I think quench would be helpful for a fuel economy motor that had improved drivability. I don't think the lowest grade fuel could be used with much quench, which would likely make the extra fuel economy more expensive. My target is 9.5 to less than 10 CR, just a little quench could be used for that. There are easier ways to make horsepower, but there are fewer shortcuts to fuel economy.

Has anyone else read "Power Secrets" by Smokey Yunick? He discusses moving the rings up on a big-block Chev (I think it was) so the top ring is just 0.15" below the piston deck, and getting a substantial (15%) reduction in unburned hydrocarbons because no more dead space between piston and cylinder, above top ring, for hydrocarbons to "hide" from the flame.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm not aiming to push limits, would like to use 87 octane gasoline. My daily driver has a claimed 9.8 CR and uses 87 fuel. Its an 8 valve four cylinder with wedge chambers. It is an alloy head which allows some heat to be lost. The chamber opposite side of the spark plug has a small flat area. Its a conservative 80s design. I read that the first year of this motor used a bowl shaped hemi chamber, but after the first year went to a wedge chamber which in most regards resembles a slant six. I get 48 MPG by virtue of the light weight and my driving habits. A new motor could do better with the weight factor of this car. I figure a 170 in a '64 Valiant could do 30+ MPG

CNC-Dude a new head would be great, but there are so many preferences that project would be more difficult than just the technical hurdles. I probably will only increase the compression, as I think that would help the torque and economy. The LA Magnum head is a good design, lots of ideas if somebody did build a new head, but most can do okay with the stock head.The '70s Datsun L-series closed chamber "peanut" heads was not bad for a simple design http://3.bp.blogspot.com/-m3xYeuZCpg0/T ... _pic12.png

I took an inline race head that I already manufacture to the Slant 6 banquet last year and got some input from the racers as to what they would like to see in one for the Slants. It likely wouldn't be too street friendly because of the larger ports and higher compression potential.
Anyway, here's a 3D model of the rocker arm body for the new Slant 6 roller rocker i'm fixing to put into production. It will be available in both a 1.5 and 1.6 ratio.

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There's no such thing as too much cam....only not enough engine!

Interesting idea. Can this be accomplished with pistons that will fit a slant?

Sam

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Sam, the short answer is no because it has to work in conjunction with a quench type chamber and having the optimum quench distance of between .040"-.060". In a slant that has between .140"-.180" deck height, and another .125" or more of dead space across the whole chamber above the piston, plus the head gasket volume additionally, simply moving the rings higher wouldn't accomplish anything by itself because you simply have too much void with its open chamber design. Also, the .150" top ring position that Smokey is referring to is now the standard today for all racing piston companies like JE, Venolia and most others unless you specify otherwise.

That's why a new head would provide a lot of valuable modern features that are proven and in use by all other performance cylinder head manufacturers like Brodix, World Products, Dart, Edelbrock.

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There's no such thing as too much cam....only not enough engine!

Sign me up for that new head