Does anyone know what the allowable deck height tolerances are for a 997.1 TT? Thanks,

 

Hmmm...I'm worried why you are asking. I hope your connecting rods are okay.

I don't know the numbers off hand, and it wasn't in my workshop manual, but you may want to PM Chad (cjv) or some of the other engine builders here.

 

Thanks. Our concern is that when the turbo let go and dumped a lot of oil through the cylinders that perhaps a rod(s) and/or bearing(s) were bent or fubared. (Oil in liquid form is basically non-compressible and something probably had to give.)The motor is pulled and disassembled to the point where we can measure deck height (top of piston to top of cylinder wall) and in the affected cylinder bank we found measurements of minus 1.2mm, 0.6mm and 0.4mm........

(Later...) Just talked with my motorman who spoke with an L&N Engineering person who opined that anything under minus 1.0mm is acceptable and that based upon our measurements and the type of detritus found in the oil filter when we autopsied that, we probably smacked a bearing. Anyway, we'll tear the rest of the motor down today, inspect rods, cylinder walls, etc. and order some new bearings and upgraded rod bolts as long as we're in the neighborhood plus anything else that is needed. Those will go along with the new turbos, intercoolers and exhaust system to replace those that were munched in the incident. And, as long as we have the motor pulled, we'll probably upgrade the clutch, throttle body, and put on a compatible set of headers and a bunch of other miscellaneous stuff. We're still trying to decide what parts we are going to use but would like to bring the car up to about 700hp (never can have too much you know) with beefier internals to handle it all. Our goal is to be back at the track in two weeks in a better car than before..........

 

Ouch! Sounds expensive! G/l!

 

Yea, it is. There was a thread a week or two ago about how rich you need to be to own one of these things. While I didn't post on that thread my answer largely based upon this experience is;

1. If you can't afford to write the check, you're not rich enough to buy it.
2. If you can't afford to fix it, you're not rich enough to modify it.
3. If you can't afford to write it off, you're not rich enough to take it to the track.

Still, it's a s-load of fun.......Head's up, Eye's Wide Open!

 

Amen!

 

Opinions are no good. You need to be working with facts. The piston protrusion or piston height tolerances should be listed in the manufacturers assembly manual. Your mechanic surely has at least one of those? Can't see rods bending from the level of oil ingress from the turbo oil feed lines. A dramatic loss of oil pressure could have caused a degree of damage to the bearings along with particle contamination of the lubrication system....thats about it. Now, depending upon the volume of oil being ingested into the cylinders from the turbo oil feed lines it may (possibly) have caused uncontrollable run on from the oil igniting with the fuel in the cylinders which would then overspeed the engine well beyond its max rpm limit....now that can bend rods. But then there should be evidence of valve strike on the piston crowns. And re using parts? What parts is he talking about? Considering the questions in your post the real concern here is, is the engine in the right hands or is your mechanic seeking to gain some experience cutting his teeth working on a 997tt engine at your expense. There are outfits that specialize in these 997tt engines you know. I'd seriously consider shipping your engine to one of them and just have this guy do the R and R of the engine before he empties your wallet.

 

Actually, I have this. It isn't listed.

 

Thanks Bob. It is true many engine assembly manuals don't list that specification when they really should. Often a manufacturer pre determines certain core parts are not reconditionable when in fact they can be in many circumstances. Outfits that specialize in the reconditioning of these engines should be able to help with these specs (one could only hope). Failing that a request to PAG may provide exact details. A good builder will measure the OEM engine for specs and tolerances when an opportunity presents...such as an upgrade on a good engine and not on a worn out or failed engine....and records the information for their future use. Mindful this engine is a small capacity high output unit, and the customers engine has been subjected to extreme operating temperatures resulting in catastrophic failure, a number of checks would be necessary on the core parts before re use/ reconditioning. (heads block, cams, crank etc) and/or renewed where necessary. The pistons would be soft on the crowns, the liners would have ovality, exh valve stems softened, valve seats contaminated. I'd say as a minimum. 1 x set of (6) liner kits, mains and be's, new crank, overhaul gasket kit, 12 exh valves/guides, shims buckets collets, springs etc, new oil cooler. Assembled within OEM specs! And then go choose your ancillaries (turbos, I/c's, exh cyst)....matched with a final retune. But better have the wallet ready .