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How do they vary the C/R across the range of same-capacity engines?

blind_elk

By blind_elk,
in General Automotive Discussion

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blind_elk Grand Master

blind_elk

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I've got a RB20DET block sitting in the garage. I intend to have it rebuilt, with full blue-print / balance.

I would like a bit of extra performance, but I'm not prepared to go as far as forged pistons.

In the RB series, there is a RB20E (C/R = 9.5), RB20DE (C/R = 10.2), and RB20DET (C/R = 8.5). All the engines are the same bore/stroke, so presumably the pistons are interchangeable.

Would it be possible to simply use a piston from a RB20E to change the C/R of my new engine, so I get a bit better off-boost performance?

TIA

FitzTech Rookie

FitzTech

Posted
Posted

The head and head gaskets vary slightly as well as the throttle body diameter. there are a few other negligible things that are different. yeah sure you could use those pistons for better off boost performance but remember that you wont be able to run as much boost otherwise you'll suffer from detonation. If u do decide to use those pistons i suggest you use a thicker head gasket (1.6mm should do it) and also get your head ported so really after you look at it it might be cheaper to use forged pistons anyway. hope ive helped

blind_elk Grand Master

blind_elk

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Posted

Using a thicker head gasket sort of defeats the purpose.

I don't intend to run more than 1 bar of boost (famous last words), so I'm confident the RB20E (9.5 C/R) piston could easily handle it. And I'll be getting the ECU reprogrammed to suit.

So, can anyone supply me with a RB20E piston, or at least the full specs (like pin height, pin-to-crown, etc) so I can work out if it will easily fit.

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