I`ve got KG parts primary and secondary fuel rails. I have a pair of greddy/denso 720cc injectors and bosch 1600cc injectors both low impedence. My bosch injectors fit perfectly. My denso injectors, I bought them from a forum member after he got them rebuilt with new o-rings and grommets on them. He was using them on stock fuel rails. I`ve got some new o-rings and grommets from Mazda on me that I bought a few months ago. I tried installing them with the mazda o-rings and they fit but not as tight as the bosch injectors.

Basically I wanna know what o-rings should I get for my denso injectors to have them installed in my primary fuel rail. The stock mazda grommets seem to fit fine but of course it`s better safe than sorry.

 

soak them in oil a lil bit and that makes them a lil more poofy.

 

Is that what everyone does ?

 

no, but how loose are they? i had to use two bungs for my primaries because it wouldnt mount tight. maybe thats what you mean?

 

Why are you using a KG primary rail? Those rails are for top feed Bosch style injectors, which are larger. Just use the stock s4 rail. Otherwise you will have to buy Bosch style injectors for the primaries or figure out some way to make the smaller Denso injectors seal properly.

The bosch injectors use their own different sized o-ring for the upper part that goes into the rail. Go to an autozone and ask for fuel injector o-rings from an early 2000's Ford F-150. They work perfectly. The lower part of the Bosch injectors... well it depends how you have them set up. What I do is I use the OEM lower grommet and the OEM s5 pintle cap on the bottom. You have to remove the blue, yellow, and orange crap on the bottom of the Bosch injectors. I have had no fuel or vacuum leak problems with that setup.

jumper the fuel pump check connector (yellow two-prong connector on passenger shock tower) with the UIM off and key in the on position. That will pressurize the fuel system and tell you if you are leaking fuel. With the UIM on you can pressurize the intake with a pressure tester (something similar to the universal tester sold at www.boostpro.net/prodtester.html ) and see/feel if air is leaking out of there.

 

I'm using KG primary rail because it was included in the kit that I bought from a forum member. Your method of using the OEM lower grommet and the OEM s5 pintle cap on the bottom doesn't work for me. Anyone here ever experimented finding proper o-rings to fit 720cc denso injectors on a KG parts primary fuel rail ?

 

why dont you email kg parts and see what they recommend? keith is on the forum too. i think using the stock primary rail would be the smart/easy thing to do. i am using 720/1600 injectors with the stock rails. witchhunter will modify the 1600's for 5 bucks each so they fit.

 

Denso 720's are NOT supposed to be used in a KG rail. The KG rail is for Bosch style injectors which are larger. That's what I've been trying to say. You need a rail for Denso injectors (like the stock one).

OEM grommets and s5 pintle caps are for installing Bosch injectors in the KG secondary rail. I'm sorry if I was misleading.

 

Well whether or not Denso injectors are NOT made to go in a KG rail. It's still an injector that's gonna go there. I test fitted the o-rings from the bosch injectors on the denso's on both the primary and secondary rails. I just need an o-ring that 's a touch thicker to make it fit.

 

Then get a hold of Keith at KGParts. (that is keith@kgparts.com)and explain what you are doing,since you are using HIS rail,he should be able to give you some answers or advice on how to go about it Roman.Cheers,Dave.

 

Is it? That will be at your own risk. I have seen people do this to save a few bucks on buying a Bosch style injector. THE RAIL IS NOT MADE TO ACCEPT OEM INJECTORS.

putting a larger o-ring to seal the injector into the rail "can" seal the o-ring, BUT it also "can" lead to a HUGE problem latter on. The Bosch style (American) injectors have a much larger ledge to hold the o-ring in place. Putting this same, much larger o-ring on a denso style injector can lead to the o-ring rolling over the ledge as it is about 3 times larger than the ledge on the injector. It may seal at idle with a lower base fuel pressure, but one you start driving, getting into boost, increasing the pressure, there is basically nothing to hold that o-ring IN the rail creating the seal. Do you really want to risk the o-ring rolling over, causing a fuel leak while the fuel pressure is increased spewing fuel all over a hot engine bay? If so, again, do it at your own risk.
If you do want to replace the o-ring, as stated, you can pick them up almost anywhere as it would be a standard replacement for most any American injector.
I would NOT recommend doing it, but if you are going to be suborn about it, I have seen people use several o-rings on the lower portion of the top of a denso injector to build up the missing ledge. Again, I am not recommending it, but if you are going to be "smarter" than everyone else, be safe.