HR Dictionary: Engine & Electrical


Have you ever looked at a forum, tech guide or catalogue of all those shiny bits you want for your car but the terms and abbreviations got you confused? Well with the HR dictionary you’ll never have those problems again!!  In this edition we cover the finer details of the engine and electrical segments of the car with all the techncial and slang terminology you could ever want!

16V: Shorthand for sixteen valve engine. Four per cylinder on a 4A-GE. Also known as ‘4-valve’ in Japan.

20V: Shorthand for twenty valve engine. Five per cylinder on a 4A-GE. Also known as ‘5-valve’ in Japan. Also known as Silvertop for AE101 engines or Blacktop for AE111 engines.

4A-C: SOHC 4 cylinder found in Australian delivered AE86s.

4A-GE: The engine found in the AE86. This version known as a ‘Bluetop’ or ‘Bigport’ 4A-GE. Also found in Redtop and Black & Redtop variants from AW11, AE82 and AE92 vehicles. The ‘Redtop’ is also known as the ‘Smallport’ in referenxw to its smaller inlet ports on the head.

4A-GTE: A turbo charged 4A-GE/GZE engine. 4A-GTE is not an official Toyota engine code, but has been adopted by most of the Toyota fraternity the world over. Similar to the Z in GZE signifies a supercharged engine the T in GTE refers to a turbo charged engine.

4.5A-GE: A standard 4A-GE engine using 83mm piston instead of the factory 81mm piston. Using this large oversized piston brings the cubic centimeter capacity (CC) to 1675cc’s or 1.7ltrs. This was mainly done by a small work shop in japan by the name of RS YASU.

5A-GE: A larger stroke crank and rods produced by HKS in the late 80’s to increase the capacity. It brought the capacity up to 1720cc using standard pistons but using a longer stroke than standard. these were fairly expensive when new, and are very rare to find in good condition second hand. The plus side with the 5A-GE crank is that it can be used with either a 16v or 20v engine.

7A-GE: This is done by fitting a 4A-GE head to a 7A-FE bottom end. The 7A-FE come from the later AE102 and AE112 nanna spec corolla’s. By fitting the 4A-GE head you get a longer stroke bottom end combined with a excellent flowing head. Needs a bit of work to make decent power, but the torque increase is immense.

8A-GE: If you have one of these it is a very serious engine. originally starting in japan using a 5A-GE crank and 83mm piston it gives a rough capacity of 1860cc or 1.9ltrs. More recently and most notably Mark Yager (Yager performance) does this with a rebuilt 7A-FE bottom end and again oversized  82-83mm pistons to bring it to 1890cc or 1910cc or 1.9ltrs. This was done to satisfy the power increases wanted by clubman owners who were restricted in the engine they could use.

AFM: Air flow meter. Situated in front of the throttle body after the intake filter, it measures the air flow and sends an electric signal to the ECU to provide the right amount of fuel to air mixture.

ADVANCE: Refers to how early a distributor or CAS sends a spark signal, or how early you want the valves to open on the camshafts.

BIGPORT: This is the early bluetop version on the 4A-GE 16v which had the TVIS and larger intake ports, hence the title bigport.

BLACKTOP: This refers to the last of the 4A-GE series engines and the last 20v engine. It has 47mm throttlebodies, and 11:1 compression ratio. this is the last and greatest factory N/A 4A-GE engine toyota produced.

BOTTOM END: Refers to the block, crank, rods and pistons as whole.

CAI: Cold air intake. pod filters, ram air intakes, intake tubes etc.

CAM DURATION: How long a valve is opened for. Usually listed as a degree within the 360* degree circle, duration can vary quite alot and be quite large with cams varying between 240* deg right up to 320*deg.

CAM GEARS: The driving gear attatched to a camshaft to run the cams themselves. aftermarket cam gears usually are adjustable to allow for fine tune adjustments on larger duration cams.

CAMSHAFT: A shaft with raised sections so that when its turns it pushes open the valves of an engine. Commonly refered to ‘CAMS’ for short, they can come in varying degree’s and duration and also camshaft numbers. Most American V8’s have one cam in the block, almost all Japanese engines have two or more cams in the head.

CARBURETOR: Commonly refered to as carbies or carb’s these are a old school fuel and air mixing device. ­T­he goal of a carburetor is to mix just the right amount of fuel with air so that the engine runs. It mixes the fuel using vacuum from the air being sucked in and fuel from the carb bowl which holds the fuel and sprays it into the combustion chamber. Carbs are a fairly in-exact fuel and air mixer and can take quite a lot of tuning to get right, and often need regular tuning and maintenance to keep running correctly.

CAS: Crank angle sensor. Used on 4AGZE’s to provided the correct ignition timing.

CATALYTIC CONVERTER: Commonly refered to as a CAT CONVERTER or CAT. This is an oval shaped item in your exhaust system designed to capture engine emissions.

COILPACK: An individual coil that send sends spark through the spark plug. Found on later GZE’s factory from Toyota, they are a very common up grade for N\A cars with aftermarket ECU’s.

CONROD: Short for connecting rod. Commonly called ‘rods’ they connect to the crank to the piston. Rods vary in strength depending on their applicaion and need to be strong to cope the strain of repeatative up and down movement.

CRANK: The crank is what turns and moves the rods and pistons up and down in the correct order, it also feeds the output to the drivetrain.

CUT AND SHUT MANIFOLD: This is a standard smallport/AE92 manifold cut and rewelded back together so as to be converted for RWD.

DISTRIBUTOR: Dizzy/dissy, the distributor provides the charge to fire the spark plugs, usually on non-turbo model engines.

DOHC: Dual over head camshaft. A twin or pair of cams situated in the head.

ECU: Engine control unit. The brains of the operation

EXHAUST SIDE: The spent and burnt gases exiting side of an engine.

EXTRACTORS: Exhaust manifold of the engine. They extract the most amount of used air out and depending on design help to make power and increase torque. Sometimes called headers.

FORGED PISTONS: Forged pistons, or forgies for short, are a high tensile high temperature forged piston made to with stand extreme pressures and temperatures. Forged pistons are usually found in rebuilt turbo or high compression motors.

FRONT MOUNT INTERCOOLER: A sealed air flow unit, similer to a radiator that cools charged intake air on a turbo or supercharged engine. Generally mounted in front of the radiator, between the front bumper and radiator support.

FUEL PUMP: Either fitted intank like most factory applications or externally to allow for bigger and more powerful fuel supply. Aftermarket fuel pumps can be fitted to allow for more powerful engines or as part of a surge tank to prevent fuel surge.

FUEL RAIL: A solid tube like item that attatches to the fuel injectors that holds the pressure supplied by the fuel pump.

FUEL SURGE: A loss of fuel supply on cornering or accelleration. This is especially common with injection converted ADM AE86’s as they did not come with a factory fuel injection set up.

FUEL SURGE TANK: Used to to prevent fuel surge to an engine. Using a less powerful lifter pump to fill the tank, and then a much larger fuel pump to send fuel forward. Surge tanks usually are about 2-3liters as to prevent a loss of fuel supply even under the most demanding conditions.

FUEL INJECTORS: Supply a precise metered amount of fuel to each cylinder by pressure squirting from the fuel rail.

IGNITION COIL: Provides the spark to the distributor which is then sent to the spark plug.

INTAKE MANIFOLD: A log shaped chamber with tubes or runners from the chamber to the head. The intake manifold is where the air is sucked in through the throttle body and forced into the engine along with fuel. The manifold usually has as many runners as it does cylinders, except in the case of a big port 4A-GE which had 8 due to the TVIS plate.

INTAKE SIDE: The clean air ingestion side of an engine.

ITB’s: Individial throttle bodies. ITB’s or quads have a individual throttle butterfly for each cylinder allowing precise controlled ingestion of air and fuel. Due to the individual nature of the throttles it also increases induction noise 4 fold, but god damn it sounds awesome!

LIFTER PUMP: A small and less powerful in tank fuel pump used to fill a surge tanks. Usually the standard intank fuel pump as it is no longer under as much stress compared to suppying a heavily worked engine.

MAP: Manifold absolute pressure. A small vacuum sensor that takes a vacuum signal from the intake manifold and sends a signal to the ECU to provide the right amount of fuel to air mixture.

OVERLAP: The overlapping of duration between the intake and exhaust cams

PCV VALVE: Positive Crankcase Ventilation valve. A valve to allow air to escape that has built up in the sump and below the pistons.

RETARD: Refers to how late a distributor or CAS sends a spark signal, or how late you want the valves to open on the camshafts.

SHIM UNDER BUCKET: A modification to the 16v 4A-GE that enables the use of high lift camshafts of 8mm and over. Shim under buckets are valve clearance adjusting shims in the shape of a small 13mm pellet shim, rather than the standard 25mm diameter shim that sits on top of the cam buckets. If incorrectly coupled with regular ‘shim over’ buckets, high lift cams will occasionally catch the edge of the shim with the top of the camlobe , destroying the bucket and possibly the head in less than a few minutes. The 20v engines do not require this modification to utilise high lift camshafts.

SILVERTOP: This is the first of the 4A-GE 20v engine, so called because of its silver rocker covers. It has 45mm throttlebodies and 10.5:1 compression. It is the most common 20v engine available.

SMALLPORT: The 2nd generation 4A-GE 16v or red top. This 4A-GE did not have the larger ports or TVIS that the earlier bigport came with

TIMING: This refers to either ignition or cam timing. Timing can either be advanced or retarded. IE 10* degrees positive (+10* deg. or 10* degrees negative (-10* deg).

TPS: Throttle position sensor. Takes a reading from the throttle body to tell the ECU how far open the throttle is and how the ecu should react.

TVIS: Toyota Variable  Induction system. This a secondary set of throttle butterflies on theside of the head that opens up at certain RPM to allow more air to flow into the combustion chamber. It was designed as to maximise bottom end torque without sacrficing top end power and was later dropped from the smallport engine.

VALVE BOUNCE OR FLOAT: When the valves can not close properly as the engine is revving to hard or over revved. When valve bouncing or floating the valves are not completely closed as the amount of RPM is too high along with the amount duration in the cams not allowing them to close.

VALVE LIFT: The amount the valves open. Usually given in millimetres (MM) or degrees, it varies from 6mm right up 12mm.

VVT: Variable valve timing. Using a oil pressurised valve to adjust the cam timing via loadings on the ECU. Single dimension, rpm only, switching of cam between no advance and full advance of about 30 degrees.

VVTi: Variable valve timing and intelligence. Using a oil pressurised valve to adjust the cam timing via the ECU. I stands for intelligence, with a couple of extra loadings namely TPS and temp. Still switches between no advance and a fixed amount of advance, usually 30 degrees.

As always we love to involve the very knowledgable AE86 community in our blogs, so if you have a few terms you want to add, just write em in the comments!


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