how much better is a 13b over a 12a
05-30-02, 06:21 PM
#1
how much better is a 13b over a 12a
I will be building up a engine when i put my car away for the winter.
I have a 82 gs.
Should I stick with the 12a or should I go for a 13b
there is a second gen NA at a junkyard near me.
thats a 6 port though
Whatever I get I plan on streetporting it with a weber carb and full RB exhaust.
If I get a 13b should i get the second gen one or should I look for a 6 port.
what about ignition, dont the secondgens have distributorless.
thanks for the info
I have a 82 gs.
Should I stick with the 12a or should I go for a 13b
there is a second gen NA at a junkyard near me.
thats a 6 port though
Whatever I get I plan on streetporting it with a weber carb and full RB exhaust.
If I get a 13b should i get the second gen one or should I look for a 6 port.
what about ignition, dont the secondgens have distributorless.
thanks for the info
05-30-02, 06:43 PM
#2
If you are gonna go 13b, go with a 4 port turbo. If you are gonna go with just a 6 port, you are in for a shitload more work and money for no more HP than a 12A will give you...
The 2nd gen 13b's use a CAS , instead of distrubutor. But I beleive a 12A dizzy can be retro fitted
But seriously think about it, a shitload of work for probally around 200 hp. Besides Ive heard SP on 6 ports are useless
BTW: All NA's are 6 port
The 2nd gen 13b's use a CAS , instead of distrubutor. But I beleive a 12A dizzy can be retro fitted
But seriously think about it, a shitload of work for probally around 200 hp. Besides Ive heard SP on 6 ports are useless
BTW: All NA's are 6 port
Last edited by MIKE-P-28; 05-30-02 at 07:17 PM.
05-30-02, 08:42 PM
#3
Old [Sch|F]ool
HP potential is the same. HP is determined by the port sizes as well as the intake/exhaust systems (that part kinda goes without saying ) Airflow = HP.
The larger 13B will make is power lower in the rev range. Or, put another way, you have wind the 12A higher up to make the same power. (For the same RPM the 13B makes more power)
BTW this is true for boingers too - HP is determined by how the ports flow and the cam size, the powerband then is dictated by how large the engine is.
) Airflow = HP.The larger 13B will make is power lower in the rev range. Or, put another way, you have wind the 12A higher up to make the same power. (For the same RPM the 13B makes more power)
BTW this is true for boingers too - HP is determined by how the ports flow and the cam size, the powerband then is dictated by how large the engine is.
05-30-02, 09:02 PM
#4
OK i figured that Bigger engine=bigger power.
plus I heard a 2nd gen with a cork sport exhaust and it sounded deep as hell, really loud and really cool. at first it looked like a apexi but i looked closer and it was a cork. I figured it was a 13b sound.
maybe my long primary RB headers with a apexi wil sound that tight and deep.
plus I heard a 2nd gen with a cork sport exhaust and it sounded deep as hell, really loud and really cool. at first it looked like a apexi but i looked closer and it was a cork. I figured it was a 13b sound.
maybe my long primary RB headers with a apexi wil sound that tight and deep.
05-31-02, 01:36 AM
#5
Rotary Enthusiast
exhaust noise should be about the same on a 13B and on a 12A port shape being equal...
I would recommend doing a 12A...there are many factors to consider.
1st you save $ by using your current engine.
2nd 12As can make a shitload of power it just depends on what you are aiming for.
3rd 12As come 4 ports from factory
4th to put in the 13B you will need to get some other parts and have some fun with the ignition.
5th when you spank the competition you can tell them that you have the smaller engine
If you want some more power I think you can use the 12a plates and mate them to the 13B housings to make a 4 port 13B. The question is how much money are willing to spend...
I have 3 12As...and I'm happy...no need for no stinking 13Bs....j/k
I would recommend doing a 12A...there are many factors to consider.
1st you save $ by using your current engine.
2nd 12As can make a shitload of power it just depends on what you are aiming for.
3rd 12As come 4 ports from factory
4th to put in the 13B you will need to get some other parts and have some fun with the ignition.
5th when you spank the competition you can tell them that you have the smaller engine
If you want some more power I think you can use the 12a plates and mate them to the 13B housings to make a 4 port 13B. The question is how much money are willing to spend...
I have 3 12As...and I'm happy...no need for no stinking 13Bs....j/k
05-31-02, 01:38 AM
#6
Super Newbie
Originally posted by mperformance
If you want some more power I think you can use the 12a plates and mate them to the 13B housings to make a 4 port 13B.
If you want some more power I think you can use the 12a plates and mate them to the 13B housings to make a 4 port 13B.
05-31-02, 02:02 AM
#7
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Originally posted by MIKE-P-28
BTW: All NA's are 6 port [/B]
BTW: All NA's are 6 port
[/B]
CJG
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05-31-02, 02:08 AM
#9
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[QUOTE]Originally posted by mperformance
[B]exhaust noise should be about the same on a 13B and on a 12A port shape being equal...
Trust me on this one, 12a 's are louder. if you measured the dicibles they would be close but the 12a's are so much higher pitch there is just more volumer of noise there. I ran a street ported 13b off the header and then did a 12a stock off a header and the 12a decimated it as far a as shear noise volume. then i ran my 12a pp down a set of streight pipes and trust me that was LOUD you could here it from 3 mi. away. then i got a 40" long semi truck stack muffler on it and that has quited it down a bunch.
cjg
[B]exhaust noise should be about the same on a 13B and on a 12A port shape being equal...
Trust me on this one, 12a 's are louder. if you measured the dicibles they would be close but the 12a's are so much higher pitch there is just more volumer of noise there. I ran a street ported 13b off the header and then did a 12a stock off a header and the 12a decimated it as far a as shear noise volume. then i ran my 12a pp down a set of streight pipes and trust me that was LOUD you could here it from 3 mi. away. then i got a 40" long semi truck stack muffler on it and that has quited it down a bunch.
cjg
05-31-02, 02:11 AM
#10
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Originally posted by peejay
Wind the 12A up higher
Besides the '74-78 13B 4-ports don't forget the '81-up Japanese-market carby 6-port 12As
Wind the 12A up higher
Besides the '74-78 13B 4-ports don't forget the '81-up Japanese-market carby 6-port 12As
05-31-02, 09:27 AM
#11
Originally posted by Rotortuner
Also if you stick the same ports in a 13 b and then do them in a 12a there is usualy only like less than 20hp difference. the larger difference is in teh tourque. the 13b has more.
CJG
Also if you stick the same ports in a 13 b and then do them in a 12a there is usualy only like less than 20hp difference. the larger difference is in teh tourque. the 13b has more.
CJG
I support the 13B if you can get it
05-31-02, 01:14 PM
#12
on mazdatri, they sell a 4port 13b as a bolt in package for a 82-85 non se.
I have decided I am going to do something like this.
not that i dont like the sound of a 12a but a 13b sounds soooo much better plus I can get more horsepower and more low end torque.
I got the 13 b from that 2nd genNA I am going to use the rotors and Eshaft from it.
I will use the side housings from my 12a
and I will find some 74-78 13 rotor housings.(these ones bolt up to the 12 side housings.
if anyone has done thi, please give me some tips
thanx
I have decided I am going to do something like this.
not that i dont like the sound of a 12a but a 13b sounds soooo much better plus I can get more horsepower and more low end torque.
I got the 13 b from that 2nd genNA I am going to use the rotors and Eshaft from it.
I will use the side housings from my 12a
and I will find some 74-78 13 rotor housings.(these ones bolt up to the 12 side housings.
if anyone has done thi, please give me some tips
thanx
05-31-02, 01:15 PM
#13
Originally posted by Rotortuner
NOT TRUE! keep in mind the rx-4 and the 74-77 REPU came NA 13b and with 4 ports. and there are quite a few of those motors around. and i would say that they are a very good motor to build up since the ports are already larger than the turbo ones and they also interchange with 12a plates. but seriously i would go 12a, i think they last longer and they are just cool. but we have to keep our info streight on this stuff. Also if you stick the same ports in a 13 b and then do them in a 12a there is usualy only like less than 20hp difference. the larger difference is in teh tourque. the 13b has more.
CJG
NOT TRUE! keep in mind the rx-4 and the 74-77 REPU came NA 13b and with 4 ports. and there are quite a few of those motors around. and i would say that they are a very good motor to build up since the ports are already larger than the turbo ones and they also interchange with 12a plates. but seriously i would go 12a, i think they last longer and they are just cool. but we have to keep our info streight on this stuff. Also if you stick the same ports in a 13 b and then do them in a 12a there is usualy only like less than 20hp difference. the larger difference is in teh tourque. the 13b has more.
CJG
05-31-02, 01:45 PM
#15
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[QUOTE]Originally posted by Rotortuner
I totally agree with you. The 12a can screem much louder then a 13b. I have first had experince on this one. '83 GSL(12a), '85 GSL-SE(13b), '88 TII(13b turbo).
Now the question is when I put the 20b into my '85 GSL-SE and see what it sounds like.
Trust me on this one, 12a 's are louder. if you measured the dicibles they would be close but the 12a's are so much higher pitch there is just more volumer of noise there. I ran a street ported 13b off the header and then did a 12a stock off a header and the 12a decimated it as far a as shear noise volume. then i ran my 12a pp down a set of streight pipes and trust me that was LOUD you could here it from 3 mi. away. then i got a 40" long semi truck stack muffler on it and that has quited it down a bunch.
cjg
cjg
I totally agree with you. The 12a can screem much louder then a 13b. I have first had experince on this one. '83 GSL(12a), '85 GSL-SE(13b), '88 TII(13b turbo).Now the question is when I put the 20b into my '85 GSL-SE and see what it sounds like.
05-31-02, 04:37 PM
#16
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Originally posted by MIKE-P-28
I knew that was coming after I posted it, I know early 13bs were 4 port. But Ive not even seen a car much less a old 13b in good enough shape to merit building a motor from it parts
I knew that was coming after I posted it, I know early 13bs were 4 port. But Ive not even seen a car much less a old 13b in good enough shape to merit building a motor from it parts
CJG
05-31-02, 04:54 PM
#17
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Hey, I just posted a reply on another thread about the 12a 6port! There is a guy here in Dallas that runs one, it is pretty quick! The car is actually for sale. 4k!!! coil overs, 13x8s(panasports),tokico 5-ways, panhard bar.....lots of goodys and set up!
By the way, last summer I bought 2 brand new 75' 13b rotor housings, still sealed in the plastic, still in the Mazda box for 200 for the pair!!!! They are going in my bridge port.
By the way, last summer I bought 2 brand new 75' 13b rotor housings, still sealed in the plastic, still in the Mazda box for 200 for the pair!!!! They are going in my bridge port.
06-01-02, 02:07 AM
#20
I saw a JDM 6-port 12a on Ebay a couple of weeks ago. It sold for $570.
I plan on going with the 12a plates and the GSL-SE rotors and housings for my next engine.
To me, that sounds like the best bet. Parts are cheap and easy to find. And, there have been a lot of folks who have had some great results.
I plan on going with the 12a plates and the GSL-SE rotors and housings for my next engine.
To me, that sounds like the best bet. Parts are cheap and easy to find. And, there have been a lot of folks who have had some great results.
06-01-02, 02:17 AM
#21
Old [Sch|F]ool
Technically the rotor housings ARE different, as relates to the air injection ports. Unless you're building a smog-friendly engine for your vintage RX-4, Cosmo, or REPU, it doesn't matter
06-01-02, 06:52 PM
#24
Also if you stick the same ports in a 13 b and then do them in a 12a there is usualy only like less than 20hp difference. the larger difference is in teh tourque. the 13b has more.
Plus If I use the 89NA rotors out of the engine I got I will get a higher compression. 9.7 vs 9.3 to 1
The main reason I want to do this is the the more low end torque available with a 13b and the much much much better sound they put out. it isnt so lawnmowerish sounding.
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