Oil line restrictors, good or bad idea?

LeakProof · 01:35 PM

Recently installed the restrictors on my 79, 3.0. Not so sure If I made the right choice? Can anyone offer advice.

MotoSook · 01-28-2009, 01:52 PM

You're fine....

Search this forum for "restrictor" and you'll find a lot of good reading.

yelcab1 · 01-28-2009, 02:03 PM

I took mine back out.

LeakProof · 03:04 PM

Souk, you live two suburbs East of me, within miles. I passed through your neck of the woods today. Thanks for the tip, will do. Yelcab1, you got me thinking.

Hoffmanmotors · 01-28-2009, 03:03 PM

Quote:

Originally Posted by yelcab1

I took mine back out.

Why? I installed them on my 79 SC and do not regret it. Waynes how to rebuild your porsche engine book suggested using them.

-Jeff

LeakProof · 01-28-2009, 04:16 PM

Jeff, thats exactly the book I read and the reason why I did it. Although some think its not the best idea. Something to do with the newer oil pumps being more compatible to the newer style restrictors.

Walter_Middie · Walter_Middie's Garage

I put them on my 2.7L when I rebuilt it. I kept the original oil pump. I removed them because my cold oil pressure would climb up higher than I wanted it to (80 to 90 PSI before the relief valve opened). After removing them, I really don't see much difference in the cold oil pressure - so now I just ignore it. Once warmed up, the oil pressure is perfect. If I had it to do over, I'd use them, and leave them in.

LeakProof · 11:44 AM

Thanks, Walter_ Middie. I guess I'm glad I haven't yanked them out yet. I just installed them Saturday.

yelcab1 · 01-28-2009, 05:03 PM

Quote:

Originally Posted by Walter_Middie

I put them on my 2.7L when I rebuilt it. I kept the original oil pump. I removed them because my cold oil pressure would climb up higher than I wanted it to (80 to 90 PSI before the relief valve opened). After removing them, I really don't see much difference in the cold oil pressure - so now I just ignore it. Once warmed up, the oil pressure is perfect. If I had it to do over, I'd use them, and leave them in.

My idke oil pressure is way too high and I did not feel good about it so out they went.

MotoSook · 01-28-2009, 05:49 PM

Quote:

Originally Posted by LeakProof

Souk, you live two suburbs East of me, within miles. I passed through your neck of the woods today. Thanks for the tip, will do. Yelcab1, you got me thinking.

You should come join us for coffee when weather allows it.

As for high idle pressure...remember there is a relief. There is more than enough oil flowing to the cams. The high pressure can't hurt the piston cooling and crank oiling.

88-diamondblue · 01-28-2009, 08:50 PM

Put them in when I did my rebuild and put the originals back in this last summer. I have no issue with high or low oil pressure. Did enough reading and decided to keep as much oil in the top end as can be. Two distinct camps on the one. The top shops that have chimed in on this issue here on PP are split on this mod as well.

I have considered drilling the new ones out somewhere in between the the new and the old ones and reinstall. No changes until spring.

f3nr15 · 01-28-2009, 09:45 PM

With the restrictors in place, I have found that the cold start oil pressure is on the high side, but the needle is sitting at the bottom of the gauge by the time a regular operating temp is reached.

Interestingly, it seems that putting the restrictors in has solved the endemic Sportomatic quirk of the low oil pressure light coming on at regular running temps - haven't seen this light up once since the engine was rebuilt with the restrictors in place!

haycait911 · haycait911's Garage

I eventually reached a compromise, I drilled out the new restrictors to smaller than stock but larger than they were initially.

camshaft oil line restrictors- two thumbs up!

ssinparadise · 01-29-2009, 06:43 AM

the restrictors raised my oil pressure significantly in my 73, but not too high as some have stated. Early 911s need a boost in idle oil pressure. I was originally concerned about the thought of trying to out engineer Porsche (a thought I think all of us should keep in mind when we are tempted by the goodies). Can't say that I have experienced any ill effects. Besides oil pressure, or God forbid strange valve train noises, how would an average mechanic know for sure? Honestly, seemed like a good idea that was advocated by smarter guys than me.

Gunter · Gunter's Garage

+1 on the middle ground.
Mine are modified, right between the two hole-diameters to get some extra pressure but not extreme.

KTL · 01-29-2009, 08:51 AM

I returned to the old restrictors on my engine after finding that my valves and rocker shafts, rocker shaft bushings were very worn when I did my top end.

My sort of wild assumption in returning to the old restrictors is based on this:

-Bought the car in 2000 with 62K mi. on it, very little oil consumption that I can recall.
-Did some freshening of the engine for leak fixes, updates, etc. and jumped on the smaller restrictor bandwagon. Drove it on the street until 2004
-After a couple years of track events, oil consumption all of a sudden spiked to one quart per track event. Rocker assemblies and valves, valve guides were severely worn and had to be reconditioned.
-Figured since the valvetrain only gets oil via cam spray bars and subsequent splash oiling, more oil via the bigger restrictors would help since my valvetrain wear problems seemed to show evidence of inadequate lubrication?
-So I put the bigger restrictors back in.

Oil consumption has returned to acceptable levels for a 80K engine with a top end refresh. Also switched oils since the Mobil 1 15W50 I was using has been well-documented to be less beneficial to air/oil cooled engines, due to the new formulation

MotoSook · 01-29-2009, 09:00 AM

You're not being very scientific here K-man. Shame on you

You are attributing wear of an aged engine that sees lots of track time while running oil that has less ZDDP than required to a lack of adequate lubrication (quantity). Valve guide wear was always a problem in 3.2's....and although some would believe that cam lobe wear is due solely to oiling (oil type and quantity), I think it has something to do with the porosity of of the castings as well. The kind of pitting that we've seen on the cam lobes doesn't look like lubrication related wear.

MotoSook · 02:23 PM

Regarding high cold start oil pressures: My 3.2 Carrera has a topend rebuild and is running the stock oil fittings. Before and after the topend rebuild, my cold oil pressure would peg the guage. Now this was happening during the summer and the fall. I never felt that was reason to worry as the pressures come back to normal when the engine has time to warm up.

What did I (or you) expect from cold 20W50 oil?

Before I tear down my 3.0 engine with the small restrictors, I'll take a video of it running in the car without the valve cover on it. I'll be cleaning up the engine anyway...the clean up will be worth it to have documentation which may settle this debate. Steve Groskemper reported doing this with a 2.7 and was alarmed by the amount of oil coming out of the spray bar.

I have a video of water flowing through ther spray bar (stock restrictor). Sure water has a different specific gravity and viscosity than oil, but at elevated oil temps, I wouldn't be surprised to see oil flow like the water did during that adhoc test. Reducing the flow with the 2.5 mm restrictor has not worried me. I'll try to run some orifice flow calculations for the two sizes of restrictors and post them.....

Steve@Rennsport · 01-29-2009, 09:47 AM

Quote:

Originally Posted by Souk

The kind of pitting that we've seen on the cam lobes doesn't look like lubrication related wear.

FWIW, engines (911-964-993) that have used oils with a sufficiently robust ZDDP package have not shown camshaft or rocker arm wear like the others have, as of 3 years ago when oil formulations really changed.

JMHO, but I think oils make the difference and its not a camshaft material-hardening issue.

KTL · 11:16 AM

Certainly not a scientific analysis on my part, but good insurance IMO since the splash-oiling of the rocker area is dependent on amplevolume of oil. I'm not comfortable reducing the oil supply to an area i've already seen suffer once. I'm referring to rocker area here, not just the known/understood valve guide issue- which I hope I did not imply is lubrication-related, when we know it's widely understood to be valve guide material-related.

Just because Groskemper documented it on the interwebs doesn't make it scientific proof. What's his definition of an alarming amount of oil? Like I said, considering that this spray bar is the only thing oiling the valvetrain, I don't see how too much (up to a point of course) can be harmful. I'd like to see the foaming of oil before we start deriding the sizing of the orifice. Somebody had to figure out the size of it to manufacture it in its original iteration, and V1.0 hasn't proven to be problematic in all the engines using it all of these years. And, yes, somebody had to calculate the resizing of it for use on the Turbo. Have we discovered what that reasoning for resizing was as of yet?