mmalacho

Rennlist Members,

I have a stock, well maintained 997.1 turbo with about 40k miles and I blew a coolant hose last summer. The car ran great before the incident.
The Car did not overheat too bad but once engine was removed to replace all the hoses, it was found that cyl #2 lacked compression and had a 20% leakdown (all through crankcase) vs less than 5% on all others.
Compression differential was 17% from that cylinder to the others as well.
Compression and leak down were done cold with engine out. Borescope saw carbon on that cylinder looking wet and oily and some deposits on top.

1. Do I rebuild the motor? All Pistons/Rods/Sleeves/rings
2. Do I repair the cylinder in question.
2. Do I assume this was pre existing and reinstall motor as is and try to get a few more years out of it.

Please let me know your thoughts. I am leaning toward rebuild but don't want to jump the gun.

Thanks!

mchrono

this is an opportunity to rebuild and go big!

and welcome to RL!

jeebus31

Rebuild, do it all with stronger internals. You will have to either now or in the near future. Doing one cyl is a band aid. Winter is a good time to get this done!

wcarson

I am sorry for your news. If you can financially swing it, I would make lemonaide out of the lemon and rebuild. I was in a similar situation and had to do a full rebuild a couple years ago. I spent more than I wanted to, but I'm ultimately glad I did. I went with a 3.8L upgrade, Carillo rods, head studs, etc, topped off with big IC's, big turbo's full supporting exhaust, etc, etc. Of course while we were in there, the cams were pinned at that time, and all other preventative stuff was all done too.

Although it was financially painful at the time, the end result is spectacular and I no longer think about the money. I only think about the massive acceleration forces that the car now provides!

nzskater

Has anyone built these out bigger than 3.8L?

jeebus31

I think 4.1/2 is the biggest I’ve seen? Tavarish on YT has a 996TT that is supposedly a 4.2

MJSpeed

There’s quite a bit which needs to be taken into account prior to making such a decision. Drivability, reliability, and how do you currently utilize your car and how will you afterwards? Do you track her? Are you driving her on a daily basis?

Depending which route you choose, how will the other components on your car be affected or need to be changed? Manual or tiptronic?

How long do you plan on keeping your car? I sent you a PM with more questions and info. I’ve been down this path with many of our clients; with some we proceed with bigger displacement builds and the end result is spectacular, but others I’ve discouraged from going bigger.

Cheers,

MJ

powdrhound

I have a 4.0L. 106mm pistons so technically a 4.05. Best engine I ever had. 773whp/610wtq at 1.3 bar on 91 octane. I had a 3.8 prior to this. The 4.0 is substantially more potent. If I was considering a build, I’d skip the 3.8 and go 4.