[Jnikic]

During an open track event two weeks ago, I noticed that my motor was running hotter than normal, though the gauge never went past the half way point. A little while into the next session, and the motor suddenly refused to rev past 5.5k (in 4th gear only, lower gears were ok up until that point) - it was almost as if I hit a rev limiter, it simply wouldn't accelerate further and hit a wall.

I came in and checked my oil level (it was okay), and fuel pressure (3.5psi on the PMO regulator). AFR's were also normal, though rich as usual. During the next session, everything was okay until 15-20 minutes in when the same problem arose - again, I noticed the motor was running warmer than usual - and so I pit in. After it did the same thing the next time out (an hour or so later), I decided to pack it up and made the 240 mile drive home without any issue - but I did notice that the motor appeared to be sprayed with oil from the catch can before I left.

My mechanic looked through the car this week, but couldn't replicate the problem. During normal driving, the motor pulls hard and appears strong. But compression test results show the following:

1. 148
2. 125
3. 146
4. 166
5. 140
6. 100

So there's obviously something going on with cylinder 6 - from the leak down test, my mechanic thinks its a broken ring.

The motor was "rebuilt" by the previous owner 25k miles or so ago with larger cylinders (98mm on a 3.2 case = 3.4), but I don't have too many details beyond that. It seems as if we could just address cylinder 6, or proceed with a complete top end - BUT my question is whether or not I'm okay putting that repair off until the end of this season. I caught the track bug bad and have an event next weekend.

Will I do any damage to the motor by running? Do you think the problem I encountered could be caused by a broken ring/low compression on cylinder 6? Or is there something else at play concurrently? Thanks!