Are BMW engines "hemi's" :)

[Russell]

Technically, they are similar, yet more sophisticated, than the Chrysler Hemi engines. Am I correct, or am I missing something?

Just a little triva/puzzler for the day.

[Bill R.]

hemi.... Hemi is a meaningless term that only describes the combustion chamber shape. It means that the combustion chamber is hemispherical in shape. Its no indicator of how sophisticated or technically advanced the engine design is.

Technically, they are similar, yet more sophisticated, than the Chrysler Hemi engines. Am I correct, or am I missing something?

Just a little triva/puzzler for the day.

[Russell]

The sparkplug location is similar on both engines was the basis for my thinking.

hemi.... Hemi is a meaningless term that only describes the combustion chamber shape. It means that the combustion chamber is hemispherical in shape. Its no indicator of how sophisticated or technically advanced the engine design is.

[Bill R.]

The chrysler hemi looks like this on my brothers donovan motor
This is what the M50 head looks like, you can't tell it but the combustion chamber shape is different, even discounting the 4 valves instead of 2













TE=Russell]The sparkplug location is similar on both engines was the basis for my thinking.[/QUOTE]

[632 Regal]

of 4 valves per cyl., it would make much more HP and torque but in a smaller torque band. it wouldnt have the advantage of the 2 valve design "pulling" the charge through the chamber at high RPM's and that would make it a slug in comparison.

Or something like that.

[Russ in Seattle]

One of the main things that distiguishes a hemi is its ability to breath. Notice in the picture that the two valves are 180 degrees opposite each other? They did this with two rocker-arm shafts per head, one for the intake valves and the other for the exhaust valves.

[Russell]

The chrysler hemi looks like this on my brothers donovan motor
This is what the M50 head looks like, you can't tell it but the combustion chamber shape is different, even discounting the 4 valves instead of 2













TE=Russell]The sparkplug location is similar on both engines was the basis for my thinking.

[/QUOTE]

[DueyT]

Bill, do you have the pic of the guy that stuffed a feather through the ports on a Mopar hemi? It really shows the straight in/out geometry and breathing characterstics!

On a different note, are the M60 pistons domed? If not, these engines wouldn't have a whole lot of quench...mind you, they are aluminum, which helps...

Cheers,
Duey

[MikeV]

One of the main things that distiguishes a hemi is its ability to breath.

Respectfully disagree, nearly any decent 4-valve design will 'breathe' better than a 180deg 2-valve.... The reason this hemi is 2v is either because of cost (it's cheaper) or because it does not particulary need to breathe that well. In it's current incarnation (5.7L 350? HP truck engine) it's built for low-end torque, not free-rev'ing HP. My best guess would be that the more restrictive 2V design gives higher-velocity exhaust outflow at low RPMs, yielding more torque. Cheaper is always a + at DC, too.

Marketing gimmick. I'm pretty sure every manufacturer in the world are not scratching their heads and wondering "why did I spend all that money on combustion chamber design when I sould have just made it semi-hemispherical?" I do love it when the kid in the Durango commercial says "Heamey," tho...

[ryan roopnarine]

the reliable folk at howstuffworks has prepared a page on how hemis specifically work

http://auto.howstuffworks.com/hemi.htm

looks like mercedes has been rubbing off a little hard on the chrystler end of things......the article says that the new hemi has 2 spark plugs per cylinder.