Stock injector size discussion...size matters

SickLL7Crenshaw

Billy The Kid
Mar 10, 2013
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I got flow data from Exergy and iirc this was the info on nozzle flow-
LB7 1150ml/min
LLy 1050ml/min
LBZ 1000ml/min
LMM 950ml/min

Interesting part is that the LMM's flow the same as the LBZ during a timed flow test because the internal reacts faster even though the nozzle flows less.
Thanks for finding this Mark.
 

MarkBroviak

DMax Junkie
Vendor/Sponsor
May 25, 2008
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Thanks for sharing that with us, Mark. I'm assuming this is all at the same pressure for each nozzle? Is that flowing the nozzle by itself or on the body? That's some very interesting info on the LBZ/LMM timed flow testing.

Yes, that info is the max nozzle flow with same pressure on each nozzle. I am using some injectors that have nozzle flow rates in the 3450+ml/min...:spit:
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Yes, that info is the max nozzle flow with same pressure on each nozzle. I am using some injectors that have nozzle flow rates in the 3450+ml/min...:spit:

Interesting, you wouldn't happen to have the actual size of each nozzle would you?
 

SickLL7Crenshaw

Billy The Kid
Mar 10, 2013
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You wanna start this shit again, go in the other thread, otherwise shut it and contribute useful information.
Easy James I have nothing against you just tired of a guy bragging about his tunes and trying to get people on this forum to use them cuz he makes '' stout tunes". You posted to prove me wrong by saying lbz/lmm flowed more and lly flowed the less of all of them. Im sorry you were wrong.. But other then that I didnt post anything bad toward you.
 

MarkBroviak

DMax Junkie
Vendor/Sponsor
May 25, 2008
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If you look at the stock pulse width tables, you can actually see this. It looks like the higher flowing nozzle of the LBZ overcomes the quicker reacting body of the LMM injectors somewhere between 10 and 20 mm3 of fuel quantity. At the same pressure and fuel quantity, the LMM has a shorter pulse width until 20 mm3. From that point forward, the LBZ has a shorter pulse width.

This is also why I do NOT recommend oversized LMM injectors because the stock 6 hole nozzle is designed for emissions(ie regeneration/DPF) as it has one less hole but the holes are larger. This allows fuel to be injected way late and it will burn in the exhaust not the cylinder so when you go larger with them they love to haze black at idle.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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Easy James I have nothing against you just tired of a guy bragging about his tunes and trying to get people on this forum to use them cuz he makes '' stout tunes". You posted to prove me wrong by saying lbz/lmm flowed more and lly flowed the less of all of them. Im sorry you were wrong.. But other then that I didnt post anything bad toward you.

I'm not about to have you and quinton start off in a good tech thread cause you wanna laugh about it. I could care less if I was wrong.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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I got flow data from Exergy and iirc this was the info on nozzle flow-
LB7 1150ml/min
LLy 1050ml/min
LBZ 1000ml/min
LMM 950ml/min

Interesting part is that the LMM's flow the same as the LBZ during a timed flow test because the internal reacts faster even though the nozzle flows less.


Any data on the latency of each say during a 1000 usec injection window? I know the LB7's look like they need to bypass alot more fuel to get the inejctor to pop than an LLY should just by comparing the internals. Haven't looked inside an LBZ or LMM injector to compare them to the earlier variants.
 

Hot COCOAL

May the farce be with you
Jun 9, 2012
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Can you swap tips onto different bodies, like say, an lmm body using lbz tips? If the internals of the lmm body reacts faster, but the lbz flows more at a higher u.s, then wouldn't you create a more precise injection event? Also using said swap, and honed lbz tips, would that make a better performing injector/performance package? If it is at all possible....

I'm really un-knowledgeable about injectors, u.s and p.w, (among other things)so, sorry for the question
 

RPM Motorsports

smokinum
May 13, 2008
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Food for thought, when running an LLY injector off the LB7 controls, fuel and timing was increased more then 35% across the board to get it to run worth a shit. Other changes were made, but not as drastic as the fuel/timing.
 
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THEFERMANATOR

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Food for thought, when running an LLY injector off the LB7 controls, fuel and timing was increased more then 35% across the board to get it to run worth a shit. Other changes were made, but not as drastic as the fuel/timing.

Was hoping you would chime in. How do the LBZ injectors off the LB7 FICM work? Simliar increases or do you have to go even more?
 

jkholder09

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Jan 8, 2012
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Anytime we have changed nozzles we putvthem in a head and pin them.
This means stick thin pins in the spray holes to make sur you are not spraying into head.
This was on tractirs with bigger holes. Thinking a long hose with red dyed fluid and a aresol needle out of nozzle may be a better test on these.
We also machined grooves in the flat part of nozzle to allow fuel into it when dow pins are removed and hole no longer lines up. The groove looks like the grooves in the disks under lml nozzles.
I would think lmm and lmm will interchange as head and body are the same.
Someone should try it. Kinda like lb7 motorsports nozzles.
On the latency of operation I agree that lly reacts faster and that's why I said before I think lly deliver the most fuel.
Great thread guys by the way
 

THEFERMANATOR

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Feb 16, 2009
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On the latency of operation I agree that lly reacts faster and that's why I said before I think lly deliver the most fuel.

LB7's without a doubt outflow LLY's, otherwise you wouldn't have to up the pulsewidth when you do an LLY head swap on the 01-02's. It would be nice to know just how the evolution of the injector changes effect the amount of fuel injected as well as fuel returned.
 

jkholder09

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Jan 8, 2012
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LB7's without a doubt outflow LLY's, otherwise you wouldn't have to up the pulsewidth when you do an LLY head swap on the 01-02's. It would be nice to know just how the evolution of the injector changes effect the amount of fuel injected as well as fuel returned.

I had read a scientific article on it and it talked allot about pressure drop through the body as the quantity's got bigger and the volumn of fuel inside the injector stayed the same. Which I got from the article that pressure drop in the body slowed down the movement of the connecting rod that closes the pintle in the nozzle, or releases it. I have also been told the motorsport nozzles have a larger sac in the tip for fuel.
At the same time its logical that anytime you have a nozzle open there will be some pressure drop.
I was thinking about a test where a position sensor that measures pintle position is installed while injector is on the test bench. Then I would graph pintle position and latency relative to electrical command of the injector and actual fuel delivery at different pressures, and nozzle sizes.
Than maybe we could mix and match and find the best nozzle body combo.
I was thinking radiactively charging the needle or something in order to track it.
 

chrisd91

Member
Jan 27, 2012
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Anytime we have changed nozzles we putvthem in a head and pin them.
This means stick thin pins in the spray holes to make sur you are not spraying into head.
This was on tractirs with bigger holes. Thinking a long hose with red dyed fluid and a aresol needle out of nozzle may be a better test on these.
We also machined grooves in the flat part of nozzle to allow fuel into it when dow pins are removed and hole no longer lines up. The groove looks like the grooves in the disks under lml nozzles.
I would think lmm and lmm will interchange as head and body are the same.
Someone should try it. Kinda like lb7 motorsports nozzles.
On the latency of operation I agree that lly reacts faster and that's why I said before I think lly deliver the most fuel.
Great thread guys by the way

What do the different nozzles measure with a pin gauge? I am familiar with nozzle sizing based on orifice size and count in mechanically injected cummins, but I have always been curious as to the actual dimensions for common rail injectors
 

jkholder09

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Jan 8, 2012
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no the pins in the nozzles were to turn them properly on the injector body while installed in the head.
IE we have a head on the bench and put pins in the spray holes such as changing nozzles between different engines.
This is to check the spray pattern is spreading out in the piston bowl, it has nothing to do with what the diameter of holes are.
On duramax nozzles you almost need a magnifying glass to see them.

For example Chris allot of guys use the 370 marine nozzles for 12 valves but The spray pattern isn't exactly right for the piston bowl in the trucks.
But they seem to work great with an hx40 and full cuts
 

chrisd91

Member
Jan 27, 2012
39
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Washington State
no the pins in the nozzles were to turn them properly on the injector body while installed in the head.
IE we have a head on the bench and put pins in the spray holes such as changing nozzles between different engines.
This is to check the spray pattern is spreading out in the piston bowl, it has nothing to do with what the diameter of holes are.
On duramax nozzles you almost need a magnifying glass to see them.

For example Chris allot of guys use the 370 marine nozzles for 12 valves but The spray pattern isn't exactly right for the piston bowl in the trucks.
But they seem to work great with an hx40 and full cuts

Thanks!
Yea, I caught that you were using the pins for alignment the second time I read your post. I had always heard common rails use (relatively) small orifices and compensate with injection pressure. I wasn't quite thinking magnifying glass small though! I know I can easily see the orifices on my 7x.012 nozzles
azu8a8y3.jpg


Sorry for the derail, back on topic!