Cemoto

I'm going to second this.

Churchill

I've never heard of oval cylinders and out of spec valves on a 40K mile 993. Maybe if 20K of those miles were on the track. And head studs definitely do not need to be changed (are you sure you're not thinking of rod bolts?)

OP, a top end on a lower mileage 993 that doesn't need much else should be in the $6-$10K range. I would do plug wires while the engine's out since they're so difficult to change with it in, the power steering belt, and chain cover/valve cover gaskets. But on a low mileage 993, that's about it. Spend your money how you like but I wouldn't start throwing new parts on a low mileage car that doesn't need them. A shop would love to do this for you though...

cobalt

Yeah I am pretty sure. The engine was purchased second hand it is an early 96 Vram. I don't have the actual driving history on it but have documentation showing it was a low mile engine and the overall condition tells me it was but lived a hard life. No doubt a low mile engine shouldn't need work like this but it all depends how it was treated. Was it run hard when cold or any number of factors can make a difference. Many of these cars are purchased second hand and we aren't the original owners so anything is possible. I can't tell you how many of these cars I have seen with override switches to shut off the speedo or simple disconnected, rolled back or replaced speedos or were tracked most of their life and sold as never tracked. So many cars are out there with more or harder miles on them than their owners realize.

I suspect my engine was tracked or just driven hard. Leak down and compression numbers were not great. I suspect it was run in the upper RPM range often and constant pounding of the valve against the seats will cause them to harden. In this case they were. As I noted the exhaust valve guides were shot at 40k miles the intake were within spec. The work done was based on everything being torn down and inspected as it should be on a proper rebuild. Irrespective of miles every component should be inspected to make sure it is in spec The case was in excellent condition. Everything measured out didn't need line boring or any case work. There was some minor marring of the bearings, the crank was perfect so we replaced the bearings. I would replace them anyhow they aren't that expensive and I upgraded to the GT3 tri metal versions. What can I say the cylinders were measured and were slightly out of round so I had them stripped, plated and honed. In this case I had Millennium do the work and they did a great job. Valve springs were checked and they all were in spec but I decided to upgrade using the Ti retainers since this is a track build. The head studs along with the rod bolts are stretch to yield. Anytime a bolt or stud is stretch or torque to yield it needs to be replaced and is cheap insurance. Porsche recommends replacement every time it is disassembled for a reason. The numbers I mentioned didn't include anything external of the engine nor did it include the R&I of the engine. Valve guides if needed, new rings, hone, studs, hydraulic lifters if needed and gaskets. No doubt hourly rates play a huge factor here and if your shop charges $100/hr vs $180/hr will change the price dramatically but you have to decide if shop rates of over $125/hr are worth spending. My numbers were based on $125/hr. No doubt inspecting the engine first is a must. A leak down and compression test should be done. Leaking oil can be as simple as needing new valve guide seals.

pp000830

Faulty assumptions seem to underly your above statement. What planted the seed of the idea that you need this work? What are the gross symptoms suggesting the need for internal engine work?

Excessive Oil Consumption is a reason owners consider a top-end rebuild under the assumption that the valve guides are worn to the point that excessive oil is slipping past them and burning. The logic in this seems sound. Then again I recently ran across the following comment in the 993 Rennlist Forum in reply to an oil consumption concern:
“How full do you keep the oil tank? When I kept mine at the full level I'd go through easily a qt. per 600 miles, now I keep it at min - 1/4 I use barely a qt. every 2500 miles. Even now, after spirited driving, the oil can expand to over 1/2 full.”
The implication here is that a true measure of a full oil tank is somewhat variable and overfilling may be contributing to the perception of excessive oil consumption where none may exist. Could burning the ingested oil over-fill over time explain the clogged secondary air injector ports, potentially a self-inflicted service issue caused by simply overfilling the oil? Who knows?

Railmaster.

I will drive my 993 until it is more than obvious that it needs a rebuild! The later the better!

Im not one of those "Om my god the leak down test was not 100% on one of the cylinders, i must have the engine completely rebuilt" guys!