Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Go Back   Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum > General > Tech Talk > Engine Tech

Engine Tech Technical discussion related to all relevant engines such as KA, SR, RB, CA, 2JZ , L24/26/28, VG, VQ, and LSx series.


Reply
 
Thread Tools Display Modes
Old 11-30-2019, 05:36 PM   #1
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
SR20det rocker cover blow by

Hi all , I recently had my car dynoed it’s a MGB with a S13 SR20det.



Stock motor

740 nizmos

GT2871r

FMIC

Nistune

Etc.



I didn’t have a catch can so the tuner didn’t want to up the boost as at over 11psi it was getting some blow by and venting out the rocker cover t piece hole straight towards the turbo. So he left it on 11psi and advised me to get a catch can setup then come back for more boost .



I’m in the process of getting all the parts to install a catch can now.



My question is: is this blow by standard and ok or is my motor a bit tired

It looked to be just puff of blackish smoke there was no oil residue and I have driven it hard on the street and there is no sign or oil coming out and obviously can’t see it on the street to know if it is still happening except for the fact that their is no mess in the engine bay or under bonnet.



Thanks steve


Last edited by mgbsr20det; 11-30-2019 at 07:25 PM..
mgbsr20det is offline   Reply With Quote
Sponsored Links
Old 11-30-2019, 07:24 PM   #2
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-02-2019, 09:21 AM   #3
jedi03
Nissanaholic!
 
Join Date: Jul 2008
Location: albuquerque
Posts: 1,784
Trader Rating: (8)
jedi03 is on a distinguished road
Feedback Score: 8 reviews
that is awesome! these motors have pretty decent blowby, using the s14 modified to fit s13 valve cover helps a lot...by chance you have a build sheet/how you installed it? my uncle has one of these stock that he gave up looking for an engine for it..may be next on the to do list lol!
jedi03 is offline   Reply With Quote
Old 12-03-2019, 01:31 PM   #4
TheRealSy90
Premium Member
 
TheRealSy90's Avatar
 
Join Date: Mar 2009
Location: Maricopa, AZ
Age: 30
Posts: 7,679
Trader Rating: (10)
TheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant future
Feedback Score: 10 reviews
Yeah the hole on the exhaust side of the valvecover shouldn't be just open to the atmosphere.
__________________
Quote:
Originally Posted by crimsonrockett View Post
Such a good signature.
TheRealSy90 is offline   Reply With Quote
Old 12-03-2019, 02:08 PM   #5
jedi03
Nissanaholic!
 
Join Date: Jul 2008
Location: albuquerque
Posts: 1,784
Trader Rating: (8)
jedi03 is on a distinguished road
Feedback Score: 8 reviews
i personally retained the OE catch can to the T then routed the other side to a Cusco style catch can with routes to the intake...I was getting to much internal pressure without the extra vacuum source so kept blowing front main...thought had cracked the crank dampener or the crank for a while lol, was nice to find was "easy" fix!
jedi03 is offline   Reply With Quote
Old 12-04-2019, 11:35 AM   #6
Kingtal0n
Post Whore!
 
Kingtal0n's Avatar
 
Join Date: Jul 2005
Location: South Florida
Age: 38
Posts: 4,649
Trader Rating: (17)
Kingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond repute
Feedback Score: 17 reviews
Send a message via AIM to Kingtal0n
0. compression test, use a decimal place, use two different compression testers (one is always bad)

1. Connect the factory PCV system and use a high quality PAPER AIR FILTER
Replace the PCV valve


2. boost leak test, pressurize from compressor cover all the way to intake manifold
it should hold 20psi for a 'while' (20-30 seconds easy)
fix all boost leaks

If it still blows oil
3. remove valve cover and inspect the baffle for sludge/carbon buildup, fully clean it out using solvent
4. leak down test to ensure rings/valve are good enough

It won't blow oil anymore if this is all done properly, unless boost/power exceeds some threshold (say 26psi and 500rwhp)
even engines with 120psi compression across the board won't blow oil using the proper factory PCV and paper air filter element

The key is pulling suction on the crankcase during WOT and this is only achievable if you are using the proper air filter element (usually a PAPER) and PCV crankcase tube applied to the valve cover baffle.
Kingtal0n is offline   Reply With Quote
Old 12-04-2019, 03:48 PM   #7
TheRealSy90
Premium Member
 
TheRealSy90's Avatar
 
Join Date: Mar 2009
Location: Maricopa, AZ
Age: 30
Posts: 7,679
Trader Rating: (10)
TheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant future
Feedback Score: 10 reviews
Quote:
Originally Posted by Kingtal0n View Post
The key is pulling suction on the crankcase during WOT and this is only achievable if you are using the proper air filter element (usually a PAPER) and PCV crankcase tube applied to the valve cover baffle.
On your illustration, the turbo is blowing air into the crank case lol.
__________________
Quote:
Originally Posted by crimsonrockett View Post
Such a good signature.
TheRealSy90 is offline   Reply With Quote
Old 12-04-2019, 03:58 PM   #8
S14rebuild
BANNED
 
Join Date: May 2019
Location: Florida-FAIL
Posts: 2,497
Trader Rating: (8)
S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild
Feedback Score: 8 reviews
Quote:
Originally Posted by TheRealSy90 View Post
On your illustration, the turbo is blowing air into the crank case lol.

No its not.... either suction on the air filter side and other side has a pcv valve...soooo
S14rebuild is offline   Reply With Quote
Old 12-04-2019, 04:52 PM   #9
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
SR20det rocker cover blow by

Thanks for your Input it’s very appreciated. My tuner recommended a vented catch can set up

remove PCV valve and go to Catch can

Rocker t piece to catch can

Crank case to catch can


What’s your thoughts on this setup please

We are planning on upping the boost to 18 psi so he doesn’t want to re-circulate back into the intake





Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-04-2019, 05:13 PM   #10
S14rebuild
BANNED
 
Join Date: May 2019
Location: Florida-FAIL
Posts: 2,497
Trader Rating: (8)
S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild
Feedback Score: 8 reviews
I run all valve cover ports to a large vented catch can. No pcv valve...i get ALOT of blow by. My catch can vent even smokes... i was concerned so i checked compression 150 across the board, so i dont worry. I have no issuse running catch can like how u stated
S14rebuild is offline   Reply With Quote
Old 12-04-2019, 05:17 PM   #11
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
Did you also remove your PCV valve and go straight to catch can. I’ve done a lot of searching and many people are saying it should be under vacuum to extract the gases that is why they run it to the intake. My thoughts on it been on the vacuum is would it then affect the maf flow sensor readings as the Motor technically is getting more air than what the maf is reading.


Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-05-2019, 07:40 AM   #12
TheRealSy90
Premium Member
 
TheRealSy90's Avatar
 
Join Date: Mar 2009
Location: Maricopa, AZ
Age: 30
Posts: 7,679
Trader Rating: (10)
TheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant future
Feedback Score: 10 reviews
Quote:
Originally Posted by S14rebuild View Post
No its not.... either suction on the air filter side and other side has a pcv valve...soooo
Hey I was just going off the drawing where the blue arrows coming from the the turbo intake into the crank case are pointing INTO the crank case and not out. Splitting hairs.

Quote:
Originally Posted by mgbsr20det View Post
Thanks for your Input it’s very appreciated. My tuner recommended a vented catch can set up.

We are planning on upping the boost to 18 psi so he doesn’t want to re-circulate back into the intake
You don't want nor need a vented catch can.
SR20's want a vacuum source to the crank case. It will make more power and run much smoother.

That boost pressure really doesn't matter since you would have a catch can in between the turbo intake to valve cover hose.
__________________
Quote:
Originally Posted by crimsonrockett View Post
Such a good signature.
TheRealSy90 is offline   Reply With Quote
Old 12-16-2019, 03:11 PM   #13
Kingtal0n
Post Whore!
 
Kingtal0n's Avatar
 
Join Date: Jul 2005
Location: South Florida
Age: 38
Posts: 4,649
Trader Rating: (17)
Kingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond reputeKingtal0n has a reputation beyond repute
Feedback Score: 17 reviews
Send a message via AIM to Kingtal0n
Don't ever use a catch can unless the engine is already blown and you just need to drive it for a little bit until you can afford to replace the engine

Also never vent the crankcase using a breather. Never use a breather anywhere- the only 'breather' should be the actual air filter on the turbo inlet tube as shown in my posted picture. Crankcase needs to be fully sealed and pressure tested for pcv to work properly.

The picture I posted is showing the intake manifold applying suction to the crankcase, and the crankcase receiving its fresh air supply from the engine's air filter- exactly as it comes from the factory OEM. Sorry if its a bit confusing, I neglected to draw the throttle body and pressure ranges, perhaps I will make a new picture some day.
nevertheless, This is an OEM configuration I have shown

The OEM pcv will work until around 500rwhp maybe 600~ at which point it will still work but needs a slight upgrade depending on how loose the piston/wall clearance is, what type of ring is used, what sort of oil pump, how much actual boost is needed to hit that number, etc... and honestly at 2L with that kind of power I'd recommend a dry sump and vacuum pump anyways.
Kingtal0n is offline   Reply With Quote
Old 12-26-2019, 09:54 AM   #14
Wookie384
Premium Member
 
Wookie384's Avatar
 
Join Date: May 2007
Location: N. Hollywood / Burbank
Age: 36
Posts: 766
Trader Rating: (10)
Wookie384 is just really niceWookie384 is just really niceWookie384 is just really niceWookie384 is just really niceWookie384 is just really niceWookie384 is just really niceWookie384 is just really niceWookie384 is just really nice
Feedback Score: 10 reviews
Send a message via AIM to Wookie384
Quote:
Originally Posted by Kingtal0n View Post
Don't ever use a catch can unless the engine is already blown and you just need to drive it for a little bit until you can afford to replace the engine

Also never vent the crankcase using a breather. Never use a breather anywhere- the only 'breather' should be the actual air filter on the turbo inlet tube as shown in my posted picture. Crankcase needs to be fully sealed and pressure tested for pcv to work properly.

The picture I posted is showing the intake manifold applying suction to the crankcase, and the crankcase receiving its fresh air supply from the engine's air filter- exactly as it comes from the factory OEM. Sorry if its a bit confusing, I neglected to draw the throttle body and pressure ranges, perhaps I will make a new picture some day.
nevertheless, This is an OEM configuration I have shown

The OEM pcv will work until around 500rwhp maybe 600~ at which point it will still work but needs a slight upgrade depending on how loose the piston/wall clearance is, what type of ring is used, what sort of oil pump, how much actual boost is needed to hit that number, etc... and honestly at 2L with that kind of power I'd recommend a dry sump and vacuum pump anyways.

I'm curious on your logic of why a catch can should never be used as the PCV system on most cars are designed to meet emissions regulations, and performance was not included in that design. It's such an issue that most "modern" cars have excessive blow by when driven aggressively.
Wookie384 is offline   Reply With Quote
Old 12-26-2019, 05:20 PM   #15
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
I ended up doing it this way, as per my tuners advice. I’m happy with the result. now I can get it back onto the Dyno for more boost




Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-26-2019, 07:05 PM   #16
S14rebuild
BANNED
 
Join Date: May 2019
Location: Florida-FAIL
Posts: 2,497
Trader Rating: (8)
S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild
Feedback Score: 8 reviews
Do u get any vapor coming from the breather on the catch can, when running/idling?


How about at idle, when oil cap is removed do u get and blowby, pressure out the valve cover?
S14rebuild is offline   Reply With Quote
Old 12-26-2019, 07:36 PM   #17
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
No not at all , just a little puff on the dyno that time. It spitting oil or anything like that it was more of a steam puff


Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-27-2019, 09:27 AM   #18
TheRealSy90
Premium Member
 
TheRealSy90's Avatar
 
Join Date: Mar 2009
Location: Maricopa, AZ
Age: 30
Posts: 7,679
Trader Rating: (10)
TheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant futureTheRealSy90 has a brilliant future
Feedback Score: 10 reviews
So again you're not drawing any vacuum to the crank case... You're leaving power on the table as well as a smoother running engine.
__________________
Quote:
Originally Posted by crimsonrockett View Post
Such a good signature.
TheRealSy90 is offline   Reply With Quote
Old 12-27-2019, 09:46 AM   #19
S14rebuild
BANNED
 
Join Date: May 2019
Location: Florida-FAIL
Posts: 2,497
Trader Rating: (8)
S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild
Feedback Score: 8 reviews
Ive been running a catch can setup as the op has for YEARS. never knew it was wrong. Never had an issuse. Now im advised to change it up, i will do so and see how all goes
S14rebuild is offline   Reply With Quote
Old 12-30-2019, 04:24 AM   #20
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
SR20det rocker cover blow by

Hi guys , I have a question .
With the pics above of my catch can setup as a reference . Can i remove the filter and cap it off like I did for one of the filters already and then run a third hose to my turbo intake pipe So then both hoses from rocker cover go to catch can and then single hose to intake , will this create enough vacuum through the rocker cover ? Just trying to delete the PCV as I’ll be adding more boost very soon and hear many issues about boost leaking through the PCV .

Another reason why I now want to plumb it back into the intake is my car is a MGB roadster (convertible) , I have blocked up as many firewall holes as I can but still get stinky engine smell and would like to eliminate the smells as much as possible . If this means putting PCV back in I would do it as long as it doesn’t cause boost leak issues .

Thanks


Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-30-2019, 05:31 AM   #21
S14rebuild
BANNED
 
Join Date: May 2019
Location: Florida-FAIL
Posts: 2,497
Trader Rating: (8)
S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild S14rebuild
Feedback Score: 8 reviews
It Needs a steady vacuum...
S14rebuild is offline   Reply With Quote
Old 12-30-2019, 06:52 AM   #22
mgbsr20det
 
Join Date: Nov 2018
Location: Merriwa
Posts: 35
Trader Rating: (0)
mgbsr20det is an unknown quantity at this point
Feedback Score: 0 reviews
SR20det rocker cover blow by

Ok so I had a dig around in my spares and found some hose and fittings to connect the PCV to the intake plenum, I had to reduce the hose size from the PCV hose size to 6mm hose to use one of the spare plenum vacuum lines (I’ll get a bigger barb fitting and run the correct size all the way once I get a chance to pickup the parts) . I went for a drive just now and I will say it does help reduce the smells so now I’m definitely thinking about changing the other side by blanking off the filter and running a 10an hose to the turbo intake to get the best of both worlds off boost and on boost.



Sent from my iPhone using Tapatalk
mgbsr20det is offline   Reply With Quote
Old 12-30-2019, 12:56 PM   #23
jedi03
Nissanaholic!
 
Join Date: Jul 2008
Location: albuquerque
Posts: 1,784
Trader Rating: (8)
jedi03 is on a distinguished road
Feedback Score: 8 reviews
that looks like a good idea to me...doing another line to drain the oil from the catch can would make it nearly maintenance free [email protected] Subaru's aftermarket uses an AOS which operates like this! And am also advised many other companies (porshe, audi etc) use it from factory
jedi03 is offline   Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -6. The time now is 02:52 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
vB.Sponsors
Copyright © 1998 - 2019, Zilvia.net™