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Pop pressure test with dyno results

ak diesel driver said:
So my ? is since the pump has been tweaked did it lose some of it's advance capabilities and hence the need for more advance?
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Oh and like WW, I also don’t have cold advance due to the aneroid. The one time I wasn’t sure it was going to start, it was in the low teens outside and it hadn’t been running in over 24 hours. I think it took 4 or 5 glow cycles to finally start.
 
Long Brown Train said:
The ideal GAS law does not apply to an injection pump (moving LIQUID). Careful you do not let that trip up your thinking.
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Thank you for the reminder. It’s been a while since I’ve gotten a text book out.

Now I’m reading a bit more and seeing the relationship between pressure, volume and velocity......velocity, that’s interesting. So with different pop pressures we could just be changing the speed the fuel hits the wall of the precup, which would shear the fluid more? I’m guessing it would do other things my brain can’t comprehend, too.
 
JayTheCPA said:
Only reason I mentioned that timing adjustments were theoretical (at least for the DS4) was that none of the tuners cared what the pop was or made any adjustment for it.

From what I can tell (and maybe I am wrong) but it does look like the DS4 timing does advance as RPM's increase. At least that it is what it looks like to me when I monitor via AutoEngenuity. So perhaps that is why the few tuners I talked with did not adjust the timing . . .
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Yes, the timing should change as rpm changes, just like the ignition advance on a gasser typically changes as rpm changes. Generally, as rpm increases, you want timing to advance to compensate for the reduced time for the injection and combustion events to happen.
 
I'm new here but this topic has been something I've been putting alot of time into myself for my up coming build.

I'm about all convinced that #304 nozzles are a better choice over the #311. With the throttling pintle you should get a small introduction of fuel before full flow when the needle reaches full travel. This should help with ignition because it allows that smaller amount to start the burn before the rest of the fuel is introduced. (In my head this is alot like preinjection on a common rail) it should result in a better burn. I also think the shape of the pintle created a better spay pattern (cone shape) vs the #311. I think playing with pop off pressures on #304 could result in even better atomization and I'm excited to see if you dyno results show any changes in HP.

I remember reading somewhere that the #311 had more needle stroke than the #304. It might be interesting to play around with machining .005-.010 off the collar and see if it makes any difference in conjunction with a high output pump like yours.

Of course these are all my own theories and I base alot of what I know on common rails because that's what I work on and tune. I'm new to IDI's so I could be way off with my thinking.

Looks like I better make my introduction post now since I'm officially no longer a lurker lol.
 
Rockabillyrat said:
I'm new here but this topic has been something I've been putting alot of time into myself for my up coming build.

I'm about all convinced that #304 nozzles are a better choice over the #311. With the throttling pintle you should get a small introduction of fuel before full flow when the needle reaches full travel. This should help with ignition because it allows that smaller amount to start the burn before the rest of the fuel is introduced. (In my head this is alot like preinjection on a common rail) it should result in a better burn. I also think the shape of the pintle created a better spay pattern (cone shape) vs the #311. I think playing with pop off pressures on #304 could result in even better atomization and I'm excited to see if you dyno results show any changes in HP.

I remember reading somewhere that the #311 had more needle stroke than the #304. It might be interesting to play around with machining .005-.010 off the collar and see if it makes any difference in conjunction with a high output pump like yours.

Of course these are all my own theories and I base alot of what I know on common rails because that's what I work on and tune. I'm new to IDI's so I could be way off with my thinking.

Looks like I better make my introduction post now since I'm officially no longer a lurker lol.
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Welcome and thank you for your contribution! I like your thoughts here and it will be interesting to see results.
 
Rockabillyrat, I like your thinking so far. That is some analysis there. I prefer 311 over 304 but definitely giving up some of the softer manners of the 304 to get to the part I like. Welcome to the site doesn’t sound right, so welcome to the “post button”. Haha

Do you have 304 & 311 to play with is the hard part. The improved airflow making the precup turn into a mega mixer intead of choked down into a centrifuge makes a big difference in the 311 having sucess. If a guy just throws 311’s into something stock he just makes a smoke show.

We need a high speed camera in a 1 lung test engine to watch injection events here— Somebody rub Aladdin’s lamp!
 
Will L. said:
Rockabillyrat, I like your thinking so far. That is some analysis there. I prefer 311 over 304 but definitely giving up some of the softer manners of the 304 to get to the part I like. Welcome to the site doesn’t sound right, so welcome to the “post button”. Haha

Do you have 304 & 311 to play with is the hard part. The improved airflow making the precup turn into a mega mixer intead of choked down into a centrifuge makes a big difference in the 311 having sucess. If a guy just throws 311’s into something stock he just makes a smoke show.

We need a high speed camera in a 1 lung test engine to watch injection events here— Somebody rub Aladdin’s lamp!
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I still need to get a good copy of Ricardo's book so I can get deep into theory. The copy I have has an abbreviated diesel section.
 
I've been wondering if a pressure transducer in the glow plug hole could be helpful. A lab scope is very fast. By measuring cylinder pressure it could tell you alot about the firing event. And if you synchronized it with a crank sensor you could see what degree the event occurred in the compression stroke.

Try different nozzles, pop off and timing and compare it's affect on cylinder pressure. I'm assuming higher pressure would be and indication of a more powerful burn. And you could measure the duration of the burn as well.

You would have to get a base line pressure of a cylinder with no firing event to see what pressure the engine creates just with compression at a given rpm.

This is the stuff that keeps me up at night.
 
Am not convinced that split injection equates to more power.

I know that the 7.3 IDI and DI folks get more power out of the motor when they remove the split injector and install a single shot.

IIRC, split shot is better at reducing emissions, making the fuel burn cleaner, and reducing the diesel clack.
 
I agree split injection is for emissions. Played with it on my 2 pump where the second injectors shot in the glowplug holes. They second pump helped by volume only. When both pumps used diesel, timing the 2 as close to identical was more power. Maybe a new wazoo komputer could do better than we did back then? Again I would dump the cash into a twin pumped 400 first. Lot of power available that way, but overkill if your not maxing wmi and heavy propane first.

Pressure transducer is a neat idea. It would take some effort to get it dialed in, but I am sure some tuning would be gained. Cant really get exact pressures at rpm without canceling one cylinder, but a starter won’t do it. Not sure how much it would do a lot unless you could do while driving. We tried a lot of tuning on bench dyno, then wheel dyno was slightly different. But actual drive time gave best results because it is impossible to load a turbo the same as real life. Now if you go belt driven super charger instead of turbo(s) then dyno is more accurate. But if you could have passanger on a laptop down the road it may help.

Not a lot of people would pay bunches for fine tuning, but if you can show it helps “X” amount or problems, plus could time a db injection pump off it- might make a few bucks to some shops and few guys.
 
JayTheCPA said:
Am not convinced that split injection equates to more power.

I know that the 7.3 IDI and DI folks get more power out of the motor when they remove the split injector and install a single shot.

IIRC, split shot is better at reducing emissions, making the fuel burn cleaner, and reducing the diesel clack.
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Actually alot of DI guys keep pilot injection and only tune out the post firing events. Pilot helps the turbo spool faster and creates more heat. Which cleans up the smoke and allows a larger main injection even because it aids in burning the extra fuel. It was designed for emmisions but is useful to make power on a common rail platform.

The 304 is not a true split injection because there is only one firing event. But with the throttling pintle you get a slight step in the flow vs a steady increase on the 311.

My though behind using the 304 is the "preinjection" might help burn the extra fuel a modified db2 can put out more efficiently. And I'm curious if increasing the needle stroke on the 304 could help anything. It should flow the same amount of fuel but at a faster rate. The step in flow might be useful on modified injectors.
 
I forget to mention pilot injection is usually disabled above 2500rpm. So a single shot is used at high rpms but the preinjection help get you there more efficiently. If only we had the capabilities to do the same on our old oil burners
 
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