18 June 2018

Had a brief dream of backing Midlana off a trailer and realized there’s a problem, in real life as well – that unless the angle is very mild, there’s a fair chance the diffuser will drag. Have to take some measurements before that happens.

On a related note, I found an unintended airflow experiment has been going on. Back when I replaced the turbocharger studs (more on that in a moment), the turbo oil feed line and feed adaptor had to be removed. It leaked a little and dripped onto the diffuser near its front center. Because of the way the diffusers attaches, some of that oil ran to the forward edge and got caught up by the air flowing under the car. The cool part – which looks better than the picture – is that the air flow remains well attached as it flows aft. What’s hard to see is that near the front edge, the air flows in and sort of “funnels” into the center channel of the tunnel, showing that the strakes are working as well. Also, along the top edge of the picture, you can see how the air flowed up onto the frame/Gurney flap, which would be expected if it was doing its thing. Good.

Regarding the turbo studs, after doing some more reading and getting some helpful hints on the Midlana Builders’ Forum, it was decided that they’re being replaced again, with the only type of stud that won’t stretch under high heat – Inconel. Actually ordering them though was a bit of a drama. For whatever reason, they’re fairly common in the aftermarket – in Australia – but not so much here. Testing the waters, I found they wanted about $50 shipping for their $50 parts, so no go there. In short, they were found domestically in a somewhat-surprising-but-shouldn’t-have-been source, Mazda. Seems the factory had such serious problems keeping their turbos attached to the second(?) gen RX-7, that they use Inconel studs. Thanks somewhat to mass production, they’re “only” $12 each, but hopefully once they’re in, that’ll be the end of that.

As an aside, a vendor in the US advertises “Inconel” studs, but reading the fine print, it turns out they’re actually “Incoloy”, which research shows isn’t the same thing. The vendor tried convincing me they were and that Inconel is just a brand name of Incoloy, yet research seems to indicate that Inconel has more nickel in it and is quite a bit more expensive (less profit). We use the material at work for really high temperature applications and use Inconel and nothing else, so there.

Lastly, if someone tries selling you fasteners and claims they’re Inconel, a simple test is that they will look like ordinary steel (not stainless) but are non-magnetic.