Mazda 929 LA2 rx4 13B wankel convertion

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357supermagnum
Helpful MS/Extra'er
Posts: 147
Joined: Tue Oct 27, 2009 3:49 pm
Location: Norway

Mazda 929 LA2 rx4 13B wankel convertion

Post by 357supermagnum »

Hi, i have some questions,
A pal of mine is planning to convert a Mazda LA2/LA3 to a Wankel engine.
The Mazda RX-4 was unpopular here in Norway since in those days the
right gasoline type was unfeasible to get hold of,
causing the engine to run hot and going belly up. This was not the cause
in Sweden.
I dont know if the octane rating,the lubricating properties of the leaded
gasoline or too high combustion temperatures caused this.
Perhaps someone can clarify?

The engine is a 13B from a RX5,he does have the required rear axle and
driveline parts. The engine is all stock.
It should be possible to convert the engine to EFI using a Megasquirt 3x
controller.
The 13B has a oil metering pump (OMP).
When engine oil is injected into the combustion chamber, it only is
partially burned, leaving some unburned deposits behind.
These deposits can build up and reduce engine performance and eventually
cause apex seals to stick, resulting in poor compression and a mandatory
overhaul of the engine.

One obvious method of preventing this is to disconnect the metering pump
altogether and mix two-stroke oil to the gasoline like some
older two-stroke engines require. It can safely be removed if a two
stroke oil premix with the ratio of 100/1 mixture is used.

With this method it has been demonstrated that two-stroke oil is an
effective lubricant and there is no build up of combustion residues.
Klotz Super Techniplate is suitable with E85 fuel, the megasquirt
controller can be fitted with a flex-fuel sensor that makes the
Megasquirt box adjust the spark timing and fuel according to the ethanol
content in the fuel.

The parts needed is:
Throttle body with idle air control and throttle position
sensor,80~100mm diameter ( S4 rx7 intake has one fitted,must be modified.
see notes )
Intake manifold (s4 rx7 inlet manifolds with an adapter plate should fit
according to a forum )with Intake air temperature sensor and injectors.
Distributor,standard
Exhaust manifold.
Stock Coils (negative connection on leading coil used for RPM signal,
fuel only,batch firing of the injectors,staging is needed)

For control of fuel and spark, this coil seems to be usable as it is compact, and has 4 coils in one package:
4 way logic coil from VW Golf / Jetta, Skoda Octavia
Uses part numbers 0040102029, 06A905097,
06A905104, ZSE029
I have not found any information on the dwell timing, or the voltage versus dwell on this coil.
The later CAS sensor is usable on this engine,but i have not found any information on how to wire it up.

CAS sensor wiring ( internal wires )
G+ Green ( the wheel with the 2 teeth or "spikes" ) This is the "cam wheel" as MS3 sees it.
G- White with black stripe
NE+ Red ( crank wheel,24 teeth)
NE- White ( crank wheel )


idle air control/bypass air control valve ( The S4 rx inlet manifoild has one)
Water temp sensor
wideband 02
fuel pump and fuel filters
Fuel pump relay
misc fuses related to the MS3x box.
Fuel pressure regulator with pressure gauge.

Throttle body mod note:
The tertiary set of throttle plates is there to smooth throttle transitions.
In the NA, it is there to prevent wide open throttle when the engine is cold.

While not part of the throttle body mod, removal of the thermowax and
coolant feed to the throttle body is often lumped in.
While absolutely a bad idea on a stock ECU street driven car, the whole
cold start cam and thermowax is unnecessary with a standalone as the BAC
now takes over its functions.
The termowax and the cold start cam will also mess up TPS calibration
There is a writeup on performing the throttle body mod at:
http://fc3spro.com/TECH/HOWTO/TBM/tbm.html

As the Megasquirt is an aftermarket ECUc,it cannot control the stock
emissions equipment so it needs to be removed.
The how-to for a S4 RX7 engine is here, note that the BAC must not be
removed, as Megasquirt controlls the BAC:
http://www.rotaryresurrection.com/2ndge ... moval.html

I know that these engines sometimes runs 2 injectors per rotor,primary
and secondary.
They list as
13B 6-Port
2x injector 720
4x injectors 430
13B Turbo Series 4 / 5
550
13B Turbo Series 6
Primary 550
Secondary 850
All the injectors are in CC/minute

According to the 130 hp this engine gives as standard, and a duty cycle
of 60%
the suitable injectors size is 284cc/min per rotor. With 48mm Weber
carbs and a proper exhaust headers this engine makes about 170 HP,so the 478
cc/min is perhaps suitable.

The closest ones that i have found is:
Siemens Deka:
partnumbers
FI114357
0280156127
0280155968
Static Flow Rate (GAS): 44.5 lb/hr = 478 cc/min @ 43.5psi


Some information about the Rx7 is sourced from:
http://www.aaroncake.net/rx-7/Megasquirt/index.asp

Any comments or suggestions ?
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