12A vs 13B power difference?

[m1tch]

Hi everyone,

Just wondering about this, what is the power difference between a 12A and a 13B? I know that the 12A is 0.1 litre smaller, im also guessing simpler with a carb and dizzy than an EGI 13B.

Just wondering as I am thinking about a project over the coming years and the 12A engine is becoming more interesting as parts are easier to get it seems

[Grant Monkhouse]

turbo or NA?
 
as far as know 12A parts are extremely hard to come by due to the fact that mazda dont make them anymore.
 
13B PP NA = near to 320FWHP
12A PP NA = near to 279FWHP
 
these would require unrestricted exhausts so would be extremely loud
 
from what i have found out is that if someone needs new 12A housing they get the 13B housings machined down, 5mm off each side i think, this way you can use 13B plates too, of which there are advantages using these parts.

[antnicuk]

there is aprox 30 hp difference on normal side ported engines

[m1tch]

Ah ok, im staying 13b then lol was just wondering as sometimes I see engines come up quite cheaply, but I guess they would be hard to rebuild when the time came.

[Steve-A]

Yeah 12\'s are fairly easy to come buy as complete running.

There\'s quite a few 1st gen 7\'s that sit in someones garage till they rot into bits, then get broken for parts, the engines normally fine with a bit of fresh oil and petrol and can go for silly cheap money.

The problems, as others have said, is that new housings are hard to come by. That said I\'ve seen/heard of quite a few people buying a cheap 12a, or two & picking the best set of housings. Then grinding in a couple of huge ports and the doing a soft seal rebuild. At a cost of £50 for an engine and £300 for the seals, if you can do the work yourself, its a cheap way to get some power and when the already worn housings give up in 5-10,000 miles it\'s not very expensive to do it all over again....

Still wouldn\'t seem very logical for an FC? If you wanted cheap parts could you get hold a 13b 6 port, as they seem to go cheapish, and a blown 13b 4 port for the plates?

[m1tch]

Thats true, the engine could be massivly ported on used housings for a short time, the higher the engine revs, the better is seals

[kiwimazda]

13b all the way. I have a 13b full bridge short block up for sale very very soon

[m1tch]

I have a 13B full bridgeported engine in the garage lol buts its not NA

[kiwimazda]

Mine is:WaveBye

[m1tch]

Hehe

On a slightly related/unrelated note, carbs vs EGI

I know that the 12A runs on a downdraft Weber, could the engine run on other carbs with a a custom manifold - shouldn\'t be too hard to make if it was a straight intake tube out the side, I did have a set of Weber DCOE 40s, but gave them away *fail* I used to have a classic mini, would 2 or 4 HS4 carbs be up to fueling if it was running a rich needle?

[Ian65]

Hehe

On a slightly related/unrelated note, carbs vs EGI

I know that the 12A runs on a downdraft Weber, could the engine run on other carbs with a a custom manifold - shouldn\'t be too hard to make if it was a straight intake tube out the side, I did have a set of Weber DCOE 40s, but gave them away *fail* I used to have a classic mini, would 2 or 4 HS4 carbs be up to fueling if it was running a rich needle?

the stock 12a in a 1st gen rx7 runs on a 4 barrel nikki carb.... some run on twin su\'s... my car runs on a single su through an AI Research turbo...



there are loads of carb options for the 12a... it\'s been around for years.

[m1tch]

Is that a HIFF44?

[Ian65]

Is that a HIFF44?

yeah, the HIF44, the same carb that they put on the mg metro turbo... this is the RX7 Elford turbo system that puts out 160bhp at 6psi of boost on the standard compression 12a engine.... some of the Elford owners have achieved over 200bhp by a few mods and increasing the boost.