The guy that rebuilt my engine used the stock 1990 rx7 return/feed line for the t04; before i rip off the turbo completly i want the turbo feed and return line to be hydraulic s/s lines. what do i need to do? i have no idea. All i know -3an is supposed to be the feed line and -10an return line. what is -3 and -10an? is that npt? what kind of angles do i need? let me know everything i need and i'll go buy it asap and see how the oil burning situation is after, everything from the type of adaptors to fittings etc.. i decided not to sell the car but to fix all the problems and if its the engine, i'll get it fixed, this is step one, second would be to pull the turbo off.

Thanks

 

-AN designation stands for Army/Navy. The number is the ID in 1/16ths of an inch. So -8AN would be 8/16" (1/2").

The return line for a large turbo should be minimum -10. I have -12. Just straight fittings, no angle.

 

in the books that I have read the return line should be twice as big as your feed line.

 

as long as there is no restriction to the drain, you can use whatever line size you want. Generally speaking, it's better to err on the side of large. -10an has always worked for me, so I stick with it.

On another note, My drain line doesn't go into the side of the pan, but the front lip of the front cover. Much more of a straight shot that way for me. Keep in mind it's a GT40 turbo on a 13B, in a miata.

 

On the FD's we use -12 s.s. braided hose for the return line and -12 fittings, usu. a brass barb end fitting at the top and a -12 90* female and a -12 to 1/2 NPT reducer [male-male] screwed into a flange that mates/bolts to the flange of the hard line going into the block. -12 maintains the factory 5/8" I.D. of the oil return lines of the stock twin-turbo unit. Using line and fittings smaller than -12 will probably restrict oil flow and cause bearing seals to blow. The I.D. of -12 line w/ -12 fittings is 5/8" [-10]. You line needs to be direct as it is gravity return. Needing to be twice as big as the feed line is a new one for me.

We repaired a return line that had been "looped" by a "pro" builder. The loop is a restriction which resulted in the turbo having to be replaced - it was a total loss. That same builder put his own 90* bend in a -12 line causing it to kink thus ruining another customer's turbo that was a near total loss. Combined losses for the two customers was about $2300. I couldn't understand what the hell that builder was thinking.

 

awesome i get the idea, i'll get on it tomorrow and hopefully the turbo seals never let go and it'll stop smoking or worst case scenario the turbo seals are shot and the engines good.

Thanks

 

I failed to mention the blown turbos were a GT35/40 and a T60-1.

This needs to be a -12 swivel fitting in conjunction with the AN/NPT reducer, and the -10 straight hose barb.

I should also mention that Summit Racing and Jeg's house brands of Aero-quip and Earl's fittings are every bit as nice and cost less. Buy the aluminum -AN wrenches to do a clean job and to avoid scuffing and marring the pretty anodized aluminum fittings. They're worth the price.


Also, here's another option you could do: You may try a straight and a 90* aluminum hose barb and only a foot of -12 line of which you'll only use 4 - 6". to connect the length of -12 braided line. Call me if you want further input. Summit and Jeg's have excellent service and prices if ya can't find the stuff at your local speed shop.

 

Are there ends you can buy that are tapped for AN fittings?

 

I don't quite understand the question, but Sweet Performance has aluminum -AN weld-on bungs. http://www.sweetperformance.com/

 

That will do, what I meant was flange's that already had the AN fitting welded on.

 

I wish I had a pic to show you guys of the last three return lines that we've fabbed in recent weeks.

I just saw pics of a bad-*** TII engine going into the Miata. The oil return hard portion looks identical to what's on the B-REW engine. That flange, which is the same as the block-off plate for the rear turbo oil return hole, is too small for a weld-on bunge and fitting; I've already tried. It's best to drill and tap it for 1/2" NPT. We made a number of flanges like this out of aluminum and we made them a little thicker for strength.

I think I may buy the straight and 90* barb hose fittings and fab up another line to see how that works. That may be a viable and really inexpensive option.

 

This is a repost of the oil line hardware that the bitches at Imagestation deleted.

....but with a 90* -12.....

.... ..... [the blue end screws into a -12 to 1/2 NPT reducer ]........

...... and a 1/2 NPT barb at the top of the oil line >>> It turns out that we need less than 6" of -12 braided line to do the job. I hope this is useful info to those who have blown or are about to blow their turbos.

 

I made it with -10an lines some generic t04 to NPT flanges, 2 -10an NPT to AN unions, and about 10 inches of -10an hose(with hose ends). I recommend AGAINST using aftermarket lines if you can still get the stock peice to fit. IE>>> Hybrid turbos with the stock center. It's perfect for the application and you can usually grind the wastegate actuator down to get the line to tuck in under there. -10an return is fine for stock and t04 applications.

 

Interestingly, stock turbos aren't being discussed here. The I.D. of -12 fittings is the same as the stock line and the braided line works better than trying to cobble up stock hard line. Try reading this thread from the beginning. And, let's see a photo of your work.

 

Interestingly if you read the first post it says That he used the stock 1990 oil return. Which would be an FC3s Return, not FD which... on a hybrid S5 t04 turbo would still fit onto the stock center (which is retained during a hybridization). Since only the compressor housing is upgraded and therefore larger it can hit the return line. Most of the time you can just trim the wastegate bracket.

Also, if it's regular t04 he needs to have a non-stock manifold, and therefore the stock return would have never fit in the first place.

This is essentially the line, however incomplete, and longer but you can see the one end on it.

 

I should add... the turbo in that picture is a t04b Turbonetics housing on a series 5 (89-91) Centersection and hotside.

 

alright ppl i have a update.. i took off one bolt off the downpipe on the exhaust side and as soon as i did that, oil started dripping out of the downpipe. my exhaust ports are dry on the engine; when the turbo was off i tilted the compressor side down and oil was drippin outta it.. any other tests i can do right now to make sure its not the engine? the guy who did my engine made backyard feed and return line for the turbo which caused the seals to blow out on the turbo, thats my theory, so im going to replace the oil feed and return with s/s lines and get a t04b wiht 60-1 wheel etc... engine only has 1300kms on it with all brand new seals, hardened bearings etc... lapped housings...

 

Yup that was my theory all along when you were talking to me... you konw I happen to have a turbocharger that seems to fit along the lines of what you want very well... we should talk...
Do you still want some new lines?

 

There are a couple of very informative threads in this forum on oil restrictors and vacuum line hookups to give the oil pan some vacuum assist in getting the oil through the turbo and keeping the pressure just right. Not so much as to cause blowby, but enough to keep it from burning up.

 

For me and several others, a short, direct line in -12 (maintaining that -10 I.D. even through the hose ends) eliminates the need for an "oil restrictor" in a -3 feed line in T66, T60-1, and GT35/40 turbos. If we were using -10 line, it would necessitate the use of -10 fittings that have an even smaller -8 I.D. (smaller than stock) which restricts oil outflow and is prone to blow the bearing seals in the turbo's center section.

 

The inlet on the front housing of the FC motors doesn't look any bigger then a -8an ID... My motor isn't here right now, it's getting built to handle a bigger turbo (T66 or gt35) But if you have access to one, measure it. I don't think it's going to help FC guys. You pretty much have to run a restrictor. Thats interesting however. I will measure it and if possible, I'm willing to try a -12an dump and a -3 feed. Do FD's pull oil from the corner of the front plate? Do you just slap a 90 degree on there and run the -3an SS to the top of the turbo?

 

exactly, my bearing seals went in the turbo center section...

 

We pulled an engine this afternoon and will install the reman from Malloy Mazda in the a.m. We use a block-off plate at the rear turbo oil return line. These lines have an I.D. of 5/8" or -10. They're corrugated to absorb vibration as well. My SFP manifold places my Turbonetics T66 inline to the front oil return. The fitting at the top of my -12 s.s. braided line is a 1/2 NPT hose barb screwed into the oil outlet of the turbo. The fitting at the botton of the line is a Earl's -12 90* socket fitting as demo'ed in the earlier posting. Then, I use a -12 to 1/2 NPT reuder screwed in the drilled and tapped flange to mate to the flange on the stem. My entire line I.D. is 5/8" thru the line and fittings, same as stock.

From what I've seen in FCs, it looks to be the same sort of thing, however, the manifold determines how the turbo will line up to the oil return on the engine.

 

All I did with my -10 an line was took my air grinder and put a stone tip on it and bored out the ends on the AN fittings to match the outlet of the stock turbo It worked well. With the larger turbo I plan on using... I'm not sure reboot/ was selling an SFP fc3s t04 manifold it's a bit more expensive then the cast HKS and I've seen no real advantage to it yet... but if it lines up that well I'd be interested in considering it.

 

scaled the photos.......