Dry Sump System. Questions related to vacuum and control
Discussion
Hi,
I have a dry sump system for a Honda K20 engine. This is the first dry sump kit that i've bought and used so as you would imagine i i'm checking into a few areas before going ahead and fitting it.
I've read about and been told about dry sump systems creating a vacuum in the engine which, apparantly, helps the engine out in a few areas. To name one it's meant to seat the rings to the bores better.
I have been advised to run a vacuum regulator (http://www.petersonfluidsys.com/engine_breath.html), welded onto the rocker cover, so that i can dial in the amount of vacuum required for my application. According to users of this engine in the USA, when using a dry sump system it's strongly advised that you should block off the oil filler and dipstick holes in the rocker cover in order to seal the engine and promote the vacuum created by the use of a dry sump system.
I just wanted to run this past another group of people that may have experience in these systems to see what they say about utilising vacuum and controlling it.
I actually spoke to the supplier of my kit (in the UK) who were not helpful with my questions and were surprised i was asking them questions relating to vacuum.
I have a dry sump system for a Honda K20 engine. This is the first dry sump kit that i've bought and used so as you would imagine i i'm checking into a few areas before going ahead and fitting it.
I've read about and been told about dry sump systems creating a vacuum in the engine which, apparantly, helps the engine out in a few areas. To name one it's meant to seat the rings to the bores better.
I have been advised to run a vacuum regulator (http://www.petersonfluidsys.com/engine_breath.html), welded onto the rocker cover, so that i can dial in the amount of vacuum required for my application. According to users of this engine in the USA, when using a dry sump system it's strongly advised that you should block off the oil filler and dipstick holes in the rocker cover in order to seal the engine and promote the vacuum created by the use of a dry sump system.
I just wanted to run this past another group of people that may have experience in these systems to see what they say about utilising vacuum and controlling it.
I actually spoke to the supplier of my kit (in the UK) who were not helpful with my questions and were surprised i was asking them questions relating to vacuum.
All of what you say is correct, although it doesnt help the rings seat on the bores, the only things that do that are ring tension and combustion pressure.
Having a vacuum in the crankcase should mean less oil deposits floating about and any combustion byproducts that do make their way past the rings will be drawn out as well. Just generally making it a cleaner and freer environment for the rotating parts.
And because of that, less chance of the oil making it's way past the rings and into the chamber, so the rings almost have less work to do.
If you draw too much vacuum you risk damaging oil seals etc which is why you need some sort of regulator. What you need to set this at Ive no idea though.
Sealing up other parts like dipstick etc is just to make it a more controlled environment as the regulator is doing that job.
Having a vacuum in the crankcase should mean less oil deposits floating about and any combustion byproducts that do make their way past the rings will be drawn out as well. Just generally making it a cleaner and freer environment for the rotating parts.
And because of that, less chance of the oil making it's way past the rings and into the chamber, so the rings almost have less work to do.
If you draw too much vacuum you risk damaging oil seals etc which is why you need some sort of regulator. What you need to set this at Ive no idea though.
Sealing up other parts like dipstick etc is just to make it a more controlled environment as the regulator is doing that job.
The amount of vacuum created is a function of how many and how good the scavenge pump sections are compared to the pressure pump. Too much vacuum and you may wreck seals (or need to fit them back to front).
Basically, if it's a kit designed for your engine, the size of the scavenge pumps and pressure pump should have been chosen to suit the engine and might not actually generate that much vacuum.
The crankcase vacuum does help improve pumping losses and is why folk often see power increases after fitting a (properly installed) dry sump system.
Basically, if it's a kit designed for your engine, the size of the scavenge pumps and pressure pump should have been chosen to suit the engine and might not actually generate that much vacuum.
The crankcase vacuum does help improve pumping losses and is why folk often see power increases after fitting a (properly installed) dry sump system.
SteveSlowboy said:
The amount of vacuum created is a function of how many and how good the scavenge pump sections are compared to the pressure pump. Too much vacuum and you may wreck seals (or need to fit them back to front).
Basically, if it's a kit designed for your engine, the size of the scavenge pumps and pressure pump should have been chosen to suit the engine and might not actually generate that much vacuum.
The crankcase vacuum does help improve pumping losses and is why folk often see power increases after fitting a (properly installed) dry sump system.
Thanks for your reply.Basically, if it's a kit designed for your engine, the size of the scavenge pumps and pressure pump should have been chosen to suit the engine and might not actually generate that much vacuum.
The crankcase vacuum does help improve pumping losses and is why folk often see power increases after fitting a (properly installed) dry sump system.
By seals what exact seals are you meaning?
The kit i have has been designed for the engine although the pump used is also used on other kits for other makes of engine.
I was planning on sealing off the rocker cover and welding on the vacuum regulator from Peterson, in link above, then being able to control the vacuum. Trouble is, as this is my first kit, what range of vacuum i'm looking for is currently unknown to me.
bertelli_1 said:
Does the engine have an oil breather system fitted already (im guessing yes since its a production engine). Surely the vacuum is only high around idle? At higher rpm you'll have combustion gasses leaking past the rings & pressurising the crankcase.
On a standard engine yes, but you said you're going to use a dry sump.Hi,
I've been running through the layout of the system. I currently use an oil cooler with a remote mount oil filter and an in-line thermostat. The block take-off has 2 ports on my current take off but the new take off has 1 port.
I'm a little confused at the moment. Would anyone be willing to add some lines in here? Please!
I've been running through the layout of the system. I currently use an oil cooler with a remote mount oil filter and an in-line thermostat. The block take-off has 2 ports on my current take off but the new take off has 1 port.
I'm a little confused at the moment. Would anyone be willing to add some lines in here? Please!
DG19 said:
Would i be asking if it did?
No idea. You really need to be hitting whoever sold you this stuff a good slap though. Supplying product like that with no instructions is ridiculous.I'm not familiar with dry sump pumps, but I do imagine there will be various inlets and outlets, so a generic image drawn isnt going to give you the important info you need. You may need to provide either an image of the pump, or a make/model.
There is no room for error here.
The front and rear scavange lines are probably linked within the pump, so the scavange ouput from the pump (only one due to internal link) goes to the top of the dry sump tank.
The bottom of the dry sump tank goes into the pumps inlet port for it's pressure stage (generally all inlets are on one side of the pump, both outlets on the other)
The pressure outlet of the pump goes in series through the filter assy and oilcooler / thermostat then into the block via the single pressure feed.
The bottom of the dry sump tank goes into the pumps inlet port for it's pressure stage (generally all inlets are on one side of the pump, both outlets on the other)
The pressure outlet of the pump goes in series through the filter assy and oilcooler / thermostat then into the block via the single pressure feed.
Go to www.secordmotorsports.com . On the Home page, click 'TechTalk-page3'. There reside a number of pictures of the dry-sump systems I use on my full-race 2.0L SOHC roller-cammed Pinto engines in our Pro-4 paved-oval race car. (1) pressure & (2) scavenge stages. The greatest benefit of vacuum pulled inside the engine is the first 10" of vacuum. 12" of vacuum is my personal max limit. Our NASCAR V-8 teams limit the vacuum to a max of 14" @ 9000+ rpm. Testing has shown that when the internal vacuum nears 17"-19", the TQ/HP suddenly begins to 'drop like a stone'. Due to the vacuum beginning to pull power combustion gasses by the ring package. I NEVER install the oil-cooler in the pressure oil line off the dry-sump pump. The cooler is installed in-line on the scavenge side output of the pump. Why? The scavenge-side oil that has been 'just used' by the engine is the hottest. So the most heat is removed from the oil by the cooler @ that point. Works for me over many years! -Dave-
84Dave said:
Testing has shown that when the internal vacuum nears 17"-19", the TQ/HP suddenly begins to 'drop like a stone'. Due to the vacuum beginning to pull power combustion gasses by the ring package.
Power may well be dropping under high vacuum conditions, but i can assure you it has nothing to do with the increase in pressure ratio across the ring pack ! (hint, how many inches of water is the pressure above the rings?? (say 100bar(peak) = 39370 inches, or 15bar (mean) = 5906inches))More likely as the pressure drops it ends up pulling back a seal, letting in air, and the work the scavange pump does increases dramatically as the Mdot increases.
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