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Hopefully you meant a 3cc valve relief...

July 9 2011 at 7:23 AM
Brent Lykins, B2 Motorsports  (Login blykins)
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Response to Streetable compression question

A negative volume would be a dome piston.

I looked in the lobe catalog and saw that there were a couple of 236° hydraulic roller lobes. One was at 286° advertised and one was at 288° advertised. I used the smaller one for my calculations.

With a 3cc valve relief, the SCR would be at 11:1 and the DCR would be over 8.4:1.

With a domed piston, the SCR would be at 11.8 and the DCR doesn't matter at that point.

An 8.4 DCR would require everything to be right in the world to run on 93 octane. No hot spots on the pistons, perfect quench, etc.

Knowing that the heads usually cc a little more than advertised and the cams have a little more "true" duration to them seat to seat, I think you could get away with it if you play the rest of your cards right.

Brent Lykins
B2 Motorsports, LLC

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