spyderman

hey

Has any one out there used the updated camhousing oil line restrictors on their 65-89 enging rebuilds? it seems like a good idea, I have already installed them, i was just wondering what i should expect, and if anyone else has used them.

thanks

spyderman

there has got to be someone out there who has at least heard of these, Right? i am basicly looking to know if anyone has had problems with them. or if they have performed any miracales for anyone.

thanks

Geoffrey

I looked into using the updated cam oil line restrictors when building my 911 Turbo. I opted to install the stock earlier restrictors because when I was thinking about the function of the volume of oil, it is there to cool the valve springs and heads, and to a lesser degree oil things. I was concerned that installing them in a turbo car with high head heat potential might cause issues. However, if I was building a N/A car I would install them IF I had the 964 style oil pump or 930 oil pump.

I've not heard of anyone using them and having problems.

Steve Weiner-Rennsport Systems

FWIW,.......

We are not using them in any race engines; N/A or turbocharged.

As Geoffrey said, the oil volume into the cam tower spray bar does many things here:

1) Lubricates and cools the cam lobes

2) Cools the valve springs

3) Helps cool the upper valve guide area

Valve springs and camshafts are subjected to major stresses and temperatures and the hottest part of the air-cooled engine is in the cylinder heads.

I will not use these restrictors until some major R&D is performed under laboratory conditions using specialized instrumentation to measure and precisely track the temperature changes from reducing the oil volume to these critically stressed parts. Even in street cars, camshaft wear is an issue.

The majority of today's racing engines use supplementary forced lubrication spray bar systems to cool the valve train at higher RPM and reducing oil volumes is simply counterintuitive to me.

If the user's purpose is to increase oil pressure to the lower end, then the proper way to accomplish this is by using one of the good multiple oil pump choices you have: 930, GT-3, GT-3 RS.

Just my opinion though,

spyderman

hey,

There must have been some major R and D done on these, porsche uses them on all the C2 turbos. it is a porsche updated part. the part number for the old one was superceded to the new one. im not even sure if porsche even makes, or sells the old one. I think porsche would have done some research on them before just throwing them into their cars. Has anyone heard of any problems caused by them?

thanks

Geoffrey

I will mention this one last point, but it is more an uneducated opinion and not fact. When I was looking for a used pair of 964 cams to replace the ones in my original engine I found 5 pairs, but all of them had wear or pitting on the same cam (I believe it was the right one, but can't remember). I wonder if that wear was because of the restrictor? I don't know for sure, but I've never seen consistent wear on factory camshafts like this before.

pjc

I thought that one benefit was reduced foaming? I also believed it was a Porsche mod on the 1991 turbo?

PJC

Richard Pankhurst

I have some anecdotal experience with the new restrictors but I want to be clear that I would not consider this a fair evaluation as I did not know the condition of my cams when I first installed the restrictors. Anyway - put the restrictors in and ran them for about 3k miles on my '89 911 Carrera street/de car. Had an unexpected engine rebuild (shifted from 4th to 3rd instead of 4th to 5th and skimmed the piston heads with 4 exhaust valves but it still ran) Tore down the engine for a top end rebuild once I worked out what had happened. In the process my mechanic and I discovered the left cam was severely pitted across 4 lobes. The right cam was unpitted. The cam tower lines, spray bars and other oiling components were clear and working well. We reinstalled the old restrictors as a safety precaution. Oil pressure has subsequently fallen back to previous levels due to increased oil flow to the top end and what appears to be more foaming. The oil pressure fluctuates more widely under track conditions (hard braking and + 0.75 g turns) The engine was rebuilt 30K before the top end rebuild mentioned above.

spyderman

hey,

you said the car was an 89. and you also said the left cam was pitted. I have heard this before, and maybe it could be because of te extreme heat of the catalayic convertor, which is right there on the left side. I have a 73, and installed these restrictors on when i did the rebuild. I was curious, so when i did a valve adjustment, i ran the car with the top valve cover off. and observed the ammountof oil. I cant see how there can be a shortage off it, even just idling for a few seconds, oil was squirting up all over on the cooling shroud. I wonder if a porsche engineer could shed some light, on why they switched to the restrictor, and what kind of testing they did.

blabla914

I considered using these restrictors as well. Actually I posted this very question about 6 months ago. I have decided not to use them for the following reasons:
1. Porsche race cars used BOTH spray bars and center lubed cams. Leads me to believe if you are going to do a lot of track or autocross, more oil is better.
2. I hear about cars with lobes wiped off the cams quite a bit. My engine had 2, one was really bad.
3. The restrictors were developed with the C2 oil pump which has a LOT larger pressure side than earlier oil pumps. I am using a '69 spec pump.
4. The benefits of the restrictors are supposed to be reduced foaming and increased oil pressure. My engine had 1.5 bar hot @ idle before I took it apart. As soon as the revs came up, I'd have 4 or 5 bar no problem. That seems to meet the 10psi/1000rpm rule of thumb no problem. More is only better to a point, then it's just more.

My vote is to fit what the engine had when new.

Kelly

Mark Hald

I installed the restrictors on my '77 Carrera 3.0 last spring after noting reduced pressure [~ 4 bar, max] at operating temp. I realize that there are other, more expensive, ways of solving the issue correctly. The restrictors do, however, raise the pressure seen at the sensor to a satisfactory level, which is what I wanted to achieve, for now.

fredseebeck

I have been using them in my 79 911SC for 2 years now and approximately 20k miles. I did notice an increase in pressure at idle by about 5-10 psi, and have nit seen any pitting of the cam lobe surfaces when I pull of the rocker covers for valve adjustments.
I track the car in alot of DE events and drive it hard. I figure the added pressure to force the oil piston squirters to get more flow thru them and the less aeration of the oil will help the overall condition of the piston and main bearings than the slight difference in flow to the valve train. Plus, the spray bars have extremely small openings and I think they restrict the volume of flow more than the orifice in the fitting overall. If it makes you feel better, possible do what the one fellow did and drill it out a little to open it up somewhere between stock and the 964 size opening.
Without real long term testing, every discussion on this is an opinion at best, and like most assume Porsche made the change and they must have tested it extensively before doing it, and that is good enuff to give me 90% confidence that it won't urt my 911SC engine.

J P Stein

I'm considering this and I thought it was simple

So, it's less oil to the cams, et al, but sooner to the piston squirters, and better pressure at the bottom end.
The first is a "maybe too little", the latter 2 are both in the plus column(insert head scratchin' smiley here).

I don't do any sustained high rpm work, but lots of squirts to the rev limiter...I'm an AX ****.. Steve, is it heat or lack of lubrication that concerns you?(both?)

Steve Weiner-Rennsport Systems

Hi JP:

Its both,....

Porsche went to a LOT of trouble on the 906, 908, 910, 917, 3.0 RSR, and all 935's ensure a healthy flow of oil where the cam followers/rocker arm rub the cam lobes. Center-oiled cams was the solution along with the spray bars (in the 911-based engines).

This not only provides lubrication to these motors that have higher seat and cam follower/rocker arm pressures, but cools the highly stressed valve springs. All current successful race engines (except F-1 which use pneumatics) have additional oil sprayers to cool these parts.

Porsche addressed the foaming issues very well in the GT-3R using a multi-scavenge oil pump and these pumps can be retrofitted to any 911 engine. Cheaper than 930 pumps, too!

joeblow

I am planning to build my 2.2T to a big bore short stoke revver and was going to find a 930 pump for her. The retrofit of the GT3-R pump sounds like a better option. It is a multi stage or single stage multi pickup? How difficult is this retrofit to do? I doubt there will be any clearance issues with my small crank. Thanks!