Which injectors do I need?
Melting Slicks
Joined: Apr 2001
Posts: 2,112
Likes: 220
From: Ca.
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Call Jon at "Fuel injecter connection" . He will let you know exactly what size injector you need so there's no guessing, but like mentioned above , you will need to know about how much HP your motor produces.......
..WW
..WW
Last edited by WW7; Aug 11, 2013 at 08:36 AM.
Racer
Joined: Dec 2007
Posts: 312
Likes: 0
From: San Antonio Texas
You can do up to 36LBs but I would make an effort to find and go with 30LB'ers......
However.....if you have persisting doubt, get with whoever is gonna do your tune for their recommendation
.
KW
However.....if you have persisting doubt, get with whoever is gonna do your tune for their recommendation
.KW
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
I ran with 30lb injectors running low 11s for years while bracket racing. I do my own tuning with an ACCEL dfi and had plenty of fuel and never a failed injector. I probably made over 1000 runs over 5 years with this setup shifting at 6300 rpms. I now run a 406 using 36lb injectors shifting at 6700 rpms and again , still have plenty of fuel. I record all my runs with a wideband. I'm not as much concerned with duty cycles and such as much as what works.
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Team Owner
Joined: Jul 2004
Posts: 28,464
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From: Hartford WI
I ran with 30lb injectors running low 11s for years while bracket racing. I do my own tuning with an ACCEL dfi and had plenty of fuel and never a failed injector. I probably made over 1000 runs over 5 years with this setup shifting at 6300 rpms. I now run a 406 using 36lb injectors shifting at 6700 rpms and again , still have plenty of fuel. I record all my runs with a wideband. I'm not as much concerned with duty cycles and such as much as what works.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
Although a wideband is best you can still read your narrow for .860 at wot. I'd be curious to see what your afr is under load?
Team Owner
Joined: Jul 2004
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From: Hartford WI
Race Director
Joined: Apr 2003
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From: moraga ca
42 should be fine if you're worried about it. As long as the motor is tuned correctly you'll be ok.
Race Director
Joined: Nov 2003
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From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
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Doesn't take batch fire on each revolution into consideration. Not looking up your year -- and IF that applies, I won't make any further statement.
IIRC, Only 96 had sequential fire, right?
A couple years back, there was a big discussion (including Jon) about CorkVette making 500rwhp on 24lb injectors. I finally figured out they're firing once per engine revolution version once per intake cycle.
I wouldn't be surprised if the stock injectors were big enough. Fuel pressure is a consideration too...since more pressure will make the injector effectively bigger.
IIRC, Only 96 had sequential fire, right?
A couple years back, there was a big discussion (including Jon) about CorkVette making 500rwhp on 24lb injectors. I finally figured out they're firing once per engine revolution version once per intake cycle.
I wouldn't be surprised if the stock injectors were big enough. Fuel pressure is a consideration too...since more pressure will make the injector effectively bigger.
Team Owner
Joined: Jul 2004
Posts: 28,464
Likes: 3,288
From: Hartford WI
Doesn't take batch fire on each revolution into consideration. Not looking up your year -- and IF that applies, I won't make any further statement.
IIRC, Only 96 had sequential fire, right?
A couple years back, there was a big discussion (including Jon) about CorkVette making 500rwhp on 24lb injectors. I finally figured out they're firing once per engine revolution version once per intake cycle.
I wouldn't be surprised if the stock injectors were big enough. Fuel pressure is a consideration too...since more pressure will make the injector effectively bigger.
IIRC, Only 96 had sequential fire, right?
A couple years back, there was a big discussion (including Jon) about CorkVette making 500rwhp on 24lb injectors. I finally figured out they're firing once per engine revolution version once per intake cycle.
I wouldn't be surprised if the stock injectors were big enough. Fuel pressure is a consideration too...since more pressure will make the injector effectively bigger.
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
A lot. Increasing fuel pressure, increasing pulse width, and increasing injector size are all ways of increasing fuel supply to your motor. Ideally you should have a way to monitor and tune your motor to it's specifec parameters.
Team Owner
Joined: Jul 2004
Posts: 28,464
Likes: 3,288
From: Hartford WI
I didn't tune it myself. I kinda leave that to professionals that have a good reputation and have a dyno or data log.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
Play with this and you'll get your answer:
http://www.csgnetwork.com/fiflowcalc.html
I don't know about a maximum pressure, but do know that newer cars are running higher pressures. Also, GM used many different pressures throughout the years of the C4 depending on the injector they used.
http://www.csgnetwork.com/fiflowcalc.html
I don't know about a maximum pressure, but do know that newer cars are running higher pressures. Also, GM used many different pressures throughout the years of the C4 depending on the injector they used.
Advanced
Joined: Jan 2012
Posts: 78
Likes: 0
injectors
Like I said before stock injectors are or should be enough on batch fire sysems,but LT1S have sequential systems as far as I know.All this will effect FR.But remember if you are driving on street,the larger injectors,do run dirtier at idle,as PCM has trouble controlling pulse width at low numbers.Adjusting injector size is also nessasary in programming ,as pcm needs to know what size injectors it has to make fuel calcuations.Also O2 switching and frequency of injector pulse will effect richness at idle and fuel economy.
Instructor
Joined: Sep 2011
Posts: 140
Likes: 7
From: Fort Ripley Minnesota
I guess what I didn't know is when you take a stock injector at 43.5 psi, can you crank just the pressure up a lot? How much till it is excessive? Also, how much more fuel will it give when you crank it to that pressure? I would suppose if you are maxed out in pulse width and if you can increase the pressure you can get more fuel into the combustion chamber. What I don't know is what is the max pressure the injector will accommodate and, if you will, how much "larger" will it make that injector. So if you have a 24pph injector at 43.5psi and now you crank the pressure up to say 60psi, does that 24pph injector act like say a 30pph injector or larger?
I didn't tune it myself. I kinda leave that to professionals that have a good reputation and have a dyno or data log.
I didn't tune it myself. I kinda leave that to professionals that have a good reputation and have a dyno or data log.
I spent over four hours on the dyno, we started with our FP at 45 psi, the engine performed OK but not what we expected. Increased the FP to 50 PSI and the engine came to life with a 35 Hp increase.
As we continued to make runs on the dyno we noticed a lose of performance at max rpm and load. We had 50 psi at idle and no load with vac line removed, at max rpm and load we started to loose performance and Hp. Now what? come to find out our FP would drop to about 46-48 psi under load because my stock fuel pump couldn't keep up with the demand. New in tank pump, now were off to the races!
In short, 30 PSI injectors work great, make sure your FP stays constant while under load. I love the 383!