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KobaltBlau KobaltBlau is offline
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Join Date: Mar 2004
Location: City of Seattle, WA
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Here's the quote from beepbeep from another thread:

Speaking about chamber design, domed pistons are usually big no-no when it comes to knock resistance. You want your combustion chamber free of sharp edges and slightly spherical. This is little easier to achieve when you have four small valves instead of two big ones.
Well, what if you have flat pistons in a Hemispherical 2 valve combustion chamber? Are slightly dished pistons in a shallow pent roof somehow better?

Furthermore, an SC piston for example has a pretty gentle dome. Can the squish near TDC cause any (just slightly early) pre-ignition?

One big thing is that if you have a single plug in a hemispherical 2 valve chamber, you have to run more ignition advance than you would in a pent roof 4 valve with center plug. And if I remember correctly, more advance can cause detonation on a turbo engine. can anyone clarify this a little more?

Too bad stephen kaspar doesn't hang out here, he might have some ideas.
Old 07-29-2004, 02:06 PM
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