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1600cc Bosch RX7 Fuel System Upgrade

I have noticed that a possible amount of 3 stock o-rings can fit on the 160 lb/hr 1600cc BOSCH fuel injectors after the grommet is in place. Do you think tripling up the o-ring seals would be a bad idea? I don't think so. I'll try it.

The stock RX7 grommet is a terrible seal because it has alot of slack along the injector, as well as overlaps the plastic base slightly when compressed. IMO, the grommet does nothing with the 1600cc except reduces vibration wear. I have a set of an 82 VW RABBIT fuel injector o-rings that are rather big, but would work better with the grommet and would work as a better seal. Only problem is, I would need to cut more of the fuel injector plastic stuff off. Pretty much just cut 3/4 of the plastic stuff off and leave 1/3 of the injector ribs.


             Stock 550cc                   1600cc with cap on bottom

The goal is to make the Bosch 1600cc fuel injector on the right to match the stock RX7 fuel injector on the left. You can use a dremal cutting tool to trim the two upper plastic ribs off. Be very careful not to nick the metal shaft and gouge it. This will cause a bad seal and result in leaking. I will be using 3 o-rings instead of one in the picture above. I would just hate to see an engine fire AGAIN!


       1600cc trimmed                  1600cc trimmed o-ring

                                                  stock o-rings & seals

Next, take out the green o-ring in the left picture above with a razor. Insert all of the stock o-rings in their correct order. The upper gap that holds the 11mm stock OEM Mazda o-ring can hold three. Leave the orange spacers against the bottom plastic (yellow) instead of against the body of the injector where it was. You can use the image on the right (above) to see the color scheme.
-Note: I like a tight seal, so I used three. Some people use two, and some use one. I think: The more, the better! Don't be cheap and use 3! Fuel fires suck!


1600cc finished                               Stock 550      

Here are images of the o-rings with the VW rabbit assisting int he spacing and sealing. In my opinion, it works even better than the above modification!!!!

Here is a rewrite if what I did than the above modification:

Socketless Hose and Fittings:

Bottom Side:
I used 2 (82/84?)VW rabbit fuel injector o-rings on the bottom of each injector. TIGHT SEAL!

On the upper

From bottom to top. I did the dremal mod to the injector.


1 (82/84?) (it's green) VW o-ring at the base, then 3 stock o rings on the other side of the lip.

The green VW o-ring has a tight seal on the injector on the inside and on the fuel rail upper, but lower it might now seal well, but doesn't matter since the inner is sealed. I guess with the VW injector seal and the stock seals, this kind of works like a double seal with the addition of 2 more stock injector o-rings.


I tried the mod with just 1 stock seal, and the seal leaked like a chopped up garden hose. Pretty scary how it sprays all over the engine bay.

AN fitting are welded to rails.

I chopped off my fuel rail ends, tapped them to 5/8 thread, and put some aluminum -AN fittings on them and had them welded for $30 with a TIG. Can't beat that! Then I paid $75 for socketless fittings and hose stuff. ouch!


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