I have searched around a bit on the forum as well as the on net and couldn't find a LOT of info but i did find some.

I really like the idea of a non-turbo 20B, Non of the complications that come with a boosed motor, but it still makes decent power. I came across two 20B N/A's that i really liked...

http://www.3rotor.com/index2.htm

and...

http://www.youtube.com/watch?v=bIGr0Oo8je8

First off i should say my horsepower goal, 300-350 hp at the wheels

I don't know how much horsepower the second one made, all i know is that it's P-ported. I would like to keep it reasonably streetable, so P-port is likely out. The first one made 300 whp on a bridgeport.

My Questions...
-Would it be possible to get 300whp out of a LARGE streetport?
-(If the answer to the above question is NO)What would engine life be like for a bridge or 1/2 bridge, I don't want an engine that i have to rebuild in 20k miles? (ceramic coated housings/irons perhaps?)
-How streetable would it be bridgeported? Would it be "less bad" because it has a third rotor (as compared to a bp 13B)?

Basically if it's not possible to get 300+whp out of this motor while retaining reasonable streetability, I would like to know that, and if that is the case then i will likely go with my original plan (13B-RE, but we're not here to talk about this motor).

EDIT: I should note this would be swapped into an '87 GXL, if that makes a difference

 

A little off subject, but you WILL need to swap in a TurboII transmission. Just thought you should know, so you can plan for that expense.

n/a tranny is no good for over 200hp.

 

you can make 350 hp with a 13bt motor. i wouldnt waste the money on swapping a 20b unless you are going all out.

 

Your looking at spending 8-10k being very tight with your budget and you do all the work yourself, if not expect to spend alot more.

 

I say go for it, there's already someone running a N/A 20B around here I think. 300 whp out off a street port is reasonable.

 

GTORX7 has a n/a 20B FD. Forgot what he was putting down at the wheels though.

 

The best I managed was 348rwhp on a standard street-port. Very nice streetability. You wont ever make that with a stock intake manifold, just a heads up. There is definitely more power to be made!

 

I didn't know a t2 tranny bolts to a 20B, i was assuming i'd need an FD tranny. The T2 would be easier to swap anyway.

I am very aware that i could get 350 hp out of a 13bt, but that's not a 20B n/a now is it.

Basically there are boatloads of people who do the 13BT swap but only a few that do a 20B swap, let alone an N/A 20B. I wanted to do something unique with my car, not just the run-of-the-mill t2 swap (not that there's anything wrong with that). It's not a matter of going all out, it's a matter of doing something different.

And besides if i DON'T do this 20B swap, I would put in a 13B-RE, not a 13BT.


If what you say is true, then that is the answer I wanted to hear.
Don't get me wrong, I love the sound of a bridgeport, but I just don't think it's as streetable/practical as a streetport, and i would like to retain as much low end torque as possible.

What would be the max hp you could get out of a streetport 20B?
Would I be correct in saying it has more to do with the fuel mapping/tuning, then the porting itself?

 

Oh yeah what would be the Weight differnece between a 20B n/a and a 13B n/a, and how would this affect handling, weight distribution etc?

 

Putting the 20b in the stock location will compromise the handling dynamics somewhat since more weight is forward of the front axle. It changes the polar moment and puts more weight away from the center of rotation. Since your using this for a street application, don't worry about it so much as you would'nt be able to tell anyways. Also the weight differance is about 60lbs. Maybe less if you do a custom intake to reach your hp goals. Just remember the extra torque you get with the 20b makes for far greater NA driveability.

 

if you use the Defined Autoworks kit (see their vendor section), you can retain a 50/50 weight distribution and if its n/a you can keep the weight gain negligible.

 

I thought Defined Autoworks only made an FD kit?...


in order to get closer to 50/50 you would have to move the trans and engine reward... that requires custom trans mounts as well... relocating the shifter... ect. I don't think moving the engine back is worth it unless your really willing to do some work

 

If this is an FC, we got no problem with the heavier 20B in the engine by with a custom front bar.
Too bad we can't track down the original shop that made it for us! :P
We do track the car, so we're fairly confident to claim it does work.


-Ted

 

D'oh! im sorry, please disregard what i said. i thought we were talking about an FD for some reason. im dumb. the FC kit is not ready yet, and its got a good bit to go still.

 

cant wait to see some pictures and results from that one! sounds nice!

 

What injectors would be needed to produce 300-350hp, and what would be the resulting fuel mileage?

With a large street port, hoe will the idle be affected?

 

Although I haven't measured the respective weights of the motors, I recall that Peter Farrell said the difference is only about 100 lb. In the RXX-7, I did measure the weights on the front and rear wheels after the project was done and got 51% front and 49% rear.

Handling has not been compromised at all. However, I'm now running 275 x 40 x 17 rear tires and 235 x 45 x 17 front tires, not the stock wheel and tire sizes.

 

That's great, cause i auto-x my car so my handling won't be greatly affected

 

Is it worth the extra money to go with the 10:1 renesis rotors, or will s5 n/a rotors do just fine? And what is the comp. ratio of the s5 n/a?

 

S5 NA rotors are 9.7:1, RX-8 rotors are 10.0:1, so there's not a big difference there, and the seals are different in the RX-8 rotors, so I've read that the dynamic compression on the S5 NA are just as good if not better because of that.

 

Mazdatrix quotes them at 9.7 compression and 9.54 lbs

 

I allready have a 20b FD proyect under way and I decided to go NA too, much more sympler and less $$$

If I ever need more power I will add a 50 or 100 shot

 

When did you start on this project, last tuesday? You should wait 2-4 months before going to the dyno out of respect for the long term hell I have been through . In all seriousness, without ever driving one, I think an NA 3-rotor is the ideal blend between performance, reliability, sound, handling and cost.

 

Who here has actually completed this swap? Any links? I'd like to start geting some idea's for manifold design, line routing etc.

 

For an example of a swap into an FC, try

http://www.cris.com/~Asam/20B.html