The attached photo is of a 4 rotor engine constructed by joining two 13B
engines........It was built by "Granny's Speed Shop" in Concrete, WA and run
in an Outlaw Racer for a year or so..........What is particularly interesting to
me is the cooling system.........Since the rear engine could not run the water-pump in the normal position the front engine pump had a plate that was blocking the normal coolant inlet and outlet of the front housing......The
pump was modified with an outlet on top and coolant was feed to a manifold and then to a fitting threaded into the top of the center housing
and slightly toward the spark-plug side on each 13B........This was the coolant
inlet.........The outlet fitting (back to the radiator) was threaded to a plate covering the opening on the center housing where the EGR valve is bolted on 86-88 13B's........89 and later 13B's did not use this same EGR valve so there is just a flat spot that would also have to be drilled and threaded...........
The coolant circulation was from the pump to the inlet fitting of the
center housing........Then horizontally through the coolant galleys to the front and rear housings of the spark plug (combustion) side then clockwise (from the front of the engine) to the exhaust/intake side of the engine and
back to the outlet fitting of the center housing and on to the radiator.......
The interesting thing about all of this is the fact that it addresses one
of the problems with the stock 13B cooling system........The coolant flow
of the stock system always cools the front rotor first then this heated
coolant flows to the rear rotor........The rear rotor always runs measurably
hotter for this reason and is usually the first one to fail from heat related
reasons............This might be a way to address the cooling problems that
the higher output Rotarys (high rpm/turbocharged) can encounter.....FWIW
------------------------------------------------------------------------------------------------------
The water pump housing is modified so that the output can not flow into the front engine from the front housing, but instead is re-directed into an external distribution manifold. From here, the coolant is split and directed into the top of the center housing of each engine. The modified rotor housing coolant flow is into each center housing from the top, clockwise (from the front) around to the top on the right side, cooling the combustion side of the engine first, then to exit ports that return the coolant to the radiator. No thermostat is used, only center housing outlet restrictors to regulate coolant flow rates and engine temperature.