Why do HEMI Rams have two spark plugs per cylinder

I know in rotary engines, since the combustion chamber is fairly long and flat, it would take too long for the fire from one plug to fill/burn the entire chamber, so they have two plugs to speed up the burn.

Could be something similar with the Hemi's? Either way, there's probably a list of benefits of using two plugs

The Nissan (Datsun back then) called their's the NapZ. It was a DOHC Hemi IIRC.

Thanks everyone

technically,
the dual sparkplugs allow less ignition timing before top dead center,
which reduces the 'wrong direction' pressure on the piston (called 'negative work')
and leads to slightly better torque and less fuel consumption

in one of the Chrysler histories there was an account of how Chrysler and Daimler engineers got together after the merger and shared previously confidential twin sparkplug research... and both sides admitted that they learned some new effects they had not known before

the gains are real but not large, in the 1 to 3% range

by the way,
the Datsun NapZ was inspired by the original Chrysler Hemi,
then in a turn around,
the NapZ good emissions performance as published in a SAE paper was used to argue successfully for the modern 5.7 Hemi V8

My 1971 250cc single cylinder 2 stroke CZ motocross motor cycle had two plugs per cylinder and two coils.

Wow, that's quite a mixed bag of responses.

Anyone want to take a guess what the power difference is between waste spark and firing both plugs in all 8 at the same time, on an otherwise stock 5.7?

6.7 jigawatts?

Hey DZ, you also have 2 plugs/mags a cylinder in ur prop so you dont foul a plug and lose the engine since you are usually taking off and landing with full rich (unless high elevation). I am sure when you've done your run ups before you ran into a semi fouled plug, then had to run up and lean the mixture, let run for a little till it cleaned up, then did your mag checks again. Now if only cars could have that leaning knob to coax a few more miles a gallon.

Mark

3hp advantage for waste spark vs firing both at the same time. This is a real, measured number not theoretical.