July 31, 2015 9:41 am - Published by

As it turns out mounting a rotary with the right parts in a mk1 5 isn’t the hardest thing to do, it’s all about smart part selection.

Straight away people reading who know rotaries will be going, “well if you’re talking about smart part selection why are you using a renesis engine”. That boys and girls who think they know better is my choice to go NA and Rev to 11k screaming past all of you with turbos too big and not enough airflow.

The renesis engine is reviewed as a poor rotary engine with only 2 oil injectors per rotor instead of the usual 3, and some clever exhaust port design by mazda means it is more frugal on fuel, cleaner and more suited to natural aspiration. The rotors are a lighter and the intake is mad clever with a series of valves to give a smooth torque curve through the Rev range.


So now the haters are appeased, by using the tail section of a standard mx5 5-speed gearbox fitted onto the rx7 FC gearbox I can retail the standard shifter location, and the entire standard tear end and propshaft, making my life very easy indeed!


So once the gearbox was sorted I considered using the 12a rotary front panel and the 13b rx7 water pump housing, pictured above, as mazda didn’t really change the design too much (a couple of bolt holes moved) so it all bolts up!

Then there were issues with mounting the oil injection system properly and having to get an adapter made up.

Then I lost my unit! The landlord, or so I thought, wasn’t the landlord and was subletting it to me, so everything went on hold and I had to find a new place to put the car. Fortunately I have a very understanding girlfriend with a car port ?.

During this period of not working on my car the smart part selction continued.


As I was using the rx7 gearbox I needed an rx7 flywheel.
http://www.rotaryresurrection.com/2ndgen/tech_na_t2_drivetrain_differ.html

Thanks to a handy guide at rotary resurrection in regards to flywheel differences, turns out the rx8 and turbo models use a larger 330mm ring gear flywheel which won’t fit my gearbox.

So ordered up a rx7 lightweight flywheel made by fidenza and I was on my way! The important part here is the counterweight you use, as its matched to the weight of the rotors in the engine! If I used an rx7 one the engine would have shaken itself apart, so I had to use an rx8 automatic counterweight.

With a few hard to source parts I gave Daniel at Apex rotary a call, hands down the second nicest person I’ve met (first nicest being my girlfriend who has an mx5 in pieces on her drive).

If you need a rotary spare part for a decent price, or an engine rebuild he is your man! He has an aladdins cave of rotary parts from a 20b engine to mad little 10a rotors, and all the easy stuff in between. After some hands on time at a work bench, Daniel pointed out that a renesis 192 friction plate fitted my flywheel and all I needed was a rx7 clutch cover! As Daniel knows a guy who can re manufacture clutches I left it with him and will get a stage 1 capable clutch in a standard clutch body.


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