mx5cartalk.com

So I want to fit an oil cooler to my SE
I already have fitted too the car a Thompson Oil Filter Relocation Kit.
I want to incorporate this kit in with a cooler and a thermostat and I'm pretty sure I can do this easily with an Earls Oil Thermostat cut into the line between the engine and the filter.
This then gives me two outlets for the cooler to be run too, plus sensor ports for temp and pressure.






My only concern with this setup is the Thompson kit uses -8AN hose, whereas the thermostat and most coolers use -10AN
I'm no fluid engineer, so, for those in the know, is it safe/wise to have -8AN hose from the engine to the thermo/filter kit and back again (like it is now), and then step up to -10AN for the lines too and from the thermostat and oil cooler?
Would this cause weird pressure issues when the thermostat opens and allows oil through the cooler wioth the bigger lines??

Iv spoken with a local hose mob and he said it wouldn't matter, but he also seemed very aloof and didn't seem to care

Iv'e been reading about line size and pressure loss and would ideally want to use -10AN for the whole lot, but I've had the Thompson kit since I've had the car and had no noticable effects (though no way to measure pressure)

Thoughts?

If you want to keep the Thompson kit, seeing as you already have it, then it wont make any noticeable difference to add -10 for the oil cooler part.

The thermostat always has flow through it anyway, just more of it when thermostat opens, so wont cause any issues.

When I put my PWR radiator / oil cooler in a few years ago it came standard with 8AN fittings. My mechanic wouldn't let me use it as he beleived 8AN was too small so we got the radiator made with 10AN fittings. As you are now going to be pushing to oil further by adding the I personally think 10AN would be a far safer bet but I am not a mechanic or engineer.

10AN lines have less friction than 8AN so I think you need the larger line because of the length to the oil cooler and back. This is so you don't get a lower pressure at the end due to the extra friction resistance. It's kind-of like voltage drop on thin wires vs thick wires... it becomes a bigger fact on the longer runs.

8AN has 60% of the cross sectional area of 10AN, so it is a fair reduction in flow rate, but it's only for one small part of the system. My guess, and it's just a guess is that the short 8AN runs would only be a small factor of the total friction for the entire system if the rest of the lines are 10AN.

I could be wrong though!

MT.net basically recommends 10-AN fittings or "don't bother" - upgrade to 10-AN fittings and never worry about this again.

Would it make sense to upgrade the thompson hoses to 10an, but having the restriction of stepping down to 8an fittings for the filter block and sandwich plate. Or just dump it all and start fresh?

The Peterson Remote Oil Relief Valve is AN10, all the oil lines in my car are AN10.

http://www.superstreetonline.com/how-to/engine/htup-0805-automotive-plumbing/#__federated=1