Oil catch tanks
Discussion
Q1: Who uses a catch tank for their gearbox oil breather pipe, and where was it sourced?
Q2: In addition, may be a stupid question...the LS7 engine oil breather pipes...currently I see that most stick a Y piece between the two outlets from the rocker covers, then take that single pipe to the top of the main oil reservoir. I may be wrong but I would have thought that there could be a fair bit of pressure build-up over time, so how does this work?
I would have thought a small bulk-head mounted catch tank with breather filter just before the main reservoir would be the right way to go? or is this over-complicated?
cheers
keith
Q2: In addition, may be a stupid question...the LS7 engine oil breather pipes...currently I see that most stick a Y piece between the two outlets from the rocker covers, then take that single pipe to the top of the main oil reservoir. I may be wrong but I would have thought that there could be a fair bit of pressure build-up over time, so how does this work?
I would have thought a small bulk-head mounted catch tank with breather filter just before the main reservoir would be the right way to go? or is this over-complicated?
cheers
keith
Call me stupid if you like (yeah! Go on then!
) but I am not sure how that effects my quest for clarification?
I have seen some comments from others saying that the LS7 is actually no a true dry sump system, however I am not qualified to know either way! ...which is why the question...
Are you saying the system is a 'closed system', ie does not need any form of venting? help me understand!
As for the gearbox, I am going on what CMS have suggested and would like to know others solution!
cheers
keith
) but I am not sure how that effects my quest for clarification? I have seen some comments from others saying that the LS7 is actually no a true dry sump system, however I am not qualified to know either way! ...which is why the question...
Are you saying the system is a 'closed system', ie does not need any form of venting? help me understand!
As for the gearbox, I am going on what CMS have suggested and would like to know others solution!
cheers
keith
pilbeam_mp62 said:
If you want to do it as per factory recommendation - You need a breather hose from the top of the dry sump tank to three rubber breather hoses - one to each rocker cover and one to the MAF housing elbow
MAF housing elbow? Wasssis please? Piccy?cheers
keith
Edited by V8 Vum on Friday 30th July 14:49
The LS7 is a dry sump motor, but unlike others it retains the pressure pump in the block. This is a g rotor pump and it slides onto the crankshaft. No drive off the distributor ect. The exterior pump on the motor provides the suction that evacuates the pan. Under most situations there shoud be a slight vacum in the block, this is a good thing. The air to feed all of this comes through The vents that come off of the valve covers. Read that again please. The valve cover vents feed air to the motor. Therefore the valve cover vents need to be filtered air from the aircleaner area but do not feed them from behind the throttle plate becuase you will be taking already measured air out of the system. Remember there needs to be a line that vents out of the top of the oil resvior to a catch can with a air filter mounted on it. If you do not know how much oil to put in the resivior I would suggest filling the tank 3/4 full then run the motor over a hour or so and check the catch can if you have signifcant oil in the catch can you started with to much oil when you quit getting more than a few teaspoons of oil in an hour of running note were the level is at with the motor running and the engine should be happy there. Obviously keep and eye on the oil level while you are doing this and don't get it too low a little common sense must prevail. Lee
Not to pick an argument with your engine builder but there are lots of very high end race motors running with the stock or upgraded g rotor pump in place on the crankshaft. One reason being that a thrown belt which can be as simple as a rock getting in the way and you have to be a quick boy indeed not to destroy the motor. Another question if you plug the vents were is the air needed to fill behind the outgoing oil coming from? And if the vents are inside the filtered area in the aircleaner and the vents are sucking some clean air into the motor as needed whats the harm? Not trying to be a smart ass but sometimes you have to sit back and question why some folks do things. Lee
ROWDYRENAULT said:
...... if you plug the vents were is the air needed to fill behind the outgoing oil coming from? ......
On a SBC you pull a vacuum on the crank case with a PCV valve. In this case the air/gas it is pulling is blowby on the piston rings. Maintaining a vacuum is good as it helps keep the oil from trying to escape past seals and gaskets. On that basis letting air in would defeat the object.In the case of a dry sump the oil is being scavenged and if working right is getting it all including some air. If you add air it will only make it harder for the swirl pot/tank to remove the air before the oil has to return to the engine.
Steve
.........pretty much what I was suggesting, whats the point of scavenging something with holes everywhere?....you are making it harder for the scavenge pump to work........what's easier for it to pull, air or oil, whats it's primary function.....the fact that it relieves crankcase pressure and improves ring seal is just a big bonus.
the company solutionF that provided my engine is well reputaded company for race engines and normally too pricey for ultima builders, I am pretty sure
they know there stuff well and I am glad that I kept with their recommandation which seem all to be very accuraten so far.
As my pressure readings can go as high as 8,5 Bar I see the main reason for the outside oil pump to have a higher pressure level than the 5 bar you
can achieve with the internal pumps - BTW first drives almost all pressured connections D-12 where leaking and needed to be retightend, what a mess......
they know there stuff well and I am glad that I kept with their recommandation which seem all to be very accuraten so far.
As my pressure readings can go as high as 8,5 Bar I see the main reason for the outside oil pump to have a higher pressure level than the 5 bar you
can achieve with the internal pumps - BTW first drives almost all pressured connections D-12 where leaking and needed to be retightend, what a mess......
spatz said:
the company solutionF that provided my engine is well reputaded company for race engines and normally too pricey for ultima builders, I am pretty sure
they know there stuff well and I am glad that I kept with their recommandation which seem all to be very accuraten so far.
As my pressure readings can go as high as 8,5 Bar I see the main reason for the outside oil pump to have a higher pressure level than the 5 bar you
can achieve with the internal pumps - BTW first drives almost all pressured connections D-12 where leaking and needed to be retightend, what a mess......
Got me worried with those oil pressures. Why are they so high?they know there stuff well and I am glad that I kept with their recommandation which seem all to be very accuraten so far.
As my pressure readings can go as high as 8,5 Bar I see the main reason for the outside oil pump to have a higher pressure level than the 5 bar you
can achieve with the internal pumps - BTW first drives almost all pressured connections D-12 where leaking and needed to be retightend, what a mess......
Did a quick Google which found a link to an LS7 handbook quoting...
41 Kpa @ 1000rpm
124 Kpa @ 2000rpm
165 Kpa @ 4000rpm
Thats..
6psi or .41bar
18psi or 1.24bar
24psi or 1.65bar
Steve
this is what my sensor picks up and I have been told 5 BAR is standard for the LS7 maybe sensor reading is not accurate, but there is sure enough pressure taking the leaks and spray patterns in account that I encountered in my first test drives. They were developping these engines for a cancelled nascar like series in DUBAI - my luck fantastic engine.
So..it seems it is a closed system, with the vacuum being supplied by the MAF elbow thus reducing pressure in the tank????
Well it looks like I do not have a MAF Housing elbow thingy!
I found a piccy in the Factory instuctions, but I don't have that big shiny tube.
..but my engine came with just a blue silicone hose in the same place and a very short MAF unit just before the filter - which is wierd??!
what should I do chaps? Should I be getting that shiny tube MAF unit with the breather elbow, or is there a better way?
cheers
Keith
Well it looks like I do not have a MAF Housing elbow thingy!
I found a piccy in the Factory instuctions, but I don't have that big shiny tube.
..but my engine came with just a blue silicone hose in the same place and a very short MAF unit just before the filter - which is wierd??!
what should I do chaps? Should I be getting that shiny tube MAF unit with the breather elbow, or is there a better way?
cheers
Keith
I dont think you are going to find one answer to your question on this matter Keith.
The factory have their methods as do GM and the many independent engine bods here .... much of which will be contradictory for the new user.
The photo you show does not really demonstrate a proper dry-sump install. If you have a scavenge/vac pump you will never maximize its use if it can freely pull air from the atmosphere, it should create a slight vacuum throughout operating range. AS its driven by the engine itself its effectiveness should be reasonably proportional with rpm.... pretty much what we want. The volume of fluid and air it evacuates is replaced by the introduction of fresh cooled oil (which heats and expands) and piston ring losses (blow by). No matter how well designed, machined or assembled your motor there will be some blow-by during running. Venting the crankcase/valvegear will not help scavenging.
You do need to vent your oil tank to allow excess air (from ring blow-by only) and the natural expansion and contraction through temp change, to occur. This is probably best done through a filter unit.
Im guessing the photo method was developed to make the IVA man happy only. (so you must factor him into your chosen method)
The factory have their methods as do GM and the many independent engine bods here .... much of which will be contradictory for the new user.
The photo you show does not really demonstrate a proper dry-sump install. If you have a scavenge/vac pump you will never maximize its use if it can freely pull air from the atmosphere, it should create a slight vacuum throughout operating range. AS its driven by the engine itself its effectiveness should be reasonably proportional with rpm.... pretty much what we want. The volume of fluid and air it evacuates is replaced by the introduction of fresh cooled oil (which heats and expands) and piston ring losses (blow by). No matter how well designed, machined or assembled your motor there will be some blow-by during running. Venting the crankcase/valvegear will not help scavenging.
You do need to vent your oil tank to allow excess air (from ring blow-by only) and the natural expansion and contraction through temp change, to occur. This is probably best done through a filter unit.
Im guessing the photo method was developed to make the IVA man happy only. (so you must factor him into your chosen method)
Edited by 738 driver on Sunday 1st August 18:31
V8 Vum said:
Q2: In addition, may be a stupid question...the LS7 engine oil breather pipes...currently I see that most stick a Y piece between the two outlets from the rocker covers, then take that single pipe to the top of the main oil reservoir. I may be wrong but I would have thought that there could be a fair bit of pressure build-up over time, so how does this work?
I would have thought a small bulk-head mounted catch tank with breather filter just before the main reservoir would be the right way to go? or is this over-complicated?
As mentioned previously - several opinions and ways to do this... for what it's worth, this is what I did for my (nearly) stock LS7..I would have thought a small bulk-head mounted catch tank with breather filter just before the main reservoir would be the right way to go? or is this over-complicated?
Originally set up with system set per factory guidence - pulling slight vac per corvette set up, but I wasn't very happy with the thought of pulling any oil vapour into a nice clean inlet tract - my understanding was that this type of set up was "invented" to meet emissions regs and need for closed system in mass produced vehicles, and improve oil life by removing nasty vapours etc (a moot point with oil changes every 3k or so)
Anyway... I now have both rockers, oil tank and crank case vent feeding into a catch tank which is filtered to atmosphere - that way everything equalises in pressure to atmosphere and any oil vapour carryover is caught in the tank. So far not got any oil in the tank (3000 miles).. although worth noting that when I was originally struggling to get my oil temp up, I did see water vapour condense out in the tank - not that I've got my oil temp up that's stopped.
Choices, choices
Paul
..And so...
To summarise, it seems, unless I have mis-interpreted your kind contributions that a suitable catch-tank with oil breater/filter, situated in between the pipe coming from the rocker-covers and the top of the oil-tank is the best method for the LS7???
How would that affect (if at all) the IVA? The factory went for the solution in the picture below, so is to comply with some IVA requirements, and if so, what are they?
I would hate to go to all that trouble only to find I fail on this due to the catch-tank?
cheers
Keith
To summarise, it seems, unless I have mis-interpreted your kind contributions that a suitable catch-tank with oil breater/filter, situated in between the pipe coming from the rocker-covers and the top of the oil-tank is the best method for the LS7???
How would that affect (if at all) the IVA? The factory went for the solution in the picture below, so is to comply with some IVA requirements, and if so, what are they?
I would hate to go to all that trouble only to find I fail on this due to the catch-tank?
cheers
Keith
Edited by V8 Vum on Monday 2nd August 09:52
I have been concerned about the apparent conflicting opinions about the need for an oil catch-tank for the LS7, and in particular because I don't appear to have any MAF vacuum port on my engine (unlike the factory setup) and so have been looking around the net and have come up with some interesting reading. In addition I am running forged pistons so the need for a vented system of some sort I would think is paramount.
It seems that most catch-tanks are basically a vented single chamber with a level tube (and filter in some cases), and most explanations as to where or how to fit are rather generic.
http://www.quillertriumph.co.uk/Quiller/Parts/new_...
What I needed to find was reference to the LS7 specifically, and so here are my findings:
The 'specialists' seem to use a small multi chamber unit for the corvette engine with a metal mesh internally to assist condensation, and it is interesting to note where they fit them and the hose connections which was not expected - see this link
http://www.eliteengineeringusa.com/Catch_Can.html
This seems to be supported by the following thread and the diagram on the penultimate posting
http://www.z06vette.com/forums/f64/please-describe...
It shows a fully vented oil breather system (with the above catch-tank in a separate circuit) but with the main rocker-cover piping leading to the oil reservoir, but then another outlet on the oil reservoir leading to a breather-filter (but then most of us don't have that additional port on the oil tank). In addition the system has several check-valves in place to prevent surge/reverse flow.
or... the alternative is to replace your oil Tank completely with one of these babies!
http://www.petersonfluidsys.com/tank_spec.html
...and then since there are 2 circuits - one clean (valve covers) and one dirty (valley cover etc) I suppose the simplest way is to use a filter vent (with one way valve) on the clean circuit. However I am not sure what to do with the top outlet on the oil tank??? I suppose the 'dirty' circuit can be closed, with or without a catch-tank????
Comments please?
cheers
keith
It seems that most catch-tanks are basically a vented single chamber with a level tube (and filter in some cases), and most explanations as to where or how to fit are rather generic.
http://www.quillertriumph.co.uk/Quiller/Parts/new_...
What I needed to find was reference to the LS7 specifically, and so here are my findings:
The 'specialists' seem to use a small multi chamber unit for the corvette engine with a metal mesh internally to assist condensation, and it is interesting to note where they fit them and the hose connections which was not expected - see this link
http://www.eliteengineeringusa.com/Catch_Can.html
This seems to be supported by the following thread and the diagram on the penultimate posting
http://www.z06vette.com/forums/f64/please-describe...
It shows a fully vented oil breather system (with the above catch-tank in a separate circuit) but with the main rocker-cover piping leading to the oil reservoir, but then another outlet on the oil reservoir leading to a breather-filter (but then most of us don't have that additional port on the oil tank). In addition the system has several check-valves in place to prevent surge/reverse flow.
or... the alternative is to replace your oil Tank completely with one of these babies!
http://www.petersonfluidsys.com/tank_spec.html
...and then since there are 2 circuits - one clean (valve covers) and one dirty (valley cover etc) I suppose the simplest way is to use a filter vent (with one way valve) on the clean circuit. However I am not sure what to do with the top outlet on the oil tank??? I suppose the 'dirty' circuit can be closed, with or without a catch-tank????
Comments please?
cheers
keith
Edited by V8 Vum on Wednesday 4th August 12:49
Keith
Great research - similar articles to those I read when trying to decide what to do....
Per my previous post, but to add a bit of info,
My concern was whether I really needed a closed system and if so getting the set up right with the whole dirty / clean air in the system.....but after much research and talking to some people I consider knowledgeable I determined that the clean air side really is to ensure that whatever you put into the system is clean (i.e. not contaminated or unfiltered) - and is only really needed/developed for total closed system (i.e on mass produced vehicles for emission compliance and convenience - after all who wants to check a catch tank on an off the shelf engine - and that helps drag incondensables out of the engine, reduces impurities breaking down the oil over time which helps oil life, again, not a consideration with a limited annual mileage where the oil is changed every few thousand miles.
So, in summary... I vented the whole lot (both rocker covers, crank case and oil tank) to a single tank with atmospheric filter on it so everything is balanced and vents to atmosphere. It passed IVA in April - wasn't even mentioned or looked at (not part of any check as far as I can make out). I don't have any oil in the catch tank after 3k miles and no noticable oil vapour blowing out of the catch tank.
Regards
Paul
Great research - similar articles to those I read when trying to decide what to do....
Per my previous post, but to add a bit of info,
My concern was whether I really needed a closed system and if so getting the set up right with the whole dirty / clean air in the system.....but after much research and talking to some people I consider knowledgeable I determined that the clean air side really is to ensure that whatever you put into the system is clean (i.e. not contaminated or unfiltered) - and is only really needed/developed for total closed system (i.e on mass produced vehicles for emission compliance and convenience - after all who wants to check a catch tank on an off the shelf engine - and that helps drag incondensables out of the engine, reduces impurities breaking down the oil over time which helps oil life, again, not a consideration with a limited annual mileage where the oil is changed every few thousand miles.
So, in summary... I vented the whole lot (both rocker covers, crank case and oil tank) to a single tank with atmospheric filter on it so everything is balanced and vents to atmosphere. It passed IVA in April - wasn't even mentioned or looked at (not part of any check as far as I can make out). I don't have any oil in the catch tank after 3k miles and no noticable oil vapour blowing out of the catch tank.
Regards
Paul
Gassing Station | Ultima | Top of Page | What's New | My Stuff