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Nice! I'll be following this. I recently did a 4 port Renesis swap in my '79. I went with a Holley carb, used the 12A front cover, and kept the stock transmission. Runs so beautifully. I can't wait to see how yours turns out. I'm considering adding the 6 speed at some point.
What did both of you do for the water pump? The Renesis pump bolts to the Renesis front cover and an older pump housing doesn't fit the Renesis front iron.
What did both of you do for the water pump? The Renesis pump bolts to the Renesis front cover and an older pump housing doesn't fit the Renesis front iron.
The FD water pump will fit the front of the 13B Renesis .. however I opted for an EWP.
Interesting! With all of the front mount and oil pan mods, did you consider a rack and pinion steering setup?
If you have a front mounted steering rack in your 1st gen .. then you can most definitely use the Renesis stock oil pan.
Chip and I discussed a number of different options for the steering .. however time restraints required steering upgrades to be put on hold for now. Chip is a one-man-show .. and he already works some insane hours just to keep up with demand.
Towards the end of this project, I will review some of design options that will impact the amount of fabrication required and the final cost.
I opted to use the RX8 S1 6-speed manual transmission. No problem lining up the shifter in the stock location in my SA .. however the RX8 tranny required a custom mounting bracket and a custom drive shaft.
For a budget swap, I think you can use the stock SA 5-speed manual transmission and maintain the stock transmission mounting bracket and drive shaft. You may have to use the bell housing from the RX8.
Q. Do I need to upgrade my stock cooling system for a 13B MSP swap?
A. No, you don't have to upgrade your stock cooling system .. but you should.
According to Racing Beat:
"The water cooling system is responsible for rejecting roughly two-thirds of the engine heat, while the oil cooling system rejects the remaining roughly one-third of engine heat. To ensure maximum engine life it is essential that a large, well-designed radiator be used."
More power means more heat load. When you modify your stock engine or engine swap your RX7 to a higher output engine, you should upgrade your cooling system to meet the demands of the increased heat load.
Increasing the width, height and thickness of the radiator will increase the surface area of the heat exchanger. More tubes and fins mean better heat transfer between the coolant inside the radiator and the air passing through it. Upgrading to a larger aluminum radiator will help to reduce the risk of overheating. An aluminum radiator will also be more corrosion resistant, and can handle higher pressures.
Don't forget that oil performs a large percentage of engine cooling in rotary engines, since there are no coolant passages for the rotors, rotor bearings or eccentric shaft.
A stock SA 12A uses an oil cooler mounted under the radiator. That cooling system is now over 40 years old and should be upgraded.
A stock FB 12A uses a beehive oil cooler mounted under the oil filter. That cooling system is barely adequate for 100hp and should also be upgraded.
Last edited by RX7_Renesis; 08-19-21 at 10:03 AM.
Reason: Clarity
Replace your mechanical fan with an electric fan even if you're not doing a Renesis engine swap.
An electric fan is preferred because when your rotary engine needs a fan the most (at idle or stop and go traffic) an electric fan is capable of delivering maximum air flow independent of engine RPMs. Every effort should be made to install a "pull" vs. a "push" fan mounted on the engine side of your RX7 radiator.
Always use a shroud with your electric fan. An unshrouded fan is only able to move air through the portion of the radiator equal to the surface area of the fan. This means that almost 50% of an unshrouded radiator is not receiving any benefits of your electric fan. Shrouding your radiator lets the fan pull air through the entire core.
Hey was your FB down at Chips shop a few years back? I think 2018.
I might have seen your car there, I took my 12A down to Chips for a rebuild around then. I'm running a 12A streetport.
You certainly found the best guy to work on it! Probably one of the best around.
Going to follow this thread so closely!
Hi tommyeflight89,
Chip has been working on my SA RX7 for a few years now .. in-between all of the other rebuilds and custom CNC work that he does for the rotary community. I spent 10+ years trying to find someone to work with me on this project. I have 100% confidence that Chip is the best guy in the business.
I've been following your build as well. Your FB is an inspiration. I can't wait to get my car back from Chip so I can start pulling it apart and restoring everything else to like new condition.
Hahha that's awesome!! Small world. What are the odds seeing an Ontario SA/FB down at Chips shop!
Glad you like my build! I was lucky to find a very clean rust free 100k KM original FB on Kijiji which was the perfect starting point. From that picture not too much has changed, recently installed a new GSL/SE rear axle, LSD and disc brakes. That was the final mechanical part to replace on the car other than the steering box, so it is my summer daily driver, I've almost put 50k KM on it since I bought it in 2014.
Been thinking about going to visit Chips again. Would be great to have a ported 13B in the car but I really can't complain about the 12a!
Those with a keen eye probably saw the billet water manifold that Chip installed on my 13B Renesis in previous posts .. however it has since been updated with a newer design.
Special Note: The use of a water manifold requires the alternator to be relocated. Unfortunately none of the side mount alternator brackets that are readily available for the RX7 will line up with the Renesis engine due to the thicker design of the front iron.
The Mazda OE exhaust manifold wouldn't clear the firewall in my SA. It may be possible to reshape the firewall with a bit of persuasion .. however once you start down that dark path, there's no turning back.
Plan A was to modify the stock OE exhaust manifold. I have no idea what kind of material Mazda used to make those things .. however they are impossible to cut and modify. A couple of saw blades later .. and it was time for Plan B.
Plan B was to use an inexpensive header that could be cut up and modified to fit. The original factory welds were pretty sloppy .. so Chip cleaned those up to improve flow and performance.
Before:
After:
The final project fits perfectly and looks great. I will most probably wrap the header to help reduce heat in the engine bay.
Last edited by RX7_Renesis; 09-15-21 at 10:05 AM.
Reason: Clarity
Shortly after buying my RX7 back in 1980, I swapped out the entire exhaust for a Rotary Engineering High Performance Exhaust System. 40 years later .. and I don't think that exhaust system owes me anything. I still have most of the OEM exhaust parts that were used less than 1 year.
The RENESIS engine moves a lot more air than a stock 1st gen 12A or 13B .. so we needed to open up the exhaust to avoid choking the engine.
Unfortunately most off-the-shelf high performance exhaust systems for a 1st gen RX7 are 2-inch .. so we had to go custom.
The custom header has a 3-inch outlet. We decided to reduce the remainder of the system down to 2.5-inch to help avoid irritating the neighbours. 2.5-inch can support up to 500hp .. and there's no way we will achieve that power level with a stock RENI.
3-inch header/collector reduced down to 2.5-inches:
A shot from the pre-silencer looking back towards the rear of the car:
** next summer's project will be to restore the underside of the car **
08-03-21, 03:09 PM
