evening peeps...

after some advice really....

i am turboing a 2L zetec black top engine, and of course i need an oil return for my turbo..

so i spoke to my tuner (paul hills @ EA) and he told me that i should have my return fitting fitted below oil level, so off the sump went to be baffled and have a -10 fitting welded in place...

heres the end result




well pleased with how the baffling turned out, and the fitting looked good too i suppose...

paul said the oil return is in a better position below oil level and also works well if you have a pukka breather system, which i have.. he said any crank case pressure is lost thru the breather outlet. and also no crank case pressure will hold up the oil from the turbo and cause it to smoke. Engine advantages run many of there zetec turbo's with the oil return fitting in the same place without any problems...

i posted up these pictures on another forum and a few people have questioned the positioning saying totally the opposite to what i've been told and that it will cause a build up in pressure, hold the oil up, cause my car to smoke and muller my turbo...

really dont have a clue on all this, only going by what i've been told and recommended.....

can anyone help or got any comments...??!

thanks

rich [/u]

 

anyone?????

 

All i can say is that a standard Cosworth oil return returns the oil above the oil level and i'm guessing that was done for a reason.

 

there is a mixed school of thought about where to situate the oil returns
one some cars they are below the oil line and on others above

if it's not been a problem for this sort of convertion before then i'd say it was going to be a good thing to follow the advise of people who have been there and odne that

on the other hand, putting the return ABOVE the oil level means there is no place for the oil to go to other than the sump
imagine you are cornering hard or on the brakes or whatever position is going to throw the oil up the pipe, if it's under the level then it's going to stop the oil coming back down from the turbo

swings and rounabouts really mate, but it looks like a good enough job, just make sure the welds are proper pucka jobs as you don't want then to let the oil out if they aren't strong enough because there are places where they might have poked through a little

 

yeah i know mate, all ford turbo'd cars are

 

thanks for that mate

 

anyone else

 

oil drain of any sort including the one from your breather should always be below the oil level, there is no chance of it being affected by crankcase pressure.....

 

thanks mate


can anyone else shed any light on this subject... cheers

 

Hi,

I would get a second opinion from a reputable tuner,
i have several books on turbo charging, and converting a N/A engine
it list It is vital that the oil drainback system from the turbo to the oil pan
be completely free of kinks, sharp bends or other restrictions so that oil back pressure in the line can't spoil the flow of fresh oil coming into the unit. OBVIOUSLY THE POINT AT WHICH YOU DUMP THIS DRAIN LINE INTO THE OIL PAN SHOUL BE ABOVE THE PAN STATIC OIL LEVEL OR THERE WILL BE BACK PRSSURE.
also to the above the return pipe diameter must be considerably larger
than the supply inlet pipe,because of aeration and foaming that takes place as the oil passes through the high-speed bearings.

Regards Dave R.

 

below oil level imo

 

I can't think of ant from factory that join below oil level,surly that says something??
Also if you have a pukka breather system surely crank case pressure(hloding up the oil) wont be an issue?
Interesting though

 

mines above oil level on mine to help with drainage also its at a slight angle to further assist

 

Hi Rich ,

The return should be fine where it is , more importantly why is there no gate in front of it , this will mean under braking you have surge towrds the front surely ?? There are gates for every other direction ??

cheers
tony

 

i say if thats what paul has told you to do then stick with it he,s a top man

 

Audi 2.5 five cylinder turbo diesel engine it's the only one i've ever seen and i've brought this question up on other forums only to be met by blank answers, or simply that won't work. Now audi have done it like this on thier engine and i'm assuimg they've had no problems cos i know of a few 2.5's on over 140k miles with no trouble.

That said this is the old A6 engine which stopped being made in 1997? and the same engine in the transporter doesn't use this method and nor does any other audi asfaik in the current range.

The clever thing is though it uses a banjo bolt as a sump bung, attached to the banjo is the oil return, obviously doing it like this would save alot of trouble when converting a n/a engine to turbo. Prehaps audi stopped doing this cos people kept overtighting the banjo bolt maybe?

 

above all level it has foook all to do with crank case pressure

 

as above i have alwas doine above

 

if you wish to test the theory of returns put a pipe on a funnel drop the end of the pipe in 4 inces of water and poor some in the funnel lift the pipe out of the water and watch the increased speed the funnel now empties.Now try it with oil .A turbo flows a min of 1 gallon per minute and that's at idle

 

regardless of the volume, the pressure in a liquid (or gas) increses proportionally to depth. An oil return should be kept well clear of oil level. The seal on a turbo relies on differential pressure, ie no pressure at the return. The return should be below the turbo but above any oil.

 

thank you everyone for your comments, i will bare them all in mind... but i will be definately keeping the sump as it is....

if anyone else has any comments to make on the subject please do...

 

get pictures of a 24V sump
the oil returns are below the oil level, almost at the bottom of the sump

but, in saying that, i've also got a TT sump where the oil returns are way above the oil line

if i was doing it from scratch i would say above, but if people have done it before and below is fine for the application then below would seem good enough for me

 

My turbo oil return is above oil level. (blacktop turbo) But I had breather problems due to the oil returnfor the breather system being above oil level on the sump and tryin to breath and return, resulting in big blobs of oil being chucked out of the breather filter! Ian Howell made me a sump plug adapter so the return is below oil level. solving the problem alltogether.

 

cheers mate

 

thanks for that mate...

 

I would go for above, for the reasons Tony gives, its a freer path for the returned oil.

 

hi tony

howz it goin?!?! long time no speak....

got any more rotors??! i'm after a set.... same size, more meat on tho...

i will look into the front gate situation more and see what i can do, i might even make that part myself....

doing this would reduce the oil going up the return hose and help the draining oil drain better wouldn't it, so that has got to be better

cheers

 

tony ryan yeah??


if so

 

I am one of the members of the "other forum" rich posted these pics on, and am quite strongly against such positioning of a turbo oil return.

My original reply:
Why do people think that placing the return above the oil level would create a problem with crank case pressure? The pressure in the crank case acts on the oil surface, and so with the oil return below the oil pressure, you're giving it the crank case pressure AND the pressure head from the oil depth to work against when trying to return the turbo oil to the sump. Poor positioning in my opinion, and it seems quite a few people on here agree. A breather is fine returning below the oil level as it doesn't deal with continuous flow (provided the engine isn't seriously sick!), but that bears no relation to a turbo oil return.

 

oil returns circles in red





even though there are welds alongside, the main holes are at the bottom so i don't think there are going to be any issues with losing oil out of the little bits that aren't welded

 

First of all....

Secondly..this thread is about turbo oil returns, what are those returns for that you've circled?

 

hmm, it seems as though i have posted a pic in error

the second pic is this one



it's the sump from a 24V granada and the oil returns are from the heads (both banks) as there is not enough space in the block to return all the oil and so it goes out through the backs of the heads and out along the back of the block into the sump

so, if ford have decided that they want to return the oil from the head back into the sump BELOW the oil level then there has got to be some sort of mega money spent by cosworth in order to make it happen
what would be the reasoning for it otherwise?

 

It's different when it's oil draining back from the heads as opposed to a turbo oil return as is being discussed here:

a) The turbo oil return is coming directly from high speed bearings, so the fresh oil supply cannot be hindered

b) There is a much bigger pressure head on the oil coming from the heads on that engine. The oil leaving the turbo is doing so from no more than about 100-150mm or so above the oil level in the sump, hence all the talk of pressure differentials.

 

anyone else got any comments

 

i understand that, every car i have seen with an after market turbo install has had the returns mounted above the oil level

again, there could be various resons why the returns were plumbed back at the base of the sump, don't forget, there is also the natural way for the oil to return from the top end, the returns are there to stop all the oil staying in the top, but there must be a reason why they are below the oil level

on te other hand, we are talking baout oil coming from the sump, being pumped up to the turbo and then being dumped back into the sump again, if the oil were to stay above the line it would take longer to get to the turbo so pumping it below the line would serve as a way to fill the sump with a fresh resivour of oil for the pick up pipe to collect it from, a cirlce of life if you will
what you really want is a perspex sump to see how the oil is getting spun around the sump to get the best results

 

I don't understand you there. Whether the oil return enters the sump above or below the oil level, it all goes back into the sump either way, then gets picked up and pump around the engine again. For that reason, it makes no difference to oil circulation whether the oil's returned above or below the oil level in the sump.

 

isnt having the oil from the turbo going below the oil level going to slow the rate down the oil travels through the turbo and give it more chance to cook the oil and the turbo as you want the oil to move as fast as posible to cool the turbo

 

edited to say... doh!

read explanation further down thread!

 

Know what you mean Martin, but with such a definite response, fancy stating a couple of reasons for it, and reasons for going against my statements above? This is General Discussion after all!

 

AS above.


Dave R.