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| SWAPPING AN 89-91 S5 ENGINE INTO AN 86-88 S4 CAR - S5 TO S4 SWAP |
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Many people have the
desire/opportunity to use a later engine in an earlier car. Though
this is usually good for a couple of upgrades and a few more horses,
it is rarely worth the work. It is MUCH easier to simply find
the proper engine for your car and bolt/plug it in. Note that
some of these swaps have differences in emissions equipment/passages
which prevent being able to keep the car emissions legal when
doing so. You’d usually wind up removing the whole emissions
rack and components to get everything back together properly,
though it could be possible to make such a swap pass.
When doing such a swap, it is important to note that the flywheel
must be obtained/used that matches the engine block you’re
using. For instance, if you’re putting an s5 NA block into
an s4 NA car, you must use an s5 NA flywheel with the s5 NA block;
using the s4 NA flywheel from your old block will throw the new
block out of balance.
These swaps are really pretty simple in theory, but it takes several
hours to get everything swapped over. Basically, you’re
going to keep everything that used to be on your old block, and
transfer it to the newer one. The only times this principle does
not apply: |
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Remember
that anything electronic, or anything that an electronic part bolts
to and would not otherwise bolt to on the newer setup, must be retained
from your old engine. Your car still has to think it is an s4, even
though it has an s5 block and possibly even s5 manifolds.
The hardest part of the swap, and the part with the most potential
for screwup, is the front cover. The oil metering pumps differ between
s4 and s5, and the front covers differ to accommodate this. When
swapping front covers, it is possible to allow the bearings and
spacers to slip on the e-shaft, doing internal damage and creating
a lot of endplay and vibration. For more information on this, see
the mazdatrix how-to section (www.mazdatrix.com).
Also note the front cover o-ring (oil passage) which is easily lost/crushed/slipped
out which will result in loss of oil pressure, so special care should
be taken to ensure that this gets re-sealed well. Mazdatrix also
has a nice writeup on this.
Now, here is an overview of
how to proceed with the swap.
Strip the s5 engine down to the bare block, leaving the flywheel
on, but removing the front cover. Repeat for the s4 engine (your
original). Decide which parts you want to use from the s5, if any
(intake manifolds or turbo/ex. Manifold are the only parts which
were really improved). It is always easiest to simply use all the
s4 parts.
Note that when swapping an s4 intake onto an s4 block, the port
air passage in the intermediate iron, below both primary intake
ports, must be blocked off to prevent a large exhaust (egr) leak.
I use a healthy amount of jb weld packed firmly down into the passage. |
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Things
you MUST keep
(originally on the old engine, which plugs into the
car) are: |
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Things
you may wish to upgrade to from the s5 engine: |
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Throttle body
with TPS |
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Oil metering pump and front
cover |
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Wiring harness with fuel
injectors |
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ecu |
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airflow meter |
•• |
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water pump housing, water
pump, fan |
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alternator |
•• |
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intake manifold set |
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turbo and manifold |
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fuel rails(s5 have an integrated
fuel pulsation dampner less likely to leak and catch
fire) |
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intercooler (s5 has a slightly
larger inlet) |
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Again, the aim of this
is to make the car/ecu think it still has an s4 engine, by keeping
all the “smart” parts, which are the electronics, from
the original engine.
The same principle can be used for s5às4 swaps, however these
are not highly recommended because s4 blocks are lower compression,
and the ecu is set up to run a higher compression engine, therefore
sometimes power and idle quality are compromised when doing such
a swap. |
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Rotary
Resurrection - Tech Section |
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NOT ACCEPTING
any new work
until
March 1,
at which time I will
accept 4-5 new jobs.
Please contact me then.
In the meantime,
I am not maintaining
a "wait list" or
"contact me when" list. |
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Rotary Engine Professionals interested in having an ad on this website contact us online. |
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