Rather than hijack Craig Trask's thread on his impending Ruf project (congrats by the way ) I wanted to pose this question:

Is it true that Ruf fits titanium rods (when changing rods) to his tuned 993tts ?

The race proven rod of choice for the 6XXhp/78XXNM GT2 EVO racers are Carrillos which AFAIK are an alloy not containing Ti.

What are the advantages/drawbacks of Ti rods relative to Carillos ? Have Ti rods ever been used in a 993tt/GT2 in a racing environment ?

 

Ti rods are lighter than Carrillo rods and have been used in turbocharged racing cars for a long time. Lighter mass means quicker throttle response, less pumping lossess, and less tensile load on the rotating assembly. Some if not most or all of the 935, 956, 962 engines were built with Ti rods so they have a history of success in racing environments. Those engines were in the 600-760hp range for the 3.2l engine depending on configuration. I would consider running a GT3 RSR Pankl Ti rod in a 996tt if the revs were limited to 7500 or less and HP was in the 600hp range as an experiment. The 993tt pistons are relatively heavy and I would want to find a lighter piston before running a Ti rod in the 993tt to lessen the load on the rod. Also, all 993 racing engines except the 993GT2 used the 964 style crankshaft and larger size rods which are stronger than 993 components.

 

Geoffrey,

Would you recommend that I have RUF change the rods while they are in there? My car only has 26,000 miles. If so, should I insist on Carrillo vs. the Ti rods?

 

How about Arrow Precision rods?

 

The Arrow rods are very similar in design to Carrillo and generally regarded as higher quality. They are slighly lighter than Carrillo rods but cost slightly more. They are a great component. Needed for a street car? probably not.

If RUF is your tuner then I would recommend talking with them and going with their recommendation. Unlike previous Porsche rods, the 993 Rods are weaker and will bend rather than break the rod bolts at the higher forces. In the 993, the Rod is the weak link moreso than the rod bolts. Carrillo rods are in the $1900 list price range so they are not a huge investment.

 

Geoffrey
So if one were to go with a Ti rods or other light rods one must also have to go with lighter pistons such Mahle.

 

I'm no expert, but RUF had a write up on the virtues of Ti rods that my PO passed onto me. I'll try to see if I can scan that and post it here.

I believe Ti as a metallurgy component has two benefits:
Performance: lighter so you get better engine performance for the same physical shape.
Durability: lighter means less inertial mass to start stop with each revolution cycle. More stable metal in high heat environment means better wear and tear in the long run. Much higher strength than other rod metals.

It may not be the best, or the only, metal suited for performance, but add the durability consideration, it's a great choice.

CP

 

No, I was not suggesting that you NEEDED to replace the Mahle pistons with lighter ones to run the Ti rods. The 993tt piston is heavy by comparison, and I know the Cup cars run to 8200rpm with lightweight Cup pistons and we begin to see the big end of the rod become oval at about 85 hours due to the stresses on them. I personally would want a lighter piston to use with Ti rods in the 993, but there are a number of factors in play and Ruf has obviously got the combination figure out well. I am just one who wants longevity and low maintenance.

 

Geoffrey,

Can you be more specific?

Thanks for the detailed answer!!! My mental database has been updated.

Tom