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

[Jake Raby]

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

Except during periods of sustained RPM and speed. Thats where I have noticed the biggest differences.

I recently had an AX customer who was having low oil pressure issues on some longer courses. I told him to try blocking off the head vents to see what the results were, he emailed me back to say the issue disappeared.

He had the issue on the street a couple of times on the way to the track on a certain freeway off ramp after maintaining constant speed and RPM for 20 miles on the way to the track. He said this issue also disappeared. He has since blocked off the vents permanently and I recommended him to increase the size of the crankcase vent.

No one needs to take any of these statements as gospel.. Every application is different along with every set of components and there is no "one size fits all".. Just try it both ways and see what happens to your vehicle/ engine.

[bandjoey]

Soooooo. If someone with a math background will be kind enough to add up all of the yesses and noooo's to head vents, divide by the number of curse words, and calculate the winner.....

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

[TheCabinetmaker]

So, I'm at the final stages of building a 2056 on a 76 case. Two hrs ago I purchased two barbed fittings to drill and tap the bosses. Then I saw this thread and just read all 7 pages. WOW! This engine is using the D-jet. If I read you right Len, go ahead and drill? The air inject sys was removed years ago and holes plugged. The owner has complained to me for years about the high oil temps. Is the unvented heads the reason for this? Will venting them cool the temps.

BTW Great thread (except for the profane gesture).

[JFJ914]

So, I'm at the final stages of building a 2056 on a 76 case. Two hrs ago I purchased two barbed fittings to drill and tap the bosses. Then I saw this thread and just read all 7 pages. WOW! This engine is using the D-jet. If I read you right Len, go ahead and drill? The air inject sys was removed years ago and holes plugged. The owner has complained to me for years about the high oil temps. Is the unvented heads the reason for this? Will venting them cool the temps.

BTW Great thread (except for the profane gesture).

Remember, the L-jet 1.8 and '75-'76 D-jet 2.0's did not use head vents and mine does not fill my air cleaner with oil. I'm going to put plugs in the holes I asked Len to put in my new heads.

[J P Stein]

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)

Can you boast a record greater than this:

Wayne Baker's Racing History

(Just the relevant parts)

In 1974 we started in PCA time Trials campaigning a 914-4 Porsche. We also prepared customer cars for Time Trials and SCCA Racing.

In 1975 with a 914-4 2.5 liter we won the PCA Zone 8 Unlimited Class.

In 1977 we entered SCCA Regional and National events running a 2.0 liter 914-4 Porsche in D-Production.

1978 we won the D-Production Southern Pacific Championship.
We progressed to IMSA Road Racing series campaigning a 914-4 in the IMSA GTU class under 2.5 liter engine.

In 1980 we finished 6th in class at the 24hrs of Daytona and 12th in class at the 12hrs of Sebring. This was accomplished with a 2.0 liter 4 cylinder push rod engine.

In 1981 we campaigned a 1,680 lb. 914 Porsche with a four cylinder. 2.1 liter engine in the IMSA GTU Championship finishing 4th. Our best result that year was a 1st at Sears Point, this was the first and only time a 914-4 push rod motor had ever won a major race of that caliber.

[Jake Raby]

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)

Can you boast a record greater than this:

Wayne Baker's Racing History

(Just the relevant parts)

In 1974 we started in PCA time Trials campaigning a 914-4 Porsche. We also prepared customer cars for Time Trials and SCCA Racing.

In 1975 with a 914-4 2.5 liter we won the PCA Zone 8 Unlimited Class.

In 1977 we entered SCCA Regional and National events running a 2.0 liter 914-4 Porsche in D-Production.

1978 we won the D-Production Southern Pacific Championship.
We progressed to IMSA Road Racing series campaigning a 914-4 in the IMSA GTU class under 2.5 liter engine.

In 1980 we finished 6th in class at the 24hrs of Daytona and 12th in class at the 12hrs of Sebring. This was accomplished with a 2.0 liter 4 cylinder push rod engine.

In 1981 we campaigned a 1,680 lb. 914 Porsche with a four cylinder. 2.1 liter engine in the IMSA GTU Championship finishing 4th. Our best result that year was a 1st at Sears Point, this was the first and only time a 914-4 push rod motor had ever won a major race of that caliber.

Mr. Baker's accomplishments are outstanding. No one can ever take that away from him.

BUT then the cars were newer and the competition wasn't primarily using OHC and fuel injection like we face today in SCCA F Production with most all other competitors..

Like I said nothing ever stays the same, including the competition...

Hell I thought JP would never sell his 914, proof that nothing ever stays the same..

BUT that has nothing to do with case and head ventilation.

This post has been edited by Jake Raby: May 4 2010, 03:32 PM

[ME733]

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)

Can you boast a record greater than this:

Wayne Baker's Racing History

(Just the relevant parts)

In 1974 we started in PCA time Trials campaigning a 914-4 Porsche. We also prepared customer cars for Time Trials and SCCA Racing.

In 1975 with a 914-4 2.5 liter we won the PCA Zone 8 Unlimited Class.

In 1977 we entered SCCA Regional and National events running a 2.0 liter 914-4 Porsche in D-Production.

1978 we won the D-Production Southern Pacific Championship.
We progressed to IMSA Road Racing series campaigning a 914-4 in the IMSA GTU class under 2.5 liter engine.

In 1980 we finished 6th in class at the 24hrs of Daytona and 12th in class at the 12hrs of Sebring. This was accomplished with a 2.0 liter 4 cylinder push rod engine.

In 1981 we campaigned a 1,680 lb. 914 Porsche with a four cylinder. 2.1 liter engine in the IMSA GTU Championship finishing 4th. Our best result that year was a 1st at Sears Point, this was the first and only time a 914-4 push rod motor had ever won a major race of that caliber.

.......................VERY COOL.......JP I was at (that race!!!)..the 12 hrs of sebring.....met you guys briefly....It was a very incredable feat that the little four cylinder performed., so well and finished at all., much less 12th, given the competition....you didn't notice probably, but I gave your car a close lookover after the race., I was absolutely astounded at the road crud, tire bits, oil, dirt, rocks,and chipped paint. the little car went thru hell, and survived!!!!..It took knowledgeable drivers to get the best out of it , while not abusing it to death.......very ,very cool.......

[J P Stein]

Murray: That was a quote from his website......I'm not part of "we". (IMG:style_emoticons/default/biggrin.gif)

Jake: a lot of pushrod motors above you on the runoff charts. The Kirby 914 won in 06....but then, that wasn't one of your motors.

[Jake Raby]

Actually the Kirby 914 won in 05 and Len and I were there..

Then shortly thereafter Dave finch stated that no other 914 would be competitive in FP due to the rules and the competition of today.. In fact he stated that in the Excellence article about that car.
That didn't stop Len andI from building one.

Yet again, this doesn't have anything to do with case venting.

Murray had you confused with Wayne Baker... Now thats funny... looks like someone is "baked" themselves.

[J P Stein]

Right, 05......

I dunno much about T-4s, but I have seen pics of T-4 valve covers filling with oil at continuous elevated rpms (IIRC). Venting the valve covers would seem iffy without using some method to keep the oil level therein down and in the case/oiling system where it belongs.

"They" had (in the old days) a similar problem with the SBC when trying to run that motor at Indy...it would pump the oil out the breathers and starve the engine of oil....dry sump or no. "They" fixed that.

[ME733]

Right, 05......

I dunno much about T-4s, but I have seen pics of T-4 valve covers filling with oil at continuous elevated rpms (IIRC). Venting the valve covers would seem iffy without using some method to keep the oil level therein down and in the case/oiling system where it belongs.

"They" had (in the old days) a similar problem with the SBC when trying to run that motor at Indy...it would pump the oil out the breathers and starve the engine of oil....dry sump or no. "They" fixed that.

.....oop,s I thought J,P,...that YOU were one of the co-drivers., the sebring race posting was by you ., my bad.

[ME733]

Right, 05......

I dunno much about T-4s, but I have seen pics of T-4 valve covers filling with oil at continuous elevated rpms (IIRC). Venting the valve covers would seem iffy without using some method to keep the oil level therein down and in the case/oiling system where it belongs.

"They" had (in the old days) a similar problem with the SBC when trying to run that motor at Indy...it would pump the oil out the breathers and starve the engine of oil....dry sump or no. "They" fixed that.

[DNHunt]

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

Except during periods of sustained RPM and speed. Thats where I have noticed the biggest differences.

I recently had an AX customer who was having low oil pressure issues on some longer courses. I told him to try blocking off the head vents to see what the results were, he emailed me back to say the issue disappeared.

He had the issue on the street a couple of times on the way to the track on a certain freeway off ramp after maintaining constant speed and RPM for 20 miles on the way to the track. He said this issue also disappeared. He has since blocked off the vents permanently and I recommended him to increase the size of the crankcase vent.

No one needs to take any of these statements as gospel.. Every application is different along with every set of components and there is no "one size fits all".. Just try it both ways and see what happens to your vehicle/ engine.

Right, 05......

I dunno much about T-4s, but I have seen pics of T-4 valve covers filling with oil at continuous elevated rpms (IIRC). Venting the valve covers would seem iffy without using some method to keep the oil level therein down and in the case/oiling system where it belongs.

"They" had (in the old days) a similar problem with the SBC when trying to run that motor at Indy...it would pump the oil out the breathers and starve the engine of oil....dry sump or no. "They" fixed that.

Ah this is great. Two of my favorite people going at it again in this thread. Just like old times. Both of you guys have been a great help to me, Thanks.

I disconnected and plugged the head vents on my engine and I upped the size of the breather hose to 7/8" inner diameter. This is what I have observed. The oil temps seem about the same, which isn't saying much cause it's been darn cold here. The oil pressure is definitely a bit higher. The VDO gauge shows about 5-10 psi increase on the highway.

I vent the breather box into the air cleaners. There is definitely less oil getting into the air cleaners even though the oil this spring is staying so cold it's foaming like mad. I haven't seen any new oil leaks so I suspect crankcase pressures are about the same.

The most dramatic thing I've seen is an increase in head temps. The heads warm up faster from a cold start and they change more rapidly on the road. I suspect this reflects the fact less oil is making it into the heads to cool them. I have not had a chance to thrash it at the track but I suspect this will be better for sweeping corners. I'm not so sure this is that great for a touring car.

I am concerned that under load the heads will heat up too fast and too much. Last year climbing up the Siskiyoos in southern Oregon at 75 mph on a 70 degree day with both trunks stuffed and two people I maxed out head temps at ~390. Oil temps were fine. I will really be watching the CHTs and I suspect this year when I make the same climb I may have to let things cool off. I'll report back in a couple of weeks. Mind you this is with stock cooling but, Nickies. It is certainly possible that the cooling is just not up to handling the heat generated by a large engine under a big load. It should be a good test though.

I've thought about putting gate valves into the head vent lines and closing them for AX and track time and leaving them open on the road.

Dave

[charliew]

Is it not possible to drain the heads to the case? If the level is lower and into the oil in the crankcase the crankcase pressure won't affect the draining. Thats how the suby is drained from it's pcv- vent -turbo drain. It's a cavity in the block that has a tube into the oil in the pan. I am sure if the oil temp is lower than the head temp the oil is helping to cool the heads. It seems to me it is easier to cool the oil than the heads.

[Jake Raby]

Dave,
Thanks for your first hand input. I have not noted any differences in head temps with these mods being made but I certainly appreciate your observations. I will continue to pay attention to the data and gather more from the logger. With this being such a hot topic now I am even more driven to more thoroughly understand the scenario and quantify our observations.

The gate valves are an awesome idea. I just recommended that to a customer last week with a 914 AX car that uses one of my engines, he is local to JP and Dave as well :-) I plan on using the gate valve arrangement to help gather data from the arrangement. I even have two electronically actuated valves with the proper size ports that I can use in line to switch scenarios on the fly while gathering data to see the exact occurrences.

An increase I head temps isn't a bad thing as long as the heads are staying in the ranges that we recommend. A head temp of 390 certainly isn't hot in a 914 thats generating 200HP while traveling up a grade like you explain.

The reason I support Len's racing activities is so we can continue to build the breed of components that we use in our street engines, not just to gain notoriety and win races. ALL of the parts in the engine that he has in the car right now are exacting to those that we use routinely in our street, non competition engines and we do that purposely. This even includes the valvetrain components, we use the same valves, springs and retainers in Len's 8,500 RPM engine that we do in a street engine that never turns over 6,000 RPM and just alter the spring pressures. The same valves themselves are used also and at the present those valves, bearings and other "standard RAT parts" in the current engine have been installed for 1.5 seasons of race abuse and got us a runner up in the SARRC last year.

Not many 914-4 race engines making this type of power can be ran for 1.5 seasons at over 8,000 RPM and live to keep performing. Thats not to mention my brutalizing testing regimen that is employed on the chassis dyno before every race when I hold it at 8,000 RPM under full load for 5 minutes at a time. This engine has done it and just 3 weeks ago on the chassis dyno here we made more power with it than we did when it only had one race under it's belt- more power than it has ever made. The reason that we race is to apply the "overkill engineering" that we do our best to develop into an application that is as rigorous as it can be. Len's engine is basically a small (1832cc), high compression street engine with a set of heavy breathing heads.

[Jake Raby]

Is it not possible to drain the heads to the case? If the level is lower and into the oil in the crankcase the crankcase pressure won't affect the draining.

Good idea and we have considered this for street engines. BUT under periods of cornering where the oil in the sump is concentrated to one side of the sump the draining of the heads into that area will be impacted. Since this situation is what we are trying to avoid we have not explored it. It could work in street applications where cornering isn;t as hard or as sustained as in AX or track circumstances.

When the G forces effect the oil level, elevating it above the drains that would be in the case from the heads, the drains would be worthless or could give the oil another path to the heads, thus making the issue worse.

[HAM Inc]

I have not seen a difference in CHT's since blocking off our rocker vents. But that could be because Jake spends a lot of effort on keeping the state of tune consistent for changing conditions. Dave I think that if you are seeing an increase in CHT's after blocking the rocker vents then you may have a tuning issue. Oil just doesn't have the ability to pull a significant amount of heat from heads in the volumes that are pumped into the rocker chambers. The springs benefit from cool oil, but considering where the CHT measurement is taken I really wouldn't expect to see much CHT drop from oil cooling.

I will say that if your oil is spending so much time in the rocker chambers that it is cooling the heads, then you have a significant decrease in the amount of oil around your sump pick-up during those periods. I would keep the heads unvented and make adjustments to the tune to deal with the CHT issue.
~390 head temp for a brief period is not bad if it occurs at full throttle, (especially with nickies) and falls back down quickly once you get out of the throttle, or reduce the amount of throttle.

Blocking the rocker vents doesn't change the volume of oil that is pumped into the heads via the pushrods. It just ensures that there are no pressure differentials between the case and the rocker chambers, which allows the oil to return quickly to the case without pressure inhibitions.

I suppose you could route lines from the bottom of the heads to the sump area. Richie Ginther did that back in the early 70's. The issue I see with that is that if the lines don't have a check valve then oil will exit the sump and run up into the outside head in a corner, possibly starving the pick-up. The complexity of a system that would function properly for a high revver (the Ginther 914 redlined at somewhere around 6200) seems like overengineering to me. The original design has tubes for the return of oil, the design just has to optimized.

I have also wondered how many of the Ginther ideas that were published for prepping a 914 for racing might have been discarded later on by Ginther. Mark Donohue said that about 20% of his chassis ideas worked, the rest ended up in the trash. This is why I love the chassis dyno for this type of work. I tried several different breathing methods, none of which worked to our satisfaction, before simplifying our system and going back to very basic ICE engineering principals. Draw the oil out of the lowest place available and breath from the highest point available.

BTW the shop in my area that builds the winningest V8 circle track engines, (My buddy Darrell Gabriel of Gabriels Race Engines) runs a pair of seperate vent lines from high up on the oil pan up to the valve covers so the three chambers can breath without interfering with the oil that is draining back to the pan from the heads. This was the only way they could keep oil in the pan on engines that don't allow dry sumping. It works so well that he now does that to his dry sump engines too.

I have said it before and I'll say it again here. We run no rocker vents, have a single 3/4" vent line running from our chimney. Oil temps are down, puking has been effectivley eliminated and the engine is stronger now (by 3 hp) than it was when it was new. The system is simple and uncluttered. True I am a rookie road racer and running regionals, but the engine doesn't know that. All it knows is that it is worked hard and never runs under 6,000 and each lap revs to 8,000. Use this info or slam it as you see fit.

[ConeDodger]

An increase I head temps isn't a bad thing as long as the heads are staying in the ranges that we recommend. A head temp of 390 certainly isn't hot in a 914 thats generating 200HP while traveling up a grade like you explain.

Jake,
Profanity, name calling, weak shots at your reputation aside, this is an informative thread. At what temperatures should we be concerned with the LE heads? Len bakes valve seats out of warn original heads at 400 degrees F.

In a dual purpose engine like mine will be, I like the solution Dave outlined. Something I can switch between for street use.

[Jake Raby]

An increase I head temps isn't a bad thing as long as the heads are staying in the ranges that we recommend. A head temp of 390 certainly isn't hot in a 914 thats generating 200HP while traveling up a grade like you explain.

Jake,
Profanity, name calling, weak shots at your reputation aside, this is an informative thread. At what temperatures should we be concerned with the LE heads? Len bakes valve seats out of warn original heads at 400 degrees F.

In a dual purpose engine like mine will be, I like the solution Dave outlined. Something I can switch between for street use.

Start being concerned at CHT of 425 peak, but I have purposely taken the heads higher than this with no failures.

Its a shame that we can't share information without conflict, oh wait a minute- we do that on my forum everyday :-)

[charliew]

In the suby it's easy to build one way gates in wings in the pan, to work with g forces. Do you think a swinging flapper over a return tube would block the drain from the head into the case on cornering? Also like a lot of other motors the suby has restricters in the heads to restrict oil flow to the valve train. It really sounds like what you've got already works and more parts cost more and there is more to go wrong though.