FLYT993

Gentlemen--

I've done my search and can't find a definitive answer to this question....i.e, What are the best aftermarket valve guides? Steve uses the "phosphorous bronze", Colin from 9M the "sintered steel" (what is that???) and Heritage Motorcar, the "Advanced Alloy"....thoughts?

FLYT993

C'mon guys...this is one of the most important and contentious issues (and it's fodder for the 996 universe) with our cars and no one has an opinion about this?

Steve Weiner-Rennsport Systems

Hi Dan:

I can provide an opinion based on several hundred engines over 27 years if you wish,...

J.PELLEGRINO

I am in the "phosphorous bronze", camp. I too have many happy clients to attest to the choice.
Good luck, Jerry

Bill Verburg

I speced phosphor-bronze (w/ the builders approval of course) when I did my 3.8

There are other newer materials out there that may or may not work out but don't have the proven record of phosphor-bronze

Amfab

I know nothing of which is better, but the term "sintered" means the material is compressed from a powder. Usually sintering is done by heating a material up (but not above melting) and then compressing it together. The meterial forms a solid, but it is much more porous than the equivalent cast material. In metals, this allows lubricant penetration, which is why it is used in bearings (often sintered bronse) and I assume valve guides for the same reason. I also would assume the sintered steel are harder and longer lasting that the phosphor bronze, as bronze is a softer metal - but Im just guessing.
Ferrous magnets are also often sintered (if you have ever cracked a magnet open you will notice the granular texture) I believe this allows further penetration of the magnetic field (permeability) when they are being magnetized at time of manufacture.
Ski bases are also often sintered of some sort of plastic. Having a slightly porous base, they tend to hold wax longer than a smooth base.
Which is better for a 993 engine? Im not sure as I am actively looking for my first 993 right now, so I have no experience - I drove my first one 2 days ago. It blew me away. After 25 years of 911s, I have to say they really nailed it on the 993 everything my old Targa is amplified
I'm looking for a white Targa if anyone knows of one for sale.
-Andrew

FLYT993

Steve, I believe at some point, at some time, my car will be seeing you

Steve Weiner-Rennsport Systems

LOL,..Mister Dan,..I am at your service, anytime,...

Land Jet

Steve, I for one would like to hear anything that you have to add!

Rick Sylvestri

Dan,
Are you asking this because of more oil consumption, smoke or less performance?
Mine runs great but has the lope / uneven idle with almost 84,000 on the clock and uses 1 quart/ 2,000 miles

FLYT993

Wow, it's been awhile since I checked this thread. But to answer your questions....None of the above. My car has 75K now, doesn't smoke (not even a puff) on start up at all, even after sitting for a week, and uses about a quart every 2k. It might actually use less because I've had leaking lower valve gaskets for a while (but just got that fixed, so I'll have to monitor oil consumption again for accuracy).

I asked because if there was/is anything that is the 993's Achille's heel, and creates vitriolic debate.. it's the valve guides. And in truth, I guess I want to be informed when and if the inevitable occurs. According to my substandard research...

1. Porsche has denied any substandard materials/performance WRT the OE guides.

2. Indy, after Indy, after Indy, states unequivocally the OE valve guides are substandard.

3. Lots of RL'ers have had top ends completed, ostensibly, because of this issue.

4. It stands to reason if the car ever needs to have the guides replaced, I want the best guides I can afford. Steve swears by the phosphor bronze and Pellegrino supports his position. Only an idiot would dismiss advice coming from such knowledgeable AND experienced pros. But in my stumbling around I came across the sintered guides from 9M and the alloy ones from Heritage...so it was my natural curiosity to inquire about the other materials.

5. PP sells the OE "bronze" guides for $15 each. It's grating on me that $200 worth of parts, can lead to a job costing upwards of $5k!!! But I guess that's the price we pay to drive these exquisite machines.

dcdude

Interesting resources:

http://www.av-v.com/TechnicalInfo.htm
"We should call this alloy ‘’zinc bronze alloy’’ instead of manganese bronze because it contains nearly 30% zinc, 2-3% manganese. Manganese is the hard part of the recipe and the zinc is the bearing ingredient, a material which is also a self lubricant."

http://www.gruppeb.org/forum/viewtop...5d76ce7a2f3809
"its not uncommon to use Phosphorus for the exhaust and Manganese for the intakes"

http://www.rpmmachine.com/pioneer-valveguides.shtml
"Manganese Bronze Valve Guide- Simply the best anti-seize, low-friction valve guide available. With today's engines consistently running at elevated temperatures and burning unleaded fuel, you need the self-lubrication protection this valve guide provides."

matt777

The older bronze alloys used to require some lead content for self-lubricating properties but newer alloys do not. Here is some info on phosphor bronze http://www.anchorbronze.com/newpdts7.htm

I don't see how cast iron or steel guides could provide self-lubricating properties that are needed in a valve guide application. It's also important to use valve stem seals that allow some oil to get by.

FLYT993

Maybe we should ask Tony to address this during his upcoming 993 Tech. Session?