81 SC Engine repair

[faapgar]

I just finished an upper end repair on 81 SC with 4 broken lower head studs.Motor had 278,000.Leakdown was 4-6% but mainly through exhaust valves.Motor has 9.3 to 1 Alusil cylinders.Replaced the head studs. Measured the cylinders and only 10 % worn.No ovality.Top ring land was basically no wear.Had the cylinders & pistons cleaned ultrasonically.Reassemble and after 500 miles did a leakdown and it was 1-2%.So much for the bad legend of Alusil.I only mention this because it is more than 100 times I have seen this result.All 944 & 928 have Alusil.I had a Euro 928S with 310 hp for 10 years.It had 150,000 on it and I put another 200,000 on.In 5,000 miles it burned 1/2 QUART I NEVER DID A LEAKDOWNI asked my machinist who has done this for 60 years.He said.Alusil has less wear than Nicasil.Rich Jascic passed this last year.Lots of people know this shop.Fred

[reclino]

Very cool.

[ahh911]

Thanks for the info,
I re-installed the Alusil as well but didn't check the rings. I'm wondering if I'm burning more oil since the last 2000 Miles. It seemed to me that the first 1000 very little oil was being used but I was babying the car, the next 2000 Miles I've been running it at much higher rpm, sometimes 45 minutes at 4 to 5.5k rpm through the hills occasionally, and non stop surging to 4.5k rpm and above and back down again on country roads, just to enjoy the engine. Anyhow, since the start of the high rpm driving, it now puffs out smoke on startup more often and burns about 1L/600 miles, the first 600 miles used 1/2 litre at most. It's still less than pre-top end rework. The spec below is from the first Techspec book and was repeated in later revisions, 1.5L/1000 km was the original and continued spec from Porsche.
Phil

[faapgar]

What brand of oil are you using?

[ahh911]

Valvoline vr20-50 non syn.
edit, woops vr1 20-50,non syn.