42lb injectors big enough?
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From: Highlands Ranch, CO
42lb injectors big enough? Still trying to decide on my injectors. Is 42lb injectors too small for my setup?
ATI D1SC @ 8lbs
MMS stage II heads
MMS blower cam (specs at home)
Walbro 340
stock shortblock
(may go with forged 6.0 block with stock crank, depends on funds)
ATI D1SC @ 8lbs
MMS stage II heads
MMS blower cam (specs at home)
Walbro 340
stock shortblock
(may go with forged 6.0 block with stock crank, depends on funds)
Re: 42lb injectors big enough? go here http://www.rceng.com/technical.htm
those 42 are closer to 48's at our fuel presure
48's at 90%duty cycle and .6BSFC are good for 576FWHP.
i would go bigger.
those 42 are closer to 48's at our fuel presure
48's at 90%duty cycle and .6BSFC are good for 576FWHP.
i would go bigger.
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From: Highlands Ranch, CO
Re: 42lb injectors big enough? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by parish8:
<strong> go here http://www.rceng.com/technical.htm
those 42 are closer to 48's at our fuel presure
48's at 90%duty cycle and .6BSFC are good for 576FWHP.
i would go bigger. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">According to that calculator, maybe I should go with 50's.
650fwhp (550rwhp) *guessing here*
.55 BSFC
80% DC
55psi at rail
49.68 lb/hr injector
<strong> go here http://www.rceng.com/technical.htm
those 42 are closer to 48's at our fuel presure
48's at 90%duty cycle and .6BSFC are good for 576FWHP.
i would go bigger. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">According to that calculator, maybe I should go with 50's.
650fwhp (550rwhp) *guessing here*
.55 BSFC
80% DC
55psi at rail
49.68 lb/hr injector
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Re: 42lb injectors big enough? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MelloYellow:
<strong> I feel comfortable with the 42# up to 600rwhp. The larger injectors are much harder to tune. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">with a blower and the higher BSFC? why would you risk it if you haven't even bought the injectors yet?
i am no expert on injectors but so far i have ran the stock 23lb units, then some 41's@58psi, and now some 50's@43.5psi, the truck idles exactly the same and my ltrims were easy to tune in, still very responsive.
<strong> I feel comfortable with the 42# up to 600rwhp. The larger injectors are much harder to tune. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">with a blower and the higher BSFC? why would you risk it if you haven't even bought the injectors yet?
i am no expert on injectors but so far i have ran the stock 23lb units, then some 41's@58psi, and now some 50's@43.5psi, the truck idles exactly the same and my ltrims were easy to tune in, still very responsive.
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From: Centrifugal City
Re: 42lb injectors big enough? I had 50# Delphi's, but returned them for tuning reasons. More reliable 42# programs out there. I definitely feel comfortable running the motor with 42#'s and that they will be plenty to 575rwhp. My setup will most likely run 550rwhp. I've seen them support up to 639rwhp.
How much injector will a 225lph pump support in any case? Or the fuel rails?
How much injector will a 225lph pump support in any case? Or the fuel rails?
Re: 42lb injectors big enough? a single walbro flows around 60gph. multiply that by 6 and you have 360lb/hr or 45lb/hr(actual flow) per injector. so yea if you dont plan on going with any more fuel pump than a single 340, the 42's would more than cover it.
but with a heads and cam blower motor i would sure go with more than a single 340 for fuel the fuel system.
but with a heads and cam blower motor i would sure go with more than a single 340 for fuel the fuel system.
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From: Highlands Ranch, CO
Re: 42lb injectors big enough? Thanks guys. Maybe 42's will be enough. Just in case, I might run two Walbro's. It's a pain with the new style pump housings soo I might run an inline Walbro 255lph to help.
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong> and at least a new pressure line and rails. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">*sigh*.... Something else I'll have to add to the list to get. Does it ever end? Is this the whole line going from the pump to the fuel rails?
</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MIGHTYMOUSE:
<strong> and at least a new pressure line and rails. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">*sigh*.... Something else I'll have to add to the list to get. Does it ever end? Is this the whole line going from the pump to the fuel rails?
Re: 42lb injectors big enough? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by INTMD8:
<strong> Lucas 42's running at 58psi base pressure have supported 634rwhp on my LT1. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Does Lucas make 42? I thought it was 42.5lb/hr? At least those are the ones currently on my car.
I assume the ATI kit utilizes an FMU as does INTMD8's. What is the MAX pressure the FMU on the ATI kit produce? I guess assuming the full 8PSI that was described above.
Let's assume a max of 68PSI. And 42.5 Lucas injectors. And also assume a 6-speed with 10% losses.
42.5lb/hr Lucas would equal 52.51lb/hr at 68PSI
52.51lb/hr can support (at 90% dutycycle)756FWHP. Assuming a BSFC of .50 of course. This would equate to 680.4RWHP.
I feel comfortable bringing the Lucas injectors into the 90% dutycycle range. Everything I've read tells me that they are stress tested to that level and have no significant failures at that range. Above that I wouldn't want to risk my motor. On an expensive motor I would also have them flowed and matched. Other injectors I would seriously look into the manufacturers claims on failure rate at duty cycle. Typically you do NOT invade the 80% duty cycle for safety reasons.
I've seen INTMD8 tune 50lb/hr injectors on the dyno and the car runs like a top. So I know it can be done.
Anyway my 10cents on the subject...lol
<strong> Lucas 42's running at 58psi base pressure have supported 634rwhp on my LT1. </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Does Lucas make 42? I thought it was 42.5lb/hr? At least those are the ones currently on my car.
I assume the ATI kit utilizes an FMU as does INTMD8's. What is the MAX pressure the FMU on the ATI kit produce? I guess assuming the full 8PSI that was described above.
Let's assume a max of 68PSI. And 42.5 Lucas injectors. And also assume a 6-speed with 10% losses.
42.5lb/hr Lucas would equal 52.51lb/hr at 68PSI
52.51lb/hr can support (at 90% dutycycle)756FWHP. Assuming a BSFC of .50 of course. This would equate to 680.4RWHP.
I feel comfortable bringing the Lucas injectors into the 90% dutycycle range. Everything I've read tells me that they are stress tested to that level and have no significant failures at that range. Above that I wouldn't want to risk my motor. On an expensive motor I would also have them flowed and matched. Other injectors I would seriously look into the manufacturers claims on failure rate at duty cycle. Typically you do NOT invade the 80% duty cycle for safety reasons.
I've seen INTMD8 tune 50lb/hr injectors on the dyno and the car runs like a top. So I know it can be done.
Anyway my 10cents on the subject...lol
Re: 42lb injectors big enough? Here's some interesting reading that I found. It really outlines some interesting testing that was performed.
http://www.supras.com/~riemer/sonict...rs/RCtech.html
http://www.supras.com/~riemer/sonict...rs/RCtech.html
Teching In
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From: Newport Beach, CA
Re: 42lb injectors big enough? I have the SVO 42# injectors. With the ATI P1 and a 220 cam, Stage II heads, etc., I have no issues and I am over 600 rwhp. LS1-Edit and a wide-band dyno will give you the answer to your question.
Re: 42lb injectors big enough? wow! now that is some interesting stuff. wish i would have seen that sooner since i have some of those old style pintle injectors now. acording to that article you difinately never want to go over 85% duty cycle. i always thought you could go higher but it just wasn't good for the injector but thats not the case, once you go ever 85% the fuel delivery rate becomes unstable and may actualy drop before going static(100% open)
here is that part
Most pintle type injectors fail at 86%/88% and the Disc will usually go to 92% +, depending on system pressure. All must cycle smoothly up to 85% to Pass. Bad injectors will sometimes go "static" at 70% or so and are discarded. NOTE: Most pintle injectors will increase flow rates up to 88%, 92% with Disc injectors, and then go "semi-static", half open-half closed, just before going full static. This time-out event occurs at different time/pulse width durations, in different injectors, but always produces a 50% or so Duty Cycle flow rate. This extremely dangerous situation will usually occur at the worst of times, full throttle-max boost-high RPM- just when you need 100% fuel delivery you get 50% and go dead lean. BANG!!! This problem seems to amplify a bit at higher pressures.
here is that part
Most pintle type injectors fail at 86%/88% and the Disc will usually go to 92% +, depending on system pressure. All must cycle smoothly up to 85% to Pass. Bad injectors will sometimes go "static" at 70% or so and are discarded. NOTE: Most pintle injectors will increase flow rates up to 88%, 92% with Disc injectors, and then go "semi-static", half open-half closed, just before going full static. This time-out event occurs at different time/pulse width durations, in different injectors, but always produces a 50% or so Duty Cycle flow rate. This extremely dangerous situation will usually occur at the worst of times, full throttle-max boost-high RPM- just when you need 100% fuel delivery you get 50% and go dead lean. BANG!!! This problem seems to amplify a bit at higher pressures.
Re: 42lb injectors big enough? INTMD8, do you have a boost referenced fuel pressure regulator?
The Lucas 42.5lb/hr injectors using a 58PSI fuel pressure can suppport a maximum of 785FWHP. That's the calculated absolute maximum that the injectors can support. That's 100% duty cycle, .50BSFC to bring you the absolute number.
Recommended calculation would be 42.5's can support 571FWHP. That's with .55BSFC and 80%duty cycle.
Now with the Lucas we know we can invade the 90% range. With that being known. We can pretty safely support 643FWHP with a .55 BSFC.
Now I argue that both the LT1 and LS1 engines seem to be pretty efficient. I would argue that we should use the .50BSFC rating even in a forced unduction application. This allows the 43.5lb Lucas injectors to support 707FWHP with a safety margin since the Lucas injectors can support 90% duty cycle with no significant failures.
Perhaps the formulas need to be updated but this is the current calculations used by most injector places for sizing.
The Lucas 42.5lb/hr injectors using a 58PSI fuel pressure can suppport a maximum of 785FWHP. That's the calculated absolute maximum that the injectors can support. That's 100% duty cycle, .50BSFC to bring you the absolute number.
Recommended calculation would be 42.5's can support 571FWHP. That's with .55BSFC and 80%duty cycle.
Now with the Lucas we know we can invade the 90% range. With that being known. We can pretty safely support 643FWHP with a .55 BSFC.
Now I argue that both the LT1 and LS1 engines seem to be pretty efficient. I would argue that we should use the .50BSFC rating even in a forced unduction application. This allows the 43.5lb Lucas injectors to support 707FWHP with a safety margin since the Lucas injectors can support 90% duty cycle with no significant failures.
Perhaps the formulas need to be updated but this is the current calculations used by most injector places for sizing.
Teching In
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From: OC, CA
Re: 42lb injectors big enough? Don't froget those 55#@42.5psi they are ready to go, much easier to tune at higher fuel pressure than 50# MSD's and will be enough for sure. The price is right too about $475 a set, let me know if you need a set Thanks Dave indacalinc@attbi.com
