Hi all,
Long term lurker, first time poster. I am considering a 12A turbo setup for my 80 model. I've read the posts about different performance levels (200 hp to 500hp), and modifications available.

My question is: How much power can a 12A intercooled turbo with street porting expect to make while keeping boost levels reasonable enough to have a decent lifespan?

Additionally, I am assuming that I will need to use high compression rotors as Mazda no longer makes low compresion rotors for the 12A.

Thanks guys,
Peacedog

 

Um. I'm sorry, but if you want real answers you'd give what turbo you are going to be using, along with exhaust setup, whether it remains to be carbed or fuel injected, along with what carb is used if you stick with it being carbed, how much boost you expect to be running, etc. etc.

I would say, however, that shooting for 250 horsepower on a turbocharged street port is beyond reasonable on a mid sized turbo with a modified nikki carb, more fuel pumping through it, exhaust, and ignition upgrade.

 

Using a stockport 12a, 14psi, TII turbo, and 2.5" straight pipe it'll make 170rwhp 180tq without a fan on the dyno(ic not doing sh*t). Streetport 12a with a t04b($300 turbo) should make 250-400rwhp depending on turbo trim and boost.

 

is 300whp feasable w/ a SP 12a, OER 45mm sidedraft and a .84 T3/60-1?

 

yeah, you could go with a bigger carb...

 

I run an internally standard 12AT block, have FC RX-7 throttle body/plenum set-up (TII in USA?), std FC RX-7 turbo, Microtech injection, custom front-mount cooler,
3" exhaust etc and I make 198rwhp @ 10psi.



I am building a new engine.... new housings, 3mm seals, large extend porting, dowelled etc, 55mm IDA injection, custom plenum and a Garrett GT3582R (GT35R)
with 1.06 trim. I'm looking for a comfortable 300 - 350rwhp at around 10-14psi.

Great little engine - and something a little different to the 13BT brigade!

Cheers
Andrew

 

You can make 193 at the wheels with a 91 13b 4 port, street ported, a set of rb headers, and a 2.5 inch exhaust. This still retains the 9.0:1 rotors and the stock turbo intake manifold.

I built this engine and dynoed it, not taking someone else's sheet and posting it.

Edit: just to clarify, this setup is all motor. No turbos.

 

I did'nt know that mazda made a 4 port motor in n/a form, in 91 with 9.0 compression rotors.....are you shure you're not talking about a s5 turbo motor?

Even still, with some mild mods and some porting, you're almost making as much power at the rear wheels, as a boosted engine did stock. I don't buy it. CJ

 

It is an s5 turbo engine with no turbo.

If you don't buy it, that's your perogative. Why would I lie about it??

 

Oh yeah, it has a haltech. Necessary to remove the MAF from the system (big restriction) and give us the fuel/spark control that was necessary

 

I see it possible. Nice work.

 

good work on that 13B!

 

GTORX7 came up with the idea, credit should go to him...

I guess my point is that it is not necessary to spend the money on a turbo setup when you can have the reliability and cheapness of NA when seeking around 200RWHP.

 

Hey shm21284, would a ported NA s5 engine with haltech injection and the rest of your make more, due to the higher compression and more optimized for being NA manifolds and VDI?

Whats the reason for starting with a T2 engine, JSPEC availablility?

 

My assumtion is that he want a 4 port oppossed to a 6 port.

 

you sir, are correct! 4 port 4 lyffeeeeee

 

The 4 port seems to have a distinct advantage over the 6 port in NA applications. I have not yet determined all the reasons, but i believe the intake manifold is freer flowing, being that it doesnt loop back over itself. Also, the intake ports do not take a sharp 90 degree turn as they do in the 6 port, althought his can be remedied with pineapple's 6 port sleeves. It is also possible that the 5th and 6th ports extend too far upward, to the point that the rotor is compressing back into the port, around the vdi, and to other rotor.

The 6 port/4 port direct comparison was done by GTORX7 with a set of street ported 6 port housings, and a set of street ported 4 port housings. It had 9.7:1 compression and the four port made 40 hp more at the wheels.

 

Its easier to port four ports for more power. The six port was designed to have more low-end torque, but is a bit more difficult to port from what I have heard.