1980 Renesis Swap
 

Step 1.

Fresh built 13B Renesis S1 w/GSL-SE front cover.

*All work performed by Chips Motorsports

https://cimg5.ibsrv.net/gimg/www.rx7...146f1cefb8.jpg

Step 2.

Rough position of 13B Renesis and RX8 6-speed manual transmission into the 1980 SA engine bay.

*GSL-SE front engine mount used just for initial mockup.

https://cimg3.ibsrv.net/gimg/www.rx7...4357af726f.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...daf88cff8c.jpg

https://cimg0.ibsrv.net/gimg/www.rx7...85c2e97215.jpg

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.

Here's a link to mine: https://www.rx7club.com/1st-gen-gene...ad%5D-1099646/

A couple of issues to overcome:

• the stock Renesis oil pan will not clear the 1st gen steering
• the GSL-SE front engine mount does not position the transmission shifter in the correct position
• the GSL-SE front engine mount does not provide for a location to mount an ECU sensor

I opted for a custom billet aluminum oil pan and a custom aluminum front engine mount.

*CAD designs and CNC machining done by Chips Motorsports.


https://cimg9.ibsrv.net/gimg/www.rx7...4ae0828714.jpg

https://cimg6.ibsrv.net/gimg/www.rx7...f55964dad2.jpg

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https://cimg0.ibsrv.net/gimg/www.rx7...4c2e80d733.jpg

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.

https://cimg5.ibsrv.net/gimg/www.rx7...940a96d856.jpg

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.

Step 3.

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.

https://cimg0.ibsrv.net/gimg/www.rx7...019a7866b1.jpg

https://cimg1.ibsrv.net/gimg/www.rx7...3256730fa4.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...995c01d1fa.jpg

Step 4 - The Cooling System - Part I

For keeping things cool under the hood, we opted for a full size Koyorad with the oil cooler mounted in front.

Chips Motorsports did an amazing job of getting everything mounted up to make it look like stock.

https://cimg3.ibsrv.net/gimg/www.rx7...d38ae64800.jpg

https://cimg3.ibsrv.net/gimg/www.rx7...a51b5272d8.jpg

https://cimg5.ibsrv.net/gimg/www.rx7...f77466d08a.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...9c14009429.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...d82c18a2ff.jpg

Like the license plate says .. "KEEP IT BEAUTIFUL"

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.

Woah!

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!

Step 4 - The Cooling System - Part II

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.

https://cimg8.ibsrv.net/gimg/www.rx7...935396086e.jpg

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.


https://cimg9.ibsrv.net/gimg/www.rx7...1ab53a5b5c.jpg

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!

Hey tommyeflight89,

I hope to be heading back down to Chips to pickup my RX7 within the next couple of months. You are more than welcome to ride shotgun.

Just try to hold off on any new build projects for Chip until he's finished with my project.

Step 4 - The Cooling System - Part III

As mentioned previously, an FD water pump will fit a 13B Renesis with a GSL-SE front cover .. however I opted for an electric water pump.

https://cimg1.ibsrv.net/gimg/www.rx7...bd4c00dcac.jpg


Benefits of an Electric Water Pump:

• Continues cooling your rotary engine after shutdown to help prevent hotspots and boiling
• No longer dependent on engine speed, so the pump is always flowing at the optimal rate. Flow speed is now based on coolant temperature, not engine RPM
• Programmable setpoints for maximum temperature and fan control
• Low power draw frees up horsepower and increases throttle response
• Easy to bleed the coolant system without running the engine (just use a 12V battery)

There's plenty of room to mount the EWP on the right side of the engine bay. Chip designed and built a custom aluminum mounting bracket.

https://cimg9.ibsrv.net/gimg/www.rx7...ded58bb632.jpg

https://cimg1.ibsrv.net/gimg/www.rx7...4147ae4dd2.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...de750a4774.jpg

https://cimg9.ibsrv.net/gimg/www.rx7...08d6756323.jpg

https://cimg8.ibsrv.net/gimg/www.rx7...bfccb6b8ec.jpg

https://cimg8.ibsrv.net/gimg/www.rx7...eb87dfe964.jpg

i'm really digging what i'm seeing here. for example that mounting bracket for the tranny is real nice.

just curious, which oil cooler are you running? also, which header are you running?

Hi diabolical1,

I'm currently away from home .. however I will try to get the oil cooler information for you.

Header information coming up within the next couple of weeks .. stay tuned! (no pun intended)

Step 4 - The Cooling System - Part IV

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.

https://cimg9.ibsrv.net/gimg/www.rx7...ae4feb7a19.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...f9a8af6992.jpg

https://cimg7.ibsrv.net/gimg/www.rx7...652100db3f.jpg



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.

https://cimg0.ibsrv.net/gimg/www.rx7...8133c401f0.jpg

https://cimg8.ibsrv.net/gimg/www.rx7...1a7945c3d0.jpg


Next week .. the exhaust!

Step 5 - The Exhaust System - Part I

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:
https://cimg8.ibsrv.net/gimg/www.rx7...1cbd9db9aa.png

After:
https://cimg8.ibsrv.net/gimg/www.rx7...cbd503391a.png


The final project fits perfectly and looks great. I will most probably wrap the header to help reduce heat in the engine bay.

https://cimg6.ibsrv.net/gimg/www.rx7...72ea3ab0e5.jpg

Looking great. Can’t wait to see and hear it run.

Step 5 - The Exhaust System - Part II

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:
https://cimg3.ibsrv.net/gimg/www.rx7...2be234a9f9.jpg


A shot from the pre-silencer looking back towards the rear of the car:
https://cimg9.ibsrv.net/gimg/www.rx7...da57f23313.jpg
** next summer's project will be to restore the underside of the car **


Up and over the rear axle:
https://cimg9.ibsrv.net/gimg/www.rx7...45db5f6788.jpg


Dual outlet exhaust tips to match the OEM look:
https://cimg5.ibsrv.net/gimg/www.rx7...a4ab0686eb.jpg


Side profile:
https://cimg5.ibsrv.net/gimg/www.rx7...a233aaa247.jpg


A view of the muffler from the underside:
https://cimg7.ibsrv.net/gimg/www.rx7...dad3043f15.jpg

Very impressive build!! Your work is top notch! I'm very excited to see how this turns out!

Small Update ...
 

Battery has been relocated to the right side (passenger side) firewall. This will free-up the original battery location for an air-intake system.

Chip used existing bolt holes, so no drilling required. The hold-down strap (belt) is temporary.

https://cimg5.ibsrv.net/gimg/www.rx7...9cb6b73a9b.jpg

https://cimg2.ibsrv.net/gimg/www.rx7...515c7de93e.jpg



The Adaptronic standalone ECU location was limited by the length of the stock RX8 Renesis engine harness.

https://cimg7.ibsrv.net/gimg/www.rx7...f233964b15.jpg

https://cimg8.ibsrv.net/gimg/www.rx7...feb91cee1b.jpg