how to figure out size of injectors needed?

[Stretch]

I want to know how one would figure out the proper size injectors to use. Is everyone just going 550 cause it's been proven to be good? If as it currently is, my goal is around 550, should I run 680's or 720's? Or should I be seeking larger. I just don't really know how to figure it out.
eric

 

[chevyeater]

There is a nice calculator on this page, along with all the information you need to use it properly- http://www.rceng.com/technical.htm

 

[Shawndude]

Tons of injector sizing calculators online. Try a few. But people usually use injectors to get around fuel cut, rather than just for getting the extra fuel.

http://www.witchhunter.com/injectorcalc1.htm

 

[Stretch]

I did it and got 601 cc/min needed, so i guess I would then get the 680's and use some sort of fuel controller, possibly the afc?
eric

 

[GrimJack]

680s should be capable of just over 600 at the wheels. You're going to need a lot more than a fuel computer to run them, though. At that level, I'd seriously suggest just biting the bullet and getting a standalone engine management system.

 

[SidewayzSupra]

AEM makes a great stand alone for around$1,600(Ebay)or$1,800-2,000 on other sites. If your going piggyback don't forget you should also run dual electric fuel pumps, with a fuel pressure regulator to keep track of fuel pressure. With bigger then 550cc injectors you'll have harder tuning problems. Whith bigger injectors your going to need more air(bigger turbo,custom intake manifold) Our stock manifolds don't flow to well. With the right tuning and upgrades you should be able to hit 550crank hp with the 550cc injectors. Hope this helps. Later-T

 

[Ckanderson]

The rule of thumb (or wrist) is the size of your injectors = the amount of HP you can make off of them. some do more, some do less. Pass1914 did 500 hp on jdm 440's IIRC. this rule ONLY applies to 6 cylinders though... thats why WRX's have to run like 720's to get 450 hp.

 

[IHI-RHC7]

The rule of thumb (or wrist) is the size of your injectors = the amount of HP you can make off of them.

I just got done watching Boondock Saints,, ahh, I laugh.
Yeah, 550s are good to 500hp with good tuning. EGTs are the big thing to watch out for. As long as you keep egts low, then you can lean the mixture out a bit, and get a really low BSFC. I'll be running 680s or 720s with the new motor, with twin walbros feeding a stock rail with a single return where the CSI usually goes.
My dad and I have had great luck with this setup. and yes, AEM EMS is the shit. Go through HPF and get their full AEM kit with wideband, Map sensor, Boost control selenoid, IAT sensor, and,,, other useful things. Even without our beloved Joe, HPF still rocks the casbah on prices and service.

 

[Ckanderson]

orr go thru a forum sponsor here... Such as AAP.....

 

[malloynx]

hmm something is not right. the site told me i need 650cc injectors for 500hp.

 

[GrimJack]

Agreed - something is not right there.

 

[drjonez]

don't forget the 7M loves fuel....