160/100 vs 205/30 Injector Testing

[cjfarm111]

Wow great info! So in your opinion what size nozzles are good for a hybrid? 80’s? For all around performance

 

[superpsd]

So what do most daily or tow tunes call for for icp at wot? 3,000?

Likely depends on the tuner and injector decision. It is all adjustable. I myself have ICP desired capped at 2800 with 200% nozzled B codes. No smoke or EGT problems.

 

[cjfarm111]

I’m currently running PIS 175/80’s and they have been “ok” ish but they are fairly oil hungry and I have always been afraid of the hybrids because of lower injection pressure fearing lower fuel economy and more smoke

 

[superpsd]

The mathematical injection ratio does not account for whats really going on inside these injectors. Such as pressure drops that can throw all that math out the door especially when talking about larger modified injectors. There will always be trade offs. If I built another set of injectors I would do a 200cc or 238cc hybrid with 200% nozzles with B code nozzle springs. Easy to do and I have most of those parts already. No machining necessary. Everyone talks about how a larger nozzle has poor atomization. Yet on the benchs the hybrids flow more fuel per time than a A code. The A code does win down low and with smaller nozzles. However correct tuning can mitigate the issue down low. Running a higher VOP can considerably increase atomization yet they typically see lower hp numbers at higher rpms. Like I said trade offs. The A code springs are 2750psi and the B code are 3700psi a substantial difference of when the pintle is going to be lifted. Higher pressure built up equals of course better atomization. The B code injectors in the DT466 and i530e engines had oem nozzles of a different pattern and number of holes but hole sizes closer to a 200% T444E nozzle. Yet those engines certified by the EPA in those days didn't have excess problems with smoke or egts etc.

Hybrids can actuate quicker as they use less HPO and do not need to stroke as far to inject the same quantity of fuel as an A code. Take a syringe and fill it with water and push down slowly and watch the slow stream of water. Now fill it and push down fast and watch that water spray at high velocity....


Some of the biggest issues with high egts in my opinion is poorly remanufactured injectors where builders favor profit over quality and poor tuning as it is difficult and time consuming for a tuner to try to tune a truck remotely and A codes are simpler to tune. A good charger helps a million as well. Engine needs lovely pressurized oxygen and needs to exhale as well.

 

[The Brad]

Running a higher VOP can considerably increase atomization yet they typically see lower hp numbers at higher rpms. Like I said trade offs. The A code springs are 2750psi and the B code are 3700psi a substantial difference of when the pintle is going to be lifted. Higher pressure built up equals of course better atomization.

With 3700 VOP, I’d imagine you’d have to run higher ICP at idle. Depending on who’s tunes, mine idles between 450-600, which wouldn’t be enough to lift the pintle....wait, how does my truck even idle at 450 ICP? 450x5=2250. Where does the extra 500psi to lift the pintle come from?

With lower ICP comes a smoother, quieter idle in my truck. I’m guessing the B code springs lose to hybrids on top because of more injector delay?

 

[superpsd]

I have mine set to 600 ICP at idle but they still idle much lower than that. Thats another math equation that you can pretty much throw out the door. Springs inside the injector likely loose strength over millions of actuations. Big B codes can compete with Hybrids if built correctly but they are very oil hungry injectors due to the larger Intensifier Piston. They need big oil to work well. A higher VOP retards the SOI but that can be adjusted for in the tune of course. As ICP is retarded timing is also retarded along with. As you advance ICP you advance timing. Becauee of course as you increase pressure things happen faster. And retarded timing of course reduced diesel knock due to lower CP.

 

[BS Hauler]

This is a very good thread. I am still on the fence about which injectors to get. I always thought that a guy with a tow rig should stay with the 180/30's to get a cleaner burn. But everyone almost always says that their hybrid's are better with cooler egt's. I am starting to lean towards the 238/80's now after reading this.

 

[cjfarm111]

Me too. I’m not saying my 175/80’s are bad but they are a little Smokey and very oil hungry. If money wasn’t an object I would try a set of 205/80 hybrids.

 

[Zeb]

Wow great info! So in your opinion what size nozzles are good for a hybrid? 80’s? For all around performance

There is no “one best nozzle size”.
The smaller the nozzle the easier it typically is to tune. The better the build quality of the injectors the easier it typically is to tune.

As superpsd noted, higher VOP helps with atomization, but the one trade off is less fuel delivery because the spring closes the pintle sooner. As he noted, ICP needs to be played with to get SOI back on track for the same reason (higher VOP retards SOI).
A good, properly prepped nozzle with 2750 springs, is quite clean.

 

[Swaan]

I always kicked myself for not going 238/80s . My 175/80s were oil hungry and hazed cold . No amount of tuning fixed it.... ******** once said his favorite all round inj was 238/80 hybrids.

 

[The Brad]

I always kicked myself for not going 238/80s . My 175/80s were oil hungry and hazed cold . No amount of tuning fixed it.... ******** once said his favorite all round inj was 238/80 hybrids.

My 200/80s haze under 60 degrees despite multiple Tuners, but I this that has more to do with the builder than the size. Oh well, live and learn.

 

[cjfarm111]

Would PIS be the builder?

 

[The Brad]

Would PIS be the builder?

I can’t remember, but the guy used to come on here and talk about how nobody could build injectors as good as his. I think it was P.O.S. :cursing:

 

[cjfarm111]

Oh yeah I heard of that guy

 

[PSD POWER007]

Definitely POS injectors. That’s what PIS should’ve been called. My 175/80’s failed in less than a year. Got FF 180/80’s and not only did the truck idle better, and smoke less, they were quieter across the board and 250k miles later, still running strong!

 

[mcnance865]

My 238/80s haze if it is cold. Like in the 30s, not as soon as it gets to 50s. I am very glad I decided to jump up to 238/80s instead of 180/30, because I wish I had the money to get all the supporting mods for 300/200 instead haha.

 

[cjfarm111]

I think you guys are talking me into trying a set of hybrids. I just have to decide what size. Lol

 

[Zeb]

I think you guys are talking me into trying a set of hybrids. I just have to decide what size. Lol

You know, if your truck could be down for a week your 175/80’s could be used as a building block for a set of 205/80 or 238/80 hybrids and would save you some money. :thumbsup:

 

[cjfarm111]

That is definitely an option.

 

[Zeb]

That is definitely an option.

PM’d you.