Black Smoke.....power or waste?

I have tried it but my head couldn't take it, I want to travel to places as far as possible.

 

I'm with you on that, I can't stand working around home, I much prefer long distance, I'd rather not drive at all than work on local jobs

 

here is very hard to find long haulage driver who want to be on road for more than 2-3days

and since this is small country drivers mostly come home twice per week

i remember when our trucks were used in long haulage my father used to come home 6times per week, driving 3700km/week

 

I’m sure Kurt Understands what Needle lift and Pop Off relate to and he knows all too well that the Pressure required to lift the needle has nothing to do with Orifice size, being simply the orifice are not exposed prior to Needle lift. Injector pressure will be proportional to Plunger size, plunger displacement over time and directly related to the orifice size.

What Hurt was leading to was that After Needle lift has occurred you would normally see a pressure rise many times above needle lift pressure due to and proportional to the restriction to flow by the varying orifice sizes used by CAT.

However when you have Nozzles that have been Extrude honed some 200% you will actually see a pressure drop depending on plunger velocity. This would be proportional to Cam grind and Engine RPM.

At a low engine RPM the time v Plunger Travel cannot maintain enough flow to maintain a suatable pressure above 400Bar to hold the needle off its seat due to the Orifice size being 200% above STD,

In actual Fact the largest C tip made by CAT is 5.5 Kg/Min and this Tip “Just” Maintains Needle lift @ Idle lift and anything above 5.5kg/min will start to chatter at low IDLE RPM.

To maintain a constant Needle lift with an orifice size above the design of these injectors you would need to increase the Plunger diameter to match.

So to put it simply the orifice size has exceeded the plunger displacement.

Pressure is a product of resistance to flow and once you removed that resistance by way of over extrude honing an orifice you have no ability to maintain a suitable pressure rise to maintain a stable Needle lift whilst displacing the same volume of fuel..

It is blatantly obvious that you will never see injectors pressures of a magnitude that would be seen with a small orifice tip when no other component was changed to increase the flow to maintain a suitable pressure or maintain the same working injection pressure prior to extrude honing the tips..


If I read what Kurt has Posted I get the impression he is implying that to Due to the excessive Extrude honing of the tips, the other components of the injector are not designed to move enough flow to maintain an suitable Injection pressure to combat the Cylinder pressure that you kindly posted and the ability to maintain a stable needle lift without increasing plunger diameter and/or Plunger displacement.

I’m sure Lenny you understand the relationship between resistance to flow and what’s required to maintain a suitable pressure when making modifications to these injectors.

WE are not talking about Stock STD injectors and the operational theories associated with the written data in books as it only pertains to the given mechanical device it relates too not modified non STD components to which Kurt is relating to.

 

I wish I could have expressed what I was trying to say as well as you did.

Thank You

 

Yes, now we are talking the same language. You can also keep that pressure high enough with increased ramp velocity of the injector cam but it might be limited by cam and rocker geometry. That's what they do here with STC Cummins engines that use tips from some 30 litre industrial engine.

Theories in the books cover also modified components and engines, you just don't get the direct answer but you have to understand what they really mean.

A friend of mine just changed marine tips to his Scania engine, it chattered when idling but that was solved with software change, you need to calibrate the software for marine injectors or the "governor" do not stay in pace. Might be different with 200% Extrude Honing but that much honing is not recommended anyway.

 

Okay here we go again. I'm a backyard Hp junkie. I'm a shade tree mechanic. I don't spend hours scouring sources for engineering answers to my questions, let alone yours. I use my azzbackwards way of thinking and deductive reasoning to arrive at my Hp achievements. ####, I must be doing something close to correct to have gotten this far in my goals. I never went to college or any higher education classes beyond high school in a small rural community roughly 35 years ago.......my physics edjucation is lacking to say the least

Why would you think the modulation of the actuator assembly and its relationship with the spill/fill port would be controlled electronically by the ECM after the injection cycle has been started?

Your correct in questioning, how would the ECM know what the injection pressure is, let alone how to measure it. Wouldn't this be much easier to use a spring in the actuator assembly to control how and and when the pressure rises and falls internally inside of the injector for injection pressure regulation during the injection cycle by modulating the spill port valve(poppet valve)? This might be a good idea to keep from fracturing a tip with extremely high injection pressure, wouldn't you think?

Wouldn't it be easier for the ECM to energize the solenoid during the complete injection cycle to trap the fuel inside of the injector body for injection purposes, but modulate the spill port mechanically, internally in the injector for injection pressure regulation at the tip?

As Far_Call stated the injection pressure is a relationship between how much volume of fuel is in the barrel and plunger area of the injector to displace through the orifice holes in the tip. It is in a direct relationship by plunger diameter, the length of the plunger stroke and the orifice hole size. Do we agree?

If we have a constant volume of fuel to displace through the orifices, then I would think orifice size and camshaft profiles of the injector lobe are the only things left in the equation of adding more volume of fuel into the cylinder during the injection cycle and raising injection pressure during injection cycle. Are we in agreement?

With this being stated, I tried in vain to find out the camshaft injector lobe specs of different camshafts manufactured by CAT. I didn't want to purchase ten different camshafts to measure and map lobe profiles to come up with the best one for my engine. What I was able to find was food for my azzbackwards brain to ponder upon.

Now what did I find that took my azzbackwards brain something to ponder upon, you may ask.

Hmmmmmm.......I found a 6NZ camshaft with a very high lift on the injector lobe compared to anything else in CAT's spec books. I searched through CAT SIS TMI website for many hours trying to find what Hp engine this cam went into. the part number is .......hold on, I'll tell ya.........hold on.......it's coming.............136-7908

This camshaft has the highest injector lobe lift of any camshaft I've ever seen injector lobe lift specs on, but ####, why didn't I use this cam? What would make me not use this cam or recommend it to anybody..........here we go again, my azzbackwards way of engineering my thought process. I didn't want to purchase the cam to map the lobe profiles.....too much money to be wasted if it isn't what I want.

What Hp engine is this 136-7908 camshaft installed in?.........Hmmm, after much time spent scouring CAT TMI......I found what it was in and the parts combination........ its a 375 Hp 6NZ C-15.........yep, they made em. Now my azzbackwards brain got too thinkin'..........see back then I wasn't as smart as I am now(I'm not that smart at all).......actually I think my deductive reasoning skills were better back than compared to today, but I wasn't as educated in how an electronic CAT diesel engine operates than.....still not that educated today. Before I found this camshaft and engine arrangement. I was worried about installing the 201-2677 1000 Hp C-18 camshaft in my engine. Why? Well my azzbackwards brain was worried about the differences in different injectors from one application engine to the next. I was worried about installing injectors with different size orifices in the tip versus camshaft profiles on the injector lobe and how the internal injection pressures would change.................I didn't want to blow the tips/nozzles off into the engine. I was also worried about the plunger bottoming out in the injector.

Now what else did I find that was sooooooo interesting about this engine arrangement. We've been talking about injectors, haven't we? The injectors in this engine had a very low flow spec on the tips........KG per minute

####!!!!!!!!!!!!!!!!!!!!!!!!! my problem is solved. If CAT can run this high profile injector lobe lift cam(136-7908) with such a small injector tip. I can run a larger injector with a high injector lobe lift without any problems and not worry about matching injector part numbers to camshaft part numbers with CAT's other engine applications(3406E marine 800 Hp cam and injector sets or 1000 Hp C-18 cam and injector sets)..........my azzbackwards rekinin' is ah workin'. I won't blow the tips off the injectors by mixing different engine parts with high injection pressures. Now back than CAT also gave you the complete parts list of different injectors when you looked them up in CAT's SIS TMI website....so I compared this low Hp C-15 injectors to the 3406E 800 Hp marine injector.......the plungers were the same.......now my azzbackwards brain got excited. With azzbackwards deductive reasoning I should be able to use a high lift cam and these big injectors without any problems involving tip failures. CAT somehow was regulating internal injection pressure was my thoughts back then......I didn't care how they did it, I just cared about the fact that they did it.........why soooo much research. Well one of the problems is I couldn't find the specs on the 3406E 800 Hp 130-9710 marine camshaft anywhere. I didn't know what the injector lobe lift was on this cam and couldn't find anyone to tell me that I trusted to know the answer at this time in my journey/quest for Hp. The problem back then was I didn't know that when you order this cam, you were ordering the Camshaft Group number, nobody back then knew the actual camshaft part number. CAT kept it a secret and still does today, unless you order the Gp number and read the part number on the camshaft once you have it in your hands. The specs on this cam are also not published in the standard CAT Service Manuals I have, so I couldn't compare it.

Now with my azzbackwards way of thinkin' I still didn't like 136-7908 part number cam. Why you ask? Hmmmm........if this cam has the same Intake and Exhaust lobe lift as the standard truck cam 139-0537 with the higher injector lobe.....it should work, No? What about the C-18 1000 Hp marine cam, it has the same Intake and Exhaust lobe lift as the two previous cams listed above.........what's a fella ta do? Hmmm.......now here is where my azzbackwards deductive reasoning is really going to kick in. I ain't gonna purchase all these #### camshafts to measure lobe centerlines and degree of separation. Hmmm, now here we go again(azzbackwards thinkin').........long stroke versus short stroke engines designs....why would this matter to my decision process? Well, I thought that if the speed of the piston traveling up and down the cylinder bore had anything to do with the combustion cycle.......with the long stroke engine having a faster piston speed, would this possibly make CAT manufacture the injector lobe profile with an advanced centerline when compared to the short stroke engine camshafts injector lobe centerline? I don't know because I didn't purchase the 136-7908 cam to compare it. I just used my azzbackwards deductive reasoning to purchase the 201-2677 1000 Hp C-18 camshaft..................the rest is history

the difference in injector lobe lift between these two high injector lobe lift cams is........ta da........0.001" or 0.026mm....not much of a difference, is there

Now with all this being said we still have other issues when you start playing with these injectors. Lately the trucks showing up at dyno contests have been using the extrude honing process on injector tips. I have refused to do this. One has shown up with the 211-3028 1000 Hp injectors this spring. To stay competitive I'll have to increase my fuel delivery very soon with larger injectors. But after reading every post of Far_Calls on this forum, I don't like the idea of extrude honing tips, hell I don't like the idea of defaulting trim numbers anymore either. So I sent some tips for testing purposes. All of them were extrude honed to varying degrees. Extrude honing more than 7-8% is starting to erode the seating area of the needle too much........fuel starts to dribble before pop off pressure is reached. Not a good thing. At low engine RPM extreme honing of the tips causes the needle to chatter against the seat as pressures constantly goes up and down above and below the pop off pressure and closing pressure. Loss of injector control. As RPM is raised the faster stroke of the plunger will over come this though.......but you still have a high dribble rate before the injector fires due to the eroded seating area of the needle. Bad idea

Now once the injector is firing you also want the pressure to rise as high as possible for the best atomization. Again Cat controls the max injection pressure by modulating the poppet valve in the spill/fill port. As orifice size increases this modulation decreases, because again we're restricted by the diameter and stroke of the plunger and the volume of fuel it displaces. Can we go under this pressure setting without hurting the injection process? This is my azzbackwards engineering thought process answer. Yes, but not by much, otherwise atomization of the fuel suffers and the fuel being injected into the cylinder doesn't get burnt completely.......more black smoke with no real HP gain.


Lenny.............do you think now that I might understand the injection process of these injectors? I maybe a ####### country redneck, but I'm not stupid. I love my azzbackward ways of thinin' and it has rewarded me well in the past. Because I can't speak/write at an engineers comprehensive level, doesn't mean I can't understand it


To increase the diameter of the plunger will create new issues also......yes it would allow for me to increase the orifice size or the number of orifices in the tip and maintain injection pressure with a larger tip. But again we have other things to consider. If I increase the diameter what other problems do you think I'll have?


Also to increase the injector lobe lift on the camshaft which would raise ramp rate speeds to drive the plunger down faster and deeper into the barrel, what other things do we have to consider?

I got a headache and my azzbackwards brain doesn't want to think of the consequences, can ya give a feller ahand?

Now my next thought is...........you probably think
Far_Call helped me with this post.........NOT..........Next thought is I've spent the last 24 hours scouring the internet for answers to your comments...........NOT

This is the reason I explained my azzbackwards way of thinkin' to ya

have a nice day

 

I meant to add one thing to my post

you are constantly referring to mt trucks idle quality, along with the chatter, sputtering and the ECM tuning at high RPM no load sistautions..........the problem is injector size and camshaft injector lobe lift. It'll do it with a stock ECM also. In fact every CAT 3406e, C-15, C-16 I've ever had any experience with this injector and camshaft profile installed will not have a good idle quality regardless of whether the ECM has a factory CAT file in it or a modified file in it.

The high RPM full load break up is an injector issue that Far_Call has given me the answer to fix, which I felt was an injector issue after the last two dyno contests. I just didn't want to buy 6 injectors at roughly $800 a piece without a solid answer first, because nobody here could tell me why it was happening. Again my azzbackwards way of thinkin' workin' again

 

mostly black smoke is caused by UN-burt fuel,

 

Whoa.......

5 pages of technical debate and 30 years of experience and an impending war between the US, Europe and Australia, and you decided to hop in and bestow us with that scientific earth-shattering revelation.

I guess I can stop chomping on my Tylenol trying to decipher all the explanations here about injector chatter, atomization, and extrude honing and leave it at that.

It's just unburnt fuel, Momma.