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| The 13B MSP has a huge stock intake port with a lot of duration. The odd little contours help control port timing and the bridge prevents side seal hang up. This is some what different from what rotary heads call a bridge intake port which is done to prevent the corner seal from falling out when the port is opened up toward the rotor housing to the max on an NA motor. The MSP has a bridged intake port from the factory. Mazdatrix does some minor recontouring to increase duration and overlap a little on the intakes. |
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| You can see the mild porting on the exhaust side here, Opening up the port increases duration and overlap. On the MSP engine you cannot open the exhaust port up too much as the port's location in the side housing can really heat up the sealing o-ring for the water jacket which can lead to premature failure if the o-ring gets hard and oxidized making it leak. You can see the witness mark for the o-ring and it is only about 1/4″ away from the hot exhaust port. Since this is a turbo engine, you don't want to go too far with port timing anyway as turbo rotaries don't like tons of overlap. Rotary exhaust is much hotter than a 4 stroke as exhaust flows out the port 3x per revolution versus every other revolution in a 4-stroke. |
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| This is the peripheral exhaust port in the 13B REW rotor housing. The Mazdatrix hybrid motor uses this rotor housing to gain more exhaust duration and overlap as well as more exhaust port area. |
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| Our article is not intended to be a guide to rebuilding a rotary, just a general overview. If you are going to do some engine work, we strongly suggest you purchase these DVD's from Mazdatrix. You can learn some tricks of the trade for building rotaries. |
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| Here Kyle is showing just how close the hot exhaust port is to the O-ring on the 13B MSP. |
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| Kyle preps the side housings for assembly by installing the o-rings and coating the sealing surfaces with Hylomar. Hylomar is one of the best sealants around. We recommend it for all engine work. |
