Use of factory rods in a race motor???

[Tinker]

Looking for any experience or recommendations.

Building a 2.7 RS type motor with the factory 2.4 - 3.0 127.8mm rods. Mr. Anderson stated these are relatively safe up to about 7,800 rpm.

Anyone out there spinning these higher??? ARP/Raceware bolts being used.

Tinker

[911pcars]

You might find the factory 2.7 crank will limit continuous rotation at high rpm. I believe they will tend to break (as in fracture), at the rod journal fillets.

To increase the life of the rods, you can strategically lighten them, then balance and have them shot peened. You can do the same with the crank too. Or you can spring for some stronger aftermarket rods or super-duper titanium rods that are both lighter and stronger than the factory units.

Sherwood Lee
http://members.rennlist.org/911pcars

[aigel]

I'd sping in for afermarket (Carrillo) rods unless you know he history of the factory rods and have them race prepped (shot peened etc.).

George

[HawgRyder]

It's a matter of insurance....
If you knew the exact time the rods would break you could stop 1 lap before that...but not knowing the time...you have to buy insurance (better rods..or crank).
If the lower end of the engine is over-built (would take more HP than you will make with the rest of the engine) it will last a long time and the peace of mind you will have is great.
I always over-build the bottom end of every engine I build because of that reason.
I can get an extra 100 - 200 rpm over the red line with confidence, knowing that the bottom end will take it but also knowing that it might not do me any good because the HP has fallen off (top of the curve).
The last reason...just plain time...you cando a top end cheaper than the whole engine...maybe 2 or 3 times before having to crack the case again.
Bob

[Wayne 962]

Shot-peen the rods for added protection in race (high-RPM) engines...

-Wayne