Oil Cam Restrictor-Rockers-ZDDP

[afterburn 549]

Originally Posted by AlfonsoR

Not hallucinating.....

Oil restricrors revisit

WOW.......
I need to get off the coffee.....Thanx for the reference !LOL
I find it interesting ......That two Great engine Builders would be so far apart on this.....!
Steve at R.S.- No
Henry of S.T. yes
Seems there would be ONE correct answer

[JFairman]

my 2 cents..

use mobil one oil, it is the best and it goes on sale sometimes at walmart.

you could not pay me to use brad penn crap in a turbo engine because it leaves sludge and carbon deposits, and i let the motor idle a minute or two after driving hard to cool down the turbo bearing housing.

do not use the oil restrictors.

[Turbo_pro]

Originally Posted by afterburn 549

WOW.......
I need to get off the coffee.....Thanx for the reference !LOL
I find it interesting ......That two Great engine Builders would be so far apart on this.....!
Steve at R.S.- No
Henry of S.T. yes
Seems there would be ONE correct answer

Henry and the Porsche factory recommend restricters. I have restricters in all 5 of my most resent 911 based engines, one being a 450+ hp 3.5 turbo.

I would think the an engine using low viscosity synthetic oil would benefit greatly from the installation of restricters. my $.02

[afterburn 549]

Well..........I have had mine in sense Break in........I guess i will stay with it........If they are a BAD thing its too late now !
LOL

[Cupcar]

All I have to say is pressure without flow is useless in an oil system.

[Henry Schmidt]

Originally Posted by Cupcar

All I have to say is pressure without flow is useless in an oil system.

Every properly functioning oiling / hydraulic system produces more pressure than it needs.
Now the question is, "is it better to circulate the excess without dumping it in the crankcase?" Then there is the issue of excess oil in the crankcase that must be scavenged. Every drop of oil placed in the heads flows into the crank case and that oil can cling to the rotating parts (windage) reducing performance.

[Iciclehead]

Very interesting discussion and certainly respect both our experts here. There have been a few threads of this type where some very good, very experienced builders make different recommendations. At the expense of pissing off all of them, my conclusion after respectfully listening is to stick with the factory recommendations on most things....which means I will be using the restrictors on my 3.4 (Turbo oil pump) and also using the 993 TT Dilavar studs....

I am a little suspicious that there is not a material difference in engine life either way....or performance either, but I have no data or specific knowledge to support that, just I am used to listening to strongly opposing opinions on technical topics and generally the truth in those situations inevitably is that "it doesn't really matter".

Dennis

[faverymi]

IMHO. As a consumer.

1 The engines I have are pre 964. 3.0 SC and 2.7 S.
2 I understand and get the need of more oil in the bottom in a turbo car.
3 The design of the valve train in 90s motors is different than previous generations

A.Older motors had leaded fuel available(helped with valves, combustion,etc
B Older motors had non ethanol gas(helped lubrication)
C Older motors had different motor oil with ZDDP( we all know)

Under modern conditions I think I would stick with a non restricted flow of oil into the cam carriers. Why would I like to have less oil than the amount that was originally designed for my "old engines" under the less desirable modern conditions? Lets say anything non turbo before 1990.

If I had a turbo motor or a post 1990 motor would be a different story.

BTW thank you for all the replies. Very constructive. Highly appreciated

[AlfonsoR]

The proof is in the pudding.... Need to have more data points with high mileage restricterred engines. When I do my rebuild, hopefully sometime this year, I will be using restricters.

Also, I wonder if a restricterred engine would be less prone to oil starvation on the rods so that the cross drilling mod is not as necessary? Probably not.

[proffighter]

Originally Posted by proffighter

After reading several threads about restrictors, I am still unsure (maybe my sometimes not perfect english) if I should mount restrictors or not

I have an '81 3.3L turbo, common mods like EFI, Headers, bla bla, somewhere around 450HP

I tend to try a 2.5mm restrictor. No other mods together recommended right?

Thanks in advance

BTW, I like to stay with my 20W50 Kendall oil (no winter use at all), so still using restrictors? What do the experts recommend here?

[Cupcar]

This is an interesting discussion.

One data point is a 2.5 liter we built over 10 years ago for vintage racing that has been rebuilt 3 times over that period with about 40 hours on each build cycle.

The car had until its last build a 901 oil pump with the small pressure side, the oil bypass mod, late pressure regulation spring package and the venturi pick up. It also had the Turbo oil restrictors. The idea being that the 901 pump is plenty adequate in a high RPM engine and the relatively larger scavenge side + venturi + restrictors would limit windage losses as Henry points is a good idea.

Cams are GE80 with first Aasco then Eibach springs and Ti retainers. Oil Mobil 1 15-50 which has more ZDDP than the other M1 oils and the engine is set to a 7500 RPM limit.

The cam wear has been acceptable and the cams have never been changed. We were surprised to find one broken Aasco spring at one build though. So to me this shows that oil flow with the restrictors is enough to protect the cams- at least in this engine anyway.

Having said that, I am still a flow freak because I like the idea in my mind of lots of cooling oil going over the parts - hey this is just me, I am not calling it right or wrong - and if an engine has a GT3 or other large oil pump, I would not use restrictors.

With the smaller pumps, I would probably restrict flow to the cams with the restrictor.

Perhaps the most cogent quote from above is "it doesn't make any difference"...

[Henry Schmidt]

I think part of the problem that is emerging in this conversation hoovers around the concept of "restricting " rather than "controlling". I believe that during the ongoing process of engine development, Porsche engineers deemed the flow of oil the the head/ cam towers was inappropriate/ excessive and that there was no appreciable temperature reduction in excessive oil flow. Their testing showed that too much oil was counter productive. Let's not fall into the oh so American thinking that "more is better". The correct amount (of whatever) is better and determining that "amount" has been our goal (as well as Porsche factory) when developing these old engines.

[jomalkay]

One wonders, if the parts were called Oil Cam Control Devices, would this even be a conversation, just saying. I have been reading through quite a bit on this topic as i am at a point of finishing my rebuild, one thing i am sure of speaking personally, it was hard for me to get past this "restrict" wording, was like that little devil sitting on my shoulder.

[quattrorunner]

My engine uses the 77 turbo pump, which I believe is the same as the early midyear pump for all 911's? I might be a candidate for the restrictors? I have adequate pressure but like the idea of more pressure.
My engine is in fact the 77 930 engine and I have lots of oil cooling so I'm not sure if I need it.
Does anyone have a thought about my application? I'm in Vegas

[AlfonsoR]

Originally Posted by Cupcar

Having said that, I am still a flow freak because I like the idea in my mind of lots of cooling oil going over the parts - hey this is just me, I am not calling it right or wrong - and if an engine has a GT3 or other large oil pump, I would not use restrictors.

With the smaller pumps, I would probably restrict flow to the cams with the restrictor.

Perhaps the most cogent quote from above is "it doesn't make any difference"...

That's a good point. I put the retractors in because, once up to temperature, the low oil pressure would come on at idle sometimes. With the restricters, no more red light. If i do put a turbo pump in during my rebuild, then I won't put the retractors in.

[scarceller]

After reading this great thread I see that Porsche introduced these restrictors in the 964 (early 90s).

I'm wondering if the engine had anything else changed at the time that the restrictors where introduced?

For example: did the oil pump change significantly at the same time? Or anything else oil related?

The reason I'm curious about these questions is to be sure that I don't put these restrictors into a 84-89 3.2L that does not have all the required factory mods that go along with the restrictors.

[AlfonsoR]

Originally Posted by scarceller

After reading this great thread I see that Porsche introduced these restrictors in the 964 (early 90s).

I'm wondering if the engine had anything else changed at the time that the restrictors where introduced?

For example: did the oil pump change significantly at the same time? Or anything else oil related?

The reason I'm curious about these questions is to be sure that I don't put these restrictors into a 84-89 3.2L that does not have all the required factory mods that go along with the restrictors.

Yes, the 964 did receive a higher flowing oil pump. Not sure about any other changes in the oil system. However, apparently Porsche sent a technical bulletin out to install the restrictors (er controllers) on older cars as well. Read more on Rennlist.com. Go to forums, 911. Search for "911 camshaft oiling update - anyone done this ?" A lot more info to consider there.

[AlfonsoR]

PS: I am currently thinking that I will not be upgrading my oil pump at rebuild. My current pump is putting out good pressure and if all the internals look good, I will keep the restrictors in as well.

[Cupcar]

FWIW - Porsche went the other way with their parts supercession for 3.6 engines, the small hole 964 connector piece has been superseded to the large hole part of the 993 for both 993 & 964

[KTL]

Originally Posted by Cupcar

FWIW - Porsche went the other way with their parts supercession for 3.6 engines, the small hole 964 connector piece has been superseded to the large hole part of the 993 for both 993 & 964

Just need to be sure everybody understands that the pieces Cupcar refers to above are not the same part as those used on the older cars. They serve the same purpose (oil feed from crankshaft/case to cam housings) but they are a completely different part, typically referred to as a "bridge."

Basically how it works, the 964 oil system was modified to integrate the old, external cam housing oil feed hoses on the pre-89 engines into the cam chain housing. The chain housing actually has oil from the crankcase pressure circuit running thru it to supply oil to the chain tensioner and also supply pressurized oil to the camshaft housing via the aforementioned bridge piece.

All that being said, the 964/993 bridge and the older style cam housing oil feed adapters/restrictors serve the same purpose- get oil to the cam housing. If an orifice within either of those parts is modified, the oil supply to the rockers and cams is directly affected.

To add a bit to what Alfonso said, yes the 964 oil pump was upsized. It is larger in physical size/pumping capacity (both scavenge and pressure) than the 3.2/3.0 pump but not as high a level as the bad boy 930 pump. It looks a lot like the 930 pump but the giveaway is its magnesium body vs. the 930 aluminum and iron combo.

964 also has larger piston squirters (2.0mm orifice vs. 930 1.5mm vs. "normal" 1.0mm) and it has a shim/spacer in the vertical pressure bypass valve in the crankcase.