fuel injectors
- Thread starter SplitzO
- Start date
- Replies 7
- Views 2K
We may earn a small commission from affiliate links and paid advertisements. Terms
turb2o_vtec
New Member
I'll say at leat 750cc or higher.
spoolin@idle
D Series FTL
baddabing. he speaks the truth. its all about the power numbers.
Injectors and Fuel Supply
click there, then scroll down and see the chart. and don't forget to add the 10% based on the duty cycle necessary for turbo setups.
Or...
Minimum Injector Size (READ NOTE ON BOTTOM) = [max airflow you want/expect (lbs/min)] / [AFR you want to run] x [454 g/lb] / [.76g/mL for pump gas] / [# of injector] / [max IDC you want to see]
Or simplified:
[max airflow you want/expect (lbs/min)] / [AFR you want to run] / [max IDC you want to see] x 149.34 (for 4 injectors)
e.g. You want to flow 30 lbs/min and run a 10.5:1 AFR and want to keep your IDC below 80%.
30 / 10.5 / 0.8 x 149.34 = 533 cc/min. Round up and you get 550 cc/min injectors.
Taking note that 1 lb/min of airflow is roughly equivalent to 9-11 crank horsepower (so say 10), you can use this to estimate injector size based on your power goals.
NOTE: The nature of these calculations are highly theoretical and thus you should apply a safety margin at all times when using these calculations. These calculations do not take into account every real world situation and there are about a billion things that could screw these numbers up. On the other hand, you get a good approximation of what you need. Always use a safety margin of 10-20% if you actually do use this (meaning divide your final answer by .90 or .80, meaning the above 533 cc/min would go to 592 cc/min or 666 (zomg!)cc/min depending on what you divided by).
This also assumes that you run 43 psi base fuel pressure which is what almost every injector company gives out their ratings based on. E.g. RC 550cc injectors are meant to flow 550cc at 43 psi base. If your base fuel pressure is 33 then they will perform like 481cc injectors.
Minimum Injector Size (READ NOTE ON BOTTOM) = [max airflow you want/expect (lbs/min)] / [AFR you want to run] x [454 g/lb] / [.76g/mL for pump gas] / [# of injector] / [max IDC you want to see]
Or simplified:
[max airflow you want/expect (lbs/min)] / [AFR you want to run] / [max IDC you want to see] x 149.34 (for 4 injectors)
e.g. You want to flow 30 lbs/min and run a 10.5:1 AFR and want to keep your IDC below 80%.
30 / 10.5 / 0.8 x 149.34 = 533 cc/min. Round up and you get 550 cc/min injectors.
Taking note that 1 lb/min of airflow is roughly equivalent to 9-11 crank horsepower (so say 10), you can use this to estimate injector size based on your power goals.
NOTE: The nature of these calculations are highly theoretical and thus you should apply a safety margin at all times when using these calculations. These calculations do not take into account every real world situation and there are about a billion things that could screw these numbers up. On the other hand, you get a good approximation of what you need. Always use a safety margin of 10-20% if you actually do use this (meaning divide your final answer by .90 or .80, meaning the above 533 cc/min would go to 592 cc/min or 666 (zomg!)cc/min depending on what you divided by).
This also assumes that you run 43 psi base fuel pressure which is what almost every injector company gives out their ratings based on. E.g. RC 550cc injectors are meant to flow 550cc at 43 psi base. If your base fuel pressure is 33 then they will perform like 481cc injectors.
Here are the basic number we use when suggesting injectors for our customers...
Flow Rate vs. HP Level
(Flow Rate for each injector,
in a four cylinder setup.)
310cc 200~220whp
370cc 220~280whp
440cc 280~330whp
550cc 330whp~380whp
660cc 380whp~425whp
720cc 425whp~475whp
880cc 475whp~525whp
980cc 525whp~600whp
Flow Rate vs. HP Level
(Flow Rate for each injector,
in a four cylinder setup.)
310cc 200~220whp
370cc 220~280whp
440cc 280~330whp
550cc 330whp~380whp
660cc 380whp~425whp
720cc 425whp~475whp
880cc 475whp~525whp
980cc 525whp~600whp
