Here is a great example of why the Wallace DCR is useless. The example comes right from Mother Mopar!
Take the 426 Wedge [ not max wedge ] & the 426 Hemi. Same bore, stroke etc...
The specs to calculate the DCR are too all intents the same, identical except for rod length. The hemi rod is about 0.100" longer which will make a miniscule difference to the final number.
The hemi has a much better flowing intake port, bigger valves & would pack more air into the cyl. Yet that is not factored into the DCR calc. And the surface to volume ratio of two very different combustion chamber designs, with diffetrent burn characteristics & timing requirements, are not factored in either.
Take the 426 Wedge [ not max wedge ] & the 426 Hemi. Same bore, stroke etc...
The specs to calculate the DCR are too all intents the same, identical except for rod length. The hemi rod is about 0.100" longer which will make a miniscule difference to the final number.
The hemi has a much better flowing intake port, bigger valves & would pack more air into the cyl. Yet that is not factored into the DCR calc. And the surface to volume ratio of two very different combustion chamber designs, with diffetrent burn characteristics & timing requirements, are not factored in either.















