Here is a synopsis of the changes made by Ford for the Model year 1989 to make
the standard 3.8L Engine into the SC version we all love (and hate at times).
To allow for the additional power generated by the engine there were new
designs for reinforcement made on the following components:
Block
Main bearings
Crankshaft Bearing Caps
Crankshaft (Dura-cast initially and forged steel for the majority of the production run)
Steel crankshaft sprocket
Timing Chain
Cylinder head
Head bolts
Rocker arms
The throttle body was designed new for the SC motor.
Water routings in the engine were redesigned for the SC motor.
Intake Manifold:
Of course to accommodate the supercharger the intake manifold was changed to
provide a way to mount all the upper engine components such as the SC, air
bypass valve, inlet plenum etc.
Exhaust Manifold:
These to were redesigned for the SC version. Each side houses a Heated
Exhaust Gas Oxygen sensor (HEGO). The use of the HEGO allows accurate sensing
of O2 level in a lower temperature exhaust gas (200C- 392F) when compared to a
EGO (unheated) sensor. On the SC the HEGO sensor on the right side is located
in the exhaust pipe just downstream from the exhaust manifold for that side.
On the left side the HEGO is located in the exhaust manifold itself.
Cylinder Block:
The cylinder block was redesigned and reinforcement was added to increase
durability and strength of the block. The water passage opening locations
were also moved.
Both the ATX and MTX camshafts (Automatic transmission equipped cars and
Manual transmission equipped cars) were redesigned to allow for newly designed
roller tappets. Roller tappets have the advantage of reducing sliding
friction and improving fuel economy. Because of the choice made to include
the roller tappets it was necessary to include guide plates and retainers to secure them.
The main bearing caps were made one inch taller and the cap bolts were
increased in length to allow the caps to be secured properly to the block.
Initially Ford planed to use an improved method of manufacturing the
crankshaft to add strength to the unit. It was referred to as Dura-cast. Due
to production issues with the Dura-cast process, the vast majority of SC
cranks were forged steel. Note that if you rebuild your SC Motor?the main
journals can only be refinished to 00.25mm (0.010-inch) undersized and the
rear main journal can not be refinished since it is already 0.010-inch
undersized. The reason for the undersize rear journal was to prohibit any
standard cast iron cranks being run down the line in an SC engine which would
surely result in a warranty problem. If a standard crank would possibly be
tried in a SC short block, the main bearing caps would not bolt down properly.
The balance shaft used on the standard 3.8 L (a feature used to reduce engine
vibration) was eliminated and replaced by a spacer in place of the balance
shaft drive gear.
A knock sensor was added to increase ignition performance. This is a
piezoelectric accelerometer sensor that is designed to vibrate at the same
frequency as the engine knock (pre-detonation). The sensor operates in
consort with the EEC IV engine control system to retard ignition timing and
hopefully eliminate the detonation before real engine damage occurs. If you
ever have to replace one make sure you get the correct version since there are
sensors made for at least 4 different frequency ranges depending on the application.
The rear main oil seal was modified to improve the sealing characteristics and
to provide more durability. Some of you may have experienced rear oil seal
failure in other Fords. Before approximately this vintage engine for Ford,
the seals were mainly two piece and over time the rubber seal would actually
wear a groove in the steel crank. The only true fix was to replace the crank.
Now with this redesigned seal it is a one-piece unit which allows the use of
a "sealing ring" which can be installed over the groove and allow a new seal
to be installed and the leakage to be stopped.
Cylinder Head:
The cylinder head was redesigned to increase the bolt boss diameter and deck
thickness. The water passages (between the cylinder head and block( were
revised to improve the sealing between the two components. The valve springs
were improved by strengthening and made smaller in diameter. The spring seats
were changed to accommodate the new spring design.
The cylinder head bolts are larger and have been made stronger.
Crankshaft Damper Assembly:
The crankshaft damper was changed to a cast aluminum piece to reduce weight.
The rear of the damper was fitted with a cutter for the Distributorless
Ignition System (DIS) system. It has three vanes which when passing past the
block mounted Profile Ignition Pick-up (PIP) sensor generates a signal to
both the DIS Module (mounted on the top of the engine beside the Ignition coil
pack) and the Electronic Engine Control Assembly (ECA {EEC IV Module}) and
gives the base spark timing.
Camshaft:
There were two different types of camshafts designed. Automatic and manual
transmission cars each had their own unique camshafts. They were color coded
yellow for the ATX version and pink for the MTX version. The paint was applied
to the rear end of the camshaft.
Timing Chain Tensioner:
A tensioner and corresponding snubber were added to the engine.
Pistons:
The piston domes for the pistons were redesigned to increase the performance.
The pistons were also constructed of high silicone aluminum (hypereutictic).
The compression ratio was 8.2:1.
Oil Pan:
The oil pan was diecast to reduce noise and vibration.
The oil level sensor was modified to also double for an oil temperature sensor.
Oil Cooler:
A Modine oil cooler was added to increase both engine and oil life.
Valve Covers:
The valve covers were diecast from magnesium for weight reduction.
Platinum tipped spark plugs were added for increased life and performance concerns of the engine.
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