924Board.org

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Is here:

931:
http://cgi.ebay.com/ebaymotors/NEW-Stainless-Steel-valves-Porsche-924-Turbo-1980-82_W0QQcmdZViewItemQQcategoryZ33621QQihZ002QQitemZ120269105490QQtcZphoto

924:
http://cgi.ebay.com/ebaymotors/NEW-Stainless-Steel-valves-Porsche-924-Non-T-1976-82_W0QQcmdZViewItemQQcategoryZ33621QQihZ002QQitemZ120269105318QQtcZphoto

I've used 931 items on customers race-car and stainless valves on my 2.5 16v engine are also from the same source. IMO price is very good and so is quality according to my machinist.
This seller carries valves for a LOT of cars. No affiliation.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Interesting. . .I see this post being assimilated into Dan's uberthread.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Those are good replacements for stocks as they are decent price and readily available.

I've been looking for bigger valves for my 931 "Gulf", also with 7mm or 8mm stems but main concern is the length. 931 valve is 133 mm long and not that many cars use such long valves, especially with 7mm or 8mm stems.

I'm considering doing just intakes as I don't see point in upping the exaust valves on 931 (already 36mm).
44-45mm intake valves seem to be good choice when exaust is left stock size.
Of course, I'd prefer using exaust valves with 7mm stems also. Not a necessity though.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

So, aside from pricing, what are the advantages of these over stock units?
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Better build quality and material, even compared to sodium-filled exaust valves of 931.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Min · Posted: Sat Dec 20, 2008 6:12 am Post subject:

I got my stainless valves from EBS for less money.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Hmm, I searched around a bit, and found a few opinions that sodium-filled has better cooling than SS. . .
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

Stock ones aren't stainless and I weighed both of them, stock ones are also a bit heavier.

Stainless valves withstand heat much better and retain good seal between valve seat and valve longer.

Of course they bend when they meet with pistons.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Porsche used sodium filled exhaust valves to aid in cooling and extend valve life (931, 911, 914). The sodium carries heat away from the valve head and into the stem.

The new Z06 engine has them as well.
_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

to quote raceboy:

Raceboy · Joined: 01 Mar 2004 Posts: 2327 Location: Estonia, Europe

This is never-ending debate.

The reason why OEM's don't use stainless valves is cost. It's cheaper to produce usual valve and fill with sodium than stainless. Even though they sell it to us for high price. And mostly they don't bother even filling the ex. valve with sodium.

I'm not it the mood for arguing (almost never am), just use whatever you like.
_________________
'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Well, based my my reading, sodium filled valves have better heat management. If it were a question of cost, you couldn't buy 8 SS valves for the cost of two sodium filled exhaust valves. It also seems unlikely that GM would skimp on their max effort ZR1 motor. . .if SS was best, I think it would have been used.

I certainly respect your experience with these engines. I also like fully exploring decisions I am on the threshhold of making for myself, and the way I do that is listening to opinions and gathering evidence.

I see it as "argument" in the classical, knowledge-seeking or rhetorical sense, not the personal or hostile sense.

But, if you want to check out of the discussion, feel free.

_________________
Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3