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Mahle Cylinder Advice
2.7 Mahles. Rebuilding at 96K miles. I put the majority of the miles on myself as an everyday driver. Smoking like a mosquito fogger.
The cross hatching is gone on all these puppies. Measurements are: No.1 90.02-90.04 No.2 90.00-90.01 No.3 90.04-90.05 No.4 90.04-90.05 No.5 90.03-90.04 No.6 90.02-90.03 They don't seem oblong by those measurements. Largest spread 0.02. But this is an area I have no expertise or experience. The Shop I have them in are recommending that they get sent out and refurbished at about $200 each ($1200). First, from pix below, what kind are they, Alusil or Nikasil? I understand Alusil are one time use (per Wayne's book). Second, in your opinion(s), if they are within tolerance, what would you do? Send them out? Get a Grape Hone, rough the surface and see of the rings set. Project Money is an issue. How much is reasonable if they need to be sent out and refurbished. What could I get a used set but refurbished set for?    
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'77 911 Targa 2.7 '05 Maserati Quattroporte |
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07-09-2010, 02:02 PM
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You can get a complete new CIS set for $2000.
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07-09-2010, 03:20 PM
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3 restos WIP = psycho
Join Date: Feb 2005
Location: North of Exit 17
Posts: 7,665
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11 fins...IIRC that means Nikasil. Nice. I don't have the spec book, but think they are in spec which means a grape hone and new rings should do! On the pistons, do the ring lands spec out? If so, a quick clean up is all that is required.
I think that anytime pistons are out is a good time for coatings. DFL on the skirts will ensure that if the cyls are near the edge of spec, they don't wear the cyls prematurely, too. Add heat coating to the crowns and head domes and even better.
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- 1965 911 - 1969 911S - 1980 911SC Targa - 1979 930 |
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07-09-2010, 03:22 PM
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That shiney glassy look to the metal on the outside looks like Alusil to me. The picture of the inside is too fuzzy for me to tell much. Color inside looks like it could go either way. Check for magnetic attraction on the inside. A dull grey inside is Alusil a golder color inside is Nickasil. Obviously it's easier to tell if you have one of each to compare.
-Andy
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72 Carrera RS replica, Spec 911 racer |
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07-09-2010, 07:05 PM
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I'm with Andy on this one,......I'd check the bores with a magnet to confirm. Good sharp pictures of the bore will also help ID them.
JMHO, but I would not use a grape hone if the crosshatching is worn away. If you are on such a budget that a new set of Mahle Nikasils cannot happen (they are more than $2K!), I'd recommend buying a set of JE's if your piston ring lands are worn, and having the cylinders replated with Nikasil to fit. This assures that the rings will seat.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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07-09-2010, 07:48 PM
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2.7 fin count doesnt mean anything because the fin count didnt start until 3.0
Bruce |
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07-10-2010, 06:08 AM
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