Quote:
Originally Posted by Two Shoes
How so? Because it keeps particulates out of the intake? I'm new to all this and very curious. I've read a couple sites that say the recirculated exhaust actually cools the combustion process.
Thanks.
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That does apply to gasoline engines more so than ours. What you read is correct, it is to slow the combustion process and stop spark knock. Since diesels ignite under compression, by design, optimal spark timing and reducing knock are not truly 'part of the equation.' Stopping the soot is the key to long engine life.
Once you've stopped the soot, think of it this way...
Octane (either the molecule or the fuel's octane rating) is to REDUCE ignition under compression. Cetane (also, both a molecule and a rating) is to PROMOTE ignition under compression.