7x10 vs. 5x12 - SAC @ 59LPM

[RCCUMMINS89]

these injectors out perform any i have had up to about thirty pounds of boost after that they do nothing

[RCCUMMINS89]

Ok.........just took my "hunting trip"

7x10s........run 150 degrees cooler going over the pass, and about 50 degrees cooler running down the highway.

Fuel economy was somehow still 18.6mpg.....which must be because I got on it more? Because no one can convince me that cooler temps does not mean better economy.

So for the sake of my personal opinion.....they net better economy.



I am EXTREMELY impressed by these injectors. So much so that I am EXTREMELY disappointed at their wot performance.



5x12 injectors netted 50psi

7x10 netted 40 psi

Keep in mind that at 40 psi my turbo is moving a massive amount more air than most turbos on most of our trucks.

[RCCUMMINS89]

To add to this.

The 7x10 injectors are insanely faster at zero to 30 psi of boost. It's only at 30 psi and above that the 5x12 out performed........and at that they out performed big time.



In a stock or near stock truck that is used for daily driving or towing........the 7x10 injectors are undoubtedly the way to go.

If one is trying to make any kind of power.......especially performance power.......7 hole injectors are about the worse decision one can make.



The above is from my personal testing and experience with the above.

[RCCUMMINS89]

After putting on 250 miles on my truck today...... I'm having issues with certain driving situations.

Mainly at higher altitudes at idle.......these 7x10s are puking at idle. way more than the 5x12s did. Isn't clear to me though on why yet.

I'll keep everyone updated on why. Maybe an injector is sticking? Or, maybe I got some bad fuel? Maybe it has something to do with 7 holes?

It's only at idle.......it looks like I have marine injectors in the truck.

[ellis93]

Remember my error with tip length,way advanced pump with thick washers= not as much timing as you think. May be worth a look into. Even with thin washers those 7s may require more timing just to be right
Just a refresher
6x9,5x10,7x10

[RCCUMMINS89]

Remember...............injector tip placement does not have an affect on timing...............it DOES HOWEVER affect spray placement in the same way as timing can.


With my testing, I'm using the thinnest washers possible. I am also running lots of timing and it may be the cause. I will back off the timing and try a few other things if it doesn't fix the issue.

It leads me to timing............due to I'm getting timing surge with them at light load high boost situations.

[RCCUMMINS89]

I've heard lots of complaints from a lot of customers about 7 hole injectors hazing.

I've replaced probably a hundred sets of 7x10 injectors with 5 hole injectors and have only 1 time (Ellis), had the customer not say that the 5 hole had fixed their hazing issue and they picked up cleanliness.


I will post back and keep updated..............but I'm starting to think that it MAY be an issue with them being so short.

[ellis93]

You got it half right with me they were cleaner,just not cleaner while running under load. Most folks don't use their trucks like me either,mine will end life with a broke back.

[RCCUMMINS89]

Wanted to add an explanation of something for the "guest readers" and those reading this thread in the future.

To explain why injector tip has no relation to timing............but the affects can be the same.


The more the timing..............the further the piston is from the injector. The more likely it is to spray outside the bowl. Therefore, the shorter the injector...........the less the timing before it sprays outside the bowl. Thus it will act like there is more timing with a shorter injector tip.

However........the piston is still in the same spot (18 btdc, or whatever) regardless of how long or short the tip is. Therefore the compression ratio at the injection event is the same as well as the burn time. Therefore it has no bearing on the timing itself.


The above leads to the injection tip placement (short or long, washer thickness, etc....) only has an affect of (for the sake of argument) changing the piston to spray relation much in the same way spray angle does.


Therefore if an injector tip is short, or if one uses too thick of washers.....it will behave in the same way as a marine injector (155 angle vs 145 angle). This will cause idle haze, very responsive driving, but high smoke at lower rpms. The smoke will also have a tendency to be bluer.

[ellis93]

So.....couldn't you lower the timing to combat that then?

[RCCUMMINS89]

Yes..............that is my first step.

That is exactly what is needed in a situation like the above........if that's actually what's going on. Since I don't have my head inside the cylinder while it's firing I can't confirm nor deny that if it is actually an issue from the nozzle being short and my love of TREMENDOUS timing.

I look back and remember ellis...........that you had without knowing your timing at a full tooth skipped mark (20+ degrees).

We realized this when you put in the 5 holers and had the same issue..........you then backed it off and fixed the issue.

[ellis93]

Yeah it was pretty high do to my misunderstanding of how much one tooth of timing was. It's still high,still one tooth with the pump Mark slightly down form the case mark.
I did buy the tools to check it,but I've not made the time to check it

[RCCUMMINS89]

So...............when the time comes and I pull these 7x10s, I'm going to have them double checked to make sure they are all popping correctly and "chattering"

I have adjusted my timing as far as the pump can go both ways and it has not made a lick of difference on the idle haze.

They are only hazing at idle............pretty badly in fact. The only injector that I have ever had haze this bad is marine angle injectors. After idle...........they are the cleanest I've ever had.

[ellis93]

Something is screwy reckon the pop pressures went to schit on them?

[RCCUMMINS89]

I'm not sure...........I've never seen that happen that fast. To be honest, I may have just not noticed the haze when I first put them in, just the slightest breeze in the wrong direction and I don't notice haze. Like I said, it is ONLY at idle.

I don't want to pass judgment until they get checked again..........I also noticed that my idle is becoming shaky. Therefore something might be off somewhere with one of the sticks. Things happen and sometimes at any time for no reason. Maybe something did this time.