12a/13b porting

[catboy]

I know there are templates available (racing beat, etc) for the 13b engine, but is there anything similar for the 12a?

I would be looking for a street port, or maybe even a bridge, but would ideally want to do it myself, unless its cheap-ish to get someone else to do it for me...       ...I would be doing the re-build myself anyway, so the cost isnt going to be extortionate anyway (hopefully! )

Also, what sort of power can be expected from a street or bridge-port engine with a fat carb (45 or 48) and free-flowing exhaust/induction?

Thanks in advance

b

[MikeLMR]

Racing beat do templates for 12a\'s

e.g. http://www.racingbeat.com/resultset.asp?PartNumber=22201

wouldn\'t like to hazzard an accurate guess at HP but 150+ for a street port and 170+ for a bridgey would be conservative guesses I think.

Might be worth talking to one of the specialists, such as Carl Hayward at //www.mazdarotary.co.uk

~ Mike

[20B_boy]

Tim/RX Motors has built and ported a few 12a\'s in his time - may be give him a tinkle too...

[catboy]

cheers guys...    its preliminary info gathering at the moment...    Looking for about 150bhp, but I love the sound of bridge-ports, so Im being drawn in that direction

its to go in something with a est. kerb weight of 450-500kgs, so 175 should be ample power (for the time being ) and I was looking for a more-simple lump than an EGi (too much wiring and other junk! ) so the earlier carb engine should be fine

I notice there are intake and exhaust templates; I am thinking of a bridge port template for the intake, however Im not really sure how extreme I would need to go on the exhaust; there is a streetable exhaust port and a race exhaust port template...    Im thinking the streetable port will be a considerably improved port over std., and so this should be enough to cope with 175-200bhp, however dont really want to have to take the engine back to bits again a couple of months down the line...    ...is exhaust port-sizing important (as on a 2-stroke engine) or is it a case of bigger-is-better?...     Im going to be building an exhaust system for the car, so manifolds and things to suit the larger ports are not an issue