Gadgetory

four little letters one big burly word synonymous with high power engines and Mopar vehicles for decades and resurgent ly lately but what does it mean Hemi is short for hemispherical okay why that's a big deal to an engine makes for an interesting story what better place to tell the story of the Hemi than the most famous place that ever built them up Keith black racing engines here in LA I can't so here we are legendary Keith black racing engines how long's this place been here since 1966 Keith black Ken's father began building hot engines for his and his friends race boats in the late 50s Chrysler came calling in 1965 asking Keith to work over there 426 hemi z4 dragsters funny cars and boats soon the Hemi engine was almost a household word by the late 60s and early 70s Dodge Hemi Chargers and Plymouth Hemi Cudas were becoming among the most fabled American muscle cars and today among the most valuable what do these engines do that almost nothing else can do oh it's just the amount of power you can obtain from them because of the design of the hemispherical combustion chamber and Hemi comes from what what is it refer to four hemispherical B the terminology so what are we looking at here this is what kind of a head this is a wedge head this is basically a conventional wedge type design head notice how the intake and exhaust valves line up but side by side across the airflow in the combustion chamber in a Hemi head they're opposite each other and you can actually get larger valve sizes in there the advantage this is the cross flow of the intake to the exhaust puts a bitter swirl on the mixture and with the sparkplug being in the center it fires off in the center of the mixture which is right over the top of the piston that gives it a better question down in the cylinder boring yeah so disadvantages well downside looking for manufacturers viewpoint as it takes a lot more to produce a Hindi head and make it work than it would a wedge it this is the layout for the valve setup your intake valves across here and exhaust valves across here and because they're opposing each other this way you have to now be able to open and close valves so now that accomplish that is be pretty tough to have one shaft inner so what they have and Chrysler did all this stuff then the engineer did all is they have a rocker stand set up and all that apparatus makes for a wide head design and a wider engine at a time when every millimeter under the hood is valuable real estate is it an efficient a fuel efficient designers it more of a power design it's boy if you talk about you know still annoyed x' and everything else I think it'd probably be in my opinion more of a power do you know efficiency this is making power the old way right yeah yeah the old-school me not yeah they don't use the same kind of Pistons that other engines do no they're unique to their own application because of the hemispherical design of the chamber for a high compression twelve and a half to one you need a piston it has more of a dome on it to be able to compress it and it also form in the shape of the chamber along with that there's a little downside to a dome with piston right yes they're a little bit heavier quite a bit heavier yeah you see this guy it's a big chunk of mount it's big yeah and the problem being when you have that if you're trying to make a high-revving engine you've got to pull this thing back every time I come to the top of the stroke it's got to be pulled back down by the rod again and it's a lot of weight to keep pulling back so for the modern engine maker is trying to do a high rpm small narrow light engine there are a number of things about a traditional Hemi that doesn't really go they're not there's not a desirable feature you want a lighter weight piston and you don't want to rev them a lot higher so yeah no boring stuff so that would not be conducive for what they're trying to do now yeah this remains a very specialized red-blooded American in of course you