Maybe Im reading this way wrong but... If stage 2 injectors are considered to flow 769cc at 58psi (RC fluid) and RC 750's flow 866ccs at 58psi, then I should start by pulling 11% fuel globaly? Or for that matter if static pressure is 43.5psi ([659/750]-1) then pull 12% of fuel globaly??
~~After looking more closely (once again I may be retarded here), but If I have a stage 2 PCM (stg 2 injectors = 761.6 cc's @58psi) and run my RC 750's at 43psi.... shouldnt I be adding 1.5% of fuel as a baseline?(761.6/750-1= .015xxx)
Your right in your % of fuel but the actual % you are "pulling" is a % of voltage from the map sensor. A 5% change in Map voltage rarely, if ever, equals a 5% reduction in injector pulse-width.
__________________
"Just because someone goes fast doesn't mean you should do whatever you think they did.
This path assumes they knew what they were doing, which isn't necessarily the case"..........RB Racing
Maybe Im reading this way wrong but... If stage 2 injectors are considered to flow 769cc at 58psi (RC fluid) and RC 750's flow 866ccs at 58psi, then I should start by pulling 11% fuel globaly? Or for that matter if static pressure is 43.5psi ([659/750]-1) then pull 12% of fuel globaly??
~~After looking more closely (once again I may be retarded here), but If I have a stage 2 PCM (stg 2 injectors = 761.6 cc's @58psi) and run my RC 750's at 43psi.... shouldnt I be adding 1.5% of fuel as a baseline?(761.6/750-1= .015xxx)
Your right in your % of fuel but the actual % you are "pulling" is a % of voltage from the map sensor. A 5% change in Map voltage rarely, if ever, equals a 5% reduction in injector pulse-width.
Correct... it more of just a starting point. I have tried to tune the car anywhere from 35psi of fuel pressure + rising rate all the way up to 58psi static and it seems that the car runs the best at 58psi static. I still think the 750's are dumping way to much fuel but I really dont have much of a choice because my stage 2 couldnt keep up with the 50 trim.
__________________
Bryan Tracy
04 Silver SRT4 - Parted and Sold
05 Aero Blue SRT-6 - New Toy
I went through the math in the Injector Sticky Speadsheet and its WAY OFF!! To get all the #s to out right and line up with the very common conversion factor from lb/hr to cc/min of 10.5, the actual density of the "RC test fluid" needs to be 723Kg/m^3 not 760-770 as was reported. Now RC and others might use a bit heavier fluid to do in house flow test with, but if you take the mass flow rates listed by Bosch, Delphi, Siemans and Mopar, (which all btw use Heptane), and apply a new density to equal the common 10.5 conversion factor where is what you get:
"Our 590cc Injectors flow the same as Mopar Stage2 and are compatible with the Mopar Stage2 PCM"
which they rate thiers at 43.5, adn thats how thier 590's can flow the same as mopar's stage 2 682's!
I am actually interested in 650's. hoping to hit the 350 mark... and the 650's at 70% max duty cycle will support 350hp(at the flywheel)
for the newbies to injectors(such as myself) what max duty cycle should i look to stay clear of?
i always thought the cc's needed per hp were about as follows
(being rated at 43.5 psi and max duty cycle of 80%)
300hp 590cc
350hp 650cc
400hp 700cc
450hp 750cc
for the newbies to injectors(such as myself) what max duty cycle should i look to stay clear of?
i always thought the cc's needed per hp were about as follows
(being rated at 43.5 psi and max duty cycle of 80%)
300hp 590cc
350hp 650cc
400hp 700cc
450hp 750cc
am i correct?
You can go up to around 85% if it is only for very brief amount a time(1-1.5 seconds) .
for the newbies to injectors(such as myself) what max duty cycle should i look to stay clear of?
i always thought the cc's needed per hp were about as follows
(being rated at 43.5 psi and max duty cycle of 80%)
300hp 590cc
350hp 650cc
400hp 700cc
450hp 750cc
am i correct?
Your whp numbers for injector size looks about right. I will say, however, that there are alot of factors that go into it (especially on the SRT4) so don't take those loose guidelines as a gurantee.
As far as max IDC, I think 85% is pretty conservative, especially if it is just for a couple seconds. We test for max IDC on our flow bench and can run them at 85% for extended periods of time w/o any hicups. Our SRT4 injectors usually go static at about 90-95%. You definately want to stay below that! For race cars I'd suggest a target of 80% IDC. For street cars, short bursts at 90% IDC are just fine.
__________________
www.DWinjectors.com
Last edited by DeatschWerks : 12-21-2007 at 07:42 AM.
Reason: my grammar sucks
for what its worth, i recently had my stock 04 injectors cleaned at 58psi with heptane at a local performance shop, the end result was suprising. each injector flowed atleast 600cc/min, opposed to the listed 577. even before the cleaning, they flowed over 577.
im going to be getting my stage 2 injectors cleaned soon, and i will post the results. good info in this thread.
for what its worth, i recently had my stock 04 injectors cleaned at 58psi with heptane at a local performance shop, the end result was suprising. each injector flowed atleast 600cc/min, opposed to the listed 577. even before the cleaning, they flowed over 577.
im going to be getting my stage 2 injectors cleaned soon, and i will post the results. good info in this thread.
A 3%-4% variance from the "quoted" flow rate for production units is more than acceptable. Good to know for reference but even a +/- 5% difference is common. Heck, even the pressure gauge on the cleaning machine could be "off" more than that to skew your injectors flow rate up/down a bit.
Its best to be off a bit as long as all the injectors are off the same amount.
MP used to sell "matched" sets of injectors that were +/- 1% from one another. (571cc/min-582cc/min for srt)
for what its worth, i recently had my stock 04 injectors cleaned at 58psi with heptane at a local performance shop, the end result was suprising. each injector flowed atleast 600cc/min, opposed to the listed 577. even before the cleaning, they flowed over 577.
im going to be getting my stage 2 injectors cleaned soon, and i will post the results. good info in this thread.
ok guys got the stage 2 injector results, they averaged out to be about 715cc/min @ 4 bar with heptane test fluid.
my 04 stock injectors averaged out to be 605cc/min @ 4 bar with the same test fluid.
hope this helps people searching in the future. so it seems adding a fuel return line and a 1:1 rising rate regulator would be the better than adding straight 650s or 750, just seems like the stockers and/or stage 2/3s would be more of a bargain and OEM quality.
i plan on maxing out my 715s, agp return line and 255 pump with my 3147 kit, ill post those results after i get a clutch
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