dynamic CR for 87 octane

What dynamic CR should I shoot for to run reliably on 87 octane in a stroked Windsor?

Plan is for a 420 (418 40 over) with good aluminum heads, zero deck with quench in the 035 to 040 range, good cooling, and EFI.

I found a Popular Hotrodding story with a chart that suggested I'd need a dynamic CR of 7.4:1 with 160 degree thermostat and 7.1:1 with a 180 degree t-stat. Boy that's low. It will be hard to find a cam big enough to get that low (and work with EFI) without REALLY low static CR (huge chambers and deep dish piston.) Should I be worried that a large chamber will reduce swirl and promote detonation? Should I be looking at a smaller stroker just so I need less dish?

The GM 5300 Vortec LM4 (all aluminum) claims to be an 87 octane motor with 9.5:1 static CR. No way it's got enough cam to get the dynamic CR as low as the Popular Hotrodding chart suggests.

I didn't see/read the article, but I can tell you that the 87 octane requirement will limit your overall possibilities.

As far as DCR is concerned, the valve timing events will have the most impact.

Even pro engine builders have a tough time nailing down any specific "target" for a given application.

An example:

http://speedtalk.com/forum/viewtopic...&highlight=dcr

If it were me, I'd consider a custom cam.

Good luck. [img]/forums/images/smiles/icon_smile.gif[/img]
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Thanks for the link, good info.