FORCED INDUCTION 3.2 (930.20 MOTOR) - REDUCING COMPRESSION RATIO
04-19-2020, 11:44 AM
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FORCED INDUCTION 3.2 (930.20 MOTOR) - REDUCING COMPRESSION RATIO
Hello gents,
I am in the process of rebuilding my motor and looking to supercharge it initially and turbocharge it later (or Turbocharge it from the beginning).
My cylinders are in mint condition and my pistons are in very very good condition too.
Since I have a 930.20 European spec motor (compression ratio is 10.3/1), which needs to be decreased especially since the climate in Greece can get really hot.
You have any suggestions for dropping the compression ratio using my pistons?
Maybe thicker gaskets or that doesn't work on the aircooled motors?
My mechanic told me that at the base of the cylinder there are copper rings that can be found in 0.25 or 0.50? Fitting 0.50 could lower the compression ratio? Any idea? If so by how much? Maybe machine the pistons would be a solution or this is not a good idea as we will weaken the pistons? Anyone done it? Any company that does it?
If the option above (maintaining my pistons) is not possible? What about buying a new set of pistons (in which case I will go twin-plug) with lower compression ratio whilst maintaining my cylinders? What pistons would you suggest?
Lastly would it be a solution to buy 3.0 Turbo pistons since they have the same bore ie 95mm? What other parts would need to be bought ?
Most importantly what would you guys do to have a cost effective but correct engine build to accommodate forced induction, trying to at least keep the cylinders that I have (replacements are not cheap!! and I find it a pity to change them since mine were found in top condition).
All the best,
Alexis
I am in the process of rebuilding my motor and looking to supercharge it initially and turbocharge it later (or Turbocharge it from the beginning).
My cylinders are in mint condition and my pistons are in very very good condition too.
Since I have a 930.20 European spec motor (compression ratio is 10.3/1), which needs to be decreased especially since the climate in Greece can get really hot.
You have any suggestions for dropping the compression ratio using my pistons?
Maybe thicker gaskets or that doesn't work on the aircooled motors?
My mechanic told me that at the base of the cylinder there are copper rings that can be found in 0.25 or 0.50? Fitting 0.50 could lower the compression ratio? Any idea? If so by how much? Maybe machine the pistons would be a solution or this is not a good idea as we will weaken the pistons? Anyone done it? Any company that does it?
If the option above (maintaining my pistons) is not possible? What about buying a new set of pistons (in which case I will go twin-plug) with lower compression ratio whilst maintaining my cylinders? What pistons would you suggest?
Lastly would it be a solution to buy 3.0 Turbo pistons since they have the same bore ie 95mm? What other parts would need to be bought ?
Most importantly what would you guys do to have a cost effective but correct engine build to accommodate forced induction, trying to at least keep the cylinders that I have (replacements are not cheap!! and I find it a pity to change them since mine were found in top condition).
All the best,
Alexis
04-20-2020, 02:18 PM
#2
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There are a lot of discussions about compression ratio, check this for example:
https://rennlist.com/forums/964-foru...ion-ratio.html
Don't take me wrong but if you have to ask how to reduce compression ratio I suggest
you find someone who has added a turbo or supercharger to a 3.2 Porsche engine and
copy that. This is not so easy and can get really expensive really fast.
https://rennlist.com/forums/964-foru...ion-ratio.html
Don't take me wrong but if you have to ask how to reduce compression ratio I suggest
you find someone who has added a turbo or supercharger to a 3.2 Porsche engine and
copy that. This is not so easy and can get really expensive really fast.