ausgeflippt951

Hi folks,

I've searched for a little while and have wound up a bit more pensive on the subject of replacing the rod and main bearings on my newly-acquired LS2. Hoping to get feedback on whether I should bother replacing the rod bearings/bolts and main bearings.


This is going into my 944 Turbo track/race car over the winter; the LS2 is currently on the stand. It has 100k miles on the clock. So, note that it gets driven hard.


My goal for this build is to effectively separate the build into two phases:

1. Phase 1 will be to keep everything as simple as possible and get her running. Develop the car over the next season in this configuration.
2. Phase 2 will be to look into power-adders (cam, valvetrain, better intake and header-back, etc.).

I know it sounds sacrilegious to say, but I am not in search for mega HP. My car currently puts down just 315rwhp (with the 944T motor); race weight (with me) is 3060lbs. So as long as I'm close to this with the V8 I'll be happy for Phase 1.



The goal for Phase 1 is reliability and simplicity. I am not wanting to do a full rebuild and had therefore been planning on replacing just the rod/main bearings as a matter of precaution. And it's my understanding that a common source of engine failure for LS motors is spun bearings -- definitely not something I want on a race motor.




In doing some research here (and a host of other places), I have seen a surprising number of folks recommending against doing just bottom end bearings if I do not plan on rebuilding the whole motor. This is contrary to the world of my 944 Turbo motor -- it's customary to replace just the rod/main bearings as a matter of precaution.


Any perspective would be very much appreciated, particularly from those of you who enjoy tracking/racing your LS's.

Thanks!

redtan

iTrader: (5)

The weakpoint of the bottom end are the rod bolts, especially in constant high RPM environment.

But by the time you buy ARP rod bolts and resize the rods you are in the same price territory as some basic forged steel rods with ARP bolts already installed.

I'd at least throw those in along with some new bearings. That will make a stout setup as the pistons will be ok given the proper tune and no knock/lean conditions.

Camaro99SS

iTrader: (4)

If the motor still holds good compression and maintainss ~40-45psi oil pressure at hot idle, leave it alone and get the rest of the car dialed in next season. My 99 SS held 45psi at hot idle running 0w30 German Syntec oil at 134k mikes, and I had it from 66k on. If maintained, 100k is nothing for these motors. For road racing i'd be more leary of weak valve springs and dropping a valve than anything else. A new set of LS2/LS3 springs is around $60. For now, run a good oil like Castol Edge 0w40 or other quality 40wt synthetic.


Jason

ausgeflippt951

Thanks for the great replies -- very helpful. Your comments above, coupled with the commentary I've received elsewhere, definitely suggest I hold off on touching the bottom end until I rebuild the motor.

gnx7

iTrader: (28)

I put a stock GTO LS2 shortblock (new rings/bearings/ARP rod bolt only) together reusing 100K mile parts, LS2 timing chain, stock LS3 heads/intake and baby cam for a road race RX-7 I sold and it lasted 2 full seasons without any issues at all. It did run a full dry sump oiling system.

I bought the shortblock and it had bearing issues from before. Polished the crank and it was good to go.

http://dumbyellowdog.com/tag/rx7/

MileHighSierra

Where are you based out of? There is a guy here in Colorado who has a 951 that he did an LS2 swap. Car runs great, might want to checkout Nasa Rockymountain and pick his brain.

ausgeflippt951

That's a great looking FD! Love those cars; I owned an NA FD for a short while. When I was based out of Road America (ten years ago?) there was a gentleman running a red FD in the GT1 class with a 3-rotor. Car sounded amazing but just couldn't keep up with the V8s at fast tracks like Road America (though he had better success at places like Blackhawk).

And of course, in true rotary fashion that poor car was rarely seen running. Seems an LS would've been just the ticket.



I'm out of the DC area. I may know the guy; there is a healthy crop of 944-V8 swap folks out there. Some say sacrilege, some say reliable horsepower.