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The Story of the 4AGE || Part I - YouTube
Channel: Gear Quest
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so let's talk about one of toyota's most
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famous engines it's evolution and some
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of its interesting attributes the 4a g
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it started life in 1983 and was produced
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until 1998.
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let's break down its naming convention
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the four means the fourth revision of
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the a block the g
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indicates it's a performance cylinder
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head and the e is for electronic fuel
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injection
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the first instances of the 4a engine
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family were far less impressive and
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performance oriented than the almighty
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4a ge
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the first engine being the 4ac
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used a carbureted single overhead cam 8
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valve platform outputting around 70
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horsepower
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the next evolution of the 4a family was
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the 4afe which introduced double
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overhead cams and fuel injection
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soon after the 4age was the performance
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option for the corolla celica mr2 and
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other midsize toyota vehicles of the
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time
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fun fact you can also find the 4age in
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the geoprism and chevrolet nova
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which are basically re-badged versions
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of the corolla ae92
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when it comes to the power output of the
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4age it started with 112 horsepower in
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its first iteration
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and bumped up to 165 horsepower in its
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final generation
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another fun fact
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the 4age shares a lot with a cosworth
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bda for those that don't know the bda
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means belt drive series a and was one of
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the first racing and production engines
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to have both cam gears driven by a
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rubber tooth belt
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the 4age was also toyota's first engine
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to have both cam gears driven by a
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rubber tooth belt
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without drifting too far off the bda was
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a racing engine designed in 1969 by my
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call for the ford escort rs1600
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the original bda spawned numerous
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variants which were very successful in
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various classes of motorsport
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are these all coincidences between
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toyota and cosworth
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i don't think so because the
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similarities don't end there
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another interesting overlap is that the
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4age has a bore of 81 millimeters and a
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stroke of 77 millimeters
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the bda also has an identical boron
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stroke
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moreover the 4age uses an over square
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design which means its bore is larger
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than a stroke allowing it to handle high
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rpms significantly well
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a large bore allows for larger valves
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and in stock form the 16 valve 4a geek
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comes with 29.5 millimeter intake and
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25.5 millimeter exhaust valves
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these are also identical in size to the
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cosworth bda
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these attributes mean both engines are
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capable of handling high rpms so it
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seems the 4age is basically a
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mass-produced version of the cosworth
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bda
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what about tuning well the 4age has been
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around for more than 30 years so
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everything possible that you can imagine
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being done to it has already been done
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some examples include high revving
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formula atlantic builds that produce
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around 240 horsepower at around 9000 to
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10 000 rpm adding turbos twin charging
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and even carburetor conversions
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i'm sure there are more crazy builds
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that i didn't even mention
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the 4ag ease block is made from cast
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iron making it heavier than aluminum
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blocks but this also means it's tough to
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handle abuse and even boost
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it also has a forged steel crankshaft
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making it a perfect candidate for forced
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induction
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but depending on how much boost you make
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upgrading the piston and connecting rods
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is not a bad idea since they are cast
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additionally the 4age is a
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non-interference engine which simply
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means when the piston has a top dead
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center it will never go higher than a
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fully open valve
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that is to say
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the piston can never interfere with the
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valves
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conversely in an interference engine the
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piston could occupy the same space as an
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open valve
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this means if you rotate the engine
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backwards in an interference engine you
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could potentially damage the valves or
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the piston due to collision
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the 4age engine has a total of 5
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generations
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but that is honestly very unreliable and
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you really can't tell what's inside
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unless you take them apart
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in conclusion the 4age is a good small
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reliable capable engine
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it's short and it's a great swap into
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older toyotas and other light cars
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it is outdated and squeezing very large
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power figures from the 4age will take a
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lot more effort and money
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than getting the same power figures from
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a more modern iconic engine such as the
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2zz or honda k series for example
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that being said it's a novice friendly
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engine that is still relatively
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plentiful and is fun and easy to tune
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and work with
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you
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