, and I primarily use the truck to tow and haul stuff, occasionally pull someone out of a ditch or snow bank.

superpsd said:

Well as long as it is a split shot truck the BIs should run ok. Dialing in a tune is going to have great effects on driveability and effeciency. Take SOI or timing. You advance timing, cylinder pressure increases, torque goes up and fuel effeciency goes up. EGTs go down which hurt spool. The reason they are not advanced so much from the factory is long term wear and tear and as cylinder pressure goes up temperature spikes and NOX production goes way up. Also increase in CP increases knock. You can run the BIs in split form but split shots have performance downsides. Reason why many go with single shots to replace splits and usually see slight fuel economy increases. Split shots also require more HPO.

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I have a somewhat related question that has been bugging me lately, that maybe you can answer...

When creating a hybrid injector, (like say to make a 238/80 inj) and they use the 7.1mm P&B vs the 6.0mm in A series injectors, they are lessening the HPO required to actuate the injector, but aren't they also lowering injection pressure, and subsequently reducing atomization?

Well its a compromise. A hybrid really shines when you use a larger nozzle vs other injectors and at higher ICP RPM etc. On the benches they will flow more fuel per time. Just like the syringe effect the faster you push the plunger down the more pressure inside the barrel and therefore more pressure behind the nozzle. A codes flow better with smaller nozzles, ICP, and lower rpm. Large B codes are in the middle. BA BB and BC are just stage 1 AC codes with B code nozzle springs and different nozzles. BE codes are ADs with B springs and Nozzles. BD are the larger 240cc singles. The rest BI, BJ, etc are all the same large B code split shots just different nozzles. They can flow up to 275cc but take a lot of PW to do so. If you covert to single shot by pluging the splill port its a 300cc+ injector. The hole sizes on the larger B codes nozzles are much larger than a T444E nozzle. I want to say it was more comparable to a hole size of a 100-200% nozzle. I can't recall the exact size off the top of my head. With really good tuning you can compromise for the short coming of a hybrid when operating at lower rpm and ICP. You can't really compromise for the issues with large nozzles on an A code as well. B codes made a well rounded injector but are more expensive, you usually need B cores and they require a larger hpop system to keep fed. That's why hybrids are cheaper to run as they don't require more HPO.

SO if BA's are stage 1 AC's why is it such a pain in the arse to get superduty nozzles on my BA's?

Well all nozzles are interchangeable. I don't know why your having problems. I do my own injector work. These injectors are not terribly hard to pull apart and put back together. Just takes some care doing so. If you nozzle a BA code you will have a AC code injector with higher VOP unless you also install A code nozzle springs.

Lt.Dan said:

I have thought about this as well, as my neighboring shop has a few wire EDMs, but never have persued anything due to lack of time.

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You're not going to do nozzles with a wire EDM...you need a sinker EDM. I'm not that versed in the specifics of the size of the electrode to sink a .0065 hole...but it's a minimum .0065 in diameter.