TALKING CIRCLES

IF YOU’VE had even a cursory interest in vehicles you’d no doubt have come across the legendary name Hemi, and the sly grin that comes across greybearded drag racers as they remember their misspent youths. So, what exactly is a Hemi? And why do people rant and rave about them? The principle is simple. Any engine, whether it’s diesel or petrol, needs a combustion chamber. Somewhere for air and fuel to be compressed, ignited and expanded in. The more efficient this chamber, the better fuel converts into mechanical power. Things like heat loss through the cylinder walls or head or uneven burns in the combustion chamber all sap power. Most engines run a combustion chamber with a relatively flat top, the Hemi by comparison runs a round or hemispherical-shaped combustion chamber in the head. The theory is a smaller surface area and more even efficient burn without the dead corners in a flattopped chamber produces more power. Is it the final word in engine technology? Absolutely not, but it’s cool as hell.