I'm installing a Defi unit with an oil pressure sensor. I want to keep the OEM oil pressure sensor so my dash gauge works. Here is what I came up with for the oil pressure sensor location (see picture). Just had the OEM sensor port drilled all the way through, and tapped with 1/8 BSPT. It looks like it will clear everything fine, so I'll update you guys on how it works once the car is running.
When researching for oil pressure sensor locations, I came across 1/8 NPT and 1/8 BSPT (aka, BPT). It turns out that most (if not all) euro and japanese sensors are 1/8 BPT, while US uses 1/8 NPT. I went to Earl's to find some adapters to splice in the Defi sensor, and they said they couldn't help me since it was all 1/8 BPT ports.
Note:
1/8 BPT has a thread pitch of 28 (28 threads per inch)
1/8 NPT has a thread pitch of 27
So it's close, but not quite.
After looking around online, it seems a lot of guys just thread in 1/8 BPT sensors into 1/8 NPT ports. This not recommended since it doesn't fit well, but with a bit of thread sealer, it seems to work for most. Still though, I want it done right so I tapped in the correct size.
Anyways, just giving you guys a heads up. I didn't know about this until now, and it seems like a lot of guys installing sensors don't know the difference.
Note:
The OEM oil pressure sensor on my 91 NA1 does not have tapered threads.
Most aftermarket sensors (including Defi) do have tapered pipe threads.
So, if you try to screw in a Defi sensor into the OEM sensor port, it will only go in a few turns before binding. I consider this unsafe. You'll need an adapter, or do what I did.
Mike B
When researching for oil pressure sensor locations, I came across 1/8 NPT and 1/8 BSPT (aka, BPT). It turns out that most (if not all) euro and japanese sensors are 1/8 BPT, while US uses 1/8 NPT. I went to Earl's to find some adapters to splice in the Defi sensor, and they said they couldn't help me since it was all 1/8 BPT ports.
Note:
1/8 BPT has a thread pitch of 28 (28 threads per inch)
1/8 NPT has a thread pitch of 27
So it's close, but not quite.
After looking around online, it seems a lot of guys just thread in 1/8 BPT sensors into 1/8 NPT ports. This not recommended since it doesn't fit well, but with a bit of thread sealer, it seems to work for most. Still though, I want it done right so I tapped in the correct size.
Anyways, just giving you guys a heads up. I didn't know about this until now, and it seems like a lot of guys installing sensors don't know the difference.
Note:
The OEM oil pressure sensor on my 91 NA1 does not have tapered threads.
Most aftermarket sensors (including Defi) do have tapered pipe threads.
So, if you try to screw in a Defi sensor into the OEM sensor port, it will only go in a few turns before binding. I consider this unsafe. You'll need an adapter, or do what I did.
Mike B
