Lightweight, Pistons, Rods and Pins

[K24madness]

During the rebuild I have managed to shave 70 grams off of the weight of the rods by using Arrow rods. I am now looking at titanium piston pins to shave another 40-50 grams. The total reduction will be about 10%-12% off of the entire piston/rod assembly. My focus was to help the known weak rod bearings (993).

Will I feel a difference is revs/response?

[BURN-BROS]

Originally Posted by K24madness

During the rebuild I have managed to shave 70 grams off of the weight of the rods by using Arrow rods. I am now looking at titanium piston pins to shave another 40-50 grams. The total reduction will be about 10%-12% off of the entire piston/rod assembly. My focus was to help the known weak rod bearings (993).

Will I feel a difference is revs/response?

I would expect a increase in response with the reduction in the rotating mass only,not in the piston weight reduction...but I would not expect much. The flywheel mass is provides a much greater change. I would expect to see a longer life in bearings with a decrease in the reciprocating mass. Getting the heavy 600 gram piston/pin combo is paramount.

Measure the reciprocating end of the rod to measure the reduction in weight over stock. I would expect a reduction of about 30 grams for a titanium pin over a stock 23mm pin, a bit more if you went with a 22mm pin.

[PFM]

K24Madness,

The Ti pins are not cheap and the gain is small. The Ti Rods are a different story much more weight to save. Light weight piston, Ti rods, lightened crank and very light clutch / flywheel. This adds up to a very quick revving engine, the tach will need a tune-up to keep up.

The reciprocating weight saved by the pins cost is better spent on the Rods or flywheel. Unless the goal is a 10,000 RPM motor then you need pin weight too.

PFM

[K24madness]

PFM,

I went with Arrow rods and saved 70 grams over stock. I want to stick with the factory pistons cause I have a nice set with 12k miles on them. The 30 grams or so saved per pin is worth the cost (around $500.00). The 993 rod bearing are weak and the combined 100 gram savings should help increase rod bearing life. My primary focus was on increasing rod bearing life by shaving weight off parts that were getting replaced anyway (rods) and possibly some extra with the pins. The motor has 29k on it and we are just doing the top end.

Without a doubt shaving more weight off the flywheel would be the ultimate bang for the buck as far as performance is concerned. Ti rods are waaaaay outside the budget. Not to mention that means cracking the case, changing the crank (GT3 to fit the rods) and new pulley.

Tom

[PFM]

K24,

Sorry I thought a quick revving engine was the goal, I did not know rod bearing life was an issue for you. The Ti pins at that point will help a bit.

PFM