So I have a foxbody with a 5.3 and a s475, and have the fittings and lines for a -12 drain. The turbo sits on the driver side frame rail, my first though was to route the drain to the timing cover but with the -12 fitting and using the truck accessories it just wont work out. So I'm going to drill and tap the pan, my first option being on the side near the front (which will be tough because of the k member and everything being there). The second option being closer to the middle/back where the main sump is, but this will have some near horizontal hose but overall going down though.

I'm hoping the -12 will be big enough for the rear point, but just wondering what you guys think and have gotten away with?

 

Fbody pan btw

 

With less than ideal drain angles, bigger is better. My drain lines have less than 10* angle to them. I use 3/4" ID brass water heater tubing. Drains straight down to a 90* bend, then 3.5' ft of tubing horizontally with another 90 and 3 foot of tubing going back to the oil pan.

While the -12 hose itsself may be 3/4 ID, usually the fittings are no where near that, esp when you get into bends.

Consider your S400 drain is .80".

Here is an AN12 90* fitting. ID is only about 1/2"

 

I tried to get some pictures so you could get an idea of it, but it was hard to get meaningful ones. It's a 45 out of the turbo, into the line thats at about a 45 degree angle, then for about a footish maybe less it's horizontal to slightly downward, then another 45 into the pan.

 

Or do I switch to barbed hoses that have true 3/4 id? Would be smaller than the an fittings and only be a couple bucks in hardware too.

 

I have a -10 drain on my set up an have never had any issues. Unless you have crazy positive crank pressure As long as you turbo is higher than the oil pan it will drain. Looks like your turbo is 8 to 10" higher than the pan and it looks like it drops A lot b4 that horizontal run. It will be fine. Especially with -12

 

Because it worked for you (or you haven't had issues yet anyway) I wouldn't go spouting a -10 is all that's needed, that's just not true.

Having the turbo higher than the drain does not mean it will drain properly either. Still needs to be large enough drain properly per the manufacturer.

Holset service manual states no smaller than 19cm (3/4") And their drain ports are smaller then BW drain ports. The fact that some get away with it, or limit the flow to the turbo to get around the issue is besides the point.

Here it is straight from Turbonetics. And the Garrett units they are talking about have no where near the drain size of the BW units.




Here is the ID of a AN10 fitting.

 

There is hose and fittings out there that have higher flow than standard stuff. My shop has started using this stuff where flow is a concern and its really nice stuff. The fitting bores are noticeably bigger than the equivalents of other companies.

https://www.aeroflowperformance.com/light-weight