maybe i missed something, what does garrett have to do with blowby?

 

Almost all the Garrett GT DBB guys have problems with large amounts of oils smoke out their exhausts on this forum. The main seller of these kits is A Spec, who states that Garrett does not want users to restrict oil flow to their turbos. that said, ATP, a huge Garrett shop, which sells many different GT DBB Garrett turbo kits specifies a restrictor for the oil inlet on GT turbos. My question is why the two Garrett shops disagree(both supposedly quorting Garrett), and why so many GT DBB customers cars are having all these issues with smoking turbos bad seals etc.
Here are pics of the restrictor I ran on my journal bearing Garrett TO4S, as recomended by Garrett at the time(~5 years ago) There are others who have this restrictor, and it has "Garrett" cast into it. So if no restrictor is needed why do they make them? I realize they make many turbos, but mine ran flawlessly for years, and others w/ restrictors have said the same. Carl

 

supposedly the gt series have it built in?

I'd be interested to see the oil return lines on the cars that are smoking.

i thought you were strictly talking engine blowby, not coming past the seal in the turbo.

my to4s actually had a restrictor pill in it about that size. it threaded into the oil feed tho, and the flange for the hose bolted on top..

 

The flow can vary, but must be very small. Look up "oil mist Lubrication " for high speed ball bearings, Normal oil flow would creat tremondous churn and drag, which could plug the normal oil exits and force oil through the turbine seals, and out the pipes. Water cooling required.

http://www.atpturbo.com/Merchant2/me...gory_Code=GTBB

Hith restrictor in, add 2nd vent from spare tubo drain port up to filler neck ... no more voluminus fluides to deal with in catch can. Catch my somewaht proven theory on this in race car ... catch tank.

 

We had a GT40R guy on the dyno at a local meet that was having bad smoking problems. I disconnected the line that goes from the oil filler neck to the uim and just ran that to atmosphere with no check valve. His oil stopped on the next run after that.




Yeah, That was my car. Just like Stephen said, once we disconnected the oil filler neck to uim it stopped smoking. I mean it was blowing a huge cloud of smoke after every pull. I also have just left it vent to atmosphere and have found no signs of oil/fuel blowing out on my engine bay. Even at the dyno pulling 19-20 psi..

 

I have a saimilar issue, only on the track. Once I hooked up a jaz catch can, i'll get a puff of smoke, usually when I let off to upshift after hitting the track-out point at 7-7500 rpm. Not replicatable on the street, or going in a straight line, so i'm sure it isn't a seal problem. It's a little more pronounced now w/ 99-spec turbos. I think whats happening is that there's more pressure buildup than the hose to the catch can can flow... particularly if its filled with oil. I'm going to try two lines, and/or a line from the can to turbo inlet.

FWIW, the "oil" in my catch can looks very foamy and fuel-smelling, but i'm sure thats normal, just like the "cheese" folks report on the inside of their filler caps after track time. These cars contaminate their oil, plain and simple. I also sometimes get more oil than a small jaz can can hold, and that gets messy.

Carl... you may see less oil in your can, because isn't the 2-gen filler neck different than the 3-gen?

 

Whats the BEST way to vent the case? How about drilling/tapping or welding a few fittings around the pan or on the lip on the front cover with some -12an fittings, and then run those to a catch can.. Has anyone done something like that? Seems like the more pressure relief, the better?

 

I was using both the vent on the filler neck, and one port off the top of the rear plate, I have since modified my filler neck to clear my IC pipes, and it has no vent. I am only using the port on the rear plate. No smoke at ~20psi, I have not boosted higher, or tracked the car since I modified the filler neck(shortened it). If I do get a problem I'll add the filler neck vent back.
The "puff of smoke between shifts is present on pretty much all 7s at the track, stock, and modded, not sure exactly where it comes from, but it is common, and seems not to be a problem.
I am not currwently running the reswtrictor, that I pictured. I have switched from the TO4S Garrett, to a T66 Turbonetics. T'Netics said no restrictor. Carl

 

I saw this same thing at VIR on a FD that was there this weekend. It looked like super dirty oil. I havent had this issue but was thinking about doing a catch can instead of the PCV valve. I was kicking around the idea of mounting the can as high as I could and then run a line back to the oil filler pcv nipple with a stop **** so that at the end of a session I could just cycle the oil back into the pan rather than drain and replace with "clean" oil.


When I saw this guys oil I was thinking I dont want to put that back into my pan...But if you think about it, the stuff in the oil catch can is the same as what is in the oil pan. There is no separation apparatus that kicks out the dirty stuff, nor is there another source of contamination in the system. Anyone ever let that catch can oil settle out and then compare to oil that is in the oil pan?

 

Any pics of your filler neck? I've modded my TB inlet, and currenty my 3" intake pipe runs right over it

 

This was my question too. I do not want this stuff back in the pan. The thing is that this came from the pan yet the oil on the dipstick looks nothing like this. I have had the brown muck that I removed from my catch can, sitting in a pitcher for a week. There is now a very thin dark layer of what seems to be oil and the other 99% of the pitcher is still the brown stuff. This definately isn't going back in. But if it came out from hard cornering and maybe a little help from positive crankcase pressure, then why isn't the rest of the oil like this? The oil on the dip stick is clean.

Peter, this is what I believe causes my turbo to smoke after exiting a hard corner and accelerating. The high loads from cornering start pushing the oil/muck out to the can. This fills the vent lines with oil so as soon as you let off after that 1st long pull after the corner your vent tubes are blocked with oil. This stops your vents from working until they can clear. the result is smoke after that hard corner. high boost in a straight line isn't enough to get the oil to flow up to the vents keeping them unrestricted.

i did have my catch can plumbed to the turbo but have now changed it. I really don't want this crap being run through my intake as well. I am already going to have to pull the intercooler and flush it. I am sure it has oil in it from all this crap.

 

You guys want me to tell you the best solution? I have no idea why this has never been discussed, honestly I've never heard a rotary guy even mention it but I know what we need.

There are multiple options, you can run it to a catch can then to your intake but then you'll be sucking up a lot of vapor into your intake which will lower your VE because the vapor isnt O2. You can run it to a catch can then vent to atmosphere but thats still not great because now your pan is atmostpheric pressure when idealy it should be vacuum.

For best results and for proper turbo drain your oil pan needs to be under vacume and this is how is should be done.....

We can sit here and debate why it gets under pressure or how much everyone's does but honestly its not going to matter. Fact is ALL engines have blow by (rotary and piston) and need to have thier crank case vented. Personally I dont think the stock evacuation setup is sufficient and thats why we end up having smoking issues with dynamic seal and bb turbos. Carbon seal turbos arent as sensitive to this which is probably why Mazda still uses them to this day. They are the only modern turbos I know of that use carbon seals.

Anyway, if any of you guys know or research V8 race engines, especially forced inducted big blocks, ect then you probably know what a vacuum pump is. Basically its a air pump similar to the emissions air pump that comes on the car. They pull anywhere from 20-40cfm of air. You plumb this into your crank case so it draws more air than what the blow by is adding in. Now your oil pan in under vacuum and the blow by **** is being sucked out. You just plumb the suctiion side up to the oil filler neck and on the discharge side you install a catch can and let it vent to atmosphere. Now your pan is under vacuum, your turbo drain will drain like a champ, and your catching all the blow by without venting it back into the intake when it causes intake dillusion.

You can buy these pumps from just about any V8 race shop, look up vaccum pump on Jegs, Summitt or Moroso's websites. There are many others as well. They range anywhere from $175-$500. A lot of V8 guys actually use thier stock air pump for this which is free.

I think this becomes a bigger and bigger problem as you get the ports larger and larger. I've heard of some rotary race cars that acutally had to run TWO -8 lines from thier oil neck to thier intake to get rid of the smoke which was caused from blow buy. These were on race engines, I'm sure they had good side clearance. To honest I dont know exactly whats causing it but personally I think its a big problem with the rotary and this would explain why we have fuel smell in our oil. I'm planning on putting a pump on my car but it'll be a while before my car is running so I havent commented about this up till now since I didnt have any first hand experience with it.

I've been looking for an electric one but have yet to find one. Let me know if one of you guys find one

BTW - A lot of V8 guys claim 20-30rwhp gains from this because they arent dilluting thier air intake anymore. Dont know if we should benifit from that....but it would be a nice side benifit.

Stephen

 

I believe its called a scavenge pump

my uncle had to get one on his twin turbo testarossa to stop it from smoking oil

 

spo, I have thought about this. there was an electric vaccuum pump on ebay for around $40. it is from a ford diesel truck. The problem is that it has to be able to handle oil. The v8 guys use modified air pumps that can work in oil. A stock air pump will fail. The vette air pumps are not meant to run for extended periods of time. Check ebay for the one I am talking about. Also if you are running a vacuum and get oil up in the filler neck you better watch out. You will probably suck out lots of oil. I wonder if it would be better to have the catch can before the pump.

mike

 

What if you switched the order and put the catch can first, and then the pump to atmosphere? If you did the turkey baster, then a good catch can, and you have the pump pulling vacuum, you would not be passing alot of liquid oil through the pump. You think it could handle the vapor over time?

Shawn

 

Well, if you get an actual vacuum pump designed for this the oil doesnt hurt them. As a matter of fact they use that oil for lubercation....or at least this one does

http://www.gzmotorsports.com/vacuum-pumps.html

Here are a Moroso listed on Jegs but its a lot more pricey

http://www.jegs.com/cgi-bin/ncommerc...61&prmenbr=361

Here is an electric vacuum pump but its designed for the brake booster on cars with very low vacuum. I have no idea how much cfm it pulls or if it can handle oil going into it
http://www.jegs.com/cgi-bin/ncommerc...55&prmenbr=361

Here is a nice looking mech pump from Aerospace Components
http://www.aerospacecomponents.com/vacp.htm


Here is a small tech article on HotRod.com
http://www.hotrod.com/techarticles/0304_381/index1.html


Now that I think about it, the problem with an elec vacuum pump might be that it pumps the same all the time. If you set it to pump enough at WOT and high rpm then at idle it might be pulling way to much.

 

I've never heard it refered to as a scavenge pump, I did a quick google search and all I could find was oil pumps that looked like they were designed for a dry sump system and some other similar uses for air planes. It could be that your uncle has a dry sump on his car.

I have heard of a scavenge method for venting the crank case but it doesnt use a pump. Basically what you do is plumb the oil pan crank case line to the exhaust. As the exhaust passes buy the line is causes a vacuum that pulls on the oil pan helping it to vent. I think this is too much of a pita and i dont know how well it would work, thats why I decided a pump would work better. But if anyone want to give that a shot it would basically be free to do. The only thing I worry about is putting it in the wrong place or something and filling your oil pan with exhaust causing extreme pressure. It seems like to use this method you'd definatly need a exhaust setup with no back pressure but honestly I dont know a whole lot about this method. It might work great. Maybe just installing some type of check valve would be enough of a safe gaurd againt the exhaust going the wrong way

Stephen

 

I put a scavanging pump on 924T. It had a low mount turbo, with oil return below the sump oil level (a no no). Any slight crankcase pressure would back up the return line, and blow oil out the turbine seals. The jabsco pump pulled the oil from the turbo and pumped it into the case. curred the problem.

The linked vacuum pumps are for NA dragsters, mostly to prevent ring reverse leakage during the intake stroke. This in not an issue for turbos under boost, and any such pump would just be a hp loss. A vacuum pump is not needed here.

The catch can catch contains oil, fuel, and some condensed water vapor, a combustion by-product, giving the oil silight milky look. Water vapor can usually be seen when the oil cap is removed from a hot engine.

Onlty 2 issues are properly venting the case, and reducing oil expulsion. Both are related.

At a long 1g right, the top of the oil will be at a 45 deg angle of slosh. This allow it to rise so high on the left side of the case as to enter the filler neck inlet, and seal the opening. case pressure now acts like a manometer, pushing the case oil level down, and the level in the fill neck up. When the level drops enough, case cases can then bubble up through the neck that is 1/2 filled with oil. None of this is an isse on a long left.

What is needed is simply a 2nd vent path on the right side of the case. Having a single turbo makes it very easy ... just use the now spare oil return line port. Simple. Plumb this vent up to the catch can, already connected by hose to the filler neck. Now only condensed vapors will collect in the catch can, vs percolating oil droplets. If you pull 1.5G long rights, you may have to move the vent to the top of the oil cap.

Tested out well on one track car ... big difference reported.

A rear cover vent sounds good too.

 

All:
Wouldn't installing an oil-worthy check valve between the filler neck and the catch can solve the problem of an atmospheric vent relieving the crank case of vacuum? Seems you could re-use the one that used to go from the neck to the UIM....

 

Good discussion guys.

Peter,

how would that work?

That is, to inhibit vacuum you'd want the valve to flow toward the filler neck (anytime there's vacuum you go to ambient). If you do that using a one-way valve to relieve vacuum, won't that stop any oil from flowing to the tank?

I think Stephen's idea of a vacuum pump is a good one, but difficult to implement.

How about multiple one-way valves and the PCV per my illustration. If this is employed the way I've drawn it, you wouldn't need a vented catch can as you retain the stock crank case venting and enable the catch can to do its job. This illustration assumes you can find one-way valves that will flow enough oil to render the catch can/drain useful.

Comments?

Thanks,

Gene

 

reduce the blow by. if the blowby is moderate you would not need the elaboate bandaid. if the oil feed line is sized correctly and the drain is done correctly.

 

Gene,
The problem that SPOAutos suggested, as I understood it, was this:

If the catch can is vented to atmostphere, then the crankcase can't build a vacuum becuse it can effectively draw air back through the filter on the catch can, correct? It'll never build up more than "atmosphere" level.

I would think that it isn't under vacuum when there's enough pressure to push oil to the can, so what you need is to be able to evacuate that pressure, through the check valve, but not basically have a vacuum leak going the other way, just as you would if there was a tube going to a little filter from one of the nipples on the UIM... your guage would show low vacuum.

This is essentially what the original system did... the crankcase would never have been able to "draw back" through the filler neck, as it can with a vented catch can. Am I totally missing something?

 

Your talking about slosh problems. Thats not what I'm talking about. I'm talking about cars that will smoke sitting still or going in a straight line because of excessive blow by which pressurizes the oil pan which keeps the turbos from draining properly. If you look at my first link they have a link to a application guide and you'll see these pumps are for any engine where the oil pan gets more blow by than it can release causing it to build pressure. Then if you go on to read, it says its even more of a problem on forced induction cars. This is not a N/A big block thing. All cars have blowby, OUR engines have blowby which is why there is a pressure venting system there in the first place....I've just found it to be insufficient, especially for cars running dynamic seal and bb turbos which are more sensitive to oil drain.

All piston engines with excessive blow by experience these same problems that we always "talk and wonder" about which are whitish stuff in the oil, condensation in the oil, fuel smell in the oil, smoking turbos, ect ect ect. To cure these problems they install a vacuum pump to pull the blowby out of the pan that would normally cause the pan to pressurize.

Its the same thing as stock...stock you are using your intake to draw vacuum on the oil pan. Your sucking the blow by into your intake where it lowers your VE. Using a pump allows you to pull MORE vacuum on your crank case and also route it to atmosphere so your not lowing your VE (volumetric efficiency). Just venting to atmosphere isnt enough because your pan is at atmosphere not vacuum.

Stephen

 

Probably not. It's most likely me I guess there are two issues here:

1. blow-by
2. slosh

Under vacuum your explanation makes sense. I'm not sure how this would work with track stuff/slosh. For example, during a long left-hander you've a slosh situation which effectively plugs the connecting tube (with PCV per your suggestion) as you've inhibited crank case venting (assume you're on the throttle/boost). I'm assuming you'd want a vent positive pressure in that situation too while allowing catch can to do its job, no?

Gene

 

You can do the same thing as a vaccum pump, without having a pump. There are scavange kits from summit and jegs both. It's basically a slash cut tube welded into your exhaust pipe, at the correct angle. This will pull suction, which you would hook to your catchcan. Don't try this without a check valve inbetween, else a backfire might cost you a few $$