Oil Cam Restrictor-Rockers-ZDDP

[faverymi]

Hi there, I guess it's been a long storm and I had a lot of time on me.

I'm working on my valve train and after looking at the Oil Cam Restrictor I couldn't make the right association between limiting the amount of oil, having no roller rockers(I guess call flat tappet) and the reduced amount of ZDDP in modern oils.

Not trying to re-invent the wheel. I'm not a pro, I work on teeth LOL. I just couldn't find a post that would explain the 3 of them together and I started wondering.

1- I guess if I use something like Brad Penn I shouldn't worry about the restrictor

2. Is the restrictor a real benefit or just makes my needle go higher at idle?

3. What would be the benefit of less foaming around the housing with restrictors?

Comments? Thanks

[Steve@Rennsport]

Dr. Avery,

JMHO, so take this with the proverbial grain of salt.

None of those restrictors goes into ANY engine here since its completely counter-intuitive to reduce oil volume to one of the hottest parts of these engines. Further, this is where the majority of the frictional loads are: cams & rockers and frankly, they need all the lubrication they can get, no matter what oil is used.

Leave them for others, use Brad-Penn oil, change it frequently, and your cams & rockers will last a very long time.

As long as you have 10psi per 1K RPM of oil pressure, you have plenty and I wouldn't be concerned about foaming.

[Cupcar]

Originally Posted by Steve@Rennsport

Dr. Avery,

JMHO, so take this with the proverbial grain of salt.

None of those restrictors goes into ANY engine here since its completely counter-intuitive to reduce oil volume to one of the hottest parts of these engines. Further, this is where the majority of the frictional loads are: cams & rockers and frankly, they need all the lubrication they can get, no matter what oil is used.

Leave them for others, use Brad-Penn oil, change it frequently, and your cams & rockers will last a very long time.

As long as you have 10psi per 1K RPM of oil pressure, you have plenty and I wouldn't be concerned about foaming.

I would like to add some pepper in agreement.

It makes no sense to me to limit flow to the valve train just to maintain oil pressure at idle in some engines with the smaller oil pumps.

If one is using a Turbo, 964 or GT3 oil pump I would for sure never, ever consider the restricted oil fittings - especially with high valve spring pressures and steep cam profiles.

My $.02, take with salt as well.

[afterburn 549]

HMM that seems to be a change in thinking here from about 5 years ago...
I had the same questions and all sorts of technical advice came up....
So far in 50,000 Miles i have had no cam wear.
The Best part it the oil tank sender works with them installed.......Not sure why...I think the oil was pumping out faster then could come back ?

[dkirk]

I thought the camshaft oil line restrictors were first installed in the 964 engines to prevent oil foaming in the heads. This was a modification by the Porsche Engineering Group that must have proven beneficial from actual engine testing, both from a performance and endurance perspective. Excessive lubricant flow over a cam/lifter interface will not necessarily improve durability; only if the surfaces are marginally lubricated is there a concern. I don't believe this is the case in the 911 engine due to the directed oil spray from the jets in the lube tubes.

I put faith in the Porsche engineering department that they had a good reason to make this restrictor change, based on sound testing.

Then again, I wonder how that infamous intermediate shaft bearing in the Boxter ever made it into production? Probably Sales and Marketing dictating to Engineering again.

[mamut]

Originally Posted by dkirk

I thought the camshaft oil line restrictors were first installed in the 964 engines to prevent oil foaming in the heads. This was a modification by the Porsche Engineering Group that must have proven beneficial from actual engine testing, both from a performance and endurance perspective. Excessive lubricant flow over a cam/lifter interface will not necessarily improve durability; only if the surfaces are marginally lubricated is there a concern. I don't believe this is the case in the 911 engine due to the directed oil spray from the jets in the lube tubes.

I put faith in the Porsche engineering department that they had a good reason to make this restrictor change, based on sound testing.

Then again, I wonder how that infamous intermediate shaft bearing in the Boxter ever made it into production? Probably Sales and Marketing dictating to Engineering again.

100% Correct!!!!!!

[tadd]

What Steve said .

Also don't forget that aliphatic hydrocarbon oils have about 1/2 the heat carrying capacity of water, so you need twice as much to move the same number of joules. So mo is better...

You might peek at the Joe Gibbs oils. I've been told by someone who instruments his engines like no other that he can use steel cams on cast rockers with no issues with the Gibbs oils. Everyone else I've asked said this is a no no that you must have forged rockers with steel cams...

t

[Cupcar]

The restrictor was first used on the '91 964 Turbo engine, 964 N/A engines have a different chain housing design without a banjo bolt.

I can't find an explanation in Porsche literature as to why Porsche used it, only "The banjo bolts fitted to the camshaft housing have a 2.3 mm orifice. A groove is machined into the hexagon flat to identify this feature".

Nothing said about oil slosh, foaming, etc., does anyone have a source here?

[afterburn 549]

Seems like several other Big Name engine builders on here advocated these things....I know they did........But maybe the tide has turned from real life experience..

[E Sully]

From my reading, it would appear to be a worthwhile update. The cams still seem to get enough oil, and increased oil to the piston squirter's reduces engine temperatures.

Originally Posted by Peter Zimmermann

AMAZING! I know that my Tutorial is promised to another site, with an MIA IT guy, but in the mean time I can tell you that I just drove my car. 100F ambient. Cruised a few miles, not exceeding 50 mph, to Stockdale hwy, where I was able to increase speed to between 60 and 70. The oil temp went to 210F and stopped. Similar pre-mod experience was 220-225F in the same conditions.

I then headed for a local neighborhood where I could cruise around for a few miles, which pre-mod would take my car up to 240F+. Today, while able to keep the revs between 3200 and 3800, I was able to keep the oil piston squirter's open (with oil pressure between 3.2 and 3.4 BAR at 3500 rpm) more often and longer. After many stops and starts, the oil temp slowly crawled up to 220F, pre-mod the car might have seen 250F.

This is why my car has spent it's last five summers in the garage. Now, I can't wait to take it for a 40-mile ride at 70+ mph on Highway 99, just to see what happens. Last time I did that I saw temps of 250F, and oil pressure no higher than 2.5 BAR (too low to open the piston squirter's). I will probably wait for the first 105F+ day to do this, so stay tuned.

It would appear, at this point, that Porsche developed these oil pressure "check valves" to allow operating pressure to be high enough to better control operating temperature (because of open piston oil squirter's, used since 1970). If that assumption is fact, then the modification is pure genius. I now consider, after only one hot-day test, that my car, for the first time, is safe to drive in Bakersfield, CA, in the summer. Hot-diggity!

911 camshaft oiling update - anyone done this ? - Rennlist Discussion Forums
Cam Tower Oil Line Restrictors Redux

[Henry Schmidt]

I've been using cam feed restricters since before Porsche first introduced reduce flow cam oiling.
I actually got in trouble with a friend/tech writer for PCA when I sold him a set of restricters we made because he found out he could buy them from Porsche for 1/4 the cost of ours.
All 964 and 993 engine have reduced flow to the can tower.
If high flow is so important, I would ask the builders who have voiced an opinion in opposition to restricters "what they are doing to restore high flow to the 964 and 993 engines?".
Porsche engineers determined that 17 gal was excessive and that 12 gal per/hr was more than sufficient.
The development of the 911 engine is what has intrigued me since I first started working on these engine. I've watch the development and embracing changes when they prove to be effective.
I do not blindly follow the Porsche engineers (case in point: Dilivar studs "YIKES") but they are generally right.
Originally we only used the restricters in high mileage street motors but as time progressed we used them in every engine we built and have for over ten years. No negatives and many positive results on record.

[afterburn 549]

I knew I was not hallucinating LOL ^^^^^^^^^^^^^^^^^^^^^^

[Henry Schmidt]

Originally Posted by Cupcar

The restrictor was first used on the '91 964 Turbo engine, 964 N/A engines have a different chain housing design without a banjo bolt.
....edit....

The flow restriction/ reduction on the 964/993 engines is built into the design which started in 1989 with the Carrera 4.

[afterburn 549]

Thanx Henry !!

[Henry Schmidt]

Resent dyno tests have shown performance increases (low temps and increased horse power) with Delo over Brad Penn. Of course horse power is only one consideration when it comes to oil selection but I found this information interesting.

[Cupcar]

Originally Posted by Henry Schmidt

The flow restriction/ reduction on the 964/993 engines is built into the design which started in 1989 with the Carrera 4.

Yoda, are you sure here? I am here to stand corrected if wrong.

The '89 C4 3.6 has the late style magnesium chain housing with the oil line cast into it and the plastic connector elbow where the banjo bolt restrictor is on earlier engines, so the piece in question does not even apply to this engine.

On the other hand, my literature shows the 1991 964 3.3 Turbo uses the old style chain housing with oil lines and specifies a banjo bolt fitting that is drilled to a 2.3 mm restriction. To my knowledge, this is where the restrictor began life in MY 1991 .

It is hard to trace back in parts catalogs since the 901.105.361.00 early part has been superseded to the 901.105.361.01 restrictor part, but I don't think it appeared earlier than 1991.

Frankly, I think the restrictors are there to maintain pressure at low RPM to the Turbocharger which also feeds off the main oil gallery. Hot turbo bearings don't like low/no oil flow.

[Henry Schmidt]

Originally Posted by Cupcar

Yoda, are you sure here? I am here to stand corrected if wrong.

The '89 C4 3.6 has the late style magnesium chain housing with the oil line cast into it and the plastic connector elbow where the banjo bolt restrictor is on earlier engines, so the piece in question does not even apply to this engine.

On the other hand, my literature shows the 1991 964 3.3 Turbo uses the old style chain housing with oil lines and specifies a banjo bolt fitting that is drilled to a 2.3 mm restriction. To my knowledge, this is where the restrictor began life in MY 1991 .

It is hard to trace back in parts catalogs since the 901.105.361.00 early part has been superseded to the 901.105.361.01 restrictor part, but I don't think it appeared earlier than 1991.

Frankly, I think the restrictors are there to maintain pressure at low RPM to the Turbocharger which also feeds off the main oil gallery. Hot turbo bearings don't like low/no oil flow.

Of course the cam feed restrictor (in question) was not used on the 964/993. My comment was that the reduce flow technology was.
It's hard to see but the restriction in the 964/993 engine is in the transfer tube.
The hole in the previous banjo fitting was 20% larger than the transfer tube used in the 964/993.

[Cupcar]

Originally Posted by Henry Schmidt

Of course the cam feed restrictor (in question) was not used on the 964/993. My comment was that the reduce flow technology was.
It's hard to see but the restriction in the 964/993 engine is in the transfer tube.
The hole in the previous banjo fitting was 20% larger than the transfer tube used in the 964/993.

Thanks. Interesting what one finds when a deeper look is taken with these engines.

The 993 transfer tubes I have here in hand measure a 5.8 mm internal diameter which is a lot larger than the 2.3 mm of the banjo bolt. The 993 tube's cross sectional area being roughly 6.5 times that of the restrictor banjo bolt.

It looks like the holes in the 964 part you picture are smaller than the 993, probably because of the hydraulic lifter's oil requirement in 993 they were increased in size? Did you measure the ID of the 964 tube?

It appears inadvisable to install the 964 part in the 993.

[AlfonsoR]

Originally Posted by afterburn 549

I knew I was not hallucinating LOL ^^^^^^^^^^^^^^^^^^^^^^

Not hallucinating.....

Oil restricrors revisit

[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