First off this is my first post and I have searched, so be gentle with me. I am finishing my T78/ clutch/ fuel/etc install. I have the power FC, upgraded lines, inline pump, injector connectors, resistors, and 1600cc injectors. I am trying to buy some cost effective primary injectors. The only one’s I’ve found that I know will work are the Greddy 720cc on the rx7store.net ($110 ea). Does anyone know where to buy some low impedance Bosch /Bosch-style 72 lb/hr- 85 lb/hr top feed injectors? I have looked at jegs and summit and they don’t seem to have any. Jeg’s has Holey(Bosch-style) 85 lb/hr injectors for $64.99ea and 75 lb/hr for $74.99. But they don’t say if they are low impedance. All they say is "Holley fuel injectors are all top-fed, Bosch-style to replace common application such as TPI, LT1, Mustang 5.0, etc. 1/pkg." Will these kind of injectors work?

http://www.jegs.com/cgi-bin/ncommerc...62&prmenbr=361

Where is a good place to buy ford injectors or Bosch injectors online? I have done a few google searches and come up with sites that either don’t look reputable or don’t have much info. This is the best one I found….

http://injector.com/fuelinjectors.php

But they don’t mention the brand and I’m not sure if these would be new.

I also noticed they have 1600cc low impedance injectors. I heard that those don’t exist (this is why we need to use resistors right?).

Anyone have any ideas or experience on this subject?

 

i'm running a t78 with 550/1600 combo, but my injector duty is already too high. many people just run the stock 850's in the primary location until they have a need for higher boost levels. they're not a direct drop in, but it's not too hard

 

My goal was to build a system that would be good for most any street hp level. I didn’t want to use the stock injectors because I already bought new fuel rails and new fittings/ lines.

 

oh, i didn't know you had an upgraded primary rail. i am going to go with 1000cc's as soon as i get a new rail. should be good for up to 26psi and a good tune. i can't remember where i seen them, but i found some siemens top feed 1000cc injectors for $100 a piece

 

You are confused about impedence. This is the deal:

1. Stock injectors are high impedence.
2. All "1600" injectors are low impedence.
3. You need to run resistors with low impedence injectors (with PowerFC, etc. -- however, some aftermarket stand-alones can run low impedence injectors without resistors)

So, if you buy those top-feed injectors for the primaries, you can use them no matter what the impedence is. You can check the injectors by measuring the resistance. If they are low impedence (<10 ohms), run resistors just like you will need to do for the 1600s. If they are high impedence (>10 ohms), you don't need resistors.

-Max

 

Thanks for the correction. I got mixed up. So I need to find some high impedance top feed injectors that flow 72-85 lb/hr or use resistors like with the 1600’s. Can anybody see a need to go bigger? I have seen some people with 4 1600cc injectors. Is this over kill for the street? I plan to run about 15-18 lbs of boost when I tune, maybe more latter. I think I’ll be fine with some 720-850cc. Can anybody recommend a site to buy these injectors?

 

Also, should I actually measure the resistance and calculate the needed resistor or blindly follow the common 10 ohm\10 watt resistor suggestion I saw posted for the low impedance injectors. Thanks for your imput!

 

10 ohm / 10 watt is probably a safe bet for any injectors, but it wouldn't hurt to do the measurements and calcs just to verify it for your setup.

You can calculate fuel system capacity on this web page I made:
http://www.maxcooper.com/rx7/how-to/...tem/calcs.html

-Max

 

Weitzel you rx-7 n00b. Are you and margrave down there trying to blow that damn thing up? How many drill bits did it take to get that stud out of the Exhaust manifold? Good luck with the rest of the build. If you ever find time to catch up with old neighbors you should call them.