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

[jaxdream]

Ok, Jake and / or Len , would a setup running off of the oil filler housing , enlarged so as to pull a bigger volume of crankcase gases out from the oil filler also need some sort of PCV valve , or just run without a PCV valve. You guys have my attention, some clarification on what exactly you are reccomending would be GR8 !! Thanks for your replies , so far this is an informative thread being that I will be using carbs for induction ( 40 IDFs ).

Jack / Jaxdream

[Gint]

Ok , Len , I came out of the rootcellar , don't let one guy dampen this thread , like I said earlier , I have some learnin to do , and having vetrans speak up is what I look for. Not all of us have the experience or the surroundings to garner such. Heck there are probaly 2 dozen on this forum that would give their eye teeth for the opportunity for such experiences everyday , but alas not all of us need to be engine builders, still need Dr.s, plumbers, even lawyers and such.
This thread is getting some hard core info put into it, I for one would like to see more of it , even including what others have to say different . There is usually differing points of view to most every facet of these cars and thier engines.
Please sir , more.

Jack / Jaxdream

(IMG:style_emoticons/default/agree.gif) In fact I couldn't agree more. ME733 is usually a bit... shall we say overzealous is relaying his beliefs. But please don't make the rest of the 914world community pay for that. This is a great thread with some good information being brought to light. I for one would love to see the exchange continue.

[ME733]

..........Ok , I shall continue to point out the absurd falacy of UNVENTED HEADS....Some of you people have become so convinced over the postulating of this little selfserving group of mechanics and marketing whizbangers, that I really wonder sometimes how you people got to the place your IN. So as JAKE wants to continue this dialog-with his -all knowing- points of view, I WILL ADD A FEW MORE COMMENTS.............1) I dont need to memorize what(years) heads have or don;t have head vents....I used to just drill-tap- made my own.( like you have previously done and discussed)....2. going down the road of ...the oil drains back faster with unvented heads....I have to wonder EXACTLY AND PRECISLY...how this observation was accomplished..(sort of along the lines of Melling oil pumps have internal oil leaks which you people have stated)...3. And If the oil drains back faster, it,s due to the FACT that the oil is MUCH HOTTER.(and breaking down)..due to the fact the HEAD is much hotter, Due to the "trapped " heat in the head.(with out vents)...4. the trapped heat has many down-sides., not the least of which is...(drum-roll)....the Increased heat affects the VALVE SPRING tension, and that affects how the engines top end, ( cam lobe tracking,)( valve bounce)...at way high RPM,s is affected. 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.). This get you into robbing Horsepower that you busted your ass to create in the first Damn place. Unvented heads have no advantages...street or race....5. Did I read that you people believe oil does not cool the HEADS/ engine? Really? honest ??????.( you probably made a typo error)...6. HEAD VENTING is a good thing in any form....O.E.M. or otherwise.

[HAM Inc]

A single central vent from the chimney needs to be no larger than a 3/4" heater hose. Where you route it is a subject for discussion. Don't even consider routing it to the exhaust for a crankcase scavenge as that only works at full throttle.
My dad conducted dyno studies on his race T1 engines back in the 70's utilizing exhaust evacutation. The engine had to be totally sealed. It would develop about 3.5-4" of crankcase vacuum and was good for a consistent 1.5% increase in power. But only at full throttle. At part or no throttle there is pressure in the ex system.

If you are hell bent on running head vents limit the I.D. of the barb to 1/4" or less.

[Jake Raby]

I was expecting a much more dramatic reply from Murray. He ruined my day. Trust me, I was prepared for engagement and still am. (I spent some time on Google last night and had a lot of really good laughs!)

2. going down the road of ...the oil drains back faster with unvented heads....I have to wonder EXACTLY AND PRECISLY...how this observation was accomplished.

How about two race seasons.. The same engine was used for both seasons. In the first season we had issues with oil control toward the end of each session. I could duplicate this situation on the chassis dyno if I simulated race conditions with throttle and RPM, sometimes seeing 8,000 RPM for 5 minute stints without mercy. The issue would occur at any oil temperature or oil pressure.

In the second season we tried a wild and crazy idea and blocked off the head vents in the heads and the problem could not be replicated on the chassis dyno. We then took the car to the track and didn't have an issue all year long. We had no more than a shot glass full of oil in the catch can all season!

Since this experience I have continued to experiment with this on my personal cars and gather data to support it from other competition and full street engines.

Murray, have you ever purposely blocked off a vented head on a 914 engine to see what occurred?

[HAM Inc]

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.

[type11969]

Murray ? ? ? ? what would Jake and Len have to gain by ! ! ! advocating for a number of years , , , to # # # use head vents then now to begin advocating not using ^ ^ ^ them? They % % % will @ @ @ not be making any money off of ( ( ( sharing this information. Obviously he is simply & & & sharing his findings . . . for the good of the community. If you doubt his results , , , that is fair but ) ) ) I suggest you prepare logged data showing a sound & & & experimental method because I know Jake and Len _ _ _ have that info.


. . . . . . . . . . Chris . . . . . . .

[type11969]

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.

Len beat me to it, putting in all that extraneous punctuation is time consuming.

[Jake Raby]

Murray ? ? ? ? what would Jake and Len have to gain by ! ! ! advocating for a number of years , , , to # # # use head vents then now to begin advocating not using ^ ^ ^ them? They % % % will @ @ @ not be making any money off of ( ( ( sharing this information. Obviously he is simply & & & sharing his findings . . . for the good of the community. If you doubt his results , , , that is fair but ) ) ) I suggest you prepare logged data showing a sound & & & experimental method because I know Jake and Len _ _ _ have that info.


. . . . . . . . . . Chris . . . . . . .

Awesome reply Chris... I love the style!

Murray for Mayor!

[type11969]

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

[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.

.....................Yes be wary of taking advice from people who avoid answering "exactly and precisly how you observed ...." and degenerate into a panicky state of personal generalities to avoid answering the stated facts....AND if you can be believed apparently a compressed valve spring has 5-to 0 ft lbs of torque at full compressed height.(valve fully open)(on the nose of the cam).... surely this too was a typo error...(seems like you guys are just digging your hole deeper). who knowes maybe you enjoy self induced flagulation.....Murray..

[Jake Raby]

You know...
Last night after Murray made his comment about my experience level and age I decided I'd do a little more research about his past in the Porsche world. I just knew that someone with 35 years of experience building super high quality, RACING 356, 914 and 911 engines would have a rich history. I thought maybe I'd read something about the guy that impressed me enough to just let his statements go, because perhaps he was just that damned good.

So I went to the 356 Registry and did some searching... I didn't find anything. I thought that was kinda weird, because all the old timers hang there and SURELY Murray had to have built thousands of engines for that crowd over the past 35 years..

Totally disappointed I then used this little search engine called Google.. The word on the street is this thing is the best thing since sliced bread for finding out about people, places and things here on this new fangled computer "thing a ma jig". So I typed in Murray Mcafee into Google and I didn't find anything at all online related to his experiences with Porsches or their engines... Since I have been known to make so many typographical errors (in the world according to Murray) I thought that just maybe I didn't spell his name right so I double checked. It was spelled right so I then started doing searches with all sorts of other combinations like "Murray Mcafee+Porsche" and that still didn't do anything..

I kept getting pissed off because it seemed that every search I did was polluted with all sorts of information and rants about some guy with the same name that ran for Mayor of his city in 2007; that was the only information that did pop up and finally I read something I couldn't believe. It seemed that the Mcafee character that everyone was bitching about had been the city manager in that city and held other jobs in the past and it was so entertaining that I just kept reading it and laughing my ass off at the wild statements of this guy's behavior in public and during city functions....

As I read more I started thinking to myself that this behavior sure did parallel my experiences with Murray in the past and also was in line with his ramblings here on the forum, especially in this topic. I started to think that maybe this guy was the same Murray here in the thread, but how the hell could a guy that had been tied up with city politics have the time to build so many engines and supposedly win so many races, it just didn't all add up. As I continued to read I'll be damned if it wasn't true!!! He really is that damn good! A phone call this morning verified that here on 914 World we are in the presence of a VERY infamous person!

So I'll share a link or two here and some of my favorite excerpts from last nights google searching so all of you can laugh just as hard as I did.
http://www.thecitizen.com/~citizen0/node/21840

Senoia mayoral candidate McAfee is a phony. Murray McAfee has been touting himself as “the best qualified” for the job of Senoia mayor, citing his tenure as the city’s administrator as one of his greatest credentials. What he failed to mention in his foul-mouthed newspaper interview (which required extensive censorship), is that he was given the choice of resigning from his former position or being fired for “incompetence.

Anyone who’s ever attended a Senoia City Council meeting and sat through the comments from the public has had to be subjected to McAfee’s crazed ramblings which are never based in fact, border on the insane, and leave everyone in the room rolling their eyes until he’s finally told by council to “make his point or sit down,” at which point he’s forced to sit down, since he never has a legitimate point to make.

DAMN!

They know that the biggest threat to McAfee’s campaign is McAfee, so they don’t want him speaking in public. When sober, they’re at least smart enough to realize they need to keep their lap dog on a short leash.

Here is my favorite!!
One Small Step for Senoia... One Giant Defeat for McAfee!!

Submitted by bellringer on Tue, 11/06/2007 - 11:12pm.
The citizens of Senoia have spoken... loudly and clearly... and have handed down a resounding mandate to Mayor Belisle and Council... "KEEP UP THE GOOD WORK!"

In a landslide victory, Belisle soundly thrashed Murray McAfee with a record 81% of the vote... leaving only one question in the functioning minds of Senoians... "Who the hell are the 19% that voted for Murray McAfee????"

It simply doesn't add up... while we know that McAfee and his cart carnies account for 3 of his votes... who else could have possibly cast the others?

Amid the victory celebrations, many citizens were left deeply concerned that either there are 85 people in Senoia with such advanced stages of Parkinsons that they simply hit the wrong button on the voting machine... or there is an immediate need to amend the City budget to add in the cost of 85 straight jackets.

Still others headed out to the local cemetaries with flashlights to determine just how many McAfite voters had been gleaned from local headstones.

Averaging one vote for every 100 signs strategically placed in City right of ways and ditches, Murray has brilliantly deduced that he need only put out 50,000 signs for the next election in order to secure his dream of becoming queen of Senoia. His chief election strategist/financier has considered this plan carefully, plumbed the depths of her own intelligence, and already placed the order for the additional signs.

On a more positive note, perhaps in two years Senoia will finally have the sewer capacity to process the enormous amount of B.S. produced by McAfee during an election

Another..

It's a toss up... but in an effort to at least attribute ONE idea in this campaign to Murray, reading between the lines we can only assume that Mr. McAfee is looking for a 'gentler touch' from the boys in black. If he's elected, we're sure to be in for such sweeping changes as pink batons, furry handcuffs, K-9 poodles, and (without a doubt) an annual policemen's ball with Mr. McAfee headlining the entertainment by singing some stimulating showtunes.

Every Village Needs an Idiot

Submitted by bellringer on Sat, 11/03/2007 - 4:23pm.
Murray McAfee has come completely unglued.

On the one hand, he complains that his signs are being stolen. On the other, he fails to mention that he's putting them on people's properties who don't support him... and they're taking them down not "stealing" them!

This of course has left him with no choice but to litter the city right of ways, and those of Rockaway Rd, SR16 and SR85 with dozens of signs, just stuck out in the middle of nowhere. I guess those represent the support of Senoia's voting worms, snakes, and rodents.

You'd have to look pretty hard to find a McAfee sign on an actual human being's property... and then after you consider whose property it is, it's fairly easy to grasp the meaning of the phrase, "In the land of the blind, the one-eyed man is king".

As we all know, Murray's been canned from the jobs he brags make him 'most qualified' to be the mayor of Senoia... and that's the best he's got! Makes one wonder which 'qualifications' he's not telling us about.

So it appears that Murray was busy managing a city when I was still shitting in my diapers more than he was producing these awesome engines that he carries on about so often here on this forum. He has gone out of his way to ruin my credibility so I felt the need to reciprocate and share a few things that were nothing more than a matter of a simple google search, and total public record.

Did someone mention self induced flagulation (SP)????? LOL

This post has been edited by Jake Raby: Feb 3 2010, 11:03 AM

[Rand]

AND JAKE RABY I was building 914 RACING engines...when you were still crapping in your diapers.

Murray, put your money where your mouth is. Build a TIV motor that kicks one of Jake's motors' ass. Maybe you could start by matching the results of his cross-country trip. Document it as well as Jake did and let's see it. Good luck.

What kind of performance specs have you achieved out of your best TIV build, and how long did it last under abusive conditions?

[HAM Inc]

Good work Jake! But I can't but help wonder. Can you be more specific about the sort of computor you used. How can we be sure that Google didn't just make up these results. They surely have an agenda, everyone else does!

I have to admit that I have been sucked into this goofy discussion now and as a result I have to respond to Murray's assertion that cam loading doesn't change with speed.

Here's what I said:

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.

Here's Murray's response:

AND if you can be believed apparently a compressed valve spring has 5-to 0 ft lbs of torque at full compressed height.(valve fully open)(on the nose of the cam).... surely this too was a typo error...(seems like you guys are just digging your hole deeper). who knowes maybe you enjoy self induced flagulation.....Murray..

You missed the point Murray. Ofcourse I know that springs are displacement sensitive. Meaning a spring with a rate of 250lbs/inch will require 125lbs to compress it a .5". What varies with engine speed is waht is actually compressing the spring.

Let's consider an engine that is properly sprung to control the valves at 7000RPM's. When the engine is turning 7000rpm's the greatest load on the cam (notice I said the greatest load on the CAM) occurs when the lobe comes around and encounters the stationary valve train, which it has to get moving in a big hurry. Once the mass is moving inertia plays an increasing role over the course of the lift event. The more inertia the less the cam load.
Eventually as the mass approaches peak lift the load on the cam may be reduced to only a few pound. This is why we can draw no meaningful valve train information from turning an engine over with a torque wrench.
Other factors include the stiffness of the pushrod. If the pushrod is not stiff enough it will bow when the lobe comes around and encounters the stationary valve train. This bowing delays the opening of the valve and stores energy in the pushrod, to be released later in the lift cycle. As inertia takes over and the load transferred through the pushrod to the cam decrreases the pushrod unloads its energy and actually pole vaults the valve contributing to valve float. Did you catch all of that, Mayor?

Now, here's a question that hasn't been broached at all yet in this discussion that could be fun and interesting to the community. Why do we need to vent the crankcase at all, and why do some configurations require more venting than others?. The answer varies by application and engine specifications and is a lot more complex than it appears on the surface.
Mayor perhaps you would like to weigh in on this.

[wayne1234]

Wow, I just wanted to clean up my engine bay, Jake has helped me in the past, with nothing to gain on his part, because the part was previously purchased by the PO.. So I feel he is looking out for the good of our community, I'm sure he doesnt have to post on here for his business. If people like Jake didn't keep pushing for more , and questioning what is "written in stone" we would all be stuck with nothing new since the 80's. I'm sure he puts so much into R&D that it would make our head spin... I for 1 am glad to have him here lending us a hand... Thanks Jake

[Jake Raby]

Wow, I just wanted to clean up my engine bay, Jake has helped me in the past, with nothing to gain on his part, because the part was previously purchased by the PO.. So I feel he is looking out for the good of our community, I'm sure he doesnt have to post on here for his business. If people like Jake didn't keep pushing for more , and questioning what is "written in stone" we would all be stuck with nothing new since the 80's. I'm sure he puts so much into R&D that it would make our head spin... I for 1 am glad to have him here lending us a hand... Thanks Jake

Thats right. If automotive technology didn't evolve over time we'd still be working with flat heads, steam and the like.

If everyone had their head up their ass like Murray does we'd not have 4 cam, 4 valve engines running 12:1 on pump gas for daily drivers.

Hell I realized I was limiting my exposure to modern day technology by only working on the Type 4, so a few years ago we jumped into the M96 Porsche engine and have learned tons about modern theory and application.

Due to that our vintage engines have benefited.

[ME733]

...Well jake arn't you special. Just like the jerk who wrote those UNSIGNED letters to the editor...Only thing is I actually know who he/they are....And because he could NOT meet the zoning, health, building code , access, lot size, ordinance requirements...to convert a GARAGE into an apartment... which I would NOT approve , and my decision was supported by a city council VOTE. this is the extent some "types" of people will go to- when they cannot get their way. I stood firmly for the law, ordinances, and for what was in the public intrest, and the city. now this leads me into the area that YOU MUST believe everything you read. especially considering, you didn't care, or notice the "articles" were UNSIGNED/REAL NAME. I guess you believe unsigned/ arthored automitive articles also. Maybe some of your "theories' come from the same unsigned sources.( completely full of c---.)...But anthing to divert attention AWAY from the points I have raised in this "case venting" discussion. Youre doing this because you are conserned that another engine builder disagrees with you, in public, up front, among the 914 owners, and YOU CANNOT comprend that you do not know everything, and it scares the hell out of you that someone(finally) has called you on the carpet to address a few simple engine breathing points. Again this is why you, are getting off the subject. I think the members are smart enough to realize the obvious....So heres are some facts, find a 1996 guide to vintage racing.(the front cover says/showes it all).the june, 1987. victory lane-pg,s 8,(guest editoral) and 53, (ad)...Victory lane , july 1988-pg-86, car collector Dec-1985, article time travelers go west pg,s 54-thru-57. Walter Mitty Challenge1985,(August-22-25), pg,4,5,7,(pg7...note driver) I built their engine/and helped with some other stuff,.VW Porsche Magizine.., October-1983, pgs 43-43....well that should be enough to get you started. After you do your homework, how about getting BACK to the subject matter ,and questions I raised, and issues related to "head venting" or not.

[McMark]

If you care to continue the debate, take it into PMs cause nobody else cares. (IMG:style_emoticons/default/rolleyes.gif)

[HAM Inc]

If you care to continue the debate, take it into PMs cause nobody else cares.

(IMG:style_emoticons/default/smilie_pokal.gif)
Great call McMark.

[ME733]

Good work Jake! But I can't but help wonder. Can you be more specific about the sort of computor you used. How can we be sure that Google didn't just make up these results. They surely have an agenda, everyone else does!

I have to admit that I have been sucked into this goofy discussion now and as a result I have to respond to Murray's assertion that cam loading doesn't change with speed.

Here's what I said:

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.

Here's Murray's response:

AND if you can be believed apparently a compressed valve spring has 5-to 0 ft lbs of torque at full compressed height.(valve fully open)(on the nose of the cam).... surely this too was a typo error...(seems like you guys are just digging your hole deeper). who knowes maybe you enjoy self induced flagulation.....Murray..

You missed the point Murray. Ofcourse I know that springs are displacement sensitive. Meaning a spring with a rate of 250lbs/inch will require 125lbs to compress it a .5". What varies with engine speed is waht is actually compressing the spring.

Let's consider an engine that is properly sprung to control the valves at 7000RPM's. When the engine is turning 7000rpm's the greatest load on the cam (notice I said the greatest load on the CAM) occurs when the lobe comes around and encounters the stationary valve train, which it has to get moving in a big hurry. Once the mass is moving inertia plays an increasing role over the course of the lift event. The more inertia the less the cam load.
Eventually as the mass approaches peak lift the load on the cam may be reduced to only a few pound. This is why we can draw no meaningful valve train information from turning an engine over with a torque wrench.
Other factors include the stiffness of the pushrod. If the pushrod is not stiff enough it will bow when the lobe comes around and encounters the stationary valve train. This bowing delays the opening of the valve and stores energy in the pushrod, to be released later in the lift cycle. As inertia takes over and the load transferred through the pushrod to the cam decrreases the pushrod unloads its energy and actually pole vaults the valve contributing to valve float. Did you catch all of that, Mayor?

Now, here's a question that hasn't been broached at all yet in this discussion that could be fun and interesting to the community. Why do we need to vent the crankcase at all, and why do some configurations require more venting than others?. The answer varies by application and engine specifications and is a lot more complex than it appears on the surface.
Mayor perhaps you would like to weigh in on this.

......................If what you say is TRUE, why is it that the Nose of the cam , especially those "flat ones" some people have had ,are worn down radically.at the nose, Instead of at the beginning of the "ramp" near the base circle? as you state., where the highest loading is supposed to be ? did you catch all that?