"hemi" heads?

chevy38fan · September 10, 2003

There's a debate on one of the dodge forums as to wether or not most modern day engines use hemispherical heads or not. I know some are somewhat hemispherically shaped, but others are still wedge shaped..

So my question is, does GM use hemispherical heads on their 4.8, 5.3, 6.0, and 8.1 Gas motors?

what about the LS1/LS6 motors?

Rotorwrench · September 10, 2003

Nope, they are all wedge shaped. On a true hemisherical head the spark plug goes through the valve cover into the cylinder head with a valve on each side. The valves are not in a straight row front to back. Intake valves are on the intake side of the head and exhaust vavles are on the exhaust side.

speedshifter · September 17, 2003

so you could probably consider a DOHC motor like the northstar a hemi right? i mean it fits all the criteria with the exception of 4 valves instead of two.

01Burb · September 18, 2003

Yes. A DOHC engine by design, has it's valves on 'opposite' sides of the chamber with the plug (or plugs) in the middle.

CMNTMXR81 · September 18, 2003

Many DOHC engines have a pentroof or angular chamber in design. A true "hemispherical" chamber is more round/rounded in it's design.

speedshifter · September 18, 2003

This is true, i was just reading what Rotorwrench posted about what charachteristics a hemi has, and the Northstar popped in my mind and fits those requirements. Working on Northstars all the caddy dealer, they just seem to be a familiar motor to me.

Isn't also true that all the Mopar Hemi's are pushrod motors? Or is the new one OHC?

cyrylyn · September 19, 2003

the new series of vortec engine heads aren't just wedge, they're high-swirl.

tjl5709 · January 17, 2004

The 5.7L HEMI is indeed a push rod motor.

This was observed at their NAIAS display.

bigdogs · January 17, 2004

I remember reading awhile ago that GM also made a hemi head back in the 60's (if I remember correctly even before Chrysler) but it was just a prototype and never made it into production as they thought it was too expensive.

Tucson_02Silverado · January 17, 2004

Diamler is confusing everyone with "HEMI" and just using the word "HEMI" to describe their new 5.7L engine.

Mopar "HEMI" heritage started (someone correct me if wrong, I'm not a Mopar historian) in the late 50's with the Chrysler 300 as a 392CI using hemispherical heads. The current floating lore of the "HEMI" is thought of as the late 60's 426CI as used in NASCAR, SuperBird-DaytonaCharger.

Diamler ads never say 5.7L "HEMI", just "HEMI" and will show a 5.7L intake cover as a way to avoid someone legally demanding a 426CI in their truck instead of a 357CI. Had Diamler been smarter they should have just call'd them Powered by Magnum 357 as a reverse word play on the handgun cartridge.

Shark Bait · January 18, 2004

Tuscon 02Silverado Not to quibble but the Chrysler "Hemi" thing started back in about 1953 with the original 331 CI used in Chyslers, Dodges, etc. It then went to 354 ci (just an overbored 331) in the late 50s, then to 392ci and finally 426ci.

You are correct in that when people think of a "Hemi" they are most likely thinking of the 392 and/or 426 versions. The old 331 was a "Hemi" but it weighted a ton and produced very little power unless highly modified.

Not being a Chyrsler lover I have no information about the new 5.7 "Hemi" configuration. I will bet however that the 8.1 Vortec heads are as good if not better than the Chrysler 5.7 "Hemi" heads. Seems to me Chrysler is just trying to get a lot of advertising mileage from the old "Hemi Ledgend". A friend had a 1965 or 66 "Street Hemi" and it was one bad car right off of the assembly line. The "Old 426 Hemis" were very, very strong!!!!

A long time ago I took a 331 Hemi, bored it to 354, put lots of carbs (6X 2bbls) and internal parts in it, coupled it to an early 50s Cad-Lassall 3 speed manual transmission and an Oldsmobile rear end and stuffed the whole mess into a 1953 Studebaker. Was kinda a neat streed/drag car - but very, very crude by todays standards.

C1500 · February 1, 2004

Diamler is confusing everyone with "HEMI" and just using the word "HEMI" to describe their new 5.7L engine.

Diamler ads never say 5.7L "HEMI", just "HEMI" and will show a 5.7L intake cover as a way to avoid someone legally demanding a 426CI in their truck instead of a 357CI. Had Diamler been smarter they should have just call'd them Powered by Magnum 357 as a reverse word play on the handgun cartridge.

Go to the Dodge website and you will see the engine specified as "5.7 Liter Hemi"

k1500chevy97 · February 2, 2004

The ads should say "5.7 litre HYPE"

Hemi_#1 · June 4, 2004

First of all you guys clearly have no idea what you are talking about because chev was rated the worst truck of the year. they are lacking in power, ground clearance and there down right good for nothing. And i saw someone advertising that they had a 98 chev with a 4.3L o no stand back he might run me over. HAHAHAHA! You guys should get your thumb out of your but and get a real truck. A hemi