Sr20det catch can setup

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datsun5104dr
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Sr20det catch can setup

Post by datsun5104dr » 16 Jan 2019 17:35

I’ve been looking online and everyone’s setup is different. (S13 Sr20det) Some eliminate the pcv, some don’t. Can someone post pictures or explanation of what goes where? The correct way please?! Thanks!
-Mike
'68 Datsun 510 4DR

datzenmike
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Re: Sr20det catch can setup

Post by datzenmike » 16 Jan 2019 19:08

Let me ask you, did the S13 or SR20 engines come with a catch can? Then why bother with one? If you have a full on dedicated race car then you may have to have one, to keep blow-by off the track, and if you have direct injection they probably help keep the intake valves cleaner as they don't have fuel injected onto the intake valve to wash any PCV deposits away. Otherwise let the PCV do it's job keeping the engine cleaner and drier inside.

Next to strut bars, catch cans are the next most monkey see monkey do items people put on their cars. All engines can produce water and oil condensation and when saved up looks like you're doing your engine a favor by collecting it but you're just making a mess. What small amount produced every second would normally be burned in the combustion chamber. Would you really take it to the oil recycling? or dispose of this toxic brew properly? or just throw in the garbage? Yeah, it would end up in the land fill.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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bertvorgon
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Re: Sr20det catch can setup

Post by bertvorgon » 16 Jan 2019 19:38

Mike is right, racing requires one, but, I can attest that I am constantly cleaning the oil/water condensate out of my catch can. It is messy! I put a piece of blue towel down mine, let it sit over night and then pull it out, soaked with that mess.

It is amazing how much water vapour is generated on an engine fire up. I bet mine puts at least a teaspoon of water into that catch can on almost every cold start fire up, except for the hottest summer mornings.

Then couple that with some normal oil vapour/blow by and you have quiet a soupy mess.

Both my block and valve cover feed mine.

If you do go that route because it looks trendy, keep in mind.....how will I drain or clean this. I have a drain plug on mine, but, it is really non functional, easier to stay on top of wicking it out and during the winter I remove it and give it the big brake clean treatment.
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"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

datsun5104dr
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Re: Sr20det catch can setup

Post by datsun5104dr » 16 Jan 2019 19:52

It comes factory with an air/oil separator which pretty much does the same thing, i just don’t have that oem one either. That’s why I’m asking... it’s a fully built motor so why not take care of it? Never really heard of anyone complaining about their catch can other than it maybe leaking from crappy fittings...
-Mike
'68 Datsun 510 4DR

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Re: Sr20det catch can setup

Post by datzenmike » 16 Jan 2019 20:22

An air oil separator is not the same thing. The separated oil would be returned to the crankcase, that's the whole point. The amount of vapor, be it water or oil is only impressive in it's volume and crappiness when you save it up over weeks. A well running engine will easily burn this up as it is produced and have been doing so since the PCV started to be installed sometime around '62?
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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Fred_L-P
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Re: Sr20det catch can setup

Post by Fred_L-P » 17 Jan 2019 06:25

datzenmike wrote:
16 Jan 2019 20:22
An air oil separator is not the same thing.
It's not the same thing, but it does the same job by keeping your intake system oil free. It only handles the waste differently.

I've been reading on the subject for the past 2 days and I don't see any downside from running a catch can other than the added maintenance.

I can't help with the routing since I have the same questions, but for a different setup.

I don't want to hijack the thread, but I'll ask anyway since it's on the subject.

I've read from multiple sources that burning the oil vapors decreases "octane rating" of the mixture. I'm building an NA sr20 with ITBs. With the high compression, wouldn't I want a catch can to help prevent knock? Or can I just plumb the PCV valve straight back into the ITBs without any issues?

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bertvorgon
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Re: Sr20det catch can setup

Post by bertvorgon » 17 Jan 2019 07:32

The key is to NOT have, or beyond minimal oil going past the rings! Having perfectly round cylinders is a key component, as is ring choice. Specialty uses a ^torque plate^ to make sure cylinders are round . That also insures zip for combustion gases blowing by into the crank case and then hence moving more oil vapour out through the system due to increasing crank case pressure.

Oil vapour should be minimal for the most part at operating temps. I now have 18 years on my motor with zip for oil consumption over a summer of driving.
"Racing makes heroin addiction look like a vague wish for something salty" - Peter Egan

Keith Law
1973 2Door Slalom/hill climb/road race / canyon carver /Giant Killer 510
1968 Vintage 3HP Mini Bike
1971 Vintage 13' BOLER trailer

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icehouse
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Re: Sr20det catch can setup

Post by icehouse » 17 Jan 2019 14:08

Do the S13.5 valve cover mod.
"People don't like it when shit doesn't match their rule of thumb." Sam

datzenmike
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Re: Sr20det catch can setup

Post by datzenmike » 17 Jan 2019 20:18

Fred_L-P wrote:
17 Jan 2019 06:25


I've read from multiple sources that burning the oil vapors decreases "octane rating" of the mixture. I'm building an NA sr20 with ITBs. With the high compression, wouldn't I want a catch can to help prevent knock? Or can I just plumb the PCV valve straight back into the ITBs without any issues?

This is the problem with them, they give the impression you are producing huge amounts of oil and water vapor but you aren't. These things save up for weeks to get that much. The amount of oil vapors is practically negligible per cylinder firing and can't possibly affect your octane rating. PCV valves have been routing combustion vapors into the intake for over 50 years and I've never heard of such a claim.

If you are making enough oil/water vapors to affect running you have serious 'other' problems.
"Nissan 'shit the bed' when they made these, plain and simple." McShagger510 on flattop SUs

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Fred_L-P
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Re: Sr20det catch can setup

Post by Fred_L-P » 18 Jan 2019 06:29

datzenmike wrote:
17 Jan 2019 20:18
Fred_L-P wrote:
17 Jan 2019 06:25


I've read from multiple sources that burning the oil vapors decreases "octane rating" of the mixture. I'm building an NA sr20 with ITBs. With the high compression, wouldn't I want a catch can to help prevent knock? Or can I just plumb the PCV valve straight back into the ITBs without any issues?

This is the problem with them, they give the impression you are producing huge amounts of oil and water vapor but you aren't. These things save up for weeks to get that much. The amount of oil vapors is practically negligible per cylinder firing and can't possibly affect your octane rating. PCV valves have been routing combustion vapors into the intake for over 50 years and I've never heard of such a claim.

If you are making enough oil/water vapors to affect running you have serious 'other' problems.
Thanks! That was my original plan anyway. I still need to figure out the right way to route all this.
icehouse wrote:
17 Jan 2019 14:08
Do the S13.5 valve cover mod.
Whats the valve cover mod?

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spriso
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Re: Sr20det catch can setup

Post by spriso » 18 Jan 2019 08:26

The S13.5 valve cover mod gets rid of the ugly catch can on S13 SR20DET engines by using the back half of a S14 SR20DET valve cover with the front half of a S13 SR20DET valve cover welded to the front-- a great article on this can be found here:

http://tougefactory.com/shop/2014/12/se ... lve-cover/

We made one years ago for my wife's SR powered roadster-- not too difficult of a project, and it certainly cleans up the engine bay!

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Michael
Michael Spreadbury
Spriso Motorsports
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Fred_L-P
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Re: Sr20det catch can setup

Post by Fred_L-P » 18 Jan 2019 10:39

Thanks Spriso! That is really helpful. I might go that route for a clean install, It looks easy enough.

Ok so let's say I have a line from the PCV valve to my runners (after the throttle bodies) and the rear line goes to the crank case. What am I suppose to do with the line that goes to the front of the throttle body to generate vacuum under load since I don't have a plenum?

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Re: Sr20det catch can setup

Post by Josh K. » 09 Feb 2019 18:34

That's a very complex question and one I've spent many, many hours researching. Most will run a dual valve catch can. One goes to the intake, another goes right at the turbo inlet. Under vacuum it pulls into the intake and under boost it pulls into the turbo.

From my research http://www.eliteengineeringusa.com/ makes the best dual valve catch cans. Some literally do nothing. These are tested and proven.

I hated all the options and so I purchased the parts to do a pulley driven vacuum pump from GZ Motorsports for my KA24DET. I'll be doing that conversion in April.

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