Oil Return Line
 

I've searched throughout the forum for information on DIY Oil Return Lines, and while there are a few posts on the Ebay kits, and other assemblies, none really applied to me. Thus, the post.

For those of you that have not seen my other two posts, I don't drive a Miata, but am working on a Lotus 7-based car, and am using the BP05 as the power supply. I am on the final stages of installing a TD05HR 16G6, and am trying to figure out the oil and coolant lines. As the coolant lines simply require hoses and hose clamps, that is not an issue. The original oil feed was hardline, I think I am going to try cutting off the engine-side banjo bolt, double-flare with a brake fitting, and after sizing and shaping more steel/stainless steel brake/fuel line, will combine the two with a female/female connector. Obviously not the world's best setup, but as I'm completely broke, it'll work on the cheap.

The oil return line is my only issue. Because of the odd location of the turbo (located east-to-west in front of the motor), it is going to need more towards 24"+ of line, rather than the original 10" or so, and the 15-17" usually supplied in the Ebay kits. Also, I would prefer to retain the two-bolt flange on the turbo side, but use a NPT fitting for the tapped oil pan.

Any suggestions? I'm thinking of using high-pressure, high-temperature hydraulic line for a temporary fix--I'll be driving it with the turbo free-wheeling until I can afford and apply a MegaSquirt. Once I can cough up some cash, I would like to replace it with a braided steel/teflon return line.

Edit: To clarify, I've read the FAQ, and get the general idea, but need help locating 16G turbo-side fittings, and long high-quality return hose.

Would recommend you contact ARTech, he might be able to help you. He does make kits, and i don't see why he couldn't make them a bit longer for you.

https://www.miataturbo.net/showthrea...t=artech+lines

As long as its all downhill and large enough, the length shouldnt be an issue.
Rubber hose is fine, just expect to have to replace it occasionally.

I've killed an engine (modded SR20) by running plain hydraulic hose instead of stainless steel braided oil-resistant hose...

if I'm not mistaken, dont some factory turbocharged cars use regular silicone hose for their return lines?

ATP sells oil-resistant silicone drain hose designed for that specific application. I ran it for about a year and a half on my turbo car, it worked very well and was cheaper than nylon/SS braid.

Nice first post

$20 says it wasnt the material of the hose that killed your turbo
more likely:
1) The size of the line
2) The location of the return to the pan
3) The orientation of the line

Or it wasnt anything to do with the line, like perhaps the oil feed/restrictor.


Ive known people to use heater line, and nothing bad happened except for the fact that the oil is alble to seep through the rubber over time, so its oily feeling to the touch, and the heat eventually starts degrading the rubber so that it has to be replaced to prevent it from cracking.

He said it killed the engine, then gave the designation of an engine to confirm that.

Likely he ran out of oil after the hose fell apart and the engine wasn't happy.

That's how i read it, anyway.

Have you already tapped the pan? The stock return spot on the block might actually be a good option for once.

All the modification tapping i've seen has been at the stock spot (or where it would be, if it wasn't a late oil pan), where is the 'good spot' to tap?

I'm not talking about taping the pan, I'm talking about the plugged hole in the block that's used in the greddy kit. Usually it's all the way on the other side of the engine, but for his setup it might be one of the shortest options.

Hrmmm... what stock return spot are you talking about? I have a '96 1.8 on it right now, adapted to a '94 harness and ECU.

I still have the '94 motor in storage waiting to be built up, so is there a stock return point on both motors? I know about turbo line points on the '94s...

Nevermind, I knew you were doing this cheap, so I figured 1.6. I don't think the 1.8's have the port.

Ah. What about coolant lines? I deleted the IAC, so can't I just use those two hoses as my in and outlets for the turbo? They're right where the turbo sits, too....

The 96+ motors don't have the return spot. Stock turbo BPs have a drain line into the pan.

So could I swap out the '96 oil pan for the '94 pan? Any idea what fittings are on the early motors? Ill have to make a trip to my parents to look at it.

Bingo. That's good stuff.

This wasn't my car, or my setup. I was just driving it at the time the failure occurred.

Thanks.

It was not:
1.) The size of the line (Please explain how the size of a drain line can cause it to break down and become mushy and eventually degrade to the point of splitting open)

2.) The location of the return to the engine, as the engine was factory turbocharged and used the stock points for turbo oil feed and drain. (Being designed from the ground-up for turbocharging, the oil return inlet is very close and nearly directly under the turbocharger. Additionally, it is in the block, not the oil pan)

3.) The orientation of the line, as again it used a completely stock route from the CHRA back to the engine, a slight bend with no sink traps.

That is similar to what happened, and the hose that was on the car was quite possibly a line to the heater core. The material breaks down when in contact with extremely hot engine oil, both because it is not designed for anywhere NEAR those temps, and also not designed to be in contact with oil. Worst situation of both worlds.

The oil feed line was a stainless steel oil resistant braided line developed specifically for a small frame GT series Garrett turbocharger on that exact engine. The oil line has an integrated restrictor, and the CHRA also has an integrated restrictor.

Back on topic: Do not use a brake line double flare fitting on the oil feed. It will leak. Drilling and tapping for pipe thread in oil pans sucks, because the oil pans are porous and even if you use teflon tape or sealant, even the super crazy thick brown goo type, they seem to leak.

I would recommend drilling the pan and having a nipple welded in. When you weld-in you can put the nipple at any angle (Angled downwards) and perfectly fit to your setup. I'd buy a length of braided stainless steel oil resistant hose and some AN fittings from ATP turbo or other such site and make your own hose. You can buy a drain flange for that turbo off the shelf with a male AN fitting, or have yours cut off and weld a new one on.

If you want to go the cheap route, use the stock outlet, the hose you were thinking of, and a simple hose barb. Make sure the inlet of the hose barb is nice and smooth to encourage oil to flow into it, and is angled upwards, not sticking out of the pan at a 90 degree angle. With such a long length of hose, see if it's possible to fabricate any support brackets that will keep it in as "straight" of a line as possible.

Additionally, running with a turbo "free wheeling" CAN damage the turbo. Don't do it.

Pick up a copy of Maximum Boost by Corky Bell...

Got it, read it. if you haven't read my build log recently, I just totalled my Mini, but they should be giving me a decent amount of cash, so its not so bad I guess. I should be able to get the right stuff. I was thinking of getting an aluminum fitting and TIG welding it after threading it into the pan. Are you guys sure those are aluminum? I am not at the car right now so I cannot see it.

BTW, I do have a Syncrowave 200 in case people need TIG welding done. I'm no pro, but I usually can get two things to stick together. I've welded my fenders and nosecone, which are .060 aluminum, and both the steel header and the stainless downpipe/exhaust.

The pans? Yes they're aluminum. Got a plan for a replacement car yet? I still say DD the se7en.