Controlling a 20B like a V6
08-17-02, 11:38 PM
#51
I plan to go injected some day, but for now I'm going with the split. I guess there's no way around it. I just thought I could be lazy hehe.
peejay, what was your 20B distributor going to use to 'distribute' spark to the plugs? You mentioned something about a custom cap. Is this like RB's clear perspex one? http://cpwww.topcities.com/rotary/images/pg20_28b.jpg
http://cpwww.topcities.com/rotary/images/pg22_03b.jpg
(gotta copy and paste thanks to topcities)
peejay, what was your 20B distributor going to use to 'distribute' spark to the plugs? You mentioned something about a custom cap. Is this like RB's clear perspex one? http://cpwww.topcities.com/rotary/images/pg20_28b.jpg
http://cpwww.topcities.com/rotary/images/pg22_03b.jpg
(gotta copy and paste thanks to topcities)
08-18-02, 02:42 PM
#52
Old [Sch|F]ool
Similar. 
Okay, a direct ripoff, for making a setup with splittable leading/trailing.
For a "non-split" setup, I was thinking of mating a V6 distributor head to the rotary base, and making the rotor dual-ended. Since the distributor turns at half engine speed, doing this would mean that you could use the terminals 180deg across from each other for leading and trailing for a given rotor, and the dual-ended rotor would ensure that they both get spark.
Either way, though, the V6's reluctor wheel is key.
Okay, a direct ripoff, for making a setup with splittable leading/trailing.For a "non-split" setup, I was thinking of mating a V6 distributor head to the rotary base, and making the rotor dual-ended. Since the distributor turns at half engine speed, doing this would mean that you could use the terminals 180deg across from each other for leading and trailing for a given rotor, and the dual-ended rotor would ensure that they both get spark.
Either way, though, the V6's reluctor wheel is key.
08-19-02, 12:57 PM
#53
If you can do it cheaply I'd say go for it. RB has laser-cut reluctors that come in their 20B dizzy kit. I once tried to buy one by itself but they didn't like that idea. Maybe you could try to get one from 'em? Did Mazda have any V6s from '81-'85? Maybe if Mazda kept the same cap and rotor sizes you could use one of their V6 caps.
If a 20B's highest RPM is around 7k, then I'd think the stock ignitors and coils would do ok. Just multiply by 1.5 to see how many more sparks it would need to produce at any given RPM compared to a two rotor. At 6k on a 3 rotor, that would be the same as 9k on a two rotor as far as sparks per minute and amp load go. 7k would be 10.5k! The tach would also need to be adjusted for 6 cylinder mode.
If a 20B's highest RPM is around 7k, then I'd think the stock ignitors and coils would do ok. Just multiply by 1.5 to see how many more sparks it would need to produce at any given RPM compared to a two rotor. At 6k on a 3 rotor, that would be the same as 9k on a two rotor as far as sparks per minute and amp load go. 7k would be 10.5k! The tach would also need to be adjusted for 6 cylinder mode.
08-19-02, 07:09 PM
#54
Old [Sch|F]ool
If none of Mazda's V6s are compatible, then there are other things that can be done.
Stock ignitors? Hell no. MSD. It's the only way to fly. If an MSD works on V8s revving to five figures then it'll work on a 20B revving only to 7k.
Stock ignitors? Hell no. MSD. It's the only way to fly. If an MSD works on V8s revving to five figures then it'll work on a 20B revving only to 7k.
08-20-02, 12:20 AM
#55
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the mpv is v6 and it has the same o ring as any rotary...
mike
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08-20-02, 01:09 AM
#56
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Originally posted by Jeff20B
<snip>
If a 20B's highest RPM is around 7k,
<snip>
<snip>
If a 20B's highest RPM is around 7k,
<snip>
Roger Mandeville, as well as the Kudzu team, ran peripheral port 20Bs to 9000 rpm.
08-20-02, 10:35 AM
#57
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Did he run 20B's or did he run 13G's?
13G is the Mazda factory race 3-rotor. 20B is the passenger car engine. The 20B e-shaft generally cn't be taken over 8500 (wisdom gleaned from elsewhere on the Forum).
13G is the Mazda factory race 3-rotor. 20B is the passenger car engine. The 20B e-shaft generally cn't be taken over 8500 (wisdom gleaned from elsewhere on the Forum).
08-20-02, 02:14 PM
#58
Ah, so it's in the ports then? That's good to know. That means I could have it rebuilt with FD rotor housings and get up to 8500 or just have the exhaust sleeves changed (that might end up being difficult though). Fortunately I'm not going to be using the RB style ignition, or MSD for direct fire. That would be too expensive. (heh, listen to me. I'm complaining about something being expensive in relation to the 20B. Man, everything's expensive in a 20B install!)
08-21-02, 04:49 PM
#59
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paul ko and i had a laugh that his "overpriced" $400 engine mounts were only 5% of my budget. the engine is by far the most expensive part of the swap (37% for me). so being cheap is funny, ha ha
mike
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08-22-02, 10:36 AM
#61
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Originally posted by Jeff20B
Ignition is coming along nicely. At least I won't have to spend any money on it.
Ignition is coming along nicely. At least I won't have to spend any money on it.
mike
08-24-02, 06:20 PM
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Originally posted by peejay
Did he run 20B's or did he run 13G's?
13G is the Mazda factory race 3-rotor. 20B is the passenger car engine. The 20B e-shaft generally cn't be taken over 8500 (wisdom gleaned from elsewhere on the Forum).
Did he run 20B's or did he run 13G's?
13G is the Mazda factory race 3-rotor. 20B is the passenger car engine. The 20B e-shaft generally cn't be taken over 8500 (wisdom gleaned from elsewhere on the Forum).
I believe he said that it used 13B-rew housings and 1991 high-compression rotors. I thought he said it used the 20B e-shaft, but I may have misunderstood.
AFAIK, the Kudzu motor was a 20B.
08-24-02, 06:28 PM
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Originally posted by Jeff20B
Ah, so it's in the ports then? That's good to know. That means I could have it rebuilt with FD rotor housings and get up to 8500 or just have the exhaust sleeves changed (that might end up being difficult though). Fortunately I'm not going to be using the RB style ignition, or MSD for direct fire. That would be too expensive. (heh, listen to me. I'm complaining about something being expensive in relation to the 20B. Man, everything's expensive in a 20B install!)
Ah, so it's in the ports then? That's good to know. That means I could have it rebuilt with FD rotor housings and get up to 8500 or just have the exhaust sleeves changed (that might end up being difficult though). Fortunately I'm not going to be using the RB style ignition, or MSD for direct fire. That would be too expensive. (heh, listen to me. I'm complaining about something being expensive in relation to the 20B. Man, everything's expensive in a 20B install!)
All of the 9000-rpm cars that I heard discussed were peripheral port. The design parameters would vary according to the designer and the intended usage. Your best bet is to go straight to Roger Mandeville or Peter Farrell, rather than relying on the second-hand information from an amateur like me.
