3.2 turbo conversion - ?turbo oil return line sump plate?
 

For those who have done a turbo conversion on their 3.2...

PASSIVE RETURN: I've read that passive gravity return to the sump/engine was adequate, but have also heard that this has its own problems. Problems seem to be related to the turbo being pretty low, so the drop any lower to the engine is not all that great (so low gravity pull), with the possibility of backup of oil in the return line.

ELECTRIC SCAVENGE PUMP: I've also read of the dangers of an electric oil scavenge pump, in that if power is lost or the external pump otherwise fails, the turbo is toast.

Two sets of questions:
1) Modification for the oil return line from the turbo:
Where to enter the engine?
Any pics of your own DIY mods to the engine?
Any suggestions related to this?

2) Electric oil scavenge pump:
Where to mount the pump? (have any pics?)
To where did you return the oil?

Has anyone tried a DUAL return lines (like with a "Y") to both the electric scavenge pump as well as a more direct return line as a failsafe gravity return?


Thanks.

I'm not sure what you're referring to as modified sump plate as the 3.2 ditched the sump plate from the 911 SC. You could run a line to the drain plug. Another option is to tap a port on the lower valve cover and return there.

Turbowerx is the brand I've seen posted a few times for electric scavenge pumps. They are self priming and are fine if the suck air and run dry for a bit.

Since I was changing cams, I went for a stock solution. I had the scavenge pump drive included on the cam and used Clewett's scavenge pump/cam position sensor and returned oil to the breather similar to a stock 930.

Jon,
You're absolutely right ref. plate - I was mixing up my Carrera and SC cars and spoke without thinking (a new dangerous trend as the 70th BD approaches....)
I have modified my initial post.

I thought I had a Turbowerx, but turns out it is labelled Mocal, BUT BUT BUT, I just compared my MOCAL with the TurboWerx pics, and they certainly look the same externally! See the attached pix.

Regarding going with changing cams and also adding pump... hope i do not have to delve that far, but who knows what lies ahead. I just was planning to change out my fuel pump and discovered a leak in my flex line between pump and tunnel lines, and now I am invested in changing out all fuel lines.

As someone recently said, "Down the rabbit hole..."

I wanted to insert the pics of my MOCAL and of TurboWerx pumps to show how identical they were, but this site is only allowing inserting a link or a URL of the image, which I do not know how to do. What has changed in posting pix? No attachments anymore?

Had to REPLY in order to get the full options in order to upload an image. First pic is from internet of TurboWerx; last two are of my MOCAL pump.

http://forums.pelicanparts.com/uploa...1590365148.jpg
http://forums.pelicanparts.com/uploa...1590365148.jpg
http://forums.pelicanparts.com/uploa...1590365148.jpg

I know people have had success returning the oil through the drain plug hole and that's the way I'm doing it. My hypothesis is; I'm running a Garrett ball bearing turbo which only requires a trickle of oil through the heavily restricted oil feed line. This means that there won't be a high volume of oil running through the return that might back up and bypass the turbo oil seal. Journal bearing turbo's require a high volume of oil to keep the bushing lubricated and they might require oil scavenging.

From following a number of 3.2 turbo builds over the years, it appears that there is a component of luck involved with the turbo oil drain. Many have successfully gravity drained back to the crankcase drain plug or welded into the lowest point of the timing cover. Others have had to install a scavenge pump with catch can / drip tank.

Clearly, getting the turbo to be as high as possible and finding a continuous downward slope to the drain location is key. However, that path needs to be sufficiently angled downwards (continuously) and ideally would drain above the oil level (believe that is in Maximum Boost or Turbocharging Performance Handbook - both excellent reads).

The pump, be it mechanical like the 930's or electrical would then return the oil to the breather at the top of the engine (near the 'idiot' light). This appears to be the best place. I gather the sensor plug that the return hose replaces gets moved somewhere else?

The electrical pump itself can be mounted high or low as it appears that doesn't truly matter for the flow.

In terms of hoses it appears that most use the steel braided hoses and not the rigid pipes you find on factory cars like the 993TT. I wonder if rigid pipes can work or if having the pump mounted on the body would cause relative movements that would crack the rigid pipes?

I have read from some posts that the oil drip tank / catch can needs to be vented although it appears some disagree.

I would agree there is concern if the pump fails - perhaps a light in cockpit to warn of failure might work?

I would be interested to learn more about this as well.

EDIT: I am having drainback issues on my build with a restrictor to my Garrett Turbo. Unfortunately, I am unable to have a continuously downward slope back to either the crankcase drain plug or the timing cover as the headers are in the way of the return path. I am looking at the electric scavenge pump solution so this a timely post!

Good inputs, thanks.

R-Bull - good rundown of the factors involved. Obviously you are developing a logic pattern. I wanna know too.

That MOCAL/Turbowerx pump is HEAVY and a little bulky. Mocal does make a "micro" pump version of the 17-530SL ("17-530M"), but even that is not that small.
Both the MOCAL and Turbowerx pumps are certified to pump dry without a problem.

I had been thinking of putting a "Y" in the return line immediately after the catchcan, with one branch going directly downward to gravity feed to the drain plug, and the other branch of the Y going to the electric scavenge pump. Would be a failsafe in case the gravity return is inadequate, OR in case the electric pump fails.
This just might be too complicated and unnecessary, as well as bulky.

One more pearl I just learned yesterday regarding the oil feed line to the turbo (from a website selling oil pumps, IIRC): route the feeder line to have a "J-tube-like" drop in the line so that there is a point that is lower than the line's entry point into the turbo -- so that AFTER the engine turns off, oil does not continue to feed into the bearing surface due to a siphoning effect. Supposedly the continuous oil feed to the bearing, after the engine is off, will seek path of least resistance, which is into the turbo seals -- resulting in turbo smoking on startup.

BTW, I am also going to use watercooling of the turbo, with maybe a motorcycle radiator with fan in the rear fenderwell. Haven't figured this out yet, but I know several have already done this -- so I'll be wanting to see the line routing and rad placement. I bought a small electric water pump that BMW uses for their water circulation.

I still have a ways to go in this turbo project -- after accumulating 98% of the parts, plus laying off the project for about 5 years (!!).

I have heard that CXRacing has an electric scavenge pump for our application as well. I am not aware if anyone has used that on their cars.

Would the 'Y' connector not allow the scavenge pump to pull oil from both the turbo and the crankcase? Perhaps not or perhaps avoided with a one-way valve? Although agreed that it might be too complicated and another point of failure. If the pump does fail, I imagine the tell-tale sign would be smoke out of the exhaust. All the backed-up oil would push through the compressor or turbine seal of the turbo - a clear warning I suppose!

For the turbo oil supply / feed line, I would have thought that having oil siphoned into the bearing housing after shutdown would be a good thing to help cool the turbo and avoid coking of the oil. It would be a good tradeoff to smoke at startup if so.

It is worth the patience and planning!

Breather on catch can: if you are using a gravity drain, I would say there isn't necessarily a need. However, the reason you want one with a scavenge pump is because the oil flow almost certainly is not going to be matched with the scavenge pump flow. When the pump runs out of oil to pull, it's going to start sucking air. So either the pump pulls air through the turbo seals, or it pulls air through a breather in the catch can. The obvious question in response is wouldn't the pump then just try to keep pulling air instead of oil? As long as you have a distinctive low point on the catch can for the oil to pool, it will cover the pump feed line and the pump will only pull oil.

Oil supply side: I'm using the stock oil feed spot at the dummy light. Turbokraft makes a spring loaded check ball for the fitting to prevent the oil draining out of the line.

Good points, thanks.

Here's the link to Motorsports explaining about the feed line loop.
https://www.youtube.com/watch?v=7-pf7GaoHRo#action=share

Thanks for the explanation of the vent / breather for the drip tank / catch can.

For the supply line draining oil into the turbo after shutdown, wouldn't that oil accumulate in the drip tank? I understand he mentioned "path of least resistance" in the video but I would have thought the drip tank being low down would help siphon the oil from the turbo bearing housing.

Alternatively, would a timer to keep the scavenge pump on for 30 seconds or 1 minute be helpful to siphon the additional oil or would this be detrimental to cooling oh the bearing housing?

After many failed attempts with the gravity drain I opted for the Turbowerks pump on my 3.2 and it works flawlessly. I also use the restrictor which you can source from Turbocraft and I have a small light on the dash which lets me know the pump is on. You need to run the pump for 20-30 seconds after shut-down and all is good. That seems to be the sweet spot because if I turn the car off without running the pump it will smoke on startup for a few minutes. The only other issue is that you'll definitely hear the pump when you first start the car in the morning. Its noticeable but once its actually pumping oil you wont hear it. Yes the electric pump will do the job 100% but you'll have the 2 small issues which may or may not be problematic for some.

Anyone have experience with the stock 930 mechanical pump on a 3.2?

http://forums.pelicanparts.com/uploa...1590541934.jpg

Car is currently apart at the moment. (engine out) but I'll either get around to fabricating a legitimate mounting system or entertain the idea of the stock 930 pump, but I've ran this setup for years so far with no issues.
(Oil is returned to the breather as others have mentioned).

"EDIT: I am having drainback issues on my build with a restrictor to my Garrett Turbo. Unfortunately, I am unable to have a continuously downward slope back to either the crankcase drain plug or the timing cover as the headers are in the way of the return path. I am looking at the electric scavenge pump solution so this a timely post![/QUOTE]"

It's timely for me too as I machined off the drive hub of my stock 930 camshaft and tig welded it to my NOS 964 camshaft. The stock pump can be rotated with your pinkie so I believe the weld will hold fine.

Also since the turbocharger is pressure fed oil, it would seem you would just overflow and know your pump failed.
This wouldn't be enough time to ruin your turbocharger imho as it was still being fed oil. It will make a mess though.

Matt
http://forums.pelicanparts.com/uploa...1635524111.jpg
Note I shortened my 4 speed, it works great.
http://forums.pelicanparts.com/uploa...1635524111.jpg
http://forums.pelicanparts.com/uploa...1635524111.jpghttp://forums.pelicanparts.com/uploa...1635524423.jpg

Obviously I wouldn't trust tig welding for other internal applications but for this little pump I do. We're not levering off the end of the cam we're simply spinning. The momentum of the cam hub pulley alone would spin this scavenge pump. I'll be installing the motor this weekend and will follow up.

Note my oil sump is also shortened as I needed to take away 2 inches to clear my custom header heat exchangers. No leaks.
http://forums.pelicanparts.com/uploa...1635524735.jpg

You can see my turbo oil feed/return setup in my post :

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1069058-my-turbo-project-adding-turbo-3-2-a.html

At first, I tried the gravity feed to the oil drail plug on the case and it didn't work, so I went ahead and bought a Turbowerx oil scavenge pump (the Nano model, a very small one which fits great) and made a return port on the vent cover plate on top of the engine, that worked for a while but then I noticed that oil would accumulate in the turbo and then drain inside the itake and exhaust sides, which caused excess oil burning smoke on startups and also pushed oil inside the intercooler, huge miss! .. then I fabricated an aluminum drip tank out of a 3 in piece of aluminum tubing and that fixed the issue, now everything works perfectly fine.

Gravity should be minimum AN10 to work well on journal turbos. I massaged a AN12 90deg fitting on bank1 valvecover near drain tube. On holset end a drilled/modded AN10 flange with dremeled AN12 adapter was largest ID I could fit there not hitting compressor housing.

How is your turbo holding up? I note that you used a "cheap ebay chinese" turbo.. still going strong?

Pic of my drain.http://forums.pelicanparts.com/uploa...1635696941.jpg