# Fuel Injector Sizing?

**URL:** <https://forums.speedlife.net/t/fuel-injector-sizing/49685>\
**Category:** NYSpeed Automotive\
**Created:** [June 7, 2008, 4:55pm UTC](https://forums.speedlife.net/t/fuel-injector-sizing/49685 "2008-06-07T16:55:52Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![jetlounge](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jetlounge/32/4994_2.png) [@jetlounge](https://forums.speedlife.net/u/jetlounge)\
**Post date:** [June 7, 2008, 4:55pm UTC](https://forums.speedlife.net/t/fuel-injector-sizing/49685/1 "2008-06-07T16:55:52Z")

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The scion tc s/c kit comes with 400cc injectors. No upgrade on the fuel pump.

I am wondering if those are sized properly, so I used :  
[http://www.injector.com/injectorselection.php](http://www.injector.com/injectorselection.php)  
and  
[http://www.rceng.com/technical.aspx](http://www.rceng.com/technical.aspx)

Crank HP: I played with between 230 - 250. The S/C consistently gets 198-200 at the wheels, many user dyno’s confirm this…so I backed out an estimate for drivetrain loss. Not sure about that number though

Injectors: 4  
Consumption: It said to use between .55 and .60 for an s/c application  
Duty: .80 (i left the default max)

Seems 400cc is low. Am I doing this correctly?

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**Author:** ![ubengineering](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/ubengineering/32/5171_2.png) [@ubengineering](https://forums.speedlife.net/u/ubengineering)\
**Post date:** [June 7, 2008, 9:43pm UTC](https://forums.speedlife.net/t/fuel-injector-sizing/49685/2 "2008-06-07T21:43:58Z")

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400cc in a kit seems like plenty for that sort of power, but im surprised theres no pump upgrade but if its a well known kit i wouldnt worry, except that you wont have a warranty anymor but the year of the vehicle isnt specified so maybe you dont have one anyways

a hahn stage 2 kit with a s16g for talons, eclipses, and neons use a booster pump and STOCK injectors of only 190cc to make around 275 crank horse, extremely low cc’s for boost applications, but somehow it works, 400 is plenty unless its something you picked offa ebay for 900$

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**Author:** ![jetlounge](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/jetlounge/32/4994_2.png) [@jetlounge](https://forums.speedlife.net/u/jetlounge)\
**Post date:** [June 8, 2008, 4:55am UTC](https://forums.speedlife.net/t/fuel-injector-sizing/49685/3 "2008-06-08T04:55:38Z")

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its a 2006…and its a trd kit, which means it has a full warranty…well, provided no changes are made to it.

anyway, so you are saying those fuel injector formulas on the web give much higher requirements than actually needed…why is that?

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**Author:** ![dftsilvia](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/dftsilvia/32/7447_2.png) [@dftsilvia](https://forums.speedlife.net/u/dftsilvia)\
**Post date:** [June 9, 2008, 9:38am UTC](https://forums.speedlife.net/t/fuel-injector-sizing/49685/4 "2008-06-09T09:38:46Z")

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if its a trd kit im sure thats more than enough. they just dont slap shit together exspecially if it keeps the factory warranty.

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**Author:** ![OriginalSterm](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/originalsterm/32/4964_2.png) [@OriginalSterm](https://forums.speedlife.net/u/OriginalSterm)\
**Post date:** [June 9, 2008, 10:22am UTC](https://forums.speedlife.net/t/fuel-injector-sizing/49685/5 "2008-06-09T10:22:22Z")

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the injector rating is at a certain pressure. typically 3 bar. if you run more than that pressure, you’ll get more than 400cc flow. but, as fuel pressure increases you decrease fuel pump capacity.