hey guys i been thinking about it for awhile but why doesnt anyone do a street ported 20b n/a with 3 carbs or something similar. It seems like it would be fairly simple to do and it would cost alot less then to set up a turbo. what kind of power would a n/a 20b produce?
it seems to me like it would be the setup to have.
what do you guys think?

 

With three carbs and high compression rotors I think it would be under powered for the amount of money and work. plus it may weigh to much for the power. check power to weight ratios

 

People are a bunch of boost junkies. That's why.

If I were putting a 20B in a car it would definitely be N/A. Why? 20Bs are hard to come by, I'd want the engine to be lightly stressed! I have a bad history with turbocharged engines. I simply cannot resist the urge to crank up the boost until the engine self-disassembles.

 

What Kinda HP/torque could u get out of that setup?

 

'Bout 150% of a similar-spec 13B.

If you can get 200-210hp from a street ported N/A 13B, then you should reasonably expect to get about 300-320hp from the 20B. Just shift the entire torque curve up by 50%. Displacement is a wonderful thing.

 

why does a 4 rotor n/a produce 1200hp?

 

you can get 210hp out of a 13b na with just a streetport and intake and exhaust?

and 310hp out of a n/a 2.0liter engine seems like a good amount of power to me.

 

Well, the reason that the 4-rotor seems so out-of-proportion is because you don't have the right power output. At least according to the SAE paper, the R26B puts out a maximum of 515 KW (690 HP) at 9k RPM. Which, given peripheral ports and a variable length intake tract, makes more sense. IMO anyway.

 

Also, it's a racing engine. It probably has some design principles that will just about never be used in production engines. And also some of it's secrets won't be made available to the public. thats my guess anyway. Plus I thought racing engines (@least indy cars) use Turbo's.

 

Well, no. Not all racing engines are boosted... most aren't in fact. But anyway... the R26B isn't turboed.

The secrets... really aren't that tricky. I mean, it's using variable length intake runners (think telescope) and it has a third spark plug per rotor but aside from that... well, it's just a peripheral ported rotary using ceramic apex seals, that just happens to have 4 rotors.

Mind you, the SAE paper doesn't talk about port timing...

 

ooh

i get ya...

but with a 13b can you really make 210hp out of it? is that like max from n/a?

 

210 is not a max for a N/A 13B. You can get more with more radicle ports. I think the max that I have heard about was from a PP with full exhust and webbers, it was like 310Hp but the engine didn't run under 2100rpm and had no torque. I think a half bridge 20B with some renesis rotors and carbon apex seals would be able to get 340-375HP range. torque well thats hard to judge but since it is a 3 rotor it wil be much better than a 13B N/A.

 

217 or 227 is the highest I'm aware of from a streetported 12A. So 200hp from a SP 13B should be quite attainable

Max I've heard of any two rotor was a 380hp Monster Bridge (even more port area than an all-out peripheral port!) but the engine lifespan was 6 racing hours, or enough to last one season before requiring rebuilding.

 

A 20b with a supercharger plumbed into 3 Dellorto 48 sidedrafts and high compression rotors. Even if it did not produce monster horsy's, that dog would sure look good! Put it in a T-bucket roadster so everybody to see it!

 

I've seen about 240 fwhp from a streetport 13B and that was a 6-port! It was strapped to an engine dyno out of the car not a dynojet.

The 26B compression ratio was higher than production n/a's. It was 10:1.

 

ive seen 200-210rwhp from a sp 4 port 13b with a weber. the 20b has way more torque than the 13b does, you would be looking at 300hp and 300lbsft

mike

 

I don't know about 300lb/ft, unless you have a way of making a 13B make about 200lb-ft...

 

I'm planning on getting a 20b but does anyone know how much the conversion is gonna cost??

 

for an fc its $10k in parts and 350 hours of labor

mike

 

where exactly would one find used 20b's?

 

www.corksport.com
www.rxmotors.co.uk
www.pineappleracing.com

those are just some that sell 20Bs

 

The best 12A streetport engine that i built in -98 made 230hp@8000rpm it had a monster streetport, carbon seals, Australian made IDA manifold with a modified Weber 48 carb and a MSD 6A ignition setup. The RX-7 was very dominant in it,s rallycross class in 98

 

Rohan Ambrose is currently working on an e-shaft for a 20B using 13B plates for his customers here in OZ this follows on from his 13B 2 piece e-shafts used in high-performance implemenations.

By using the 13B plates you can do it for a half decent price! He is also building a quad engine racer for next year.

 

How much are the shafts?

 

13b = light/short good power for it's size, can put
motor behind wheel centerline

20b = heavy/long not good power for it's physical size
and weight. might as well get a v8.


just my .02