Yep. The plugs would thread in from the top, in the center of the hemispherical combustion chamber. There would be no distributor due to the EFI system. So basically we're describing a Toyota cylinder head...!

Dang, did not notice the haiku. Nice one, Dan...

Lou

_________________
Home of Slant6-powered fun machines since 1988

I guess that is a special racing head or sumptin?? Pretty sure I don't have one on my car yet!!

_________________
2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

but you really don't want a hemispherical combustion chamber, the valve layout gets complicated and Hemi's are really not that efficient, to the extent what Chrysler touts
today as Hemi, is not.

what you want is a pent roof chamber, you get a truly central spark plug with four valves
https://www.privatefleet.com.au/glossar ... roof-head/

or a wedge with a lot of squish, if going two valve

_________________
Doo Ron Ron and the Duke of Earl are friends of mine.....
https://www.youtube.com/watch?v=uX8Nj8ABEI8

It's a brand of spark plug; wars have been fought.

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

The LS and LV3 two valve heads do okay. If not for Cummins and "Hemi" I doubt Ram trucks would be as popular. Hemi is a smart branding.

The BMW S54 ( E46 M3 ) is a 198 cubic inch motor with a 3.43-inch bore. Very sophisticated motor with dry sump. If you have a good head the small bore can work, but the power comes at very high RPM. Probably the best effort is to build a better turbo or supercharged slant six and get more power at 3,500 rpm. The 4.2 XK6 Jaguar had a decent head but they had to beef up the block so much that it was kind of heavy - horsepower was at higher rpm. With the 3.40 bore and 4.19-inch stroke it would break the block at high rpm, so the block became heavier, but that motor made good low speed torque. The last use of the XK six was in a military vehicle - great lugging motor. The 3.8 E-type was fun in a very light car, not so much fun in a 4,200 lb sedan. The 2JZ is a great motor when turbocharged, we probably should think of boost more than more sophisticated design.

EDIT - the Jaguar 4.2 has a 3.625-inch bore ( 4.1732-stroke) with siamesed cylinders. 1&2 are paired - moved slightly closer together as were 3&4 and 5&6 - to maximize the bore on the 4-inch spacing. As they were concerned about cylinder wall thickness, sleeves were used. In warmer regions of the U.S. the material between cylinders is known to crack from overheating, but that was uncommon in Europe. A large bore slant six block would have to deal with the same technical issues - sixty years later and better technology