MAGK944

Did all 951's have forged rods or do some have cast? If so which year did they change and how do you identify them? Thanks GK

brad-cam

Check this:

https://rennlist.com/forums/showthre...ighlight=RARST

My understanding is all 951's had forged rods and very early NA's (1983, maybe 1984). Part numbers have "RARST" at the end.

Oddjob

I have seen a MY89 Turbo motor with cast rods, and others have confirmed this. The official changeover for Turbos to cast rods was for MY90 (RoW cars), but seems that the cast rods did make their way into some of the late MY89 motors. All Turbo rods prior to this were forged.

Kool

Why the switch? Was forged considered to be overkill? Or were the MY90 cast pcs. redisigned and stronger?

MAGK944

Do you know if the MY89+ cast rods still used the RARST designation in the part #, or was that strictly for the forged rods?

Olli Snellman

Even forged rods has at least three different designs. For MY '90 design was changed to cast.

Here's two different OEM forged rods and something better.

Oddjob

No way of knowing for sure why porsche discontinued the forged rods for MY90. I would speculate some combination of the following: they were starting to cut costs, were running out and didnt want to do another run of forged rods, and didnt feel the forged rods were absolutely necessary, even in the 250hp cars....

The cast rods are the same rods as the 944 N/A, same part number - they do not have the "RARST" on the parts. Also, they look quite a bit different than a forged rod so there are various visual clues other than the RARST lettering to differentiate cast from forged.

Olli, thanks for the pics - I was not aware of different versions of the forged rods. The forged rods that I have seen are all the same as the one on the far right in your pic. Ususally different versions (either updates, or different OEM supplier of the same component) will have a different part number suffix ...02, 03, etc. But there is only one version of the forged rod that shows up in PET, and it has the -00 suffix. Which should indicate that there were never any updates to the part, and it was only supplied by one mfgr. I would think any changes to the forging dies would require recertification/qualification by Porsche and would generate a updated part number suffix... but guess not in this case. Good to know.

Kool

Thanks for the info very informative.

MAGK944

+1 thanks.

Olli, those rods sure look sweet, saw them on your website and drooled for a while.

Mike

brad-cam

In the pics, the middle forged rod is the one from the early NA's (83-84). The one on the right is the 951 rod. They both have RARST in the part number. The difference is the early one has more rounded edges and the 951 ones have sharper edges on the big end. That's how I tell the difference. The forged rods have a slightly smoother finish. The cast ones have a rougher finish.

I stare at one of the 951 rods every day, as I have the one damaged from a failed #2 rod bearing as a paper-weight on my desk.

Olli Snellman

I have taken that rod from MY '86 951 engine. All rods where same design. If they are N/A rods, don't know how they have ended up into that engine.
Both of those OEM rods weight about the same. Here pictures where you can see the weights. Hope those figures says more to you, i just understand the metric system
It's odd when factory put those cast rods to '90-'91 engines, they look weak and quit unfinished items to me.