The HITman - 12A Turbo Setup

12A Turbo Setup Tips
So , you got yourself a 12A Turbo engine and you want to know what the best things are to do to it to get that little bit extra. Well this is the place. Standard , these engines are not the most powerful engines available , making only around 90KW to the wheels (around 160HP flywheel) , but they can be made to get up and boogie !

The Engine Management
Throttle Body :
First of all I will cover the OEM injection system. Basically it was designed in the early 80's and it looks like it! It has a 3-throat throttle , as do all the Turbo engines , and it looks a lot like a carburetor. What this does is allow a single throttle to work as the primary throttle , which means that it opens first , then the two secondary throttles open at around 15% throttle. The benefit to doing this is that Mazda could get away with running only two injectors , located in the centre engine housing in the primary ports. At closed and up to 15% throttle, the primary ports are the only ones getting air-flow through them , which means a higher gas velocity , which in turn means better atomisation of the fuel. See, Mazda did a little homework before diving in ! If they were to have one big throttle, then they would have had to mount the injectors where the highest gas velocity is , which would have been much higher up the manifold and very close to the throttle body itself. It would have made things rather messy. The OEM throttle body is more than large enough to cope with the airflow of the engine. Leave it as is.

ECU Selection :
These engines are quite straight forward to tune , and just about any aftermarket ECU can do the job. I prefer the Haltech F9A fuel-only computer due to its high level of load adjustment, and run the factory distributor.

Download Haltech F-9 V4.9 MAP for : 12A Turbo

Injectors :
The 12A Turbo engine runs some of the largest injectors available from an OEM. At 800cc/min they are capable of handling a few mods to the motor but if you go too far you will require more fuel. 800cc may be big but it only has two of them. Two more injectors can be mounted to the outside of the secondary runners of the inlet manifold, but it would be a good idea to get an expert to do this.

Ignition :
The OEM distributor on the 12A Turbo is unique in that it is the only rotary distributor that Mazda produced that incorporates a boost retard mechanism. Leave it all standard and run the ignition timing as per what the timing marks say. If you advance it any more than stock you can pick up power , but the risk of detonation is quite great with these engines. Run NGK B9EGV spark plugs in these engines. If you want to go for a better ignition system, run the Haltech E6K computer along with the ignition system from the 13B Turbo Series 4 / 5 RX7. It produces a much stronger spark and allows adjustment of the ignition timing so it can be tailored to the motor.

Turbo and Boost Levels
Boost Level :
Standard boost level is 6psi. Due to the lack of an intercooler and the standard 2 x 800cc injectors , PLEASE limit yourself to around 9psi. If you push more standard you are certain to blow up the engine. With an intercooler you can just get around 11psi ,but I would consider 10psi a lot safer until you get more fuel into the motor.

How a customer has ducted his intercooler.

Turbo :
The standard turbo is way too small. It is a bottleneck in the scheme of things and should be removed and replaced with something larger. A turbo from the Series 4 13B Turbo engines is a good choice. Boost response is still as good , but expect around 30% power gains when running the same boost. The 13B Turbo is water-cooled as well and will run much cooler, whereas the OEM 12A Turbo is just oil-cooled. You will need to manufacture a new exhaust manifold to suit. If you want more power and have a little money to spend , a T04 turbo with an H3 or 60-1 compressor mated to a P-Trim turbine in a 0.88 housing will do wonders for power. By this stage you should be looking to upgrade to a fuel/ignition computer , big intercooler , more injectors, and higher flowing inlet system.