Duramax Larger Injector Discussion

[sweetdiesel]

CP3 everything is adjustable except atomiztion. that being the holes in the INJ tip them selves.

i belive i got that damn near on target...

pressure changes atomization and so would injection timeing due to heat in the cylinder

fuel temp also would change this and charge air temp

volume of fuel injected should also change atomization



perhaps Im way of base on atomization Adam?

 

[Mike]

I like the bigger injectors also.... I like the fact we can lower timing 40 percent in most cases and save the huge pressures do to the injector being on so long.... But, just my thought, it will be interesting to find the results as time goes on.

Anyone care to start a thread on how more fuel will lower EGT's? This would be another good topic.

 

[sweetdiesel]

X2 on that, cylinder pressure testing will be the mythbuster for us

X3 Knowlege is power

 

[Fingers]

Bigger injectors are a mixed bag.

You can see the evaporation time increase on the Pressure graph with bigger injectors. Though it becomes negligible at high rail pressures.

They "hit" harder over all than the smaller injectors at full flow, but are softer at lower pressures.

Big injectors seem to like a hot chamber better than the stockers.

This is comparing my stocks with my 50% overs. You have to use custom tuning to get the best out of the bigger injectors. Bursting is way too easy to do with the bigger sticks. As well as a dead pilot injection.

EGTs play a huge part in chamber pressures. A hot chamber will show 10%-30% higher pressures than a cold chamber. The net affect is similar to adding timing. But that is not the only source of the increased pressure. The hot chamber pre-heats the air charge on the compression stroke.

...But what do I know.

 

[WolfLMM]

how do high egt's cause bent rods

Fingers just answered that question

 

[Fingers]

Jonathan (Fingers) is selling a commercial unit, but I'm not on the beta team for it, so I can't recommend it one way or the other. You can PM him here.

Not ready for prime time. Still about a month away. I still have 2 weeks till I get off the road to work out some bugs Nick has pointed out.

 

[02freighttrain]

This is wierd, but I have never, even once, had a "Burst" event with my truck. Never.
I run fairly large injectors with the dreaded A5K. I have had more tunes than a juke box in the truck and drove it every way you can. The only white smoke I have ever seen is on a chilly morning on start-up. I did burst a charger off it a while back.
Damn, you guy's get to have all the fun with that bursting stuff.....

 

[2wd_Sled_Puller]

This is wierd, but I have never, even once, had a "Burst" event with my truck. Never.
I run fairly large injectors with the dreaded A5K. I have had more tunes than a juke box in the truck and drove it every way you can. The only white smoke I have ever seen is on a chilly morning on start-up. I did burst a charger off it a while back.
Damn, you guy's get to have all the fun with that bursting stuff.....

Its Crazzzy aint it. Its like u wanna burst something

 

[McRat]

but honestly pat, I don't think you can say that more can't be achieved with bigger ones in your application without trying them... the MDEs don't count, too many others had trouble with them as well.

Not saying you will but to continuously say the stockers are good enough is a bit much when you don't really know if bigger ones may make more or make the same amount while being easier on parts....


whatcha think???

If I had my choice between bigger holes or 50,000 PSI small hole injectors, I'd take the pressure.

Yes, once more (if nothing goes wrong again) we will change injectors and start testing. I've spent lots of time and thousands of dollars on injectors with no answers yet.

If injectors help, you're damn right I want them. But I'm a natural skeptic.

 

[maddogg101920]

can anyone prove that bigger injectors decrease EGTs?

 

[02freighttrain]

I wrote my name in concrete with a pressure washer today.......
Only kidding, but at what point will the fuel from high pressure "small hole" injectors, start eroding a hot piston? I'm probably way off here.......but this is how we figure this stuff out.

If I had my choice between bigger holes or 50,000 PSI small hole injectors, I'd take the pressure.

Yes, once more (if nothing goes wrong again) we will change injectors and start testing. I've spent lots of time and thousands of dollars on injectors with no answers yet.

If injectors help, you're damn right I want them. But I'm a natural skeptic.

 

[SmokeShow]

If I had my choice between bigger holes or 50,000 PSI small hole injectors, I'd take the pressure.

Yes, once more (if nothing goes wrong again) we will change injectors and start testing. I've spent lots of time and thousands of dollars on injectors with no answers yet.

If injectors help, you're damn right I want them. But I'm a natural skeptic.

I see.

 

[maddogg101920]

I wrote my name in concrete with a pressure washer today.......
Only kidding, but at what point will the fuel from high pressure "small hole" injectors, start eroding a hot piston? I'm probably way off here.......but this is how we figure this stuff out.

X2 on that, my 2 pistons that just got replaced had holes all over them, mainly the #3 piston, one guy said it looked like i took a 12 gauge to it.

 

[malibu795]

there is a balance between small hole high pressure cuts shit

large hole high pressure less likely to cut and less atomitain... its a trade off

 

[dmaxtruck]

there is a balance between small hole high pressure cuts shit

large hole high pressure less likely to cut and less atomitain... its a trade off

I think you mean "large hole low pressure"? Large hole, high pressure looks like a best of both worlds type deal.

 

[Killerbee]

The key to atomization is small orifice, high pressure. Need more fuel, just add more holes. I think there is a point where normal economy starts to go into the toilet. One idea is to add a secondary injector...that would be the best of both worlds IMO.

 

[malibu795]

I think you mean "large hole low pressure"? Large hole, high pressure looks like a best of both worlds type deal.

you X fuel to make Z power.

to get X fuel through small holes one of 3 things needs to happen.
1. raise the supply pressure
2. increase time the vlv is open
3 all the above

hypthetical engine.. 3000ms pulse width @26,000 pound with stock injectors

we increase the injector and keep same power one of two thig needs to happen cut pressure or cut pulse width..

personaly i like the idea of increase INJ keep same pressure and cut pulse width

something i am looking at doing that with my build that is coming up..

 

[02freighttrain]

I do like the Idea of increasing the number of holes in the injector. If the blast effect of high rail pressure could be distributed in a wider band over the bowl of the piston then erosion may not be an issue.
Short timing-tuning, lower cyl pressure, no bent rods, cracked pistons, may be the result.
I do see a problem of putting more holes in the stock injector tip and maintaing integrity of the tip itself. A modified cyl head and injector with a larger nozzle could support more holes. Then you could increase rail to whatever and atomize enough fuel. and..........keep the timing out of the motor.

 

[malibu795]

and cut some of that 158* cone pattern down as well by ~20%

 

[02freighttrain]

:exactly:

and cut some of that 158* cone pattern down as well by ~20%