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-   -   EFR 6758 leaking into compressor housing (https://www.miataturbo.net/engine-performance-56/efr-6758-leaking-into-compressor-housing-105866/)

curly 04-14-2024 11:33 AM

Yeah, that's on my short list. I have Radium's giant catch can on the intake side, barely catches anything. I'd like to swap that out for two of the smaller ones, one for intake side, one for exhaust side. Just need to get them purchased.

ryansmig 04-17-2024 04:06 PM

I think I'm going to try that AOS for the hot side. I recently rebuilt and have been having my catch can fill up like crazy on track. Previous motor build was basically dry after 3 months. Haven't changed the breather system at all. Stepped the oil drain from kinked -10 AN to new bung and -12 AN.

Repurposing the old 3 bar MAP sensor to measure crankcase pressure and will hopefully have some data tonight once it's wired in

MiataMir 04-21-2024 10:10 PM

So I am in the same boat in terms of oil pooling in the compressor housing and intake tubes. I do already have -10 an lines from the valve cover to a VTA catch can. If I am understanding this correctly, you used this setup, at least for the turbo side, to help? if so, should I keep my PCV side vented to atmosphere via the breather can used in my current setup and run the turbo side the way the picture is showing to see if that helps?


https://cimg5.ibsrv.net/gimg/www.mia...97572c6e77.png

curly 04-22-2024 02:08 AM

Yes, that's what I did. Again, very preliminary results, only ~40 miles and a dozen or so dyno pulls. Just spent all weekend at Sonoma, didn't get a chance to put any additional miles on it.

curly 04-24-2024 10:25 PM

Someone asked for a picture of my current setup, here it is. Exhaust side will eventually get a small radium catch can. The new ones have built in check valves, I'll probably end using one on each side.
https://cimg0.ibsrv.net/gimg/www.mia...d13a4664d.jpeg

SlowTeg 04-25-2024 08:29 AM

Wow interesting, so relieving crankcase pressure solved your problem with oil getting past the seals.. As someone else said maybe the EFR's don't like any crankcase pressure.

Does that crankcase line from the valve cover to intake pipe have an AOS at all? My concern would be over time it would pull vapors into the intake tract from the crankcase but if it's working that's awesome. I've had discussions with folks where people swear the crankcase needs vacuum on it vs just letting it vent to atmosphere but depending on the car and setup (like on a track car), I'm always worried about oil getting into the intake tract from the crankcase. I know another old school way is a slash cut tube in the exhaust pipe to the crankcase but I'm sure that'd get smelly/messy.

curly 04-25-2024 11:15 AM

As I've said multiple times, my plan is to add a catch can eventually. Yes, it could suck in oil, but nothing so far, both raw oil from turbine seals, or oil vapor from crankcase.

Lukazade17 04-28-2024 09:34 AM

I’m fairly late to this conversation but I have been following it while trying to rack my brains around my EFR oil issues. I hope that I can add little to someone’s else’s journey!

Quick back story back in 2020 I restored a 1998 NB with the vision of dropping most off my boosted set up from my previous NBFL. Upgrading to a forged engine and EFR setup.

Pretty much since day one after the initial break in and dyno I started to notice oil in the air filter also intercooler/pipework.

First fix, I opened up the drain full bore from the turbo outlet to sump with a continuous fall.

Second fix, drilled out the rocker cover on the hot side similar to how SPS motorsport advise in higher HP applications and fitted 2x 3/4” bore breathers to atmosphere. The cold side is also vented to atmosphere AN8.

Third fix, fitted a Turbosmart V1 OPR.

Fourth fix, utilised a breather on the block i pre drilled during my second rebuild. AN8 hose line to a catch can vented atmosphere.

Fifth fix, fitted an additional oil restrictor (1.8mm).

All of these mods helped the issue but none of them have completely solved it.

I am pretty sure the engine isn’t creating excessive blow by I have done a leak down test in the past along with compression tests. I even rebuilt the engine again (rings, shells, machine shop rehoned, another crank all balanced and new boundary oil pump) after a bad set of injectors from the initial build diluted the fuel somewhat coupled with the extra oil from the BW it wasn’t 💯 so couldn’t rule it out. Still running well but I took the plunge again 😂 I upgraded to ID1050s and replaced the CHRA for the ally version. Again after this it was run in and dynoed with a professional made 352bp at
15psi but the problem persisted!

On reflection;
The greatest fix being the oil restrictor (which I tried to avoid all along as per BW manual)
Nearly stopped the oil leakage but over time it has reappeared slightly and Im still not happy to hit the track!

https://cimg6.ibsrv.net/gimg/www.mia...4f6df2abb.jpeg
https://cimg8.ibsrv.net/gimg/www.mia...d09e5459e.jpeg
https://cimg9.ibsrv.net/gimg/www.mia...59d78aeca.jpeg



@curly I am relieved for you to see your problems have ceased! I am going to try a similar solution just deciding whether to attach the block breather to inlet filter via the catch can. Or bung that and use the hot side via catch can.

I really hope this solves it as this car has been a pain in the arse compared to the first which was beaten hard for 5 years. The original engine still sits there taunting me 🤣



curly 04-28-2024 11:13 AM

Very clean engine bay. My thought is while 0 crankcase pressure is good, crankcase vacuum is better. In order to create that vacuum, you'll have to plug all but two of your vents. Under boost, my PVC side is check valved closed.

leboeuf 04-29-2024 11:50 AM

If it's of any value, I have a "catch can" of sorts between my valve cover and turbo intake fitting and have never accumulated much of anything in it.
The stainless mesh medium is even mostly dry.
There are some details in post #103 in my build thread. (from 2016... what happened to the years?)


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