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Hi Everyone,
I am usually on the C7 Forum side but I have been helping a friend out with his car.
He has a Holley Sniper EFI syst
The big question we have is where would you mount the O2 sensor? Holley says it needs to be pointed downward, so that leaves out mounting on the bottom of the exhaust collector before the muffler. Seems like the only place is on one of the individual tubes?
It needs to be pointed downward for corrosion. I've seen it installed just after the collector at a downward angle entering at 4 o'clock on the circle.
Dunno if that works for you, as the frame rail may be in the way, but it is hidden.
there has been problems discussed about your situation.
collector is best and as long as it , O2 , doesn't hold moisture when engine off, you will be ok.
also discussion about a "shielded" O2 using adapter
This might have been the thread, or a different one. It may be up to the specific geometry of your car if you can get it angled down, while still hidden.
If you search the C3 forum, you'll find several threads regarding this exact same situation. You have basically two choices:
Place the O2 sensor in the collector in an upright position - which will be exposed / visible on the top of the side pipe. This would be more "ideal", but less desirable.
Place the O2 sensor on the side (possibly with a slightly downward angle) and install it slightly below the frame. (As pictured)
There are folks who have done it both ways. Doing the latter way can (but won't necessarily) lead to premature O2 sensor failure due to thermal shock from moisture build up on the sensor.
I personally did it via option #2, and I have over 5000 miles on that O2 sensor. I would recommend using this O2 bung extender (which is really a heat sink / flow port): the HBX-1
Using the HBX-1 and "hiding" my O2 sensor has worked flawlessly. However, the counter-point always cites the "moisture failure" due to non-ideal mounting angle. In my experience, that just hasn't happened yet. Perhaps the O2 sensor won't make it to 100,000 miles, but at the rate I put miles on my C3, It'll take me 25 years to fail a sensor this way. By the way, I am not running the "Holley Provided" O2 sensor, that actually was erratic out of the box - so I got rid of it. Been on the "non Holley" sensor ever since.
Sniper EFI
