Compression Question

[mmason2005]

I have a Turbo 1915 motor and I am having my mechanic do a lot of work to my rail over the course of this winter. He said that he was turning over the motor by and can do so with one finger, whereas typically on the VW engines he has worked on it takes his entire hand. He never has tried turning over a turbo motor (although I would not think this factor would be any different than a non turbo motor). I know the obvious thing to do would be a compression test, but without all the specifics, what is your initial though on this?

He thinks I need new jugs and rings, but I was just curious. I have spent a lot of money on my rail already, but to me this sounds like an issue that needs to be resolved. if I do need new jugs and rings, could someone point me to a link which may be a good place to buy exactly what I need? I know I have 94 mm pistons. The gearhead side of my brain is minimal when it comes to VW engines.

Thanks in advance!!

[madmike]

Yepper sounds like the rings are Kaput?
make sure he gaps the new once right! research!
most of us use Forged Mahle's or Wisecos'(spelling?)

[Clonebug]

Just do a compression test.
It's the only way you will know.

[mmason2005]

Hey madmike, not sure exactly what you mean by the gap, but my friend has tons of experience working on VW engines, just not turbo VW engines and is really nervous only because of that reason. In replacing the jugs and the rings, would their need to be specific things he would need to look out for and check with it being a turbo engine to prevent bad things like detonation. I know timing and advance is important, and I do know what the timing needs to be set at but as far as installation of the jugs/rings should there be things to be concerned about?

[madmike]

I gap them at .018 minimum for turbo applications
.012 for N/a

[slowsixtyduece]

A few thoughts come to mind. What is your compression ratio? If it is between 7-8, it may feel a little different to him than a 9-10:1 motor. This may sound dumb, but did he have the spark plugs in...and were they tight? Also, we're all the valves adjusted properly too? Either of those might cause a bit of a leak. It will also depend on how fast he turns the motor. I noticed that on my brand new 2276 turbo motor, it was quite easy to turn by hand when I did it slowly, giving the compressed air a little bit of time to get past the rings (engine was cold). Not sure if any of this helps.

You may indeed need new rings or perhaps a valve job...or both. As someone stated earlier, you won't know for sure until you do a leak down or compression test.

As for you mechanic working on the turbo motor itself, it really is not much different than n/a. Not sure who built your motor, but if you don't know the compression ratio, you may want him tocheck the deck height/ copper head gasket size of applicable and combustion chamber ccs just to see what compression ratio you are running and make sure it's correct for turbo. The only other different thing he will need to check is, as stated above, the ring gap on the first and second rings in order to make sure there is adequate room for expansion with the added turbo heat/ compression. I can't think of anything else that a turbo top end would really need that is different from NA. Detonation will have more to do with overall tune of the motor than the parts themselves (although the chamber shape and deck height may have a little to do with it...). Hope this helps!