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mic mic is offline
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resurfacing of 'fresh' cylinders?

I have a low miles turbo motor (3.8ltr - mahle kit) with too high compression. I am planning to either machine the Pistions for lower compression (about 7.5:1), or purchase new JEs.

With only 1500miles on the motor:

Does it make sense to just drop in the new pistions (or machined pistions) with new rings without resurfacing the cylinders?

Thanx,

mike
Old 11-02-2005, 04:38 PM
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Assuming all the parts are within tolerances at 1500 miles everything is like new or maybe better because they're tested. I would machine the pistons to your desired specs, measure ring gap (making certain the put keep the pistons and rings with the original cylinders and you're go to go.
With turbos I have had less then good results using JE pistons. Don't get me wrong I like JE pistons they just seem a little questionable in turbo engines.
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Old 11-03-2005, 07:24 PM
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Henry:

How do you feel about 8.5:1 compression in a turbo motor running upto 1bar boost? I am concerned that this is too high compression. However, this is the compression in a off the shelf Mahle 102mm turbo kit.
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Old 11-03-2005, 08:13 PM
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8.5 to 1 is high for a street turbo but with proper engine management it is doable but risky.
My thought, 7.5 offers good performance with a more acceptable risk. 91 octane fuel takes a bite out of the best laid plans.
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Old 11-03-2005, 08:21 PM
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Thanks Henry. That is the concensus of what I have been hearing. I need to pull the P's to see if there is enough 'meat' on the domes to determine if I can machine them. Any advice on where to do this? Wondering if any coatings should be considered on the dome after machining. Any recommendations?
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Old 11-03-2005, 09:09 PM
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