Part 12: 13B Rotary Engine Rebuild - My 76 Mazda RX-5 Cosmo Restoration

Just as I promised last episode, it is finally time to build the engine! Part 12 of my RX-5 Cosmo restoration covers the entire process of building the 6 port 13B Mazda rotary engine. While this engine is a hybrid of GSL-SE RX-7 and Cosmo parts, the process is the same for any rotary from a 12A to a 13B NA, 13B turbo, 13B-REW or any other variant of the 13B. This video shows the whole process of the engine build, starting from measuring the rotors and covering everything else including clearancing the side seals, assembling the rotors, complete assembly the short block, setting the eccentric shaft end play and installing the front cover and everything underneath it. It's probably the most complete engine build video outside of what you can buy from the vendors, and as such, is an hour long. After this one, I'm going back to videos under 20 minutes. But for now, grab a beverage of your choice, sit back, and enjoy.

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Part 13: Clearing The Engine Bay - My 76 Mazda RX-5 Cosmo Restoration
With the engine built, it seemed logical to focus a bit on where that engine is to live: under the hood. Episode 13 has me stripping all the remaining mechanical components out of the engine bay in preparation for it to be blasted, repaired and painted. This is dirty grunt work, not particularly stimulating but at least it isn't sheet metal. It's been a while since my last update and rest assured, what you see here is only a small fraction of what has been done. I have plenty more footage ready to edit. Included in this episode: removing all engine bay mechanical components, removing brake lines and cylinders, labelling and removing wiring harnesses, removal of the steering gear, orderly disassembly of an engine bay.

The Mazda Rotary Engine Part 1
Educational film by Toyo Kogyo about the Mazda Rotary Engine. Shows how the Rotary engine works with comparisons to the Piston Engine. Also shows the Mazda RX500 test vehicle on a banked circuit and the Mazda Cosmo Sport (or 110S). Originates from the late 60's.

Part 14: Oil Pan! Engine Bay! Floor! - My 76 Mazda RX-5 Cosmo Restoration
Part 14 of my '76 RX-5 Cosmo restoration is a collection of three random tasks. First, I add a -10 AN fitting to the oil pan to serve as a turbo oil drain. Next, I continue stripping down the engine bay by scraping off the undercoating and then cleaning off the residue with kerosene. Finally, I begin some of the work on the floor by patching a small area on the drivers side of the transmission tunnel. Included in this episode: drilling a turbo oil drain hole in the oil pan, TIG welding a -10 AN flare to the pan, scraping engine bay undercoating, trying to clean it with Castrol Super Clean, cleaning the residue with kerosene, finding a few rust holes, cutting out a rusted area of the transmission tunnel, fabricating a patch panel, welding it in place, grinding the welds.

Part 25: Turbo Manifold Fabrication - My 76 Mazda RX-5 Cosmo Restoration
Episode 25 of my '76 Mazda RX-5 Cosmo restoration is another long one, covering in its entirety the fabrication of the turbocharger manifold. Suddenly the engine bay started to look a little cramped when I began to position the GT3076R, so it took some plumbing to build the required manifold. Constructed out of 1.5" SCH40 304 stainless steel pipe, it was fully TIG welded with an argon back purge. Yes, this is another long episode because I wanted to show the manifold fabrication process in glorious detail so that this video would be a useful resource for anyone wanting to build a custom turbo manifold. So as I say, grab your favourite adult beverage, sit back, and enjoy. Included in this episode: fabricating a 13B Exhaust flange, fabbing a merge collector, positioning a turbo in the engine bay, measuring, cutting and fitting stainless pipe and els, tacking in position, setting up a back purge, final welding, port matching, custom heat shields. A huge thank you to ATP turbo ( ) for helping out with some of the parts used in this episode.