Another Endless Air / Onboard Air installation

G'day all. I have been considering this mod for some time, having been inspired by the older discussion here

onboard air , that goes back quite a way. Given that thread was started in 2007 I thought I would post my more recent experience.

It took me a long while to get my head around how it would all fit together- I know nothing about compressed air systems- the web page put together by the most excellent Grungle (Grungles Homepage) was essential reading. I read and re-read that page, and the thread already mentioned, many times before I felt I was ready to start.

The one thing I will say at the outset is, this was the most complicated DIY I have attempted yet, and it turned out to be far more expensive than the older threads and posts indicated. Maybe I'm doing it wrong lol.

Note: This is not a how-to, just advice for someone wanting to attempt this. refer to the above links for drawings, parts lists, etc. I will try and break it up into various sections to make this more readable. At the time of writing I have the project 90% completed, I don't have it running yet but hopefully will soon

Compressor: The first and most important part was finding the compressor to modify. In the older threads the Sanden SD508 compressors were apparently commonly available from wreckers; in 2023 I couldn't find one secondhand anywhere. Luckily the internet is full of 'em; $120 saw one (brand new) delivered to my door. Once I had that, I needed to mount it to my engine- as I had a silvertop I was able to use @OldMav 's custom brackets, which are a lot simpler than the ones required to mount the same compressor on a later model TD42.

This worked really well, except I found that the given dimensions for the thickness of the bracket did not match my compressor- I had them made at 14mm thick and had to shim the lower rear bolt that secures the compressor to the custom bracket with a 1mm washer. No big deal. These brackets cost me about $200 to have them laser cut.

Compressor top view:

In the above pic, looking downwards past the injector pump, you can see the inlet and outlet are facing upwards, I was able to do this because my vac pump is on the alternator. I was sceptical as to whether the pipework would all fit in, given it is very close to the engine mount, but miraculously it did.

Piping: I opted for 1/2" stainless steel braided teflon hose for the outlet piping, as everything else is prone to getting a bit melty due to the heat. This stuff was very expensive (cost me about $300 for 3m), but I felt the advantage of being able to measure and cut it at home outweighed the advantage of having hydraulic hoses made up, given the engine was out of the bay and it was exceedingly difficult to measure hose lengths accurately.

The next problem was joining the teflon hose to the compressor; I was able to source a 1/2" 90deg barbed fitting to suit the compressor outlet, and a 5/8" 90deg barbed fitting to suit the suction side, from old mate's "just in case" parts bin at a local auto aircon shop. Both of these parts were not commonly used on modern compressors I was told, as the crimp-on collar was a separate piece (usually aircon fittings are one piece now). I also learned that the thread pitch on aircon fittings is completely different to anything else, so hydraulic, metric, SAE threads don't work. With my plain barb and teflon hose, a couple of o-clips were all that were required to attach the hose and I was able to cut it to exactly the right length, once I got the engine back in the car.

Inlet piping I opted for 5/8" heater hose, as it was cheap and seemed to be thick enough. Hope it doesn't collapse on itself but as I said, it was cheap; if it doesn't work I'll have to do something else. The local Pirtek guy said I was limited in hose choice in the 5/8" size.

Pressure switch: I opted for the Condor MR2 pressure switch, because that is what everyone was using in the older threads, but in hindsight I should have bought a much cheaper and simpler pressure switch such as this one on eBay:


The Condor cost me about $90 from eBay, and at my local air compressor shop I found the same unit for $60-something. That gave me the sh*ts.

I mounted the Condor on a bit of 3mm flat bar using the fuel filter housing bolts, as others before me had done:

In the pic above we are looking at the back of it (i.e. from the engine side). The gauge faces the outside of the car. This mount was really easy to do. I hope when I put the bonnet back on there is enough height clearance . (Edit: there is.)

The rest of the fittings: This bit took me ages to get my head around. Here is what I came up with:

The bloke at my local compressor/air tool shop was most helpful in helping me get the right bits. Also the barbed fitting marked "to tank" in the above picture I ended up replacing with a 90deg barb facing downwards, as otherwise the hose would be heading straight to the firewall.

Mounting the fittings: I made up a bracket, secured to the fuel filter housing bracket using the original bolt holes, and secured the assembly to it with a worm drive clamp. The bracket isn't painted yet in this pic:

Installed:

In the above pics you can see how it bolts on top of the fuel filter housing bracket, and the whole assembly is very nicely tucked in out of the way under that brake thing. As it turned out the nipple thing on the fitting for the unloader valve was centred exactly where one of the oil filters needed to be... so I unbolted my bracket and just zip tied the assembly out of the way. Ah, it was so close to being perfect...


To be continued...