Completely hypothetical rotary question

Let's say for a minute that you own a rotary engine and you wanted to build more torque so that you could occasionally autocross and drag race it. You don't want to spend any substantial money on it because very soon you will have to buy a V8 drivetrain to put in a car. You accidentally speak with someone who might have a used Jackson Racing Miata supercharger on the shelf with the majority of the bits to go with it.

Would the M45 supercharger positively affect idle-5000rpm performance AND would it negatively affect 5001-redline performance?

Asking for a fiend.

Sooooo, once your friend is done with the hypothetical supercharged rotary, would it be available for about $1K kinda Challenge money? Hmmmmm?

If the answer is no go on the rotary, i have a friend with a miata that may be looking for something like this....

For really cheap.

(Me, because we may feild 2 challenge cars this year?

There are m45 flow charts online that you can use to estimate. My guess is by the time you spin it slow enough to survive 9000 rpm it won't do much down low

I think a baby turbo would be much better

In reply to DeadSkunk:

Approximately give or take

Hey! I own a rotary engine!

MrJoshua wrote: There are m45 flow charts online that you can use to estimate. My guess is by the time you spin it slow enough to survive 9000 rpm it won't do much down low

What's a couple thousand RPM over the original expected impeller speed?

Party pooper

SVreX wrote: Hey! I own a rotary engine!

Yes you do!

I found the following stats:
-45ci/.737L of air per revolution
-14,000 sustained RPM max

It's math time!

I think an m90 might be a better option due to rpms. You can spin I slower meaning you could probably boost through the whole rpm range.

If I think of it tomorow I have a spreadsheet that I can figure ot out with.

I once knew a guy that autocrossed a bugeye sprite, with a 13b rotary motor, topped with what he described as "a blower from an 8.3 liter offshore boat motor".

It was very entertaining to watch and swapped ends faster than anything I've seen before or since. And he was running very wide cantilevered slicks.

Assuming we're talking 13B here (and not necessarily an RX8 13B because super/turbocharging that one has its own set of challenges) I'd be concerned that an m45 would not move enough air. I'm with dean re the M90 or similar, in this case you probably do want to consider the equivalency of 1.3 rotary == 2.6 boinger.

John Brown wrote:

MrJoshua wrote: There are m45 flow charts online that you can use to estimate. My guess is by the time you spin it slow enough to survive 9000 rpm it won't do much down low

What's a couple thousand RPM over the original expected impeller speed? Party pooper

Be sure to follow the instructions when it says to aim away from face.

John Brown wrote: Let's say for a minute that you own a rotary engine and you wanted to build more torque so that you could occasionally autocross and drag race it.

(see avatar)

You don't want to spend any substantial money on it

(see avatar)

You accidentally speak with someone who might have a used Jackson Racing Miata supercharger on the shelf with the majority of the bits to go with it. Would the M45 supercharger positively affect idle-5000rpm performance AND would it negatively affect 5001-redline performance?

I wanted to go down this road, and I bought books, did a bunch of math, and bought a few used Eatons.

A stock rotary will flow more than an M45 can flow if you want to keep it from overspinning near redline. Waste of time.

A stock rotary MIGHT benefit from an M62, maybe, but gains would be minimal at best. A ported engine will flow more than the M62 will. Waste of time.

In short, if you want to put a supercharger on a rotary, you need to start with an M90 at a minimum.

Next problem: The supercharger is longer than the engine...

M45s are only good to around 150 at the wheels, too small for a 13b IMHO. Really, it's too small for the 1.6 Miata they sold it for.

Previa SC14?

Weight: 12kg
Displacement: 1460cc
Dimensions: 31cm long x 15cm wide x25.5cm tall
Max Safe Operation: 12000 rpm
Theoretical Discharge cc/rev 1160 – 1460
Maximum RPM Continuous) 11,000 – 10,000
Maximum RPM Instantaneous) 14,000 – 13,000
Maximum Pressure Ratio Continuous 1.8
Maximum Pressure Ratio instantaneous 2.0

From here

All sorts of good stuff on that site about factory pulleys that may bolt on.

In reply to BoxheadTim:

I'm pretty confident Mr Brown is not talking about a 13b.

This sounds fiendish..

BoxheadTim wrote: Assuming we're talking 13B here (and not necessarily an RX8 13B because super/turbocharging that one has its own set of challenges) I'd be concerned that an m45 would not move enough air. I'm with dean re the M90 or similar, in this case you probably *do* want to consider the equivalency of 1.3 rotary == 2.6 boinger.

Oh god no, I like challenges. Let's say it's a Renesis like SVReX's car... you know, in theory.

MrJoshua wrote: I think a baby turbo would be much better

I would be interested in knowing more about the infant wonder snail. My resources all say making the whooshing sound involves an expensive exhaust manifold or a hand built one (outside of my skill set honestly)

John Brown wrote:

MrJoshua wrote: I think a baby turbo would be much better

I would be interested in knowing more about the infant wonder snail. My resources all say making the whooshing sound involves an expensive exhaust manifold or a hand built one (outside of my skill set honestly)

And putting a supercharger on it would be any easier?

I'd venture that making a turbo manifold would be easier than making brackets to firmly and precisely align a supercharger so it doesn't throw belts constantly. This is non trivial.

The heat generated by a rotary make the exhaust manifold not trivial as well.

Also a renisis is a 13b in terms of volume yes?

Knurled wrote:

John Brown wrote:

MrJoshua wrote: I think a baby turbo would be much better

I would be interested in knowing more about the infant wonder snail. My resources all say making the whooshing sound involves an expensive exhaust manifold or a hand built one (outside of my skill set honestly)

And putting a supercharger on it would be any easier? I'd venture that making a turbo manifold would be easier than making brackets to firmly and precisely align a supercharger so it doesn't throw belts constantly. This is non trivial.

Brackets, bracing and structure my hypothetical Luddite mind comprehends quite easily, tuning tubing for velocity and proper pulse for scavenging and mass velocity as it drives an impeller becomes as mysterious as magic spinning triangles.

I was hoping that a small hugger would suffice without excessive engineering as a stop gap performance improvement until the V8 program is fully fleshed and funded, you know... in theory

My thoughts of easy are similar but biased towards a turbo. You can make lots of power with a cludged together system.