DR

According to PET that was a Rod change during the 88 year model, but they only list the current part number for both Serial # ranges,
See 87-91 Illustration 102-00 Item# 17

Thanks for posting those pics and links, I just realized I have a set of those GT rods out back from an 8700 mile 89GT engine... with surface rust on them

blown 87

Have them shot peened, it will knock the surface rust off, them have the rods blueprinted, and you have a better than GT rods set.

slate blue

My guess is that the early rods are best, they used a sintered metal compound and engineers use this when you try to get metals that normally would not mix properly in a molten solution. The GT rods to which I have had a set and sold them, the buyer a fellow Rennlister also bought a set of the 87 early style 944 rods. For me the broader beam is going to be better for an average of all the loads the rods see, I haven't seen any forged aftermarket A style rods get really narrow up top like the factory rods.

Also the fine parting line the GT rods have, indicate to me they are cast. The broader parting line on the forged rods is proof they are indeed forged. Personally I would use the early rods and try and trim some excess weight off them, the balance pads and the square edges around the big end are not required and are just extra weight to move, a good set of bolts would then also be a good thing. I don't know if a CNC program could be written to trim some weight off? It might be able to remove 100 grams.

Greg

atb

My mistake then Dennis. I equated the center rod in your pic as the early S4 rod. My understanding was that these were only run in the squirter blocks, but apparently not the case if you found them in an '88. The rod on the right is what I would equate as a typical S4 rod, but it appears that maybe the '87- '88 had the I beam design and then in '89 Porsche went to the A beam design but in two different configurations based upon what Greg says about the GT rods.

slate blue

Also Argo rods which are made in Australia and have a decent reputation are sold on Ebay for 950 Euros or about $1,300 USD, the thing is that you still will be stuck with the standard rod bearings. I think when you are building a engine with the standard bearings and crank drillings you should stick with economy versions as you gains will relatively small in terms of power and performance. So why spend a fortune chasing it. The only thing that would change my mind would be the use of the Argo rods in an early GTS, that may be good value.

Greg

86'928S MeteorGrey

Belgium Barry,

I'm not sure how to react to your questions/statements. You say you have proof of these rods failing? I'd sure love to see some photos of these failed rods. I'm always on a quest to learn more about Porsche engineering. You say you have hundreds of these available? How much can you get me 8 nice ones for? Take some close up photos of the rods and part numbers. After I get 8 and check em out, we will probably buy all of them from you. Especially if you are selling them to us at "junk" rod prices! Just let me know. PM me if you like.

Best Regards,

Mike

slate blue

Mike I can probably get my hands on two sets, maybe more I will speak to the owner if you are serious, $300 per set should do it. Combine shipping etc.

Cheers Greg

ptuomov

Greg G. --

Let me push you a little on this comment. Suppose that one is indeed stuck with the standard crankshaft. Doesn't the fact that the rod bearings are the weak spok make it especially important to get lighter pistons and rods? If I have understood this correctly (and that's a big if, I am the first to admit), lowering the reciprocating mass will lower the loads on the bearings proportionally. Or perhaps you are refering to the large crank journal diameters? High rpms will give some pretty fast bearing speeds in 928. Is this the weak spot?

Best, Tuomo

ptuomov

Just in case someone finds this interesting, there's a debate going on between manufacturers about traditional and powder forging processes. It's about as close to a flame war as it ever gets between corporations and trade associations! ;-)

http://www.metal-powder.net/business/jun2005.asp

ptuomov

These rods from Australia are abiyt 575g without bolts. I think that's decent percentage weight savings:

Larry928GTS

+1

I have no idea which are stronger, but as far as the argument about whether Porsche would put new but weaker rods in the higher output GT engine, isn't that exactly what they did with the GTS rods? The GTS made more power, had a longer stroke and therefore faster piston speeds, and yet the rods that they made and put into the early GTS engines are problematic to the point that Porsche says to not reuse them.

It would be interesting to see some real data on the strength of the various rods, even though it seems like there haven't really been any issues that have been talked about with any of them, other than the early GTS ones.

blown 87

Well, here is the rods that came out of the car, they do have a 944 part number.
Thoughts on these being forged or not?

blown 87

side quarter view of the early S4 rod.
Now I don't know which, if any are forged, and I don't know which ones to use.

belgiumbarry

'85 and later ... was crisis in Europe car factorys.... so they all went searching for "profits"... that's why , " we think" Porsche went from decend, expensive forged rods to cheap cast ones... ok, they are adequate for the stock engines HP... but... most engine builders don't reuse them when they find them in a engine... so, my builder has several sets laying around , NEVER reuse them, must be the case in the US also... anybody interested can contact a "former"???" respectable" Rennlist tuner... they have sets in stock enough for the amateurs !

now , seriously, don't use those weak rods. Please.

Norbert

blown 87

Who is the person you are talking about?
So are the rods pictured above cast of forged?