Why do bigger nozzle injectors haze and have higher egts - Ford Powerstroke Diesel Forum
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Old 07-08-2014, 02:15 PM
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Why do bigger nozzle injectors haze and have higher egts

Well I run into this issue a lot and I wanted to start a thread talking about why this happens. I have experienced it personally and have many customers that experience this once they upgrade to bigger nozzle injectors. Also a bigger turbo seems to exaggerate the situation even more.


I first noticed this when I switched from 175/stock to 175/75. All I did was add nozzles to my injectors so nothing else changed. With my 175/stock my truck never hazed under light throttle, cleaned up my injectors to nothing at WOT, cruising egts were great, and low end spool up was great. Once I added the 75% nozzles is when the issues started. My truck hazes all the time even under light throttle, my egts skyrocket even on light throttle runs, my cruising egts are higher than they used to be. I basically lost a lot of drive ability that I used to really enjoy.

I thought tuning would make those issues go away... but they did not. They only helped a little bit.

I have had many customers experience the same issues. Especially if they are running a bigger turbo. I have been talking about it a lot recently with many people and I thought I would start a thread to talk about it.


Here is my theory:

I think ICP is a lot more important than people think. It is what controls our "injection pressure" similar to a common rail injection system. With conventional injectors there is about a 7:1 ratio which means that at 4000psi of icp you have 28,000psi of fuel injection pressure. That is similar to a common rail truck and is really good. But at 3.6v (3000psi) you only achieve about 21,000 psi of injection pressure which would cause a hot smokey mess.


When you add "bigger nozzles" you are essentially dumping more fuel sooner which usually equates having a lower ICP. The ICP in our trucks is very dependent upon RPM and is not easily controlled through tuning. If you are dumping more fuel sooner then it is kind of like running a much longer pulse width with a much lower ICP... kinda like really hot FICM tuning...

Running smaller nozzles basically forces you to dump the least amount of fuel with the highest ICP possible which is why I theorize that they run so much cooler...

Basically:

ICP + Pulse width = amount of fuel dumped
Low ICP + High Pulse width = hot smokey mess
High ICP + low pulse width = cooler cleaner running truck


So... If a good tuner could lower the pulse width tables while at the same time raising the ICP tables... then in theory that would help to eliminate the hazing and high egts under light throttle that many of us experience when upgrading to larger nozzles.




Anybody have any thoughts on the subject?
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Old 07-08-2014, 02:54 PM
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When we used to write smoke files, we would command the motor to open the IPR in order to drop ICP. When the ICP is lower, the fuel will not atomize well causing a slower rate of burn thus more fuel burning while exiting rather than in the cylinder.

Larger nozzles will obviously dump more fuel at a quicker rate. There is only so much you can do with large nozzle injectors inside of the tuning.

With maintaining adequate ICP being as important of a variable in the ultimate goal for power as pulse width, having a higher oil volume to feed the oil system is huge. This is actually one thing that I am hoping to prove when running just the HPODS on my truck while keeping the factory HPOP.

I know a lot of 6.0 guys do not follow the 7.3 crowd much, but in the 7.3l world, if you upgrade your injectors, you upgrade your HPOP. It is just the nature of the beast in a HUEI injection system. For some reason 6.0 guys haven't had this same mentality until recently.

Quote:
Originally Posted by peixinho View Post
ICP + Pulse width = amount of fuel dumped
Low ICP + High Pulse width = hot smokey mess
High ICP + low pulse width = cooler cleaner running truck
ICP and PW are absolutely relative to each other. One thing that is left out of your example is atomization of fuel. Optimized atomization of fuel will cause the 'cooler, cleaner running truck' you mention. Poor atomization will cause the 'hot smokey mess'

The higher ICP you can maintain, the higher the PW can go to maintain the same optimized atomization of fuel.
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Old 07-08-2014, 03:13 PM
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Quote:
Originally Posted by Chatham036 View Post
When we used to write smoke files, we would command the motor to open the IPR in order to drop ICP. When the ICP is lower, the fuel will not atomize well causing a slower rate of burn thus more fuel burning while exiting rather than in the cylinder.

Larger nozzles will obviously dump more fuel at a quicker rate. There is only so much you can do with large nozzle injectors inside of the tuning.

With maintaining adequate ICP being as important of a variable in the ultimate goal for power as pulse width, having a higher oil volume to feed the oil system is huge. This is actually one thing that I am hoping to prove when running just the HPODS on my truck while keeping the factory HPOP.

I know a lot of 6.0 guys do not follow the 7.3 crowd much, but in the 7.3l world, if you upgrade your injectors, you upgrade your HPOP. It is just the nature of the beast in a HUEI injection system. For some reason 6.0 guys haven't had this same mentality until recently.



ICP and PW are absolutely relative to each other. One thing that is left out of your example is atomization of fuel. Optimized atomization of fuel will cause the 'cooler, cleaner running truck' you mention. Poor atomization will cause the 'hot smokey mess'

The higher ICP you can maintain, the higher the PW can go to maintain the same optimized atomization of fuel.

Thanks Jay...

Atomoization is exactly what I was getting at... just talking about it without mentioning it.


Something interesting you bring up... what good is more oil if the IPR just dumps the excess? I have been running a couple of different tunes and I have twin HPOPs and it seems that I can't get the tuning right.


I have been running a lot of tunes this week and have learned a lot. My tow tunes run the cleanest and still have great power. I was using my canned SCT tow tune and PHP econo FICM tune. At WOT I would see 1.3ms of pluse width and 4.0-4.4v of ICP and it runs strong and clean... still burns the tires if I am not careful

I have other tunes that runs 2.4ms of pulse width and hit 4.7-5.1v of ICP (way too much fuel for me)

I have another tune that runs 2.4ms of pluse width and only hits 3.6v of ICP and max IPR duty cycle of 60%... (ok amount of fuel but runs hot from what I believe is poor atomization)


I won't go into every tune but I have about 30 of them and each one has something different that I like and something that I hate. I am not a tuner so I don't know how it works but if I was to make my own tune I would want the lowest Pulse Width Possible with the highest ICP possible at all times.


My goal would be to have 4.7v of icp and 2.0ms of max pulse width for a good street tune... but according to a few of my tuners... it is not as easy as that. If would want the ICP to max out as quickly as possible and then start adjusting the Pulse Width Accordingly. My SCT canned tow tune seems to do that pretty good, but it maxes out at 1.3ms of pulse width


Jay... maybe you could get bill to comment on this.
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Old 07-08-2014, 03:40 PM
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It could just be that larger nozzles just flat out dump more fuel than the tuning is capable of controlling and just because someone may have a larger turbo that runs the same boost as a stock turbo, doesn't mean they'll flow more air than a stock turbo flows at that point in the rpm band and with the increased level of fuel from larger nozzles (because I don't think stock injectors are emptied at low rpms) the truck is just more smokey...
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Old 07-08-2014, 04:06 PM
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God I havnt seen 4.8 in ages
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Old 07-08-2014, 05:22 PM
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Your chasing your tail, you want less smoke so you turn up icp, more icp gives you higher pressures but adds more fuel in the same pw so your smoke doesn't really go down at all... Run 30% nozzles
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Old 07-08-2014, 06:07 PM
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Quote:
Originally Posted by borsky4 View Post
Your chasing your tail, you want less smoke so you turn up icp, more icp gives you higher pressures but adds more fuel in the same pw so your smoke doesn't really go down at all... Run 30% nozzles
But I want it all!!!


Also a 30% nozzle will only dump about 190-205cc of fuel... I need about 225cc for my goal.


Theoretically if you were able to raise up ICP and keep your PW down then it would not dump more fuel. It would dump just the right amount of fuel but with better injection pressure/atomization.

Let say for example you just kept your pulse width at 1.0ms and instead of raising pw to get more fuel you simply raised injection pressure to get more fuel... then that would be a much cleaner running truck.

I think Chris @ TSD did something like that with Mike's truck. He is running something like 285/150s and said it runs super clean. But I know the tune had a max pulse width of 1.5ms




But I have seriously considered dropping down to 30% nozzles for my daily driver. I am probably obsessing a little bit... but I like really clean running trucks.
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Old 07-08-2014, 06:26 PM
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Well I am not sure why the tuners can't turn down he pw and crank up the icp, that is how my tow tune runs and it runs super cool, like 1050F with converter locked in 4th and wot pulling 12k. I estimate it to be over 400hp at the wheels based on et.

Sounds like you need 50% nozzles... Haha
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Old 07-08-2014, 06:33 PM
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Charlie....I'm really interested in seeing what the PHP FICM tuning does for your truck with regards to the smoke and egts. Now as far as upgrading the hpop....is it really necessary if you're already maintaining ICP? I'm running 190/75's and when I had my truck down to Warren Diesel, I had Jesse tune the truck and he said it maintained 4.8-4.9v of ICP at 4000 rpms. I'm experiencing the same thing Charlie mentioned with high egts with little throttle input. If my ICP is good....would a upgraded hpop like Dieselsite's adrenaline pump really benefit the truck? I haven't checked to see what my PW is with the tune. Maybe i'll set it up on the edge insight CS and see what the PW is.
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Old 07-08-2014, 06:33 PM
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Quote:
Originally Posted by borsky4 View Post
Well I am not sure why the tuners can't turn down he pw and crank up the icp, that is how my tow tune runs and it runs super cool, like 1050F with converter locked in 4th and wot pulling 12k. I estimate it to be over 400hp at the wheels based on et.

Sounds like you need 50% nozzles... Haha

Exactly. I have a canned SCT tow tune that does the same thing. My egts max out at 1250... but I do have 75% nozzles. PW is 1.35 and ICP is 4.5v...

I am going to try hard to learn how to use the sct tuning software so maybe it will help me understand better
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