I have a 90 Mazda RX7, 5 speed with 13B FI. What years of 13B FI
motors
can I bolt into this car? How do I tell what year of 13B I'm looking
at if
it's already out of the car? I plan to take off the
stock exhaust and put a header on it. The original motor spins
freely,
just has no compression, stuck apex seals. Looking to take one motor
out
and put another right back in. If you can help with
any info please e-mail answer to Armilite@aol.com
Thanks
Rich
Rich,
You're going to have the least aggravation by installing an engine from
1989-1991. This is due mostly to differences in the engine controls and
manifolding on the engine.
For example, the '86-'88 engines used a mechanical rod attached to the
throttle to actuate the oil metering pump. The '89-'91 oil metering pump
contains an electric stepper motor which is controlled by the ECU. The
ECU reads a throttle position sensor. So, on the '89-'91 engines, the
TPS has two sensors on it.
The another significant difference is "VDI". The '89-'91 cars use a
pneumatically controlled solenoid on the intake which shortens or
lengthens the intake tract.
Finally, the auxiliary intake ports and the VDI (above) are controlled
with positive pressure from the air pump on the '89-'91 cars. On the
'86-'88 cars, exhaust back pressure is used to activate the auxiliary
intake ports, and VDI was non-existent. There are plenty of people who
will tell you that they installed a racing exhaust and discovered that
there wasn't sufficient exhaust back-pressure to actuate the auxiliary
intake port, resulting in a net loss of power.
If you install an '86-'88 engine, you will have to address each of these
problems, and perhaps others as well.
Attached are pages scraped from Mazda parts lists, which show the
appearance of the intake manifolds. You should be able to visible
differentiate the engine by the intake manifold.
Regards,
Rob
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