SECOND GENERATION RX7 TURBO II RACECAR:
· CHASSIS: Stock with welded 8 point Rollcage. Fuel Safe fuel cell, gutted interior, and custom aluminum dash finish the interior. Minimum wiring for essential systems. Coil over suspension with Koni race struts and shocks from Ground Control. Mazda Competition sway bar (front only) with urethane suspension bushings.
· ENGINE: Street ported 13bt, low compression rotors
(new), hardened stationary gears, high volume and pressure oil
pump, stock turbo and wastegate (new), Turbo II intake manifold
with 4 700cc RC injectors, stock TII throttle body modified so
all butterflies open simultaneously, front mounted intercooler,
larger remote oil cooler, stock leading and trailing coil packs
with the ignitors, stock Crank Angle Sensor (CAS), and a Haltech
E6K programmable fuel injection and ignition ECU. Motor makes
230HP at the rear wheels at 8psi of boost on a Dynojet chassis
dyno. All dyno and Haltech tuning done by Jim
McFarland at Mech-Tech in Escondido, Ca.
· TIPS ON FUEL INJECTION SYSTEMS: This car took
13 months to complete, and eight of those were spent on the ignition
and fuel injection systems. This car was kept close to stock,
since we wanted a very reliable racecar for endurance racing.
Most modifications were made with reliability in mind not pure
speed. We started with a stock engine with a larger intercooler
and exhaust, and immediately needed more fuel than the stock ECU
could deliver. Two additional injectors were installed in the
intake manifold with a simple RPM activated injector box. The
stock ECU was retained, but a new chip was used (unknown manufacturer,
before my time). A manual boost control was also installed to
raise the boost from the stock setting to about 10 psi. The motor
was immediately destroyed needing two new rotors and housings,
so a complete rebuild to current specs was done. All motor building
was done by Pablo a well-known rotary builder in Southern California.
A new turbo and waste gate was installed since the original was
in bad shape. We also determined that the stock ECU was not going
to work for our project. We felt an ECU that could be programmed
easily would be a better choice for our racecar. The programmable
ECU would allow us to make modifications and not have to burn
a new chip each time. Plus tuning at the track would be possible.
The first ECU we tried was an SDS EM-2F from Canada by way of
the US representative in Florida. The company in Florida uses
the system, which controls both the fuel and ignition on a couple
of high boost rotary drag cars. After a few questions about the
compatibility with our setup and application a system was ordered.
The ECU, a new crank pulley, and all the wiring were included.
An aluminum ring is mounted to the pulley with three magnets installed,
and an adapter is mounted to the engine case to mount the Hall
Effect Sensor. The HES gives the ECU the crank angle and the RPM
for the ignition and fuel injection. Problems arose after the
system was installed with the orientation of the magnets. Magnets
have a north and South Pole to them, and the HES is triggered
differently depending on the pole. Our pulley unfortunately had
the poles reversed. After this was fixed the engine could be started,
but idled poorly. One of the disadvantages of the SDS system is
that it does not have any provisions for separate control of the
trailing ignition. We were not aware of this missing feature at
time of purchase. This would be the systems ultimate downfall.
The trailing ignition needs to fired between 15 and 20 degrees
after the leading ignition. Since the SDS system was designed
for piston engines this ignition specification was not needed
and therefore not available. We could never get the engine to
run correctly at all engine RPM's with the SDS. The system was
not going to work for our intended use, so after a couple of discussions
it was determined we would need a new ECU. SDS was sympathetic
to our problems and was very cooperative when we had problems.
This story is included to help other racers in choosing an ECU.
The SDS guys were very helpful and accommodating, but the system
was just not suited to the special ignition needs of the rotary
engine. The system was easy to install and program, and would
work well on almost any piston engine.
The next problem was what other alternatives were there? One of
the biggest names in programmable fuel injection is MOTEC. The
MOTEC system is well known in racing circles as one of the best
and most flexible systems available. It is also one of the most
expensive. This was to be our last resort, as the budget didn't
allow the additional cost for the MOTEC. We tried to see what
other local RX7 racers were using, and found that most were not
using the fuel injection at all. They were using carbs and distributors
(not the best setup either). So we looked to the Internet for
people who might be using a programmable ECU for the RX7 turbo.
Many were found almost all outside the US. A large group of racers
in Puerto Rico were using the Haltech ECUs on some very fast drag
cars. An even larger group of racers in Australia were using the
Haltech ECUs. We also looked at the Electromotive TEC-II and the
EFI Technologies units. We could not find any example of cars
with these systems installed, but the manufacturers said they
would work on the rotary engine. We also looked at a couple of
cars in Australia that had the Wolf 3d ECU and the Autotronic
ECU. After many calls to Haltech USA to check the stories seen
on the net, we decided that the Haltech ECU would be a good choice.
So we ordered an E6S from well-known RX7 shop Rotary Performance
in Dallas, Texas. Their shop is very close to Haltech USA also
in Dallas area. The E6S is not the latest ECU Haltech has, but
because of limited supply of the newest ECU the E6K we decided
the E6S would work for our application. We would use the Mazda
Crank Angle Sensor (CAS) and the leading and tailing coil packs.
The Haltech is a much more complicated system and the wiring was
quite a bit more difficult to install. This is where having a
detailed wiring diagram would be helpful. None was included so
the wiring took a lot of specialized knowledge of rotaries, fuel
injection, and digital ignitions. A couple of calls to Haltech
USA and Rotary Performance got the wiring straightened out. The
other problem was there was no base MAP (settings for the ignition
and fuel) included with the ECU. Luckily one of the Australian
web sites on Haltech has a database of maps for the 13b turbo.
The Hitman's site has a bunch
of great information on rotaries and Haltech fuel injection systems.
With the new map installed and the wiring finished we attempted
to start the car, but it would not fire. There was no spark. After
fine tuning the ECU setup the car would start and run, but not
very well. The timing was the problem again. Seems the E6S doesn't
work very well with the stock CAS. This was going to be a problem.
Haltech USA suggested using the S1 Hall Effect Switch. We would
now have to fabricate a new crank pulley and a mount for the new
hall effect switch (S1). This was not what we had been expecting,
and not the setup we wanted. These parts would have to be made
by us as they were not available from Haltech. A few more calls
to Haltech USA and finally Haltech in Australia (Home Office)
got to the problem diagnosed as interference from the alternator
and or ignition wires (Magnecor and Taylor). This was causing
a poor signal from the CAS to the ECU. It is a known problem that
was fixed with the introduction of the E6K, which is able to filter
out the noise better. If you use the S1 HES there is no noise
problem. Since there were no brackets or wheels available and
custom fabricating these were deemed too difficult. We decided
to ask Rotary Performance to exchange the E6S for an E6K, which
was now in stock. After a little negotiating they agreed to an
exchange as long as we paid the difference in prices. Done deal!
After double-checking the wiring and installing a new map from
the Hitman's site we attempted to start the car. The car started
immediately and idled better than ever. With the Hitman's map
installed the car was now driveable. This was a great accomplishment
for us as the car ran well and could be driven. Now came the tuning
of the engine. If the car is street registered then the tuning
can be done on the road, but our car is a track car. So, we decided
a chassis dyno would be an easier alternative. We had a bad experience
trying to tune the car at the track. The search for a dyno was
almost as difficult as the ECU search. Most chassis dynos it seems
are not setup to tune engines. They are primarily used to calculate
horsepower and nothing else. We needed someone who could monitor
the exhaust gases and tune the Haltech for maximum power and fuel
economy. We finally found Mech Tech Motorsports in Escondido California.
Jim McFarland knows Haltech, rotary engines, and has a Dynojet
chassis dyno setup for fuel injection tuning. Jim agreed to do
the final tuning and map the fuel and ignition on the Haltech.
Mech-Tech does a lot of custom turbo charging and fuel injection
projects for all types of engines. The car now runs great and
we are looking forward to racing it this year.
Tim Spencer
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