jwmelvin and I are talking about real A/O separators. Not the baffles in our valve covers (1/4" diameter holes) or just a collection of rubber hose.
jwmelvin and I are talking about real A/O separators. Not the baffles in our valve covers (1/4" diameter holes) or just a collection of rubber hose.
So to re-evaluate our situation,
1. we examine our cups ports and seals, as the engine is run (during and after run time) to find weak ports, where seals or baffles are inadequate for the performance we demand.
2. Take measures to catch, or return that leaking oil from the cup wherever it appears.
Jason, when searching for (2) A/O separators for my N/A setup, I saw the RX design. However, it is(was) $350+ for one, and I needed two. That's why I settled for two of the cheaper Moroso's. No, they're not perfect, but I didn't have time to design my own, and it was the next best alternative in the effectiveness/$ ratio IMO :smile:.
It's a moot point now since they are sitting in the garage collecting dust while I've changed setups. It was just another way for me to gauge how well I built my first engine.
I never had a problem with a gunked TB or oil in the intake manifold when I took apart my N/A engine with ~120k miles on it. Others have seen significant crud around the TB plate (could be due to an improperly-oiled K&N or Unifilter), and even Honcho mentioned he had pooled oil sitting at the bottom of his N/A manifold when he took it apart (N/A stock engine).
I think a proper A/O separator and functioning PCV system is even more essential on a boosted OEM engine. That's due to the increased combustion pressures and (probably) richer tunes that wash the cylinder walls and rings leading to accelerated wear. That's why richer is not always better in FI. People quote their A/F ratios on here for boosted setups and they are much too rich IMO. Oh well, I'm no tuning expert and I guess it is better for the engine to die a slow death than a quick one!
Dave
Kicking this thread back up. Dave, I have a Moroso-style can that I intended to put on the PCV (front head) line before the intake manifold port to remove some of the oil/vapor. The intent was to keep my manifold and TB clean. Reading through Rob Morrison's notes, I'm not sure this will solve the issue of oil burping out of the rear valve cover under WOT and hard cornering at the track. Would connecting the front and rear valve covers via a T-fitting and moving the PCV valve in-line after the T solve the issue? This would equalize both heads and subject both to PCV valve function under intake vacuum. My concern is that at WOT, the PCV would close and the engine would have no way to vent because the air intake hole on the bellows is no longer connected to the engine. I can't figure out how to solve that problem...
On my turbo charged engine I use two Moroso cans: one for each cylinder bank.
For the rear cylinder bank, the catch can is positioned on the right hand side of the engine.
This ensures that any engine oil moving into the (long) hose due to G-forces get zeroed out and gravitates back into the engine in the straights.
Simple but straightforward.
This solved the issue of the catch can filling up with oil after a 15 min track outing!
BTW due to the turbo design, the fumes out of the catch can are vented to air (not proud here) but the principle will also work if you vent them back to the engine of course
Thanks for the response! I'm trying to preserve the OEM operation of the system, but with cleaner air circulating. Here is a helpful picture below from Kaz. Under part-throttle operation, the PCV valve is open due to manifold vacuum. The intake manifold sucks out the crankcase gases and vents them into the engine to be burned, creating a vacuum in the crankcase, which draws fresh air from the rear head connection to the throttle bellows. This helps ring seating, power, emissions and keeps your oil cleaner. But, it really soils your throttle body and intake manifold with nasty gunk.
My current solution places a simple catch can on the PCV line so that, under part-throttle operation, it will intercept and separate much of the oil rather than allowing it to enter the intake manifold. This hopefully will help keep my throttle body clean.
The problem is what happens at WOT and under hard cornering. According to Rob Morrison at DAL Motorsports, you get the below picture. When you mash the gas and go way into VTEC, the manifold pressure rises to near-atmospheric and the vacuum disappears. This causes the PCV valve to close, rendering the catch can useless. Honda anticipated this, so now the crankcase gases flow OUT of the rear head vent and into the intake tract, again to be burned by the engine. But apparently they made a mistake. With all this positive crankcase pressure in the heads, the rear head fills with oil as it sprays out of the VTEC rocker assemblies and is slow to drain back into the pan. When you yank the steering wheel into a hard right turn, the lateral G's push this oil out of the tube and into the intake bellows.
Your solution works, but the engine is now venting to the outside under positive pressure. Rob's solution at DAL was the same. I'm trying to think of a solution that keeps the circuit closed.
CB72 said:You've depicted exactly the issue I was facing when cornering hard in right hand corners.
Why not try my solution with the Moroso can on the right hand side for the rear cylinder block but returning the output back to the throttle body as in the OEM setup?
You are back to the close loop system but without the nuisance of the oil in the throttle body.
I'll try to find a picture of my setup.
I understand your issue but connecting both cam covers with a T-fitting negates any fresh air coming into the cranckase or didn't I understand your proposal?
In fact, I believe it's a moot point if the rear hose fills up with oil during a hard turn in my configuration as first of all there will not be that much oil as the hose folds back to the righ hand side and secondly as soon as you hit the straight the gravity will drain the oil back into the cranckase with the help of the vacuum created from the front cylinder side as soon as you shift gears.
I think I have solved it. I will use your solution to mount the catch high on the right side of the car (perhaps where the fuel injector resistor box used to be). But, I will route the hoses like the NA2. So, the front bank will vent to the intake bellows and the rear bank will have the PCV in-line to the catch can and then to the intake manifold.
I like to see oil fumes flow like an electric current.
The (variable) voltage source comes from eitheir sides of the throttle body (that acts a variable resistor)
When the throttle is closed there is a high voltage and when it's wide open very little voltage and little current will be drained through the circuit.
The circuit itself comprises a resistor ( the catch can ) and a diode ( the PCV) that let's the current go only one way.
So in your proposal the fresh air comes into the front bank and exits through the rear bank but due to the PCV valve cannot return to the rear bank.
This will stop the return of any oil gathered into the rear bank hose during a hard right hand turn...
To achieve your goals of a closed circuit and draining the oil out of the rear hose after a hard right hand corner why not go back to your initial plan with the fresh air coming into the rear bank and the fumes routed out the front bank through both the PCV valve and the catch can.
So what about the oil pouring into the rear bank hose?
You keep my proposal of a long hose routed first above and to the right hand side of the car to eventually get back to the intake bellows like in the OEM scheme.
Inserting a catch can along the way would be a bonus but maybe not compulsory.
This is why I love Prime. There need to be more threads like this! I see what you are saying, but I think the issue is that the crankcase needs to vent, not a particular cylinder bank. Under hard cornering at WOT, the PCV will be closed (little to no vacuum) on the rear head, preventing any flow of oil out of the head. But, the front head will still vent to the bellows, providing crankcase ventilation. So, there never should be any oil in the rear hose. Or am I wrong? I think routing the NA2 way and including the catch can on the PCV line solves all my concerns:
1. Trap crankcase blowby and prevent it from reaching the intake manifold when the PCV is open.
2. Stop oil from exiting the rear head under hard right turns at WOT (PCV closed).
3. Allow crankcase to vent to the intake tract when the PCV is closed.
4. Preserve a closed circuit.
Your reasoning is correct (it's the OEM setup in reverse) but...the PCV valve only acts as a switch as long as there is no positive pressure differential across it.
However when the oil flushes out of the bottom cylinder head towards the PCV valve, there is obviously positive pressure build up and the valve opens letting the oil through.
What's even worse is that the PCV valve will not let the oil flow back when the throttle is closed.
The engine will then just swallow the oil trapped in the hose to the PCV valve...
BTW: I admire the work done on your "Long road to Imola'.
You should publish it in an electronic readable format and sell it through the internet.
Personally, I'd keep it simple.
Keep the OEM scheme with the breathing going from the rear to the front cylinder bank with the PCV valve in it's current position and the catch can as on your drawing.
The income path is like the OEM scheme except that the hose serpentines first to the right before going back to the intake.
Be sure to use a real Moroso type Catch can!
Why not try this scheme and look at the amount of oil in the throttle body after running the car in.
Good luck!
Mac Attack said:Honcho, your post #132 is the correct depiction of what happens during light-load and heavy-load operation, and is why you need two A/O seperators as I described earlier in this thread.
To fix the rear bank oil issue, the line pickup needs to be modified on your valve cover. For my dry sump, I wanted breathers on both valve covers, but didn't want to deal with any oil puddling in the lines. Basically, it's a Honda design defect and I wanted to fix the problem. This applies to both dry sump setups and conventional systems. So, I plugged the side vent and fitted a 10AN 90 degree bulkhead fitting on the top of both valve covers. It involved drilling into and filing flat the rear cover.
But, it works. No oil in the line in sustained high-g turns on the track with r-compounds. That's one of the reasons why I did the dry-sump many years ago. I also removed it due to maintenance concerns since I really don't drive this car on the track anymore.
I don't know the size because mine was all customized with the dry sump, but I wouldn't want that fitting for sure! Why not spend the money on a nice fitting?
Dave, with all the delays on my project, I've decided to stick to my original plan and just use the one catch can on the PCV side and keep the rest OEM. Maybe once the car is back together and driving, I'll take a crack at hacking up some used valve covers and use the "nice" fittings. Good to see you posting here again!