Lets talk big injectors

WolfLMM

Making Chips
Nov 21, 2006
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Pretty sure he made in the 800s.

I had pats race tune on a 366, 2xcp3 LLY and the pulse was a lot lower than you would think.
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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regardless, that number was from years ago. it was quite the feat back then and IMHO, it still is today but it should not be used to base where things could be used to make reliable HP. We have come along ways since then and i know things have significantly improved in tuning and what we know. if stock injectors were the way to go, we wouldnt be seeing guys doing 250-400% over injectors. there is a reason for it and Mark partly showed that with less cyl pressure but more power with a significantly larger injector over another one. that will add to reliability of an engine

Now im not after the HP those test were shown in but if an LML is using a 60% bigger injector over previous years, that again points to the same direction i am basing mine and others "theory" off of. Im not soley basing this off the LML setup either, just using as an example in a very small part of what i see.


Where im curious is where "too small uS" is an issue for those running bigger injectors and is the smoke guys see an increase from, due to the fact limiters were not in place or could the fueling tables just not be made to work to clean them up? i know this tuning isnt going to be fun for steve or i to get dialed in for my picky ass so i want to make sure its a route i want to go in a 100%+ injector before buying.

it wouldnt hurt to know what guys injector size they are running and what power they make on the smallest tune is (80% overs and bigger injectors only). odd request but would fit my bill here
 

ikeG

Oughta Know Better
Apr 19, 2011
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In my experience on lly nozzles, we've ran 40s, 80s, 120s, & 180s all on stock bodies. They all behaved well enough to be daily driven. Just the bigger we went, the more effort on tuning it took to get them to smoke little at idle and not flood the charger out at part throttle with little boost. I personally would like to have our 120s back, cuz they were the best balance between power and cleanliness. Fwiw we made 946 rwhp on 80s and two stock pumps at 25xx us back in 2013.

Now have 485% in the truck and it took bunch of time to even get it to idle and start ok. I've decided not to worry about haze at idle :D. Too many other factors involved now
 

Chevy1925

don't know sh!t about IFS
Staff member
Oct 21, 2009
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In my experience on lly nozzles, we've ran 40s, 80s, 120s, & 180s all on stock bodies. They all behaved well enough to be daily driven. Just the bigger we went, the more effort on tuning it took to get them to smoke little at idle and not flood the charger out at part throttle with little boost. I personally would like to have our 120s back, cuz they were the best balance between power and cleanliness. Fwiw we made 946 rwhp on 80s and two stock pumps at 25xx us back in 2013.

Now have 485% in the truck and it took bunch of time to even get it to idle and start ok. I've decided not to worry about haze at idle :D. Too many other factors involved now

Stock body's?? how did the balance rates do with the 120s and 180s? were the stock bodys holding back fuel/power that high? its against the "forum norm" but the 60% overs i was going to run would have been on stock bodys as well. i would have figured above 100% you would need the body modded to get an actual 100% over fueling worth
 

gmduramax

Shits broke
Jun 12, 2008
4,072
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Nor cal
regardless, that number was from years ago. it was quite the feat back then and IMHO, it still is today but it should not be used to base where things could be used to make reliable HP. We have come along ways since then and i know things have significantly improved in tuning and what we know. if stock injectors were the way to go, we wouldnt be seeing guys doing 250-400% over injectors. there is a reason for it and Mark partly showed that with less cyl pressure but more power with a significantly larger injector over another one. that will add to reliability of an engine

Now im not after the HP those test were shown in but if an LML is using a 60% bigger injector over previous years, that again points to the same direction i am basing mine and others "theory" off of. Im not soley basing this off the LML setup either, just using as an example in a very small part of what i see.


Where im curious is where "too small uS" is an issue for those running bigger injectors and is the smoke guys see an increase from, due to the fact limiters were not in place or could the fueling tables just not be made to work to clean them up? i know this tuning isnt going to be fun for steve or i to get dialed in for my picky ass so i want to make sure its a route i want to go in a 100%+ injector before buying.

it wouldnt hurt to know what guys injector size they are running and what power they make on the smallest tune is (80% overs and bigger injectors only). odd request but would fit my bill here

I daily drive my 250's and don't smoke anybody out. Mileage is decent. Running an 80mm is what makes it hard to get smoke down but it's maf limited. I average 17mpg 50/50 driving like a jack ass. Smallest tune is 1800 pulse and traps 120mph. Big tune is 2250 and traps 126mph pretty smokey.

My 100's trapped 120mph with 2200 and 125mph with 2800.
With twins your pulse should be quite a bit lower to make the same power as a single turbo. Hopefully this gives you an idea on pulse. These are LBZ injectors
 

ikeG

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Apr 19, 2011
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Stock body's?? how did the balance rates do with the 120s and 180s? were the stock bodys holding back fuel/power that high? its against the "forum norm" but the 60% overs i was going to run would have been on stock bodys as well. i would have figured above 100% you would need the body modded to get an actual 100% over fueling worth

Balance rates were all fine with any of the nozzles. These were new injectors summer of '12. Never changed the injector, just swapped out the nozzles. The 40s & 80s were used. The 120s were made from brand new nozzles that came on the new injectors in '12. The 180s i think i remember were used stock and i sent them to be done. I have to admit, the only ones that really got street driven were the 40s and 80s but even the other bigger ones, i spent piles of time adjusting tuning in the driveway for haze, smoke output at part throttle etc.
I dont think stock bodies hold back most trucks. Injectors big enough for modded bodies were out of budget at the time. We never had a lack of power for the given class with the stock bodies for sure.
 

WolfLMM

Making Chips
Nov 21, 2006
4,005
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AL
regardless, that number was from years ago. it was quite the feat back then and IMHO, it still is today but it should not be used to base where things could be used to make reliable HP. We have come along ways since then and i know things have significantly improved in tuning and what we know. if stock injectors were the way to go, we wouldnt be seeing guys doing 250-400% over injectors. there is a reason for it and Mark partly showed that with less cyl pressure but more power with a significantly larger injector over another one. that will add to reliability of an engine

Now im not after the HP those test were shown in but if an LML is using a 60% bigger injector over previous years, that again points to the same direction i am basing mine and others "theory" off of. Im not soley basing this off the LML setup either, just using as an example in a very small part of what i see.


Where im curious is where "too small uS" is an issue for those running bigger injectors and is the smoke guys see an increase from, due to the fact limiters were not in place or could the fueling tables just not be made to work to clean them up? i know this tuning isnt going to be fun for steve or i to get dialed in for my picky ass so i want to make sure its a route i want to go in a 100%+ injector before buying.

it wouldnt hurt to know what guys injector size they are running and what power they make on the smallest tune is (80% overs and bigger injectors only). odd request but would fit my bill here

Oh I agree completely! My post was more me reminiscing in the past than anything else.
 

THEFERMANATOR

LEGALLY INSANE
Feb 16, 2009
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As I understand it, the lml is using an injector that flows roughly 60% more than it's predecessor, but as each gen progressed, the injectors got smaller until the lml when they went piezo, and alot bigger. The 45 over lb7's should flow pretty close to a 60 over lly from what I've seen and researched. I know just looking at pulsewidth, a stock 5 speed behind an lb7 will begin to limp in the 1800-1850 range from my experience(limped several now at 1850 with 55% timing), but I set lly's up to 2100 and haven't limped one yet(that was driven within reason).

Just throwing that out there to help you compare your lb7 injectors to lly. So 60 over lly's should put you roughly where you were at with 45 over lb7's.
 

ikeG

Oughta Know Better
Apr 19, 2011
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I daily drive my 250's and don't smoke anybody out. Mileage is decent. Running an 80mm is what makes it hard to get smoke down but it's maf limited. I average 17mpg 50/50 driving like a jack ass. Smallest tune is 1800 pulse and traps 120mph. Big tune is 2250 and traps 126mph pretty smokey.

My 100's trapped 120mph with 2200 and 125mph with 2800.
With twins your pulse should be quite a bit lower to make the same power as a single turbo. Hopefully this gives you an idea on pulse. These are LBZ injectors

Maf limiting will be your best friend. You will spend a pile of time in table B0751 on a LLY with big injectors, assuming if MAF equipped.
 

NC-smokinlmm

<<<Future tuna killer
May 29, 2011
5,201
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At Da Beach
Just an FYI, if you use cruise control regularly your going to want to stay smaller than 100 in my opinion. The computer just can't figure out what's going on with throttle input and if you go to a 68r it will get worse...
 

S Phinney

Active member
Aug 15, 2008
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Actually LML nozzles are the smallest of all duramax injectors at 880 ml/min flow. They just happen to be much more efficient since they return much less fuel. I have ran 30 percent up to 200 percent in my personal truck. For one that sees considerable street time and smoke is a concern I beleive you will be happiest with 100 overs. The bigger you go there is considerably more effort in tuning to keep clean. It becomes almost impossible. Your choice of parts and how they complement each other will be a key point in getting what you want out of it.

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Harbin_22

Active member
Dec 4, 2010
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Southern Indiana
Mine could probably be cleaned up some with MAF tuning, but once you've had the fuel, hard to take it away lol. People with super clean running trucks are missing out on aggressive, quicker spooling tuning. My right foot has alot of control over the smoke, just takes more effort on my part the bigger the injectors have gotten. I actually have a tamer MAF tune for the street just for smoke control. I like it to be aggressive at the track so I have no issues spooling quick
 

Chevy1925

don't know sh!t about IFS
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Oct 21, 2009
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Ferm, I'd personally like to see flow data for stock lb7 compared to lly. Guy posted a while back that lly and up injectors were flow tested at less pressure than lb7 are. I can not find any significant data the proves or disproves this but I also have not delve beyond just internet searching. I'm sure a call to any of the injector modding company's would tell me right away. That said, I want more fuel than lb7 45% overs can give. 3000uS is what netted me my time and 800hp. I want less uS than that an attain the same or more power. 2100 netted me 600hp.

Issac that's interesting to know! Thanks for that info



I certainly miss the bigger injectors in throttle response, spool up, and fun. Steve had that thing running very clean with minimal MAF adjustments. The Lbz we just finished has 60% overs on a 68 stg2r and it has MAF limiting to about 80% throttle. It was an absolute blast to drive. It spooled extremely fast and left just an initial slight haze when under heavy part throttle. You could get into the throttle harder in his truck than mine and have much less smoke than mine would produce doing the same yet it spooled and pulled just as fast.

I'm really leaning towards 100s based on what you all are saying. I was curious how 250s would be under the same circumstance and how if someone took the time, how well they can be dialed.
 

SSchmi5519

LLY Cult Leader
Oct 19, 2008
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Arizona
As far as power on stock injectors goes...here's a little bit of data for you from my own personal experience.

LLY injectors, bone stock. Dual fuelers with LBZ regs pushing 27k rail.
Running 3500uS, and an assload of nitrous the best I could do was 11.8@116 which at my weight calcs out to around 625-650 wheel horsepower. I haven't had the huevos to go any higher than 3500.

If someone made 800whp on stock injectors that would be incredible from my perspective.
 

SSchmi5519

LLY Cult Leader
Oct 19, 2008
3,387
1
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Arizona
As far as tuning goes on large (100%+) injectors, the real issue becomes proper atomization of the fuel. Tuning can only go so far before physical limits start to take a toll.

You can somewhat band aid the issue of atomization on large injectors by running a ton of rail pressure, but that only goes so far and it makes the fuel temps go through the roof...as well as just being harder on everything. Harder on the pump, injectors, increased parasitic drag on the rotating assembly, etc.

The only real key to having an efficient, high flowing injector is to put more holes in the nozzle.

More smaller holes atomize fuel better than fewer larger holes, and you can get the flow you want.
 

malibu795

misspeelleerr
Apr 28, 2007
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As far as power on stock injectors goes...here's a little bit of data for you from my own personal experience.

LLY injectors, bone stock. Dual fuelers with LBZ regs pushing 27k rail.
Running 3500uS, and an assload of nitrous the best I could do was 11.8@116 which at my weight calcs out to around 625-650 wheel horsepower. I haven't had the huevos to go any higher than 3500.

If someone made 800whp on stock injectors that would be incredible from my perspective.

Here you go
http://www.duramaxdiesels.com/forum/showthread.php?t=13790

After looking more carefully at the factory MIPW table for a LLY, it seems the CP3 cannot keep up 100% after ~45mm of fuel, and slowly starts to lose efficiency for whatever reason. It also appears the "dwell time" that the injectors take before fuel starts to flow is 200msec. Using both those numbers, and assuming 250rwhp stock at 1500 msec/160mpa fuel shot, I come up with:

875rwhp at 3350 msec. While I hit about 800rwhp with stock injectors, it seems there was about 10% I left on the table. Probably because I had to reduce msec down to 2900 to get the engine to rev high enough. With twins, and peak HP at 3200, I think you could go 875rwhp on stock sticks.
 

Blackmax123

Member
Aug 2, 2014
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1
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central Pennsylvania
Now have 485% in the truck and it took bunch of time to even get it to idle and start ok. I've decided not to worry about haze at idle :D. Too many other factors involved now

These are what I'd call big injectors. 100's really aren't that big anymore. I think you'd be fine with 100's. The bigger tunes might get a little dirty, but with that much air it should clean them up nice. Personally I'd go bigger so your not buying another set down the road.

I'm running much bigger than 100's on an s400 charger in my lmm. I had 60's and the 60's hazed just as bad at idle. My 60's were lmm nozzles and my new ones are lbz nozzles. The some in my big tunes seems to be about the same as my 60's were. I had Mark dyno tune the 60's. Haven't got to him with the new ones yet, but I will say the new ones drive a lot nicer than my 60's. Spool up is way faster. But I think that's due to the extra hole in the lbz nozzle.
 

SSchmi5519

LLY Cult Leader
Oct 19, 2008
3,387
1
36
Arizona


That boggles my mind. Do you know if this was dyno numbers or calcd numbers based on weight and track times? Even being the latter, I get numbers all over the place depending on which calculator I use.

I have only pushed my own truck this hard, as I wouldn't feel comfortable running that kind of pulse duration on someone else's.

Maybe my CP3's really are that tired and I'm losing out on a bunch of power.

:shrug:
 

Lb7_Katie

Lb7 Duramax
Sep 8, 2013
851
31
28
34
Ive ran 60s and 150s in my Lb7 and surprised at how clean the 150%s are with the stealth 64.5 and the 91mm setup.

Have 60% in the boyfriends LBZ not yet fine tuned still clean, little more haze than I would like but we're still breaking it in.

I'm happy with my 150s! Plenty enough fuel, not sure what power in my lower tunes, I know bob drove the truck from their shop to SDX last year and averaged 18mpg on my biggest tune.


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