fuel injector worksheets (cc/min -> lb/hr, hp calculations, etc)

gurov · 2008-10-09 13:17:46

Matching the Injector to the Engine To calculate the injector size for a particular application:

Engine Horse Power(1)
BSFC(2):
Number of Injectors:
Injector duty cycle(3):
Flow Rate:
Lb/Hr cc/min
NOTE: Unless otherwise noted, all injector flow rates are calculated at a fuel pressure of 43.5 PSI (3 BAR).
(1) Whenever possible, use actual dyno results for engine horsepower. If no dyno results are available, consult with your engine builder for a horsepower estimate.
(2) BSFC is usually a number between 0.4 and 0.7 for gasoline engines. Although BSFC can be estimated, it is best to determine an actual number on a dyno. If a dyno is not available, the following numbers can be used as a rule of thumb:

For naturally aspirated engines, estimate BSFC to be 0.4 to 0.5
For nitrous engines, estimate BSFC to be 0.5 to 0.6
For forced induction, estimate BSFC to be 0.6 to 0.7
For rotary engines, estimate BSFC to be 0.6 to 0.7
For engines running methanol, double the appropriate gasoline BSFC (e.g. a forced induction methanol engine has a BSFC between 1.2 and 1.4)

(3) Injector duty cycle should be 0.8 (80%) or LESS. Numbers higher than 80% are generally NOT RECOMMENDED. If maximum injector duty cycle is not known, use 0.8 as an estimate. Note that some factory engine controllers have substantially lower duty cycle numbers (some 2nd generation Mazda RX7 engine control modules, for example, are limited to 55-60% duty cycle.)Remember that these numbers are ESTIMATED and cannot be considered as accurate as actual numbers achieved on a dyno! Marren Fuel Injection accepts NO RESPONSIBILITY for errors made using estimated, unverified information. Always verify engine performance information on a dynamometer!

To calculate the horsepower capacity of injectors based on their flow rating:

*NOTE: This formula take into account a properly functioning fuel delivery system. Damaged components, clogged or modified injectors, insufficient fuel delivery, or other fuel system problems that alter the injector flow rates will render this formula useless!

darsondriss · 2008-10-09 14:42:56

wtf....

MajorMods · 2008-10-09 14:44:52

thats says for 310whp, i need 600cc injectors

darsondriss · 2008-10-09 14:46:54

is this page failing at embedding or is it just my comp?

gurov · 2008-10-09 14:48:54

nah, it's jacked, hang on, i'm fixing it.

speedjunkie · 2008-10-09 15:19:40

http://i69.photobucket.com/albums/i75/u … titled.jpg
not saying that your wrong pimpsmurf but the chart above says that 55 lb/hr injectors (43.5psi) will become 64.59, basically 65 lb/hr injectors when the fuel pressure is bumped to 60 psi

Last edited by speedjunkie (2008-10-09 15:20:18)

gurov · 2008-10-09 15:58:28

page fixed.

16g-95gsx · 2008-10-17 14:43:53

The problem that I see here is that you do not use rising rate FPRs, so what happens when you throw manifold pressure into the mix and your injectors effectively become smaller and smaller as boost rises?

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2008-10-09 13:17:46 (12 weeks 6 days 13 hours 1 minute 52 seconds) #1888211 | | view posts since this #1

fuel injector worksheets (cc/min -> lb/hr, hp calculations, etc)

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Re: fuel injector worksheets (cc/min -> lb/hr, hp calculations, etc)

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Re: fuel injector worksheets (cc/min -> lb/hr, hp calculations, etc)

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Re: fuel injector worksheets (cc/min -> lb/hr, hp calculations, etc)

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Re: fuel injector worksheets (cc/min -> lb/hr, hp calculations, etc)