Jim bailey - 928 International

That chain is really NOT very highly stressed since it is ONLY turning one camshaft on a "four cylinder " engine and not at overly high RPMS . I do not remember ever hearing about one failing but that might just be my failing memory... Kibort ran his with multiple teeth missing from the cams which is perhaps some indication that the chain drive was over engineered for the task. The extra finishing of the Silver Boxed Iwis certainly does look nice. My guess is the 944 guys have had a lot more experience with chain failures !

BC

Kibort did mention that he felt the chain was "larger" then some other comparison mark, and therbey was concerned that the "stretched" chains were causing his teeth problems. Something I remember.

Jim bailey - 928 International

Everything wears over time and as mentioned Porsche says to replace anytime there is a valve incident. And certainly nothing wrong with using a better finished part.

H2

The 968 guys tell me that the cam chain should be changed out every 60K to 90k miles...depending who you talk with. Just cautionary. They do fail occasionally. I've also been told that the 944/968 chains have a heavy duty version. That's all I know at it's not certain. However, with Variocam on the 968s the cam chains take on a bit more importance. Worn cam teeth and tensioner pads are the larger issue. If you replace the cams and/or pads might as well replace the chains. Relatively speaking, they don't cost that much

Harvey

Ketchmi

The cam profiles and spring rates are much less on a 928 than a 944 and 968 thus we have less problems with the chains and tensioner pads. The racing chain we sell is actually a 944 part number and has been used by that crowd for a long time with good results.

jpitman2

I would have thought that the quality/spec of the pins and rollers much more important than the finish of the side plates. I note in the pic above what looks a seam on a roller - surely thats not good for the teeth of the cam gear? The high spec chains used on bikes cost a lot more because they have 2 O rings inside each roller to keep oil in and dust out of the working area of roller to pin, but a fully encased chain like these probably dont need this type of help? Do these chains have a clip that comes off to break them, or are they endless?
jp 83 S, no chains

Ketchmi

No master link or seperation point. A true roller isn't made for the inside of an engine, this thing is in a constant oil bath.

The finish of the side plates is critical to the fatigue strength of the chain. The rollers do have a seam but I have never seen one that didn't.

EB338

True rollers go inside the front covers of small block chevys all the time, constant oil bath and all, very common upgrade......double true roller chains even.......

mark kibort

yes, the racing chains are what i used for my replacement on the Holbert car. the racing chains were beefier, and so happened that the stock stuff wasnt available at the time. upon installation , I found that the entire set up was much tighter. dont know if it was wear on the chains that did this, or if that was improved by the racing chains. probably a little of both. not much cost difference, and i was told that these chains were for the 968 guys, if i remember correctly.

Mk

FlyingDog

A friend spent $135 for one of those beautiful pieces of engineering only to have it fail and destroy his new $4000 motor in under 100 miles. The new(er) engine has a $45 aftermarket stock-type chain and runs perfectly fine.

*I am not refering to a Porsche engine, replacement part, or Motorsport product*

928SS

might have something to do w/having all the teeth on your cams too

I used the 944 motorsport cam chains on my old gal too... got them from garrity at motorsport, seemed to fit perfect, but we all know that only means 1 thing - the tbelt will definately be the 1st thing to go now (if it's ignored)

IIRC, rubber belts have a lot less friction and heat build up than metal chains - so I don't think the Tbelts are the bane of our motors as much as 1/2 assed TBelt OH's that ignore tensioners, rollers, etc... later MY 928 tensioners do seem a bit beefier though.... maybe a kevlar reinforced unit could be cool though...

atb

It's old school wisdom that when you relace any type of chain, that you replace the sprockets as well. We don't have this luxury with the 928 chain drive gears, but it does raise the question of whether putting a new chain on used cams might creat a environment for failure of the parts?