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zarpoxx zarpoxx is offline
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Join Date: Nov 2008
Posts: 13
Porsche Crest Please advice: Maximum RC with CIS.


firstly, let me introduce myself: My name is Gisleno and I'm from Madrid (Spain) . I have a 964 3.3 turbo with the following modifications:

Sc cams (Option X33 )
K27 HFS (for sell)
1 bar
GSF headers
Cat bypass
Bypass waste gate
KN air filter
Forge Diverter valve

With the original turbo (K 27 7200) gave 415 hp at the flywheel.

I intend to make deeper changes, but keeping the CIS which I have the following questions:

I would like to improve the off boost mode (performance and response), but I do not know what the RC I must to go (taking into account a maximum pressure of 1 bar blowing, but if you say that is too risky could lower it to 0.7 or 0.8).

You see dangerous operation at 8.5 RC? And a 8.0 RC?

My choices would be:

1. Install only 97 mm pistons of JE Pistons RC 8.0 to 1
2. Install only 97 mm pistons of JE Pistons RC 8.5 to 1
3. Install Mahle pistons and cylinders with 3.4 RC 7.5 to 1 or 8.0 to 1.
4. Install Mahle pistons and cylinders with 3.3 RC 8.0 to 1 ( I donīt know if this option is possible)

What option for you is most advisable? Do you recomend JE pistons? I have read that JE pistons with Mahle cylinders cold make noise (due the different tolerance between materials), but that means I will have problems? They will have durability?

What is the real gains that I could expect from these changes? It is worthy? What is the total amount of horse power that I could expect?

which is the theoretical limit between CIS and RC?

Which is the theoretical limit between RC and 1 bar boost (with CIS)? And with 0.8 bar?

On the other hand, as I will do a complete review, could you say to me what pieces should change (valve springs, ect ...)

Thank you very much in advance

P.D: A picture of my car:

Old 11-23-2008, 03:58 AM
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