Injector size question
TECH Apprentice
Joined: Feb 2005
Posts: 384
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Burden of proof is on the individual making the positive claim -- not my job to go chasing down nebulous third-parties. Please post concrete data substantiating your claims:
Did you not once post here claiming a +5hp increase from running tiny injectors back-to-back on the dyno? On a 500~600hp engine, correct? So a net power increase of 1%? Can you post the graphs? Did you make any attempt to isolate whether the gain was due to the injector design, or due to the rail pressure increase? (I assume the latter).
That wasn't even my main point. My point is that a wideband should be installed on any car running excessively high duty cycles -- which proponents of small injectors routinely fail to mention. I think we can all find common ground on that point.
I'll respond to the rest of your post later -- some of us have day jobs...
Will your blown **** outrun my NA stuff? I doubt it. I also don't have that kind of junk on mine. I have customers use those. Most are gone now.
That was 5 rwhp through a non-lock 6200 RPM converter. Any gain is worthwhile if you actually run NHRA S or SS.
If you raced at the level and against the guys I do, you would almost slap your Momma for 5 hp. Those seemingly small, at least to you, gains add up.
I sold my dyno at the end of 2010 when I had to have a couple of surgeries. I'm up and going again now. I no longer have dyno graphs.
If you ventured out into the real racing world you would fine many engine builders, tuners & racers finding the same thing. You evidently are the typical know it all engineer.
I love racing engineers. When you keep kicking their butts it's always because you spend more than them, or are cheating. Never is because you know something they don't. LOL
I'm not wasting any more time on your know it all ***.
That was 5 rwhp through a non-lock 6200 RPM converter. Any gain is worthwhile if you actually run NHRA S or SS.
If you raced at the level and against the guys I do, you would almost slap your Momma for 5 hp. Those seemingly small, at least to you, gains add up.
I sold my dyno at the end of 2010 when I had to have a couple of surgeries. I'm up and going again now. I no longer have dyno graphs.
If you ventured out into the real racing world you would fine many engine builders, tuners & racers finding the same thing. You evidently are the typical know it all engineer.
I love racing engineers. When you keep kicking their butts it's always because you spend more than them, or are cheating. Never is because you know something they don't. LOL
I'm not wasting any more time on your know it all ***.
Who is arguing?
You are quick to make a big deal out of someone disagreeing, and then even quicker to just say "no you are wrong, I am right cause I have a fast car".
I just am curious, I listened to the internet, went conservative on injectors and now am regretting that.
You are quick to make a big deal out of someone disagreeing, and then even quicker to just say "no you are wrong, I am right cause I have a fast car".
I just am curious, I listened to the internet, went conservative on injectors and now am regretting that.
Who is arguing?
You are quick to make a big deal out of someone disagreeing, and then even quicker to just say "no you are wrong, I am right cause I have a fast car".
I just am curious, I listened to the internet, went conservative on injectors and now am regretting that.
You are quick to make a big deal out of someone disagreeing, and then even quicker to just say "no you are wrong, I am right cause I have a fast car".
I just am curious, I listened to the internet, went conservative on injectors and now am regretting that.
So, Mike Moran built your stuff? He races where more boost or nitrous is always a possibility. Not where I race, nor the engine builders I converse with build for.
If 80lb injectors make somebody with an NA car feel better, that's fine. I was just sharing what myself and others learned. Don't believe it, don't use it.
I told what myself and many other learned through much testing. Nobody I know of found any differently. If people don't want to use that info, I really don't care. I don't appreciate fools like that last one calling me a liar.
So, Mike Moran built your stuff? He races where more boost or nitrous is always a possibility. Not where I race, nor the engine builders I converse with build for.
If 80lb injectors make somebody with an NA car feel better, that's fine. I was just sharing what myself and others learned. Don't believe it, don't use it.
So, Mike Moran built your stuff? He races where more boost or nitrous is always a possibility. Not where I race, nor the engine builders I converse with build for.
If 80lb injectors make somebody with an NA car feel better, that's fine. I was just sharing what myself and others learned. Don't believe it, don't use it.
So, you are saying that NA stuff is more suited to the smallest injector as possible?
For instance, if you size a boosted car for the "right" size injector and then you run a 1:1 reg, you now may run out of fuel as most pumps go to hell at higher pressures. My 4301 will be out of steam as I am pushing it to hold ~65psi rail pressure to make my baby 80# injectors stay "safe". Where as if I went to 96# injectors contrary to internet lore, I would have a happier fuel pump and frankly, technology these days I fail to see such a large high Z injector being difficult to tune for. Hell a ID unit will most definitely have idle characteristics most likely better than stock units would..
IDK really. Just ramblings of a LT1 guy
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No, I was using him as a source that you would credit as reliable, his injector spreadsheet plots me at the duty cycle I posted above. I am not calling you a liar, I would just like some more evidence to prove or disprove stuff. Without data everything is just opinions ya know. That guy above isn't the only train driver here.
So, you are saying that NA stuff is more suited to the smallest injector as possible?
For instance, if you size a boosted car for the "right" size injector and then you run a 1:1 reg, you now may run out of fuel as most pumps go to hell at higher pressures. My 4301 will be out of steam as I am pushing it to hold ~65psi rail pressure to make my baby 80# injectors stay "safe". Where as if I went to 96# injectors contrary to internet lore, I would have a happier fuel pump and frankly, technology these days I fail to see such a large high Z injector being difficult to tune for. Hell a ID unit will most definitely have idle characteristics most likely better than stock units would..
IDK really. Just ramblings of a LT1 guy
So, you are saying that NA stuff is more suited to the smallest injector as possible?
For instance, if you size a boosted car for the "right" size injector and then you run a 1:1 reg, you now may run out of fuel as most pumps go to hell at higher pressures. My 4301 will be out of steam as I am pushing it to hold ~65psi rail pressure to make my baby 80# injectors stay "safe". Where as if I went to 96# injectors contrary to internet lore, I would have a happier fuel pump and frankly, technology these days I fail to see such a large high Z injector being difficult to tune for. Hell a ID unit will most definitely have idle characteristics most likely better than stock units would..
IDK really. Just ramblings of a LT1 guy
An awful lot of the top Stock & Super Stock racers run high duty cycles with zero issues other than running faster. Not like you spend several seconds there. I do know if you hold a Lucus injector wide open too long the windings fail sooner than Bosch. Longer than you will ever see in the car unless you are running a flying mile someplace.
Most people that work with this stuff also know the reported duty cycles seen on scan tools with factory ECUs (GM at least) are inflated. Measure them with a good fast DSO and you find large differences in the scanner and actual measurements. Not many pros go by the scan tools for this.
Most people that work with this stuff also know the reported duty cycles seen on scan tools with factory ECUs (GM at least) are inflated. Measure them with a good fast DSO and you find large differences in the scanner and actual measurements. Not many pros go by the scan tools for this.
That help?
Like I said the wideband will tell you if an injector is too small.
Fuel pressure/injector size/fuel pump capacity relationship is another discussion.
But you really didn't answer the question anyway.
I also glad that you can highlight other peoples post in a lame attempt to answer a question.
Thread Starter
On The Tree
Joined: Jul 2013
Posts: 194
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I'm just gonna through this out there...how come GM engineers saw it fit to put 28# injectors on the 330HP LT4 over 24# 300HP LT1 injectors? Discuss. 
I found this on the Grand sport registry:
The engine's higher rpm also exceeded the LT1's fuel injector's ability to keep up, so the LT4 got larger fuel injectors rated at 3.5 grams per second (28lbs/hr), replacing the 3.0 gram (24lbs/hr) injectors of the LT1. The larger injectors were designed to keep pace with the better breathing, higher revving engine.
I found this on the Grand sport registry:
The engine's higher rpm also exceeded the LT1's fuel injector's ability to keep up, so the LT4 got larger fuel injectors rated at 3.5 grams per second (28lbs/hr), replacing the 3.0 gram (24lbs/hr) injectors of the LT1. The larger injectors were designed to keep pace with the better breathing, higher revving engine.
My point was a scan tool is not worth a damn for determining injector duty cycle. They do make toold that will do that accurately. A lab scope.
TECH Apprentice
Joined: Feb 2005
Posts: 384
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Guys, I apologize for taking a few days to respond. The past few days have been really busy in my personal life.
Please, everyone calm down. I think we finally have enough information to walk away from this with more meaningful conclusions on both sides of the argument. And I can answer some questions regarding the erroneous duty cycle values.
I'm going to split this into multiple posts.
Please, everyone calm down. I think we finally have enough information to walk away from this with more meaningful conclusions on both sides of the argument. And I can answer some questions regarding the erroneous duty cycle values.
I'm going to split this into multiple posts.
GM fitting the LT4 with 28# injectors had nothing to do with power output or fueling margin. It had more to do with emissions. With smaller injectors, you lose the benefit of sequential injection as you get into the higher duty cycles; the injectors stay open longer and the system starts to act more like batch fire. Batch fire doesn't make any less power than sequential
TECH Apprentice
Joined: Feb 2005
Posts: 384
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First off, to Ed:
I'm going to extend you considerably more courtesy than you've afforded me, but first we have to clear up the mud.
This is not a pot-shot, no disrespect is meant, so take no offense.
1) Understand that ad-hominem, shifting burden of proof, shifting the goalposts, etc. -- are examples of logical fallacy, and as such, will never help you prove your point. Such arguments can only make you appear illogical, because they are illogical concepts. You are resorting to these because you are having difficulty communicating your tuning knowledge effectively.
2) Follow your own rules. I recall you previously argued with BigCat about this, who is running half a second quicker than you in the quarter mile. That didn’t stop you from arguing with him. If the rules don't apply to you, then they don't apply to me.
3) I would remind you that you are a professional tuner, but you are using equipment created by professional engineers and programmers. Without them, you wouldn’t have a car to brag about. You wouldn’t have tuning software. You wouldn’t be a tuner.
For what it’s worth, I’ve programmed Motorola 68HC12 microcontrollers using assembly language (I believe the successor to the 68HC11 used in our cars), and I can assure you that what you see in the tuning software is a severely simplified user interface. Assembly language is about the closest language to computer language that humans can still comprehend — it’s incredibly tedious, like building a pile of sand one grain at a time.
I'm going to extend you considerably more courtesy than you've afforded me, but first we have to clear up the mud.
This is not a pot-shot, no disrespect is meant, so take no offense.
1) Understand that ad-hominem, shifting burden of proof, shifting the goalposts, etc. -- are examples of logical fallacy, and as such, will never help you prove your point. Such arguments can only make you appear illogical, because they are illogical concepts. You are resorting to these because you are having difficulty communicating your tuning knowledge effectively.
2) Follow your own rules. I recall you previously argued with BigCat about this, who is running half a second quicker than you in the quarter mile. That didn’t stop you from arguing with him. If the rules don't apply to you, then they don't apply to me.
3) I would remind you that you are a professional tuner, but you are using equipment created by professional engineers and programmers. Without them, you wouldn’t have a car to brag about. You wouldn’t have tuning software. You wouldn’t be a tuner.
For what it’s worth, I’ve programmed Motorola 68HC12 microcontrollers using assembly language (I believe the successor to the 68HC11 used in our cars), and I can assure you that what you see in the tuning software is a severely simplified user interface. Assembly language is about the closest language to computer language that humans can still comprehend — it’s incredibly tedious, like building a pile of sand one grain at a time.