injector size ?....please help
Thread Starter
Staging Lane
iTrader: (4)
Joined: Aug 2008
Posts: 91
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From: Hometown, Illinois
injector size ?....please help i have done all the caculations on the lbs/hr and for around 530 hp i will need the 65 lbs/hr injectors to run about 80% duty cycle...which they cost about $45 each....in the future i plan on addin boost once the motor is built stronger...and to prevent buying higher lbs/hr injectors then....can i just go with the 80 lbs/hr injectors now and run them at a lower % duty cycle untill i want more boost....or is there some sort of an efficency problem if they are not at 80%???? can someone please simplify this for me
Yes, you can run 80's at a lower duty cycle. What sort of numbers are you looking for when you go boosted? To figure injector size, use the following formula:
Injector Flow Rate (lb/hr) = Horsepower x BSFC (use .60 for boost) / Number of Injectors x Duty Cycle (85% = .85)
Example: Injector Flow Rate (lb/hr) = 900hp x .60 / (8 x .85) = 79 lb/hr @ 40 PSI
To convert into 60PSI We do: Square root of (New PSI/Old PSI) * lb/hr
Example: 60/40 = 1.5, the square root of 1.5 is 1.22. 1.22 * 79 lb/hr = ~96 lb/hr
We can also do the reverse so if you're shopping for 43.5PSI rated injectors for your LSX.
Square root of (PSI Injectors are rated at/LSX PSI) * lb/hr
Example: 43.5/58 = .75, the square root of .75 is 0.86. 0.86 * 79 lb/hr = ~67 lb/hr injectors
What are your injectors rated at? 43.5PSI or 58PSI?
Injector Flow Rate (lb/hr) = Horsepower x BSFC (use .60 for boost) / Number of Injectors x Duty Cycle (85% = .85)
Example: Injector Flow Rate (lb/hr) = 900hp x .60 / (8 x .85) = 79 lb/hr @ 40 PSI
To convert into 60PSI We do: Square root of (New PSI/Old PSI) * lb/hr
Example: 60/40 = 1.5, the square root of 1.5 is 1.22. 1.22 * 79 lb/hr = ~96 lb/hr
We can also do the reverse so if you're shopping for 43.5PSI rated injectors for your LSX.
Square root of (PSI Injectors are rated at/LSX PSI) * lb/hr
Example: 43.5/58 = .75, the square root of .75 is 0.86. 0.86 * 79 lb/hr = ~67 lb/hr injectors
What are your injectors rated at? 43.5PSI or 58PSI?
Last edited by BahN; Dec 29, 2010 at 12:10 PM.
Thread Starter
Staging Lane
iTrader: (4)
Joined: Aug 2008
Posts: 91
Likes: 0
From: Hometown, Illinois
im going to by the set of 83 lbs from summit for $465 and i should be looking at around 530 to 600 crank hp. im doing the ebay front mount kit with a t4 60 mil turbo...i bought the stuff last year in march and its been sitting ever since....i am finally getting the money to finish the setup so maybe ill have a build post on here...hoping to start in march this year and have it finished in about a week if all goes well...
