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The results of static timing

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Alright so I have never seen the actual visual effects of different static timing degrees on these trucks to any accurate degree other than word of mouth so I did it myself at 0* then at 20*. I thought I was at 2* ATDC a year or 2 ago but apparently I was wrong. All of this will go to show that accurate info can make a world of difference. The 0* video is done and the 20* one will be done in a few hours. The 0* one tells a lot of the story though. Though now I question how CR's can run at timings after TDC. As the video shows, it gets better as it warms up, so I'm thinking CR's retard more as the engine temp allows, but still, how can they pull off 5*ATDC! One thing that was interesting was that every single number was identical, though idle speed seemed a few revs lower (5-10) with the 20* timing when it was at the same 140F as when I noted the RPM at 0* at the same temp. That is significant because idle speed is set with the idle screw so it is giving it the exact same fueling in both cases, nothing electronic to do any magic. At this point I can change the timing in about 20 minutes... I have a dead nuts TDC mark and if timing hasn't slipped then I can reference the last point to advance or retard however far I want. I just want to know how far I can advance it before you think I will see negative effects such as what I experienced as I went up in RPM's with 0*. I want to find the advanced timing's lower RPM limit... When will it start to run like crap.. When this is done, I will confirm the timing and confirm the TDC mark again, using a different valve. That way I will know if anything slipped in the process (timing gear) or if somehow the TDC was off. I did measure 14.2* as where I set it last time, which is basically where I set it last time (I aimed for 14.5) so the TDC mark should be pretty spot on, but I want to make sure. This begs a lot of questions that I am too involved in other things to think about right now. Why did the RPM-to-roughness go up as the engine block temp increased at 0*? Why did it run rough at 0* at those RPM's?, why didn't it just smoke more and be less efficient but do it smoothly? HmmmmmmThis might still be processing so refresh it later if it is..

http://youtu.be/i4QhHmAjUpI

I'll get the other one up when it's done uploading.

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It will be 40F tonight so in the morning I want to see how it starts. When I had the diesel shop in rolla do it, it barely started at 50F. It is still at 20* timing so it will tell me just how far they actually went. They didn't measure anything they just popped the timing gear off and turned the engine and put it back on. They took the delivery out for some reason but I don't remember any dial indicator going into it. They sure couldn't have got TDC off anything. I said I wanted it at 16* after the dillweeds on cumminsforum made such a commotion about it. I didn't even have the money at the time, I sold some things to do it. After doing it and telling the CF minor leagues how it started, they said it sounded like it was at more like 20*+. So, tomorrow will tell me everything I need to know. It's water under the bridge but to think they would do something like that and charge me $150...and have to drive an hour there.. :ahhh: It is really neat that once you get a TDC mark and know where the timing was previously, it only takes 20 mintes to change the timing. Really you don't need anything but to know what the timing is on the pump. If you knew what it was previously you are basically golden. Of course it could have slipped and whatnot. I've never seen it slip but its another CF myth that goes around. I'm going to test and see how close the mark is inside the pump as well since someone mentioned it's accuracy and I'm not 100% sure how accurate it really is. I heard the timing pin gear can be up to 2* off, though I was seeing a 2*ish gear lash so I'm not sure if they account for that or not. Update:So today I went out and it started like crap but it was 16F colder than my 56F vid and it was cranking a lot slower (battery is corroded). It coughed and stuttered but started, the 56F vid coughed once and started but had cranked with no hit for a few seconds. I believe batteries that are charged would show today's start to be the same as the 56F start (it cranks slowww). So whatever they did set it anywhere >20* :banghead: Idiots.

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at slow idle, piston speed is slow enough to 'use' the retarded timing... then the higher the rpm will start to show the effects of late timing??? Of course on an unloaded engine it's easy to feel/hear.As it warms up.. combustion gets easier, and possibly firing quicker? (which is akin to more timing)...You noticed a rpm drop with 20* @ idle. I think you might have found the upper limits to timing @ idle. (engine is now firing too much 'against' itself). In the CR engines.. do they have multiple injection events? If they do, maybe a series of smaller 'shots' can be done closer to tdc (or after) and still have the same results as one large shot. :shrug:And this brings up another question (12v vs. CR)When the injector is 'fired' on the CR... that is AT the point of injection. Our 12v's have about 12" of line, then the pop valve to overcome...THEN it's 'firing'. (maybe that alone is the difference).They need time (degree's) to actually 'git er done'???? :shrug: What i'm trying to say here is: a mechanical pump @ 14* may be way late as to a CR's 14*.This is just a 'shot' in the dark!:lol:

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... Of course it could have slipped and whatnot. I've never seen it slip but its another CF myth that goes around.

My blue '96 slipped time on the IP and popped the exhaust then shut off, not to refire.. My buddy came over and in 20-25*F night air, with a flashlight, reset my IP timing.. So yes, it can and has happened :)

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Just saw this thread...been a busy week..I am not surprised at all by your results. As we have talked about in other threads static timing is set for a specific rpm. So at 0° you were setup well for idle/starting/low rpm. Free revving is really not a good indication, put a decent load on it. But you saw that it didn't like to rev up, and here is why. We want peak cylinder pressure to be 12-18° TDC. When you inject at 0° you are introducing fuel into a piston that is reducing pressure, which makes compression ignition hard. At idle and low rpms the piston moves slow enough that you still get a good ignition event and idle/start well. As rpms increases the pressure drops too quick for proper combustion, and well you saw the results.. As the engine warms up the ignition delay decreases, and thus the better performance. When you went to 20° the fuel is igniting too soon and your creating a rapid ignition, as it lights when pressure is rapidly increasing. That results in a lot of combustion noise. But put your motor WOT at 2600-3000 rpms and 20° works great! The ignition delay is reduced, and the peak pressure occurs at the desired 12-18° ATDC. The reason a CR can run the reduced timing is simple, it has a pilot injection. The pilot injection is a small event that precedes the main event and gets the fire going, and reduces the ignition delay of the main event. This is also why they are quiet and have lower emissions. On my truck I start getting noisy at 8-8.5° of timing in the cruise rpms, where your truck would probably barely run. It's all about ignition delay. So here is an example of peak power at 2,000 rpms on a 04.5-07 5.9 HPCR. Rated power is at least 555 ft/lbs. The WOT main injection event occurs at about -5.8° (or 5.8° ATDC). But here is the kicker, there is a pilot injection event that occurs at 51.6° BTDC. That's early enough that the fuel doesn't ignite rapidly, it actually has to wait for the conditions to be perfect. But the commanded 13mm3 of fuel that is burning early will make that 140mm3 of fuel injected at -5.8° ignite very quickly and thus it still makes a lot of power. The power isn't as efficient as possible, or as cool as possible (1450° EGT's) but the cylinder pressure is low and the piston temps are low. Clear as mud?

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just curious, why is the cyl pressure lower, but egt higher? :shrug:Also, those mm3 aka cc's, numbers are "per 1000 events'?Thanks

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just curious, why is the cyl pressure lower, but egt higher? :shrug: Also, those mm3 aka cc's, numbers are "per 1000 events'? Thanks

With a retarded injection event the pressure is lower because the peak pressure occurs long after TDC and the flame chases the piston down the powerstroke, thus less pressure. The EGT's are higher because the ignition occurs closer to the exhaust stroke, which results in less heat absorbed by the piston and cylinder walls, and more heat in the exhaust. Its the mm3 of fuel being injected per main injection event. Cummins uses the volume measurement of mm3, which is 0.001CC's per 1 mm3.
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I wonder if you could have dynamic timing with variable pop pressures. I know it affects the timing but I wonder if doing it that way is efficient or if the droplets become so big that some of it starts to not burn. Apparently bigger droplets retard timing since its like trying to get a bucket of water to boil with a lighter. The smaller droplets is more like a spray can with each mist particle going across the flame and turning to steam. Drastic examples but you get the point. I just wonder how efficient that method would be.

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I wonder if you could have dynamic timing with variable pop pressures. I know it affects the timing but I wonder if doing it that way is efficient or if the droplets become so big that some of it starts to not burn. Apparently bigger droplets retard timing since its like trying to get a bucket of water to boil with a lighter. The smaller droplets is more like a spray can with each mist particle going across the flame and turning to steam. Drastic examples but you get the point. I just wonder how efficient that method would be.

How would you vary the pop pressure?

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With a will theres a way. But would it be better than injection timing?

Well you know that I am partial to HPCR's. I happen to like the adjustability of pressure/timing with a key stroke...

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With a retarded injection event the pressure is lower because the peak pressure occurs long after TDC and the flame chases the piston down the powerstroke, thus less pressure. The EGT's are higher because the ignition occurs closer to the exhaust stroke, which results in less heat absorbed by the piston and cylinder walls, and more heat in the exhaust. Its the mm3 of fuel being injected per main injection event. Cummins uses the volume measurement of mm3, which is 0.001CC's per 1 mm3.

:banghead: I work with a lot of injectible medicines here.. (everything is cc's)... I had my head on backwards when I read your post about MM3!!! I work with Ml's, :doh: which is 1 cc! uggg! my mistake! thanks btw CC's per 1000 injection cycles is the same thing as MM3 per single injection cycle. Your 140+14 works both ways.

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:banghead: I work with a lot of injectible medicines here.. (everything is cc's)... I had my head on backwards when I read your post about MM3!!! I work with Ml's, :doh: which is 1 cc! uggg! my mistake!

thanks

btw CC's per 1000 injection cycles is the same thing as MM3 per single injection cycle. Your 140+14 works both ways.

I'm not sure I ever posted this but it might help you out. mm3 is one cubic millimeter and also one MICROliter. cm3 is one cubic centimeter and is one MILLIliter. Maybe you already knew this, it will help someone else.

Anyhow this will show why we use microliters. 1 milliliter = 1000 micoliters. So if you multiplied all those mm3 numbers by 1000 you would get the CC's you are used to.. But they are too big to work with so they use microliters.

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Yeah yeah stop avoiding the question lol.

Depends, how much adjustability are you thinking? You chart is cool, 34mm3 is more than I would have expected. I wonder if the motor is below peak efficiency? Meaning if you were at 1800 rpms would the burn rate be lower?The mileage is good, but the burn rate is higher. When looking at tuning 35mm3 in on the edge of the cruise burn rate, with 45mm3 being the highest burn rate for tuning "cruise"..generally. By 45mm3 I am tapering into spool/accelerate/tow timing and am fully there at 55mm3. There is a common misconception that lower rpms always means better economy, but it's simply not true. I get better mileage towing at 2000-2100 than 1600-1700. If I ever get to datalog I will do some testing, but reading about it from EFI guys they see the same thing as they are able to watch commanded mm3 and lower rpms doesn't always decrease the mm3.

:banghead: I work with a lot of injectible medicines here.. (everything is cc's)... I had my head on backwards when I read your post about MM3!!! I work with Ml's, :doh: which is 1 cc! uggg! my mistake! thanks btw CC's per 1000 injection cycles is the same thing as MM3 per single injection cycle. Your 140+14 works both ways.

Too funny! 140 cc's per event would be some serious fire hoses!!

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Well seeing as how I just do 1 injection at a time I would say 10* to 18*, as in 8* of variation. I've noticed the same thing. I drive at 2000RPM 70mph with our trailer everywhere. Without it there is no load at all and I see a pretty linear mileage drop with speed. I added something just now that you can play with as well, tells MPG. Only edit the yellow things on all of these...rest has formulas. Oh and at the bottom I wanted to compare the actual size so side of cube mm means uh, the side lol. Then I wanted to see how big if it was a pea size (sphere) so that shows the diameter of the sphere. Those are based on the mm3 per injection (B15).I played with the RPM/MPH/MPG just now and I put in actual values as in 55mph, 27mpg, 1611rpm, and thats 26.5mm3. However, if I change just the MPG to 20, it goes to 35.8mm3. In other words, it doesn't take much and that makes me ask how accurate this edge display is? Like I noticed on the scangauge it has a refresh rate of like 3 seconds and the RPM seems to be a little iffy. If the edge isn't showing accuracy of at least every 1mm3 if not 0.1mm3, then I don't know how trusting it is. I mean my calculator is over the course of a tankful MPG run so everything is calculated and basically dead nuts. Basing mm3 off only something that gives live feedback that has a crappy data range isn't really accurate results. I have no idea though so I assume it gives good results but I'd like to hear your thoughts on this. I put in all digital gauges for my EGT/ECT/RPM and I love them. Dead nuts results and I can set the RPM gauge to 6 digits. Meaning it can measuring 000.000 or 0000.00 if I want. I did a bunch of trig and put 4 magnets around the damper to maybe get a more accurate reading or a faster one. I didn't really notice a difference but if it has 4 inputs per revolution then I figure that's gotta get its accuracy way up there. I can actually see the rpm drop of the alternator from just rolling the window down (2rpm). One thing I am really curious about is how even the engine runs. The RPM is pretty constant in the whole digits, varying barely 1, but one decimal place in is all over the place and I'm not sure if I'm actually seeing the variances between piston power strokes from injectors wearing different, whatever. I would like to stick my thing on a brand new 6.7 and see what it does.

Injection Amount.xlsx

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So I was just thinking about that spreadsheet and I think I figured out why the mm3 is higher than expected. That's all based on 1 injection event. So with the snapshot you posted if there is a 7mm3 pilot even then the main in only 26mm3 and that's a little better and more expected.

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meh, no problemo on multi injection with our 12v's:whistle:DUAL PUMP'D p7100... all it takes is $$... pretty sure 'sphincters' are not required either! :lmao:

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So I was just thinking about that spreadsheet and I think I figured out why the mm3 is higher than expected. That's all based on 1 injection event. So with the snapshot you posted if there is a 7mm3 pilot even then the main in only 26mm3 and that's a little better and more expected.

I did a little looking at the stock tune. At 1800 rpms and 30mm3 of commanded main injection fuel the pilot injection is 4.0mm3, so 34mm3 total. At 1800 rpms and 45mm3 of commanded main injection fuel the pilot injection is 4.3mm3, so 48.3mm3 total. At 2000 rpms and 30mm3 of commanded main injection fuel the pilot injection is 4.8mm3, so 34.8mm3 total. At 2000 rpms and 45mm3 of commanded main injection fuel the pilot injection is 5.6mm3, so 50.6mm3 total.

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I did a little looking at the stock tune. At 1800 rpms and 30mm3 of commanded main injection fuel the pilot injection is 4.0mm3, so 34mm3 total. At 1800 rpms and 45mm3 of commanded main injection fuel the pilot injection is 4.3mm3, so 48.3mm3 total. At 2000 rpms and 30mm3 of commanded main injection fuel the pilot injection is 4.8mm3, so 34.8mm3 total. At 2000 rpms and 45mm3 of commanded main injection fuel the pilot injection is 5.6mm3, so 50.6mm3 total.

I don't understand this "commanded" fuel thing. I mean you press the pedal and it gives it more fuel.. Or are you just stating snapshots at certain throttle percentages? Basically we need a reference for yours... All I can do is mpg things since I can't measure fuel flow without buying sensors. In other words, go certain speeds in the highest gear and note the RPM, mph, and mm3. It should be identical to the MPG you get. For instance, at 1800RPM and your summer tires in 6th gear you should be at 65.3mph. At 34mm3 that works out to 22.4mpg. At 48.3mm3 it works out to 15.8mpg. I just want to see how legit all this is seeing as how you can monitor the fuel rate it would be interesting to see if it works out on the calculator.

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just curious, why is the cyl pressure lower, but egt higher? :shrug:

Also, those mm3 aka cc's, numbers are "per 1000 events'?

Thanks

Because the later you inject the fuel in the "powerstroke of compression" or "early exhaust stroke (CR)" the hotter your exhaust will be.

In essence, the piston is pushing the flame into the exhaust manifold earlier. This reduces NOx emissions but reduces efficiency drastically!!!!! Something the EPA doesn't seem to gather................or care about.................because in our country that'd mean reduced tax revenue!!!!!!!!!!

That's the rub...............we "can" get 25mpg out of our 8000lb. Cummins if the EPA would let us. But that'd reduce the amount of fuel tax that gets paid to the various forms of government!!!!!!!!!!!!!! ALWAYS, ALWAYS, ALWAYS follow the money aspect of things when you cannot understand why things happen!!!!!

I'll start another thread here shortly about that!!!!

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