Injector questions/problems, part II.
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From: Sears Point, CA
Injector questions/problems, part II.
Alright here is the problem:
Please look below for my current state of modifications.
When I had the stock injectors the A'PEXi PowerFC was telling me that I was running at 100% duty cycle around 7000rpm, so I called RC and spoke with their sales reps, and consulted with some people on this board, I purchased some 310's, now the PowerFC is telling me that I'm running at 98% duty cycle with the 310's installed, at around 8500rpm...RC will switch out the injectors for free to 370's, are there any problems that I will have with doing this?
Thank you,
Austin
MODIFICATIONS
TODA B cams
TODA cam gears
TODA valve springs
Portflow Ti retainers
Comptech Icebox intake
HyTech header
Carsound 54006 cat
Comptech cat-back
A'PEXi PowerFC
J&S safeguard
RC 310 injectors
Please look below for my current state of modifications.
When I had the stock injectors the A'PEXi PowerFC was telling me that I was running at 100% duty cycle around 7000rpm, so I called RC and spoke with their sales reps, and consulted with some people on this board, I purchased some 310's, now the PowerFC is telling me that I'm running at 98% duty cycle with the 310's installed, at around 8500rpm...RC will switch out the injectors for free to 370's, are there any problems that I will have with doing this?
Thank you,
Austin
MODIFICATIONS
TODA B cams
TODA cam gears
TODA valve springs
Portflow Ti retainers
Comptech Icebox intake
HyTech header
Carsound 54006 cat
Comptech cat-back
A'PEXi PowerFC
J&S safeguard
RC 310 injectors
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From: Sunnyvale, Ca, USA
Re: Injector questions/problems, part II. (Austin)
thats crazy you are running so much fuel. You shouldn't need so much fuel. Have you been tuning on a dyno? How do your af numbers look. I bet you are in low 12's. You can run 100 percent duty cycle, but thats is independent how much fuel you actually need.
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From: Sears Point, CA
Re: Injector questions/problems, part II. (98TypeR)
thats crazy you are running so much fuel. You shouldn't need so much fuel. Have you been tuning on a dyno? How do your af numbers look. I bet you are in low 12's. You can run 100 percent duty cycle, but thats is independent how much fuel you actually need.
Yeah, I know that it sounds crazy that the car is using that much fuel. With the 310's I'm currently running with a 12.6-13.2 A/F measurement, as you notice I'm not running a FPR to run an increased amount of fuel pressure, I wanted to change out the injectors as opposed to using a FPR, just one less variable when it comes to tuning. I'm having Lawrence look at it this weekend, so I'll be in town on Saturday morning.
Austin
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From: Kelowna Canada
Re: Injector questions/problems, part II. (Austin)
Get a FPR! The amount of fuel that gets into the cylinder is dependent upon fuel pressure and duty cycle of the injectors. Higher fuel pressure will give you better atomization of the fuel and make fine tuning easier. What's your base pressure?
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From: Sears Point, CA
Re: Injector questions/problems, part II. (Big Phat R)
Get a FPR! The amount of fuel that gets into the cylinder is dependent upon fuel pressure and duty cycle of the injectors. Higher fuel pressure will give you better atomization of the fuel and make fine tuning easier. What's your base pressure?
Austin
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From: Sears Point, CA
Re: Injector questions/problems, part II. (sgT)
Stock ITR fuel pressure is still higher than the pressure that most injectors are
rated at. 50-54psi vs 43psi.
rated at. 50-54psi vs 43psi.
I don't understand your reference, can you explain.
Austin
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From: WI
Re: Injector questions/problems, part II. (Austin)
310cc injectors are rated 310cc@43psi. when you increase fuel pressure(in this
case you are using somewhere in the 50-54psi range) you effectively make the
injector larger. Using the following formula you can calculate the new flowrate
of the injector.
sqrt(new pressure/old pressure) * old flow rate = new flow rate
sqrt(50/43) * 310 = 334cc
sqrt(54/43) * 310 = 347cc
Do using the stock regulator you are effectively running a 334-347cc injector
depending on what the pressure is currently at.
In the case of my car, I am using 310cc injectors at 67psi which makes the
injector about 387cc flowrate.
case you are using somewhere in the 50-54psi range) you effectively make the
injector larger. Using the following formula you can calculate the new flowrate
of the injector.
sqrt(new pressure/old pressure) * old flow rate = new flow rate
sqrt(50/43) * 310 = 334cc
sqrt(54/43) * 310 = 347cc
Do using the stock regulator you are effectively running a 334-347cc injector
depending on what the pressure is currently at.
In the case of my car, I am using 310cc injectors at 67psi which makes the
injector about 387cc flowrate.
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From: Sears Point, CA
Re: Injector questions/problems, part II. (sgT)
Thank you for the explanation Steve, the numerical representation is helpful being put into real world terms...I had a feeling that is what you had meant, but needed clarification. Do you foresee any problems with changing the injectors over to the 370cc/min, as I recall that you are about to change over to the 430cc/min, correct?
Thank you for your help, I'm sure you've been through a similar situation to this before, I prefer to not have to redo something because it wasn't done correctly.
Austin
Thank you for your help, I'm sure you've been through a similar situation to this before, I prefer to not have to redo something because it wasn't done correctly.
Austin
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From: Santa Barbra, CA, USA
Re: Injector questions/problems, part II. (Austin)
Hey Austin Let me know what you end up using for your set-up with you r ride as far as setting's with your power FC ect...(Your set-up is very close to mine 
) And I just ordered 310's from Russ Collins so it seems that you will just need tomget a FPR...No..?? ....Good luck tuning that Bad Boy.! 
) And I just ordered 310's from Russ Collins so it seems that you will just need tomget a FPR...No..?? ....Good luck tuning that Bad Boy.!
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From: Sears Point, CA
Re: Injector questions/problems, part II. (JDM_DOHC_SiR)
Alright, recent development with my injector dilema...I thought that the 370cc/min injectors were going to be a little large...well RC calls me back today and has decided that they want to send me 440cc/min injectors as RC is telling me that the 440's have a better atomization pattern, as opposed to the 310's and the 370's which both have a single port for the fuel whereas the 440's have 3 ports.
Any opinions, am I going crazy with these thoughts?
Any opinions, am I going crazy with these thoughts?
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From: Kelowna Canada
Re: Injector questions/problems, part II. (Austin)
You might want to install an after-burner in your tailpipe and a "KEEP BACK 50 FT" sign so that people who mistakenly pass through the toxic gas cloud your car is spewing don't die or catch on fire or something. 
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From: WI
Re: Injector questions/problems, part II. (Austin)
yes, the 440s will be much better than the 370s. Since you have the PowerFC
you should be fine using large injectors. Anyone using a stock ecu however
shouldnt really try anything over 370
you should be fine using large injectors. Anyone using a stock ecu however
shouldnt really try anything over 370
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From: Atlantis
Re: Injector questions/problems, part II. (Austin)
I'd say go ahead and get the 440's...
Easiest way to figure out what to get is tell rc what you have in your car and what you're planning for it. They have lots of customers with the same or similar setups and goals...
Or just ask Lip and sgT what they are running or would suggest... Oops, Lip is running itb's, right? Well, that leaves sgT.
What are your plans and we'll be better able to help you...
BTW: how much $ for this stuff?
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From: Sears Point, CA
Re: Injector questions/problems, part II. (Black R)
Steve,
Thank you for your comment, as that is what I was looking for.
I plan to spend some time on the road course(3-4 times a year), autocross(once a month during season), and some drag racing(3-4 times per month during the season).
$$wise, I initially paid retail for the injectors from RC after discussion with RC we chose the 310's...that was a little over a month ago, they are swapping out the now used 310's for the 440's free of charge, they are paying to have them shipped to me, I'm paying to have the 310's shipped back to them. The 440's are only a couple of dollars above the 310's...RC is sending me the 440's without me sending the 310's to them so that I don't have down time without a car, they're not even charging me for the injectors, I just have to send them the 310's after the 440's are installed...so far RC has been pretty nice to me, I would recommend them for their customer service...
Thank you for your comment, as that is what I was looking for.
....
What are your plans and we'll be better able to help you...
BTW: how much $ for this stuff?
What are your plans and we'll be better able to help you...
BTW: how much $ for this stuff?
$$wise, I initially paid retail for the injectors from RC after discussion with RC we chose the 310's...that was a little over a month ago, they are swapping out the now used 310's for the 440's free of charge, they are paying to have them shipped to me, I'm paying to have the 310's shipped back to them. The 440's are only a couple of dollars above the 310's...RC is sending me the 440's without me sending the 310's to them so that I don't have down time without a car, they're not even charging me for the injectors, I just have to send them the 310's after the 440's are installed...so far RC has been pretty nice to me, I would recommend them for their customer service
...
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From: Toronto, On, Canada
Re: Injector questions/problems, part II. (Austin)
problems with 370's?
from Hondata.com Tech FAQ
check out this site which gives injector sizing for hp needs at BSFC 0.55, 100% duty cycle. In a 4 cylinder engine 310's should support around 215 hp.
http://www.sdsefi.com/techffhp.htm
cheers
from Hondata.com Tech FAQ
http://www.hondata.com/techfaq.html#tech
What are the biggest injectors I can run?
The ECU can be re-calibrated to suit any sized injector (make sure you match injector impedance if you are
replacing you injectors). However, injectors take a finite amount of time to open and close, so the bigger
injectors tend to be less accurate with their fueling at low durations, such as idle. Much depends on the
mechanics of the injector, and how quickly it can open and close. With disk type injectors (such as RC
440cc injectors) you can not tell the difference between stock injectors and injectors which flow twice as
much as stock injectors, once the ECU has been reprogrammed for the larger injectors (and there is no
difference on the dyno either). With race engines we have run injectors up to 4 times the size of the stock
injectors.
How come people say that the biggest injector I can run is 310 cc?
This assumes that you are not re-calibrating the ECU to the new injector size. If you don't, the bigger
injector will over-fuel. If this happens then the ECU will compensate to some degree using closed loop
operation to reduce the injector duration. The limit of the long term closed loop adjustment is about 40%,
which is close to the increase in size from stock to 310cc injectors.
What are the biggest injectors I can run?
The ECU can be re-calibrated to suit any sized injector (make sure you match injector impedance if you are
replacing you injectors). However, injectors take a finite amount of time to open and close, so the bigger
injectors tend to be less accurate with their fueling at low durations, such as idle. Much depends on the
mechanics of the injector, and how quickly it can open and close. With disk type injectors (such as RC
440cc injectors) you can not tell the difference between stock injectors and injectors which flow twice as
much as stock injectors, once the ECU has been reprogrammed for the larger injectors (and there is no
difference on the dyno either). With race engines we have run injectors up to 4 times the size of the stock
injectors.
How come people say that the biggest injector I can run is 310 cc?
This assumes that you are not re-calibrating the ECU to the new injector size. If you don't, the bigger
injector will over-fuel. If this happens then the ECU will compensate to some degree using closed loop
operation to reduce the injector duration. The limit of the long term closed loop adjustment is about 40%,
which is close to the increase in size from stock to 310cc injectors.
http://www.sdsefi.com/techffhp.htm
cheers
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From: Toronto, On, Canada
Re: Injector questions/problems, part II. (Michael Delaney)
I didn't see a fuel pump on that list of yours...did I mention that the stock pump is only good for 200hp or 75psi FP?
supply the injector with some priming or head pressure.
oh yeah and if you exceed the max. stock range for FP by more than 20% the stock ECU fuel map calibrations are now obsolete. Running high FP reduce injector life as well.
75 psi FP!!! no thanks.
supply the injector with some priming or head pressure.
oh yeah and if you exceed the max. stock range for FP by more than 20% the stock ECU fuel map calibrations are now obsolete. Running high FP reduce injector life as well.
75 psi FP!!! no thanks.
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From: Land of Oz, KS
Re: Injector questions/problems, part II. (Big Phat R)
You might want to install an after-burner in your tailpipe and a "KEEP BACK 50 FT" sign so that people who mistakenly pass through the toxic gas cloud your car is spewing don't die or catch on fire or something.
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From: Sears Point, CA
Re: Injector questions/problems, part II. (Michael Delaney)
Michael I have a few comments and questions about your statements...
I'm not worried about changing the injectors to the 440cc/min as with the PowerFC I can change the injector calibration and not have a problem with the ecu fuel maps.
At what point do I need to add in a FPR or a larger sized fuel pump? I thought that I would not have to do that with the larger sized injectors and the ability to program the fuel curve via the PowerFC.
Austin
I'm not worried about changing the injectors to the 440cc/min as with the PowerFC I can change the injector calibration and not have a problem with the ecu fuel maps.
At what point do I need to add in a FPR or a larger sized fuel pump? I thought that I would not have to do that with the larger sized injectors and the ability to program the fuel curve via the PowerFC.
Austin
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From: WI
Re: Injector questions/problems, part II. (Austin)
You will never need a regulator unless yours goes bad. This is because you have
the powerFC.
At some point your injectors are going to push more fuel than your pump can supply.
I would recommend a walbro since you run stock pressure. It should be fine for
your needs.
the powerFC.
At some point your injectors are going to push more fuel than your pump can supply.
I would recommend a walbro since you run stock pressure. It should be fine for
your needs.
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