Epic2112

I'm not as active on the boards as I used to be, but I remember there being some back & forth about whether or not all turbo cars had forged rods. I'm finally taking apart the original engine from my car, which I'll eventually rebuild. As far as I know it's the original engine from the car, which is definitely a Turbo S spec car (confirmed by the chassis reinforcements, VIN, etc.), and the block is stamped M44/52. The rods look like cast rods, though. Is this what I should have expected to find? I have all the records going back to 1993, I really doubt that any major engine work was done in the first 4 years of the car's life.

Sorry about the crappy phone pics.

Thom

Not sure if they are cast or forged, but they are not the forged ARST rods featuring a thicker neck near the wrist pin.

Epic2112

Yeah, they look totally different from the rods that I pulled out of an old '83 engine that I parted a while back.

Regardless of wether these are cast or forged, is the general consensus that the thicker RARST rods are stronger? I'll just replace these when I rebuild. Should kept the set from the '83 I guess, doh.

Thom

The thinner rods may bend exactly where ARST rods are thicker. Have a pic of this, will post it later if I can find it.

Dougs951S

I thought this question was settled a long time ago, and the collective decided that all 951's had forged rods? It certainly would seem ill advised by porsche to not have done that, and you dont hear of any particular year or years of cars having more troubles with rods, despite cars of all years being pushed well past stock power on stock internals. I would think if some had cast and some forged, a trend would have developed by now clearly demonstrating which years had inferior rods.

Oddjob

Whats the VIN/production date of your car? Factory changed over from forged to cast rods on the 951s mid to late MY89.

Epic2112

WP0AA2951KN150846

Dougs951S

Amazing? Was that a cost cutting measure? That would mean most of the turbo S cars running around have cast rods.. Makes me even more glad now I didnt hold out for a late model car and bought an 86. I presume the crank and pistons were still forged? I find it interesting as well that the necks are thinner. IIRC all the forged 951 rods I've seen look more like the rarst rods, they are fairly beefy. One more question, I have oft seen ~400 rwhp as the safe upper operating limit for factory rods. Is this for the cast, or the forged rods. I would assume the forged would be more forgiving..

Oddjob

xxxx846 VIN will be a later half MY89 Production. VIN xxx503 (sep '88 build date) had forged rods in it. So sometime after that, the factory converted over. I have seen cast rods in an 89 M52 engine first hand (block # 47K01812).

It means that none of the 88TS cars have cast rods, and maybe half or fewer of the 89T cars do.

As far as I know, all 951 Forged rods are the same RARST rods. The cast rods were implemented in MY89 and carried thru the end of production on the RoW (MY90-91) cars. Pistons were the same forged 951 pistons. No such thing as a cast crank.

Epic2112

So, assuming they switched over to cast at a distinct point, it's somewhere between VIN XX812 and XX846? Just my luck :P. Or do the block numbers not match the VINs?

Oddjob

Engine # 1812 had cast rods. They have a sequence or serial number, but as far as I know, there is no way to correlate the engine #'s w/ VINs or mfg dates (unlike trans codes, which are a date).

My guess is that somewhere between VIN 503 and your 846 was the transition. I know that 503 had forged rods, because the engine blew apart - including a failed forged rod. The engine that replaced that motor was from an 89T (the 1812 engine #), and that had cast rods when we opened it up.

Not sure I would be very concerned at all about having cast rods, depending on use. Street use with moderate power will be no problem. After nearly 25 years of use, the late 89Ts dont have any signficant or documented rod problems/failures, compared to earlier cars w/ forged rods.

I have been told that S2s (which have a similar cast rod) used in racing, are often upgraded to aftermarket rods (carillo or other). But I don't know if thats actually required for the hard use/abuse of racing, or if its an optional upgrade.

blade7

They look like S2 rods.

lart951

what you got there are na 944s and 944s2 cast rods, they are definivetly not RARST rods, the right name is not ARST but RARST, btw i have seen other 89 T S with cast rods and one 944S2 1990 with RARST rods, just to show that the S on the Turbo S stands for "Suckers"

Thom

Did someone ever notice that the first R is actually just the last digit of the embossed part number?
Whoever called them RARST in the first place instead of ARST probably did not pay attention.

lart951

I see that's so interesting, so actually for as far as we know people have been pronouncing the word wrong, i actually did a google search under arst name but came up with nothing except one place but they spelled **** which kind of throw me off.