Math injectors
#3
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read other peoples list o' mods and it'll give you a good idea.
but for a starter we need to know the turbo you want to use. from that we can figure out how much air yours sucking. then you'll need 1/12 as much fuel. add 20% flow to keep your injectors below an 80% duty cycle. then you'll need a fuel pump that moves enough volume at the at your boost level plus your base pressure (40psi). anything bigger then a walburo pump and you'll need to upgrade your FPR and your FPD.
but for a starter we need to know the turbo you want to use. from that we can figure out how much air yours sucking. then you'll need 1/12 as much fuel. add 20% flow to keep your injectors below an 80% duty cycle. then you'll need a fuel pump that moves enough volume at the at your boost level plus your base pressure (40psi). anything bigger then a walburo pump and you'll need to upgrade your FPR and your FPD.
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Go to the "Fuel Injector Worksheet" at the bottom of this web page.
http://www.rceng.com/technical.aspx
Here is a general guide:
HP = Horsepower at the flywheel
Number of Injectors = 4 if you are using the same size of injectors for both primary and secondary. Otherwise, enter 1 and that way the calculator will give you your total required flow. Then you can figure out what combination of the fuel injectors would meet that requirment.
BSFC = .55 for NA, .64 for low boost, .70-.80 for high boost.
Maximum Duty Cycle = .80
Fuel Pressure = 37psig for the stock FPR, or enter your custom value if you have an aftermarket FPR.
http://www.rceng.com/technical.aspx
Here is a general guide:
HP = Horsepower at the flywheel
Number of Injectors = 4 if you are using the same size of injectors for both primary and secondary. Otherwise, enter 1 and that way the calculator will give you your total required flow. Then you can figure out what combination of the fuel injectors would meet that requirment.
BSFC = .55 for NA, .64 for low boost, .70-.80 for high boost.
Maximum Duty Cycle = .80
Fuel Pressure = 37psig for the stock FPR, or enter your custom value if you have an aftermarket FPR.
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the smaller the injector the better it is for fine tuning. 550cc injector = 0.0091 cc per millisecond. 1600cc injector = 0.0267cc/ms, smaller injectors will also atomize the fuel better, not much more horse power but you'll gain like 10-15km to a tank.
try not to make your secondary injector more then twice the size of teh primary, like a 550primary and a 1600secondary, this combination tends to create hesitations when you roll into throttle, depending on your EMS and tuner.
go with a 550 and 1000, or 860 and 1600. and if your running a large frame turbo use 1000 and 2200cc. thought people do make 1600 and 1600cc work.
try not to make your secondary injector more then twice the size of teh primary, like a 550primary and a 1600secondary, this combination tends to create hesitations when you roll into throttle, depending on your EMS and tuner.
go with a 550 and 1000, or 860 and 1600. and if your running a large frame turbo use 1000 and 2200cc. thought people do make 1600 and 1600cc work.
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One I found a while back that is fun to play with:
http://rx7.com/cgi-local/2ndgencalc.cgi
http://rx7.com/cgi-local/2ndgencalc.cgi
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Go to the "Fuel Injector Worksheet" at the bottom of this web page.
http://www.rceng.com/technical.aspx
Here is a general guide:
HP = Horsepower at the flywheel
Number of Injectors = 4 if you are using the same size of injectors for both primary and secondary. Otherwise, enter 1 and that way the calculator will give you your total required flow. Then you can figure out what combination of the fuel injectors would meet that requirment.
BSFC = .55 for NA, .64 for low boost, .70-.80 for high boost.
Maximum Duty Cycle = .80
Fuel Pressure = 37psig for the stock FPR, or enter your custom value if you have an aftermarket FPR.
http://www.rceng.com/technical.aspx
Here is a general guide:
HP = Horsepower at the flywheel
Number of Injectors = 4 if you are using the same size of injectors for both primary and secondary. Otherwise, enter 1 and that way the calculator will give you your total required flow. Then you can figure out what combination of the fuel injectors would meet that requirment.
BSFC = .55 for NA, .64 for low boost, .70-.80 for high boost.
Maximum Duty Cycle = .80
Fuel Pressure = 37psig for the stock FPR, or enter your custom value if you have an aftermarket FPR.
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One I found a while back that is fun to play with:
http://rx7.com/cgi-local/2ndgencalc.cgi
http://rx7.com/cgi-local/2ndgencalc.cgi
The acceptable range is 34.1 to 39.8 psig, which averages to 36.95 psi, which is why I used the 37psig number earlier.
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Hmmm. Well ii have a supra pump waiting to be put in. While we are on here and discussing injectors for power. Before i upgrade the turbo i was thinking about getting a boost controler and getting more power out of the stock tiurbo. How much power would i be looking at with the boost tuned to 11 or 12psi?
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Go to the "Fuel Injector Worksheet" at the bottom of this web page.
http://www.rceng.com/technical.aspx
Here is a general guide:
HP = Horsepower at the flywheel
Number of Injectors = 4 if you are using the same size of injectors for both primary and secondary. Otherwise, enter 1 and that way the calculator will give you your total required flow. Then you can figure out what combination of the fuel injectors would meet that requirment.
BSFC = .55 for NA, .64 for low boost, .70-.80 for high boost.
Maximum Duty Cycle = .80
Fuel Pressure = 37psig for the stock FPR, or enter your custom value if you have an aftermarket FPR.
http://www.rceng.com/technical.aspx
Here is a general guide:
HP = Horsepower at the flywheel
Number of Injectors = 4 if you are using the same size of injectors for both primary and secondary. Otherwise, enter 1 and that way the calculator will give you your total required flow. Then you can figure out what combination of the fuel injectors would meet that requirment.
BSFC = .55 for NA, .64 for low boost, .70-.80 for high boost.
Maximum Duty Cycle = .80
Fuel Pressure = 37psig for the stock FPR, or enter your custom value if you have an aftermarket FPR.
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You are probably beginning to see why I recommend professional tuning.
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Hmmm. Well ii have a supra pump waiting to be put in. While we are on here and discussing injectors for power. Before i upgrade the turbo i was thinking about getting a boost controler and getting more power out of the stock tiurbo. How much power would i be looking at with the boost tuned to 11 or 12psi?
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the stock turbo I've seen reach as high as 13psi but it falls out of efficiency near redline and drops back to 10psi. so i'd say 10psi is the highest you want to run a stock turbo.
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Some people modify this by using "2" if they will always use matched pairs. For example, if the calculator comes up with 1500cc/min, that means you can use a primary/secondary combo of 750/750, 550/1000, 460/1100, etc.
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AS far as the turbo goes im getting it ported with the build. Im already creeping at 10psi without it dropping it just stays there until i let off ofcourse. Speaking of which does anyone make an upgraded waste gate actuator for the stock turbo? I want to run a boost controler when its ready.
Last edited by Linguo415; 01-19-11 at 02:33 PM.
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