Paging Paging - ROTARY EXPERIENCED

got boost? got a pretty engine bay? stuck in gear? rebuild your shifter and then post here
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RevolverRob
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Paging Paging - ROTARY EXPERIENCED

postby RevolverRob » 04/18/17 @ 14:19

CorkSport - Derrick and others who may have extensive experience with rotary engines.

Sitting around, contemplating whether or not to Miata swap my Sunbeam, another alternative came up - a rotary. Specifically, thinking an NA Carbed 12A either basically stock or street ported. The wife really likes this idea and I like it too. Because it's a smaller, lighter engine that definitely produces more power in stock form than even a very hotted up Sunbeam engine. And the size should save my considerable trouble in terms of swapping the motor in related to steering (why the Tigers suck is they had to radically change steering to fit the V8). Plus, it appears freshly rebuilt 12As and 5-speed trans are ~$2-2500 in price and frankly that's what I was going to spend overhauling (not even properly rebuilding) my Sunbeam motor.

So, those with experience, yay or nay? You're spending my money, but I have a limited budget currently, I need a running/driving car by September of this year and I've got about $3k to spend on overhaul/rebuild and/or engine swap.
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RevolverRob
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Re: Paging Paging - ROTARY EXPERIENCED

postby RevolverRob » 04/18/17 @ 14:23

Additional thoughts. COOLING ISSUES. I've already got cooling issues in this car. Are there overheating issues with rotaries (specifically 12As) that I need to be aware of? I'm planning on fitting a fan shroud and a big paddle-type pusher fan on the front side to go with a paddle-type puller within the shroud. Which should help considerably, but this little British engines just aren't efficient in terms of cooling.
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theAngryMarmot
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Re: Paging Paging - ROTARY EXPERIENCED

postby theAngryMarmot » 04/22/17 @ 22:46

I have found that running two fans (in a pusher and puller) configuration doesn't help. Sometimes it is actually detrimental to the cooling of the car. I see it all the time at the shop. Go with a single, high cfm, efficient s-blade style fan. A good fan, in a pull type configuration is the best.

I prefer to wire the fan to a relay, and use a temp switch to signal it to turn on. This is simple, and most reliable method.

We use a matched fan/shroud combo from a company called Cooling Solutions. They are very nice, and available in several sizes. I have installed at least 30 of them, and they have no issues cooling even big-block cars with A/C.

Go with a quality aluminum radiator - and I usually install a sacrificial anode into the petcock port. Cooling isn't hard - just go with what works and don't overthink it. Good fan + good shroud + clean, correct cooling system = no problems.

I deal with vintage cooling issues daily.

As far as rotary swapping, that is your preference. Personally I would probably go with a vintage/period solid lifter 289 w/ light flywheel, moderate cam and a 4 speed - but that is just me.
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RevolverRob
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Re: Paging Paging - ROTARY EXPERIENCED

postby RevolverRob » 04/24/17 @ 15:03

Well, I have a 302 and front-shift T5, but the bottom line is that the V8 swap is much more intensive.

To go V8 I need to do firewall cutting and trans-tunnel fabrication. I need to swap the front suspension. Install a steering rack, replace the steering column. Re-do the steering arms, tie-rod ends, and motor mounts. I also have to cut 2.5" holes in the passenger-side frame-rails to route exhaust. And I have to swap in a narrowed rear-end of some type (Dana 44 is the original, but Ford 8" is more likely). Build a driveshaft of some sort. I also need to remote mount the clutch and brake MCs.

Meanwhile, back on the rotary front I have to...

Fabricate some front motor mounts. Cut a new hole for the shifter (no other trans tunnel mods). Make a trans crossmember. Re-do the driveshaft. Build a custom header to route the exhaust out properly. No steering, no suspension, no major modifications to the structure of the car. I don't even have to replace the rear-end if I don't go crazy on power output from the rotary. I spoke with a guy who has been doing rotary stuff for 3-decades this morning. I'm told a carb'ed 12A with mild-street porting should net me about 150-horsepower or so, with dead nuts reliability. Nothing special really needed, just clean up, rebuild, new seals, tune the carburetor for the street porting. He is local to my dad and the car, so I'll probably go to him for tuning and any additional work I need.

As for cooling. I looked it over and I may be able to use a 1st-gen RX7 crossflow aluminum rad, with an RX7 shroud in the car (they are only about 1" taller and are virtually the same width. Factory they have excellent mechanical fans. But I might switch to an electric to slim the package down. My current pusher is wired on a relay, but is manually switched in the cockpit, because I want to be able to run it, with the motor off. Although, I realized recently that with the motor off, you're not pumping water, so blowing air through the rad doesn't really do much... :suicide:

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