After finding and clearing vacuum leak. Cranked the car up and was rewarded with a helluva lot of smoke coming from the exhaust. Before I cleared the leak there was a slight bit of smoke on startup but no where near as much as what it's doing now. I thought the premix was too much (1 ounce per gallon) so put 9 gallons in with a 1/2 ounce per gallon. Still getting smoke but not as bad. After I let it idle for a while the smoke calms down but under load / acceleration and it comes back. Here's a video:

So is it just going to take time to clear out the overly rich pre-mix, or is it possible I need an oil restrictor for the Turbo (Journal Bearing - 4AN feed line).

 

I would do some research on needing an oil restrictor or not. I am not sure if you need one or not, but I do know oil can get through the turbo C-clip and cause smoking. It is very noticable when letting off the throttle after boosting. a little is normal, a cloud of smoke is not.

 

I am going through similar issues, not as bad as in the vid, but its there; gets worse if the car is not on a leveled surface (IE front is higher than the rear). I thought about the turbo oil restrictor, but from my research, journal bearing turbos should not use one.

The issue came up when the REW engine was installed (never had this issue with the S5T engine). Could it be the oil psi?

Inquiring minds would like to know

BTW - REW + Miata is my dream car, probably next project in 10 years

 

i was told to run a dash 3 line to my current BW journal bearing. no restrictor.

no smoke at 1 oz per gallon.

howard

 

I was told the same by Full-Race. Run the same style oil lines to a BW journal bearing turbo that you would a ball bearing Garrett unit. Either -3an with no restrictor or a -4an with restrictor.

 

Already running -3AN, and now that I think about it, the turbo's inlet/oulet is are not at 12 o'clock and 6 o'clock; they are sitting at 1 and 7, would that cause this type of issue?

 

"the turbo's inlet/outlet is are not at 12 o'clock and 6 o'clock; they are sitting at 1 and 7, would that cause this type of issue?"

indexing turbo oil ports is all about the drain port as you could run the pressure port anywhere on the clock.

numerous factors effect drain performance and one of the overlooked and most significant is crankcase/windage pressure. drain flow relies on gravity not the system oil pressure. the primary flow opposing force is the windage pressure.

windage pressure is influenced by the number of vents.

the single turbo setup offers two, not one, vent. i recommend you remove the rear blocking plate and use the OE rear turbo drain port that Mazda so thoughtfully provided, to better vent the crankcase. a 90 degree fitting, some hosing up and over the motor to the oil breather container you have for the oil breather vent on the driver's side.

the bonus, in addition to vastly decreased crankcase pressure, is you will have constant crankcase venting whether turning right or left. w just the oil filler vent you have NO venting on left turns. anyone tracking their FD on a road course needs this simple mod.

since static "Full" oil level is above the pan rail overfilling can influence pressure if you are using the pass side vent. i find 4.3 quarts, not 5, hits the mark.

excess porting is another area that promotes excess crankcase pressure. i see lots of motors where the supportive oil seal step has been ported away. i simply turn the 90 degree step into a 45 and leave the supportive surface. you will get increased crankcase pressure if you remove the step.

probably the most significant contributor to crankcase pressure is the use of overly worn steel oil rings. if they are over factory spec for wear they will allow oil into the combustion chamber and also pressurize the crankcase.

the same goes for excessive sideseal clearance.... in the piston world we are talking "blowby."
from worn oil control piston rings and valve guides.

all these issues oppose the gravity flow from the turbo and increase flow past the bearing into the exhaust. they also load the combustion chamber w oil which also goes out the exhaust.

the good news is if your exhaust is mild steel it won't rust.

hc

 

Solved the issue,wasn't the pre-mix nor a restrictor issue with the turbo. Ended up being crankcase pressure causing the turbo to not properly drain and spit it into the exhaust. After reading Howard's post I pulled the oil fillet cap and no more smoking.