Mazda 20 B engine in SL-C

Any words of wisdom about putting the rotary engine in the car?

I have a 20 B turbo, Mendeola Sequential gear box, Kennedy flywheel and the tranny is turned upside down.
 
Gary, welcome to the forum!

Yes it will easily fit into the SL-C. There is one going together with a 3 rotor on this forum as well. Great combo and noise...
 
I'm doing a 20b with a g50-52. I'd love to see another.

Fran has the dimensions of the 20b rear side housing to make an adapter in-house...providing he has the dimensions of the Mendy box.

You will have to go dry-sump, as the engine sits between the frame rails, not above them. No room underneath for a wet sump to hang down below the car with only 4-1/2" ground clearance. I have made engine mounts that bolt to the topside of tabs protruding from the side of my 3/4" sump plate and parallel 2x2 frame rails. The engine is 1/8" above the bottom of the frame. Can't get any lower really. It looks like the engine belongs in there, unlike those LS lumps.

Not sure what turbo you have but if you have the stock twins, throw them in the garbage. I have a GT4202r which is about the largest (frame wise) turbo you could fit in the car. You may be able to fit a GT45 or larger if you relocated one of the 2x2 diagonal aluminum tubes, but turbos of that size really belong on drag cars and dyno queens unless you want a one-mile runner.

I finally just ordered a Water-to-Air (W2A) intercooler system. You will in all likelihood need to do the same. This has been a huge challenge and expense to (hopefully) engineer correctly. I have planned for the exchanger to mount horizontally above the tranny and behind the upper crossbars. You will need the street tail for this, no way around it. My IC will mount in front of and above the engine. Custom spec'ed unit, as is the heat exchanger.

It could be possible to run an Air-to-Air (A2A) system if you plan on not running too much power and mount the IC where I will mount my heat exchanger. There are two side ducts, which I have enlarged, but I am running dual oil coolers behind those, so no room for A2A IC. You should know the importance of oil cooling for rotaries and understand you will need those in place.

The fuel tank as delivered will not work. The outlet for the shifter cables and any wiring you have going through there will come out right at the main pulley. The hole/tunnel through the tank that allows this will have to be angled left, right, or above depending on how you run things.
 
Thank you for all the information, I am picking my car up from Fran on Wends the 30th. and looking forward to building it and have it ready for the spring.

I didn't know about the dry sump, I know we are turning the tranny around 180 degrees so it can be lower in the car.

The motor, tranny, clutch and bell housing are all scheduled to ship in the next week or so.

I have a Greedy turbo, Microteck lt 16, billet throttle body, around 600 RWHP. This is just going to be a street type car, its geared for 160 at 8000. I am a hour away from MID OHIO and NELSON LEDGES courses and would love to take it to. Raced shifter carts at both places in my younger days.
 
Awesome, another rotary SL-C. Can't wait to see your progress, hopefully it is at a better pace than mine. 600 rwhp will be easy.

You can fit a 4-rotor in the car, no problem. That is the route I would/should have gone so I wouldn't have to deal with the turbo setup. No better sounding engines on the planet except F1 cars and the new 6-rotor.

I'm sure Fran could easily change the thickness of the adapter to accommodate whatever you need. Then again, with your own CNC shop, so could you. I have yet to purchase my clutch/flywheel package but I hope I'm not in for an unpleasant surprise.

Which Mendy box did you get?

There is no way to run 4" exhaust, which is the same as I am running, out the center of the car, you will easily realize this once you get the car. It is easily routed out the rear on the passenger side. A perfectly straight shot coming right off the turbo.

Did you get the street tail or the original race tail?

Carts - then you and Dave have more than just your car and engine combo in common.
It's kart, with a "K" :tongue3:
 
I'm run ning I think its a s5. Kennedy flywheel and clutch I had to make a adapter for the tranny to be turned upside down so the porsche bell housing can be used. My final ratio is 488 and top gear is .8.

Kennedy said for the he starter to line up it needs .625. The one I bought from Fran is .5.

Race tail. Fran said the 4 rotor wouldn't fit
 
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I'm run ning I think its a s5. Kennedy flywheel and clutch I had to make a adapter for the tranny to be turned upside down so the porsche bell housing can be used. My final ratio is 488 and top gear is .8.

Kennedy said for the he starter to line up it needs .625. The one I bought from Fran is .5.

Race tail. Fran said the 4 rotor wouldn't fit
With the race tail, you will be forced to do something different with your IC setup. There are always the side ducts, but like I said, I have and believe those should be reserved for oil cooling and I believe those ducts and space behind them will not be big enough to accomodate an IC for us, unless you want to throw efficiency out the window and run twin IC's (one for each side) for one turbo. There is room on top of the engine if you build a scoop for fresh air or something. You could run an A2A or A2W heat exchanger up there...maybe. There is always the front of the car for an A2A IC or A2W heat exchanger, but your charge time will be forever in the prior case and and the radiator doesn't need any competition for fresh air in either case.

Have you thought about what you plan on using IC wise or have a general plan?

A 4-rotor will fit, I don't care what Fran says :lipsrsealed:
I've done the measurements to confirm it and have thought of switching courses several times.
 
I've been off of here for a while, and glad I checked back in. Sounds like someone else is going the direction I've been considering. I have always loved the Mazda RX-792P ever since seeing it in '92. My plan is a 4 rotor NA build. Is there room for sliding intake horns? My plan is a 4 piece, 5 bearing eccentric shaft build similar to the Defined Autosports motor. I think that it will be easier to keep the G50/52 gearbox together at 600WHP due to the rotary motor's higher RPM and lower peak torque. My redline will be in the 9500rpm range. Dry sump was already in the plan for this motor.

Has anyone looked at brushless electric motors for the A/C compressor drive? Also electic power assist steering?
 
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Dave:

Yes, thank you for them, I hope at least that's the plan to document the complete build. I noticed on the cars nobody powder coats the billet aluminum parts, is there a reason for this?

My motor is 2 colors, candy rasberry and silver vein. here's a pic of the manifold. I do my own powder coating here.
 

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Not sure what the power specifics are but here is an OEM electric compressor from a Nissan Leaf
Very interesting. You could mount the compressor in the front to improve weight distribution as well. Also, simplifies the engine front end dress, and makes plumbing easier and shorter if it all resides up front where the evap and condenser are.

Wonder if it has sufficient power to run the AC systems we have?
 
Not sure what the power specifics are but here is an OEM electric compressor from a Nissan Leaf
I did look into electric AC Compressors, but couldn't find anything that wouldn't require a major electrical upgrade. This was a couple of years ago when I was trying to install a 6 stage dry sump and maintain AC. There may be more viable AC options now...?

Ultimately, I engineered this:

 
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