Just wondering what brand you guys are using for your primaries. I can't seem to find a 720cc made by bosch and the Greedys are stupid expensive.

I found a set on Five-o-Motorsports. They are 83lbs/hr (850cc) by Siemens. Are they any good? $148.77 USD per pair.

 

Most 850s are the stock secondaries used either in a modified stock primary rail, or used with extra "O" rings.

A search will explain it all!

 

I am using 83lb Siemens injectors. I purchased the injectors and rail from KGparts. Initially, I was using them with 10ohm resistors and couldn't get the car to start after making the usual injector size/lag time adjustments. I then switched to 5 or 4 ohm resistors (it has been awhile) and the car started without a problem, but required a fair degree of tuning to get the afrs back to normal. I spoke to another forum member that used 72lb Siemens injectors with 10ohm resistors and didn't have a problem, so the complications I experienced might be due to my car rather than the injectors.

fwiw -I went with the 83lb low impedance injectors instead of the stock 850s because Demetrios said that they work better at low duty cycle settings. My car idles at 13.75:1 at 950rpms with a duty cycle value around 3.3%.

 

chuck is refering to a FD by the way. I believe you have a T2. The rx7store sells the 720's for $110 each....how cheap were you expecting. I dont consider that all that expensive

http://www.rx7store.net/index.asp?Pa...ROD&ProdID=646

 

the answer to your question is yes, they are good injectors. They however do not fit the aftermarket T2 rails. You can use GSLSE secondaries, or buy the ones Stephen refers to. You can also buy any number of other brands, venom, Rc, Marren etc. The style is a top feed "import style". Look at a picture of a Bosch 1680, that is what you need but in a 720/850. As far as tuning, a 720, or an 850 are really no different, you will just have a shorter duration on an 850. What is your target HP, and on what turbo? carl

 

Carl,

I'm looking for 400-450rwhp on a TD07 25G. I'm using a Haltech E6K. Will I need to use resistors with the 850cc as mentioned above? And you are correct, I have an S5 FC3s TII. Street Ported rebuild w/ 3mm apex seals and supporting mods. 400 here I come!

Thanks for the help.

 

The 850s will work with the E6K, you need low impedance ~4-5 ohm injectors, and no resistors.