Aluminum heads

Phreakish said

Here's a decent lecture I found on heat transfer:
http://web.mit.edu/2.61/www/Lecture notes/Lec. 18 Heat transf.pdf

Without the accompanying notes, it's incomplete. However, there are useful bits there. In-chamber temperature is lower on an aluminum head (slide 22, page 11). This makes sense. But the amount of energy removed won't be any greater with the aluminum head. The greater conductivity and lower resistance means that for the same energy 'wicked' away, the resultant temperature of the chamber walls will end up being lower.

The lecture also points out that convection is the main means by which heat is conducted, and that until ignition happens, there's little convection going on and so little heat transfer.

One of the slides also lists the exhaust valve and the spark plug as the hottest items in the chamber - which would suggest that proper mixture and spark plug selection matter more when it comes to pre-ignition than cylinder head material.

Click to expand...

Exactly. Spark plugs have been around since the invention of the IC engine, and yet way too many are woefully ignorant of how to select and read a spark plug.

The information has been out there for decades. With the web, it's become even easier to find the information and learn how to do it. All the EFI whatever and such means nothing if you can't read a plug. There is no one size fits all A/F ratio for all engines. Get the plugs correct and happy and THAT is what YOUR A/F ratio should be.

In another thread I talked about CR, pump gas and tune up. That's another reason I know I can run more CR than the nattering nabobs love to prattle on about.

And you'd be surprised how many people I've offered to teach plug reading and only two took me up on it. Guys want a plug and play, fast food, convenience store build but they also was 580 HP and a butter smooth 500 RPM idle like their boring assed Camry. But they don't expect the Camry to make 580 HP.

It's just plain mental and experimental laziness.