beaver34
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| posted on 25/5/11 at 07:09 PM |
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dry sumped engine breathers
hi,
im dry sumping my zetec s engine, normally the forumla fords thatn ran the dry sump blank the block breather off totally, now i have this blanking
plate but was think if this would be beneficial to me as mine is a turbo engine, i was think about running a breather from that plate bank to the top
of my dry sump tank?
any thoughts on this or what is best as regards engine breathers in theis case
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SeanStone
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| posted on 25/5/11 at 07:11 PM |
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It is usually better to have you engine breathing after the scavenge pump i believe. Helps the pump create a better vacuum within the engine
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v8kid
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| posted on 25/5/11 at 09:29 PM |
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quote:
Originally posted by SeanStone
It is usually better to have you engine breathing after the scavenge pump i believe. Helps the pump create a better vacuum within the engine
Only if you have a humongous scavenge pump! Works best with BIG breathers on block/rocker cover. I drilled out rocker covers and have 25mm breathers
dumping into separate clear plastic bottles to act as catch tanks.
I did try blanking them off as you have suggested and only succeeded in seriously pressurizing the block - thank goodness I cut the engine after a few
seconds to check ad heard the air hissing out or it may have blown every seal.
Vacuum scavenge pumps are huge and use loads of hp.
Cheers!
Forgot to say the bigger the breather the less oil gets carried over
[Edited on 25-5-11 by v8kid]
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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SeanStone
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| posted on 25/5/11 at 09:37 PM |
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Sounds like bad design to me. If it is done properly the gains outweigh the losses.
With your system, you can gain around 10% power at least if you section off your cylinders all the way to the bottom of the sump and scavenge each
individual cylinders oil. By doing this, the piston compresses the air beneath it and instead of just blowing around the bottom of the engine, it
actually acts like a pneumatic spring and pushes the piston back up. Can be done relatively easily!
Couple this with your crank spinning in a vacuum giving less wind resistance and you have a great package coming on! A good scavenge pump should
scavenge at least 5 times the rate that it pumps the oil back in
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beaver34
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| posted on 25/5/11 at 10:15 PM |
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Now I'm confused,
I have a pace 2 stage setup, does this affect what I do?
I presume ford block it for a reason but I was wandering what I then do for a breather just you the one on the rocker to a catch tank?
What are the advantages or disadvantages to running it blocked up?
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v8kid
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| posted on 25/5/11 at 10:15 PM |
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quote:
Originally posted by SeanStone
Sounds like bad design to me. If it is done properly the gains outweigh the losses.
With your system, you can gain around 10% power at least if you section off your cylinders all the way to the bottom of the sump and scavenge each
individual cylinders oil. By doing this, the piston compresses the air beneath it and instead of just blowing around the bottom of the engine, it
actually acts like a pneumatic spring and pushes the piston back up. Can be done relatively easily!
Couple this with your crank spinning in a vacuum giving less wind resistance and you have a great package coming on! A good scavenge pump should
scavenge at least 5 times the rate that it pumps the oil back in
Have you actually done this?
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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SeanStone
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| posted on 25/5/11 at 10:22 PM |
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Not yet, but when i dry sump mine i will. It is common place in F1 and a lecturer (who designed a few f1 championship engines) showed me how he did it
on a touring car engine.
You wont do this on a 2 stage pump though
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plentywahalla
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| posted on 25/5/11 at 10:40 PM |
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The benefits if running a partial vacuum in the crankcase is not just reducing energy losses through reducing windage, A vacuum also helps oil
circulation through the oilways.
What SeanStone is suggesting sounds dodgy to me in that it could retard oil circulation as the oil pump will be fighting against high crankcase
compression. I'm sure the F1 designer knew what he was talking about but there must be more to it.
On my dry-sumped Z20LET the 2 scavenge pumps are roots type and have a combined displacement of 4 times the gear type oil pressure pump. I will be
blocking off all ports and running a partial vacuum.
There should be no problems with blocking off the breathers on a well balanced healthy engine. Breathers usually come in the use on older worn engines
where the individual cylinder compressions start to vary wildly.
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v8kid
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| posted on 26/5/11 at 07:52 AM |
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The trouble with forums is any fool can post an opinion based on heresay.
I have made the mistake in the past of listening to wannabe engineers who have not actually done anything and would always advise not repeating my
mistakes.
One of these is outlined earlier. Speak to people who are actually doing what you propose but first ask yourself if you are really running a F1 car 
Cheers!
You'd be surprised how quickly the sales people at B&Q try and assist you after ignoring you for the past 15 minutes when you try and start a
chainsaw
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