case and head vents, do I need to run a breather box? Options

[jcd914]

I personally won't do away with my head vents.

I understand why Jake, Len and others would want to insure the oil return fast to the crankcase but I don't see where the average 914 engine is going to suffer from the oil build up that their racing engine has. A true racing engine is a different animal than anything most of us have, nor would we want one the way most of us drive our cars. I don't recall seeing how much the oil temperature was raise and I did not understand what Jake meant by "oil control issue" but in a racing engine you need to do what ever you can to control temperatures and insure you are not sucking air instead of oil.

I am going to retain the stock PCV (Positive Crankcase Ventilation) system as originally installed. The concept of a flow thru PCV system is to get all the fumes and moisture out of the whole engine. There will be some moisture, vapors and such that are released from the hot oil in the heads and should be vented. And if in the future I move away from the stock FI and go to carbs I will not be venting mine to the atmosphere but routing into the intake to be burned by the engine. It is not as easy on a carb'd engine but it can be done.

IMHO Use the stock system for a stock engine and for most mildly modified engines. Do not use a road draft tube or and if you can't bring your self to route the fume back to the engine to be burned at least use a catch tank or vent box the contains the mess.

Jim

[HAM Inc]

I am going to retain the stock PCV (Positive Crankcase Ventilation) system as originally installed.

Engines still running the O.E. F.I with vented heads should definitly maintain the original vent system. IIRC it is a draw through system, meaning air is drawn into the heads and down the pushrod tubes.

I don't recall seeing how much the oil temperature was raise and I did not understand what Jake meant by "oil control issue"

The oil temp difference was ~10*. And by oil control issue what Jake was referring to was the observations we made in our test' of various venting ideas.

We found that more oil wound up in our catch can when the heads were vented than when they weren't. And we also found that the more head venting area we tried the more oil ended up in the catch can. The test' conducted were always of a full throttle run (on Jakes chassis dyno) of ~ the same duration. We then simulated race conditions (to some degree) by running at full throttle then half throttle then back to full throttle. The results were the same.
When we completely did away with the valve cover vents the amount of oil in the catch can almost completely went away.

The lessons were very clear. The oil will take any path out of the rocker chambers available to it.

When the rocker chambers are vented it has the effect of creating three seperate pressure chambers, with the central crankcase area having the greatest pressure as it is the gathering point for blow by and the very strong pulses generated by the movement of the pistons. Because the pressure is greatest in the crankcase, and because the drain back slots in the case are relatively small, the returning oil must overcome this differential with gravity only. Remember that the oil being pumped into the rocker chambers is done so under pressure, while the returning oil in a vented rocker chamber has only gravity to work with. Take a look at the incline of the pushrod tubes. They are pretty level.

As I said earlier in this thread by eliminating the rocker vents we turn three seperate pressure chambers into one which eliminates any pressure inhibitions to oil returning to the crakcase. And since the oil being pumped into the rocker chambers is done under pressure from the oil pump, by sealing the rocker vents that oil pressure can actually help evacuate the rocker chambers. I should also point out that if the pressure in the rocker chambers is allowed to drop to atmospheric, valve guide oiling is reduced as well.

It also bears pointing out that the vapors that are generated and circulated in the crankcase are the result of blowby and windage and have little to do with the rocker chambers.

It doesn't matter to me if folks want to vent their heads or not. It blows my mind that the whole debate has gotten so heated at times. I just thought I'd share the results we came up with in a serious study of the issue. Our 8,000RPM race engine has a single -12 (3/4") vent coming from the top of the chimney and that is all. No oil leaks or oil consumption.

[Gint]

We found that more oil wound up in our catch can when the heads were vented than when they weren't. And we also found that the more head venting area we tried the more oil ended up in the catch can. The test' conducted were always of a full throttle run (on Jakes chassis dyno) of ~ the same duration. We then simulated race conditions (to some degree) by running at full throttle then half throttle then back to full throttle. The results were the same.When we completely did away with the valve cover vents the amount of oil in the catch can almost completely went away.

If the heads weren't vented, where would the catch can get any oil from? In other words what was/were the input to the catch can besides the head vents? Or is the answer to that question what you said in the next quoted text:

It doesn't matter to me if folks want to vent their heads or not. It blows my mind that the whole debate has gotten so heated at times. I just thought I'd share the results we came up with in a serious study of the issue. Our 8,000RPM race engine has a single -12 (3/4") vent coming from the top of the chimney and that is all. No oil leaks or oil consumption.

I appreciate you taking the time to pass along your observations.

Let me see if what I now have in my mind is correct. You're saying that if the heads are vented, oil will find it's way out of the vents regardless and that the force of gravity for the oil to return to the heads and subsequently the crankcase can't overcome the force of the crankcase pressure pushing the oil out of the head vents in the first place. Yes?

[HAM Inc]

If the heads weren't vented, where would the catch can get any oil from? In other words what was/were the input to the catch can besides the head vents?

We tested with both the the chimney and head vents, then we tested with just the head vents and we tested with just the chimney vent. Lots of oil came out of the heads. Very little came out of the chimney.

Let me see if what I now have in my mind is correct. You're saying that if the heads are vented, oil will find it's way out of the vents regardless

That was our observation.
It is my opinion that if the return area below the pushrod tubes in the case were nice and large like a T1 this wouldn't be an issue. Because they are narrow slots in the T4 the pressure pushing through them towards the vented heads overpowers the oil trying to drain. Think of it as a wall of pressure at that critical point.

[Gint]

Thanks!

[yeahmag]

Are you venting from the only from the oil filter/baffle at the top of the engine? I've all ready disabled and opened up my PCV, but would like to try this modification on my carbed engine...

Any pictures?

Thanks!

[ConeDodger]

Len,

You say you had a >10 degree difference in oil temperature. I assume you mean your oil was cooler? Did you see any change in CHT between your test configurations?

Jim brings up a good point. If your engine is stock it should remain as designed. Mine is not. When finished, (soon) it will be just under 2.4 liter TypeIV with Jenvey throttle bodies and SDS injection with crank fired ignition.

[7275914911]

Don't mean to open any old sores here but....

Here's what I am trying with CFR Breather Can after reading this thread and the thread at Jakes site. My heads were not vented and I was going to vent the VC's(lazy way) and butcher the tin.
Instead I have modified the Filler a little more by adding an extra vent in the base of filler. I will keep 1 opening of the can plugged.
I had noticed cooler oil temps since installing CFR breather with just the filler vent and flow back installed. I was using a 1.8 filler straight to BP oil bottle with KN on top. Bottle filled up quickly and was a little messy. CFR breather keeps the mess contained in the case.


Thoughts??
Ken

[HAM Inc]

.

I had noticed cooler oil temps since installing CFR breather with just the filler vent and flow back installed.

That's plenty of breathing capacity for a healthy street engine.

Did you see any change in CHT between your test configurations?

No.

[ME733]

You know Murray, for a guy who was building engines when Jake was pooping yellow you sure have a weak grasp of theory.
Oil cools the valve springs, not air. But I will concede that in as much as the heat that the oil draws from the springs and rockers is generated by the heads one could accurately state that the oil does cool the heads. But it's BTU absorbing capacity is not up to the task of drawing a significant amount of heat out of the heads, so it only benefits the springs and rockers. Which brings me back the point about unvented heads running slightly cooler oil temps.

I'm not interested in going down the line point by point by point with you as you clearly have made up your mind.
But I will point out one commonly held misconception that you suffer with yourself, further indicating that your understanding of engine theory is very elementary.

Hotter the springs=loss in valve seat pressure.=shorter valve spring effective pressure/life. Ok .(solution)..so just increase installed seat pressure..=...that increases rotational force...just to turn over the engine. (use torque wrench to conferm.).

The cam loading at speed is nothing like what it is at assembly. At near redline speeds the load on the cam at max lift (as the lifter goes over the nose of the lobe) may be 5 lb's it may be near 0. At speed the greatest load that the cam sees is when the lobe encounters the stationary valve train and has to get it moving...and in a hurry. This is why higher rev engines want a higher spring rate (not to be confused with seat or open pressures). And it is why turning an engine over with a torque wrench to gain some understanding of the value of different spring rates AND pressures is useless.
I pass this forward not to educate you (you already know it all) but to inform the community at large who have a real interest in these things and because they are not experts like you are willing to learn.
I have not stepped in in the past when you have made post' that spread misinformation, it's just not my style, but on this subject you have attacked my credibility and the findings of an exhaustive study done by professionals. And I will point out to you that I have nothing to gain if people vent or don't vent their heads. I'm not selling breather systems.

Folks be very wary of taking advise from this guy.

...................Well HAM...It seem like you are one of the ones "folks should be leery about"....here,s why....1.you FINALLY concede that oil cools the valve springs.2. fuck you, requarding you opinion of my "elementary" knowledge.3. how long you been building racing engines?, and customer engines that WIN PLACE OR SHOW at National level races.???, anyone who knows anything about SCCA racing, knows that regional racing is for begginers....so what.... you "beat" a few begginers in racing, in the lowest level of racing....I, aint impressed. when you know it alls qualify 4-5th on the qrid at the SCCA NATIONAL RUNOFFS for at least SIX YEARS in a row I might give you a little respect....when you have 12 customer cars-that finish 1-12 at a race...maybe I,ll give you some respect....so far all you seem to be is a smart ass, think you know it all....(with a conceded attitude)....BUT LETS GET SPECIFIC about "cam loading"and the necessity of keeping the valve springs cool, by virtue of oil temperature control, with vented heads, assisting....SPECIFICALLY. WHAT IS THE CAUSE OF....the flat cam problem....this occurs at the "NOSE of the cam, NOT, NOT, NOT at the camshafts ramp.".your ..quote''is ...the highest loading is when the cam has to get things moving".....this is simply NOT TRUE.....That is why a properly made cam has a big radus base circle, and gentle ramps to EASE the lifter,pushrod,rockerarm, into action....The highest loading IS on/ at the NOSE of the cam......thats why it wears down, even in a perfect assembly...very slightly....so if you are right .....why is the "nose " wearing off...instead of the base circle, acceleration ramp???....it,s because your wrong in terms of where the highes point of loading occurs....5 you say rotating the engine over to assess valve springs is USELESS....this is because you have a valve spring compressor and believe it,s the only tool necessary for this analysis...and you like shortcuts, and must have your "theory Book"right beside you............................Now just so you know...I owned a engine dyno for some twenty years.and used it extensively, yep even on type IV engines....what.... you guys are into your 2nd or third year?.I aint impressed.your want me to get into how you bump up your H.P. numbers?..just keep making your shitty comments......OTHERWISE. just address the CAM LOADING question, and facts .................................your buddy, murray.

[Jake Raby]

2. fuck you

WOW! Talk about an awesome display of tact and professionalism.

[Rav914]

2. fuck you

This just infuriates me. Completely uncalled for. I don't care what your gripe is, comments like this degarde the civility and clout of this board. You got a problem, call the man on the phone.

If it were up to me you'd be banned this instant. This is/was a very informative thread. Keep it out of the gutter.

[ME733]

2. fuck you

WOW! Talk about an awesome display of tact and professionalism.

...............hello jake...........I attempted to join in on your website...AS YOU... invited me to do so....., however I decided that ALL THE PERSONAL INFORMATION you require , including an existing member REFERENCE is just a level of your parinoid bullshit I wont deal with. Clearly this is your way to C O N T R O L the members, their comments, and opinions...you have a problem with honesty.you might make a 2-3-rd class dictator......and I never claimed to have ANY TACT whatsoever especially with lieing bastards with conceded attitudes....in any walk of life... I know it,s a fault, but I,m an old dog.

[VaccaRabite]

2. fuck you

WOW! Talk about an awesome display of tact and professionalism.

What? WHAT?! I was totally looking forward to a classic Raby chew out here. Come on, he put it right over the plate, and you bunted! (IMG:style_emoticons/default/bootyshake.gif)

Seriously though. Murrays comment was uncalled for. You are a drain on our forum sometimes, and just seriously insulted one of the members here that has dedicated himself to producing quality new parts for our cars - helping to keep us on the road.

Admins, can't we get a ban for this guy already and be done with it?

Zach

[HAM Inc]

I have very little time to address the lunatic ramblings of a pile of (IMG:style_emoticons/default/stromberg.gif). To busy making torque for engines with no head breathers!

Mr. Mayor you may have bolted together some engines over the years that performed well, but hey, even a blind squirell finds a nut once in a while!

I won't waste much time on your cam loading nonsense, but as for the nose wear, think about what I said.

At near redline speeds the load on the cam at max lift (as the lifter goes over the nose of the lobe) may be 5 lb's it may be near 0. At speed the greatest load that the cam sees is when the lobe encounters the stationary valve train and has to get it moving...and in a hurry.

How much time (expressed in % of run time)do you suppose an engine spends at redline or near redline speed? Not much on a typical course. As speeds slow from redline, loading on the nose increases, as does wear. This is not evidence of the non-existence of cam load shift that varies with speed. In other words where the max load occurs on the lobe varies with speed.
Think about it dumbass. Then watch a spin-tron in action. Then spend hours on the phone with valve train specialist. Maybe your knowledge base will catch up to ours, though I doubt it as you are to stubborn to allow facts to interfere with your accepted ideas.
BTW, considering how much time I spend reading, talking with valve train specialist with whom I have been doing business for years and on R&D and track testing I think it is very unlikely that I deserve the know-it-all tag. That is generally reserved for people who do no R&D and whose knowledge base has not expanded in over 30 years.

Please feel free to go (IMG:style_emoticons/default/sheeplove.gif) yourself!

[ME733]

2. fuck you

WOW! Talk about an awesome display of tact and professionalism.

What? WHAT?! I was totally looking forward to a classic Raby chew out here. Come on, he put it right over the plate, and you bunted! (IMG:style_emoticons/default/bootyshake.gif)

Seriously though. Murrays comment was uncalled for. You are a drain on our forum sometimes, and just seriously insulted one of the members here that has dedicated himself to producing quality new parts for our cars - helping to keep us on the road.

Admins, can't we get a ban for this guy already and be done with it?

Zach

.................ZACK........why don't you read the "GANGS" comments transposing youself into my shoes.... I have put up with plenty of nasty, crummy comments,selfserving,arrogent, comments from these jerks long enough....and they AVOID answering questions, and , with people like you chiming in distracting the question line...just playes into their hands...so ZACK just shut up., unless of course you are one of their toddys., in which case you can"t.

[J P Stein]

Give em' hell, Muarry. (IMG:style_emoticons/default/biggrin.gif)

How bout a new rule: Anybody that critizes Jake & company gets an automatic ban. That would fit nicely with the mentality on this list.

FYI, many racers back in the 70s & 80s ran T-4 quite successfully....and *had the results to prove it*.......they always had an extra engine or 2 in the trailer....
You wanna rewrite history to include your present heros, feel free.

[charliew]

This has been a pretty good thread, I wasn't aware of the small return passages of the t4. Except for the on going comments from one who thinks he knows it all about old technology, these were thoughts from the 60's. I like to learn about new theorys. One of the first places I learned about the new oils was from Jakes discussion about the flat cams, I actually found it searching for the changes to new motor oils, it made sense about the oils being changed to keep the cats and o2 sensors working to remove all the good friction stuff as roller cams were now being used. Ok all I want to contribute to this is a little of what I know from trying to do breathers on all my past modified motors. NONE of which were race motors. In the late 70's I started trying to get pcv stuff to work as I was tired of the moisture buildup in the motors. I have found out many years later it was from trying to keep the oil too cool mostly. One motor had larger than stock ring gaps and forged pistons and was spinning 8k a little each day usually for only short intervals. I was also trying to run 10:1 compression on premium gas during the summer with 100 degree days. This required water injection. I used a 160 degree thermostat. All of these things were helping to put water and blowby in the motor. The forged pistons were loose, the ring gaps were bigger than stock and it took a longer time to warm up. The warm up is the thing, the quicker the oil gets to 200f the better for the motor. I learned some of this working with the flat 4 suby turbo motors. The turbo suby always uses oil, especially the loose built motors. The suby uses a oil heater/cooler. The suby has bigger return passages than the t4 but it also has a valve cover balance tube between the heads along with the pcv system. We have also added a port in front of the turbo with a one way valve (another pcv turned around) to give a lower pressure path under boost to try to eliminate the crankcase pressure of the loosely built turbo motor under boost. We also use a Mann Provent from a diesel application that drains to the pan. We got the idea (my son has the hotrod suby, he is also a me) from the Ligenfielder turbo corvettes. I do believe race built motors need a entirely different breather system. You call a race breather system a oil control system. The race oil doesn't stay in for months in the motor. The street car gets idled a lot and doesn't ususlly get the care in the oil area that a race motor does. I live in the country in TX where cow farts probably cause more problems than my 6k miles a year causes so emissions is just a by product of my breather systems. I want whats best for the oil and the motor, to keep it from breaking down and getting contaminated and to keep it in the motor as much as can be achieved for 3k miles. Thanks to Jake and Ham for the shared knowledge here.

I forgot about this: several years ago I tried to make a 1200 sportster keep up with my v65 v4 1100 honda. The honda was 130hp stock the sporster was about maybe 60hp stock. About $4000.00 dollars later with everything we could come up with including coatings and redesigned hemi design heads, roller rockers and all. A big improvement came from a bigger scavengeing oil pump to get the oil out the case and maybe pull a vaccum on the rings and get the oil out of the rocker boxes and a crank vent on the rocker boxes. I could actually feel the high rpm difference. It also stopped the excess oil from coming out the breather line into the air breather and leaking down all over the side of the bike when you put it on the kick stand. This would happen every time it spent any time at 5k or more. Well the hd only made 95 hp at the wheel but it did still sound like a hd and had a good idle at about 1k. I guess this is kinda like comparing the four valve suby or honda to the t4 or t1 though so it's really not a fair comparison.

[Jake Raby]

..............hello jake...........I attempted to join in on your website...AS YOU... invited me to do so....., however I decided that ALL THE PERSONAL INFORMATION you require , including an existing member REFERENCE is just a level of your parinoid bullshit I wont deal with.

Yet again you are incorrect. The "reference" is NOT REQUIRED, and it is built in to the forum software as a way to give existing members a pat on the back for recruiting new members. Had you left the reference field blank, you would have still been allowed to gain entry.

Clearly this is your way to C O N T R O L the members, their comments, and opinions...

Damn right it is, because I own the site where I post critical information. I consider entry into that site just as critical as entering the gate to my facility, which is also a controlled environment that you will never see.

I started that forum to share information in a controlled setting so I could keep trolls and pirates from stealing our ideas and copying and pasting them on their own sites, like happened to us in 2004. So yes, it is a controlled environment for those who have an OPEN MIND to both share and learn.

you have a problem with honesty

.
and you have a problem with perception and are somewhat paranoid.

you might make a 2-3-rd class dictator......

Probably a good first class dictator, because in this business that bears my name and on top of this hill what I say goes. If someone doesn't like that they don't have to pay the price of admission. I am not conceited, I just say exactly what I feel and don't take smart assed statements from anyone, and I don't care if you like that or not.

and I never claimed to have ANY TACT whatsoever especially with lieing bastards with conceded attitudes....

Now you are making statements that we have falsified statements and data..Nothing like some false accusations to help build your credibility.

I know it,s a fault, but I,m an old dog

.
We noticed.

Glad to see you lacked the mental capacity to properly complete your registration onto my forum- it saved me the effort of having to eject you.

Sure seems like you are filling the role that the "lying newspaper reporter" explained in his article about your ramblings and antics.. Sure that guy was a liar?


I'll close by stating that I have been working to quantify what we have learned on the track from the FP 914 engine in our street cars. So far the data I have gathered seems to be absolutely in line with the findings that we have experienced on the track. When I collect an amount of data that can shut down even the best argument I'll be sure to post that over on my forum where we can chat about the Mayor and his ramblings and have a good laugh.

Nothing ever stays the same. Closing the mind because one feels they have been there and done that since the sixties is the fastest way to beat yourself. Had our minds stayed closed and we let our theory and experience get in the way we'd still be having issues that were solved by some experimentation.
What hasn't changed since the 60s in this world?? (other than Murray's mind)

This post has been edited by Jake Raby: May 4 2010, 11:22 AM

[SirAndy]

IIRC it is a draw through system, meaning air is drawn into the heads and down the pushrod tubes.

From my (limited) experience, the head vents have negative pressure (suck in air) at low rpm and have positive pressure (blow out air) at higher rpm.

That would explain why you see that much oil pushed out of the heads at constant high rpms on your race engines.

On a street engine, that oil will have a chance to be sucked back into the heads during lower rpm phases.

On my (street) 2056, i observed oil being pushed into the catch can during higher rpms and then drain back when the rpms dropped.
My catch can was designed to allow for the oil to flow back into the system.

(IMG:style_emoticons/default/popcorn[1].gif) Andy