How to properly size your fuel injectors - Dodge Caliber SRT-4 Forums

macsperformance · 08-05-2006, 08:45 PM

How to properly size your fuel injectors!

INJECTOR SIZING

Engine Power @ Flywheel X BSFC / (# of cylinders) = Required lbs per hour

BSFC = Brake Specific Fuel Consumption

For BSFC you can use these numbers as a *safe guideline*
Naturally aspirated engines .45 - .50
Supercharged or Turbocharged engines .55 - .65

Here is an example:

(400 HP X .5 BSFC) / 4 = 50 lbs/hr

Now keep in mind this equation is for a 100% duty cycle. If you desire a 80% duty cycle than multiply the number by 1.2. For a 70% duty cycle multiply by 1.3

Here is an example:

50 X 1.20 = 60 lbs/hr

It would take 60 lb/hr injectors to make 400 HP at a 80% duty cycle!

Here is the lb/hr to cc/min conversion:

lbs/hr to cc/min
lbs/hr X 10.2 = cc/min

here is an example:
30lbs/hr X 10.2 = 306cc/min

cc/min to lbs/hr
cc/min / 10.2 = lb/hr

here is an example:
306cc/min / 10.2 = 30lbs/hr

Thank You
Chris Macellaro

bjeffries · 08-05-2006, 08:47 PM

Um...will someone explain what this means to the little blonde girl who is clueless

macsperformance · 08-05-2006, 08:56 PM

Hi... lol

Thank you for visiting this section of the forum. In many engine build-up projects power levels are increased over a factory vehicle so larger fuel injectors are needed to feed the engine. The above equation is a good guideline for people to use when they need to find the proper sized fuel injector.

thank you for your question
Chris Macellaro

bjeffries · 08-05-2006, 08:58 PM

Thank you sooo much

I feel much better now. I understood once you told me WHY I needed to know that.

macsperformance · 08-05-2006, 09:01 PM

Quote:

Originally Posted by bjeffries

Thank you sooo much

I feel much better now. I understood once you told me WHY I needed to know that.

Thank you for the kind welcome!

Chris Macellaro

08-05-2006, 08:45 PM	#1 (permalink)
macsperformance Supporting Vendor Join Date: Aug 2006 Location: Arlington, Texas Posts: 52	How to properly size your fuel injectors How to properly size your fuel injectors! INJECTOR SIZING Engine Power @ Flywheel X BSFC / (# of cylinders) = Required lbs per hour BSFC = Brake Specific Fuel Consumption For BSFC you can use these numbers as a safe guideline Naturally aspirated engines .45 - .50 Supercharged or Turbocharged engines .55 - .65 Here is an example: (400 HP X .5 BSFC) / 4 = 50 lbs/hr Now keep in mind this equation is for a 100% duty cycle. If you desire a 80% duty cycle than multiply the number by 1.2. For a 70% duty cycle multiply by 1.3 Here is an example: 50 X 1.20 = 60 lbs/hr It would take 60 lb/hr injectors to make 400 HP at a 80% duty cycle! Here is the lb/hr to cc/min conversion: lbs/hr to cc/min lbs/hr X 10.2 = cc/min here is an example: 30lbs/hr X 10.2 = 306cc/min cc/min to lbs/hr cc/min / 10.2 = lb/hr here is an example: 306cc/min / 10.2 = 30lbs/hr Thank You Chris Macellaro __________________ Macellaro's Performance Tuning Freelance Traveling Automotive ECU Tuning Services www.macellarosperformancetuning.com chris@macellarosperformancetuning.com 817-542-4151 Instructor for EFI University www.efi101.com/contact.html World Wide Freelance Tuning Service Overview Last edited by macsperformance : 03-13-2008 at 12:11 AM.

08-05-2006, 08:47 PM	#2 (permalink)
bjeffries Senior Member Join Date: Jul 2006 Location: Indianapolis Posts: 182	Um...will someone explain what this means to the little blonde girl who is clueless __________________ Marine Blue Caliber, SXT Indianapolis, IN

08-05-2006, 08:56 PM	#3 (permalink)
macsperformance Supporting Vendor Join Date: Aug 2006 Location: Arlington, Texas Posts: 52	Hi... lol Thank you for visiting this section of the forum. In many engine build-up projects power levels are increased over a factory vehicle so larger fuel injectors are needed to feed the engine. The above equation is a good guideline for people to use when they need to find the proper sized fuel injector. thank you for your question Chris Macellaro __________________ Macellaro's Performance Tuning Freelance Traveling Automotive ECU Tuning Services www.macellarosperformancetuning.com chris@macellarosperformancetuning.com 817-542-4151 Instructor for EFI University www.efi101.com/contact.html World Wide Freelance Tuning Service Overview Last edited by macsperformance : 08-05-2006 at 09:02 PM.

08-05-2006, 08:58 PM	#4 (permalink)
bjeffries Senior Member Join Date: Jul 2006 Location: Indianapolis Posts: 182	Thank you sooo much I feel much better now. I understood once you told me WHY I needed to know that. __________________ Marine Blue Caliber, SXT Indianapolis, IN

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