Glossary of terms

 corner. This reduces traction on the inner wheels which is undesirable from a handling point of view.

The ARB links the wheels left to right via a springy bar. What this means is that as the body starts to roll the compression of the suspension on the outside of the car also causes compression on the inside suspension helping to keep the body level and the weight distribution even side to side</TD> </TR>

 on airflow over it's surface to cool compressed air which flows through if.
 <p>It generally looks like a radiator with a large amount of small fins 
 between narrow channels. Hot compressed air flows into one end of it causing 
 the fins to heat up. These in turn are cooled by air flowing over the 
 intercooler. The net result is that the air goes in one end hot and comes out 

The 185 is the only GT-Four which uses an ATA intercooler in a <a href="#TopMount">topmount</div> configuration. In this setup the cooler has a scoop on the bonnet to channel air over the intercooler. Suffers from severe <a href="#Heatsoak">heatsoak</div> when the car is stationary as there is no cooling airflow and all the heat from the engine rises through the core</TD></TR>

 valve e.g. an atmos(pheric) dump valve<p>In this configuration excess boost 
 pressure is dumped direct to the atmosphere. This type of dump valve tends to 
 be loud and makes the familiar whoosh noise that so many people associate with 
 turbocharged cars</TD></TR>

</TD></TR>

 Read the <a href="/website/technical/TurboOperation.htm">Turbo Primer </div>for 
 more information on how this works</TD></TR>

of boost means that the inlet manifold is actually at a pressure of 23.7psi since ambient pressure is 14.7psi nominally</TD></TR>

pressure during sudden closed throttle moments (changing gear etc).

 <p>Improves turbo life as it helps to stop the turbo shaft from stalling or breaking due to sudden 
 stopping of airflow in the inlet path.  Read more in the

Can be vented to atmosphere (making that wooshing noise) or re-circulated back to the inlet pre-turbo (minimizing noise - maintaining metered air). Stock only on ST205</TD></TR>

</TD></TR>

 from the engine.
 <p>In a stock car it resides between the turbo and the flexi exhaust section, 
 directly behind the main cooling radiator. It's purpose is to provide an 
 environment for a chemical reaction where unburned hydrocarbons (unburned fuel 
 and other gasses produced during the bang) are more completely combusted. This 

Car catalytic converters typically use platinum or palladium and rhodium as catalysts.</TD></TR>

 separate any oil vapor from the PCV gasses before they are fed back into the 
 inlet system. This helps prevent the build up of contaminants in the inlet 
 system<p>Fitted to the ST205 as standard (the small black plastic box located 
 at the right rear of the chargecooler) but not present in other models.</TD></TR>

 of the turbo.
 <p>It consists of a box which sits atop the engine. This box ix connected 
 directly between the outlet of the turbo and the throttle body. The box 
 contains a water cooled core over which the hot post turbo flows. The water 
 that flows through this water cooled core is then in turn passed through 
 another radiator at the front of the car to cool it down. The net effect is to 
 greatly cool the inlet charge while maintaining a very short path from turbo 

The downside is that sitting on top of the engine it gets very hot when the car is stationary (heatsoak). It is also ultimately limited in it's heat capacity and hence power handling capacity

Used on the ST165, ST185CS/RC and the ST205. The standard 185 uses a topmount IC</TD></TR>

 spring actually fits over the suspension damper<p>Technically speaking this is 
 something of a misnomer on the GT-Four as they are all fitted with coilover 
 suspension. In this context almost without fail it refers to more adjustable 
 aftermarket coilover setups</TD></TR>

 Carlos Sainz drove in 1993</TD></TR>

 other end remains stationary<p>In the GT4 there are 4 driveshafts, one per 
 wheel. The front two are connected to the fixed engine at one end and the rear 
 are connected to the fixed rear differential at the back. In all 4 cases the 

Obviously each of the wheels can move up or down in relation to the transfer/differential. So the drive shaft needs to be able to "bend" while rotating to allow this. It is the CV joint which allows the driveshaft to do this</TD></TR>

</TD></TR>

 movement<p>In simplistic terms it consists of an oil filled tube with a 
 plunger in it. As a force (from the road wheel) tries to move the plunger p 
 and down the oil tries to prevent this. The faster the plunger moves the more 

See <a href="#Suspension">suspension</div> for a brief description of how the whole suspension system works</TD></TR>

 The 3S-GTE engine uses a knock sensor to detect detonation and take 
 appropriate measures by retarding the timing</TD></TR>

 two output shatfs<p>Diffs are used to transfer power from the engine to the 

When a car turns a corner the outside wheel actually travels further than the inside wheel. So in a road car you cannot simply connect the two back wheels together. So the differential actually performs 2 roles - it transfers power from the input shaft to the two output shafts and it lets the two output shafts spin independently to each other. It is quite a complicated piece of engineering with a number of gears.

The GT-Four has three differentials. The engine is connected to one diff which splits drive between the front wheels and the rear wheels. This diff (the so called center diff) is housed in a single casing with another diff which split power sided to side between the front wheels (this whole unit is commonly called the transfer box). the rear output from the centre diff is sent to another differential at the rear of the car (the rear diff) where it is split between the two rear wheels</TD></TR>

 wheel to the front and rear differentials. Also has a CV joint each end to 
 allow the wheel to move up and down</TD></TR>

 The angle part of the name is a throwback to the days of points based ignition 
 systems when the points were closed for a given portion of a rotation of the 

In modern systems where the ECU controls the charging of the coil it is more commonly expressed in mS.

Dwell It is a tradeoff. Too much dwell (The ignition coil charged for a long time) and the coil can become very hot and suffer damage. Too little dwell (too short a charge time) and the coil does not build up enough charge to create a decent spark</TD></TR>

</TD></TR>

The standard 3S-GTE ECU is made by Denso and cannot be remapped to accommodate for major changes in engine performance.</TD></TR>

The first part is a <a href="#Solenoid">solenoid</div> which is usually located in the engine bay

The second part is the electronic brains which drive the solenoid. This is usually located in the passenger compartment and often has controls which allow the driver to simply adjust boost pressure up or down.

NB you cannot lower boost below <a href="#ActuatorPress">actuator pressure</div></TD></TR>

 There are a number of components in the fuel injection system. A high pressure 
 pump supplies fuel to the injectors. Each injector is, in simple terms, a tap 
 which can be switched on and off by the ECU. The ECU turns the injectors on 
 briefly to allow a calculated amount of fuel into the cylinder based on the 
 volume of air flowing into it. Finally the air/fuel mixture is ignited to 

The EFI system is described in more detail <a href="/website/technical/EFIOperation.htm">here</div></TD></TR>

 <a href="http://localhost/website/glossary/acronym.htm#EBC">EBC</div> </TD></TR>

 which needs to exhaust burned gasses. Gasses from all 4 cylinders are 
 collected in the exhaust manifold which is essentially a pipe running across 
 the front of the engine.<p>Each cylinder has a connection to this pipe and the 
 pipe has a further outlet on the bottom. This is where the turbo is connected 
 so that exhaust gasses from each cylinder are able to drive a single turbo</TD></TR>

</TD></TR>

 fuel cut</div> boost PSI to be increased<p>This is most usually done by limiting 
 or altering the output of the <a href="#PIM">PIM</div> sensor that the ECU sees 
 and hence fooling the ECU into thinking that boost pressure is lower than it 
 actually is. This means that boost can be increased beyond the level at which 

NOTE

While a FCD is a useful tool it should not be used on a ST205. This uses the PIM sensor to determine timing and altering this signal will cause fuelling problems with potentially fatal consequences</TD></TR>

 topmounted cooler of some sort<p>A FMIC is a variation on the standard 185 Air 

The significant difference is that rather than being mounted on top of the engine the core is mounted behind the front bumper. This means that it does not suffer from heatsoak like the stock ATA item

The other major difference is usually the size of the core. While the 185 ATA core is of modest size front mount units are usually significantly larger

Should be considered an essential upgrade for any high power car or one which is expected to take prolonged "abuse" such as a track day special</TD></TR>

 the fuel rail keeping it at a constant pressure above the inlet manifold. 
 <p>In any turbo application this means that the fuel rail pressure must 
 increase as boost increases to keep the differential the same. This type of 
 regulator is commonly referred to as rising rate</TD></TR>

 ECU.
 <p>The ECU monitors boost pressure via the PIM and if this exceeds a preset 
 limit the ECU will cut fuel to the engine. This has the immediate and somewhat 
 alarming effect of effectively switching the engine off to prevent possible 

Fuel cut is there for a reason and it is important to understand this before using a FCD. The ECU knows (see <a href="#Maps">maps</div>) how much fuel to feed the engine and how to alter the timing BUT there are limits to it's knowledge. When boost pressure exceeds it's limits the ECU simply cannot fuel or time the engine correctly. Since this can lead to serious damage the ECU will shut the engine down. If you override fuel ct you are preventing one way of the ECU saving your engine. This is acceptable as long as you know the risks and are careful in upping boost levels</TD></TR>

</TD></TR>

 engine output shaft<p>The gearbox has an input shaft (which is connected to 
 the crankshaft via the clutch assembly). There are a number of gear assemblies 

At the other end of the gearbox is the output shaft. This also has a number of gear assemblies attached to it. Depending on which gear is selected different gear clusters on the input and output shafts are meshed together to provide a different cog ratio which in turn changes the number of engine revolutions per wheel revolution</TD></TR>

</TD></TR>

 The 3S-GTE is a very hot running engine. Consequently when the car is 
 stationary the engine bay rapidly gets very hot and all of the ancillary 

This causes the greatest problem for inter/charge coolers which are located in the engine bay (as they are on all stock GT-Fours) as they rapidly become hot and loose their cooling ability leading to very high temperature air being sucked into the engine. This can lead to <a href="#DET">detonation</div>

If your car has been stationary for a while you should take it easy for a while to let airflow cool everything back down to normal operating temps</TD> </tr>

</TD></TR>

 Sensor</TD>

 engine<p>The ECU needs to know the temperature of the air so that it can work 
 out the volume of air entering the engine since air density changes with 

The ST1x5 models have an air temp probe built in to the AFM assembly while the ST205 has a separate sensor built into the inlet manifold</TD></TR>

 under the control of the ECU<p>The ST165 and all ST185 variants use 440cc 

The ST165 uses topfeed injectors where ST185 and ST205 models all use sidefeed (although they do not share a fuel rail)</TD></TR>

 fitted into a stock suspension strut<p>Note that the GT-Four rear struts are 
 all technically sealed units so fitting new damper inserts is not 
 straightforward</TD></TR>

 See <a href="#ATA">ATA</div>, <a href="#FMIC">FMIC</div> and <a href="#TopMount">
 TMIC</div> for </TD></TR>

 the combined air/fuel mixture for the combustion process. In the 3S all 4 
 ports are commoned together in a large single chamber known as the inlet 
 manifold. It is the large aluminium "pipe" for want of a better word which is 
 connected to the intercooler towards the rear of the engine bay<p>On a 
 technical note the ST165 and all ST185 model inlet manifolds are very 
 different to that of a ST205 due to the presence of the T-VIS system on the 
 ST1x5</TD></TR>

 speed of the engine.<p>When the butterfly in the throttlebody is completely 
 closed no air can flow past it. In this situation the engine would stop 
 without an air supply. It gets this from the ISC valve which allows a small 
 amount of air (controllable by the ECU) to bypass the throttle body. By 
 varying the amount of this air the ECU is able to carefully control the idle 
 speed of the engine<p>On the ST165(only) there is an adjustment screw on the 
 throttlebody to help set the idle speed. On all other models the idle is 
 completely ECU controlled</TD></TR>

</TD></TR>

 Common slang to refer to a car which has been imported from Japan</TD>

</tr>

</TD></TR>

</TD></TR>

 valve lift can help to increase flow capacity but it slows down the air at low 
 rpm and causes a loss of low end power</TD></TR>

 the wheels to rotate independently (with the possible problems that come with 
 that) a limited slip differential actually limits the allowable difference in 
 rotation between wheels. So in the scenario where one wheel starts to spin the 
 differential will only allow so much before it "locks up" and links both  
 wheels together<p>There are various methods of doing this with Torsen (TORqueSENsing) 
 being the most common. In this system the diff intelligently diverts torque 
 away from the wheel which is spinning faster (i.e. slipping) to the slower 
 wheel. Technically speaking this is an ATB (Auto Torque Biasing) diff not a 
 LSD but in common parlance it is referred to as a LSD</TD></TR>

</TD></TR>

 Not used on the 3S-GTE which uses either an <a href="#AFM">AFM</div> or a
 <a href="#MAP">MAP</div>/<a href="#IAT">IAT</div> system</TD></TR>

 combination with the IAT sensor allows the ECU to determine how much load is 
 on the engine and which entry on the fuel and ignition <a href="#Maps">Maps</div> 

Only used on the ST205</TD></TR>

 combustion process. To do this it looks at how much load the engine is under 
 (from the MAF in a ST1x5 or from the MAP/IAT system in a ST205) as well as the 
 engine RPM<p>Armed with this information it will then consult two maps - one 

The maps themselves are made up of a 2 dimensional table. One axis is indexed by the engine rpm and the other is indexed by engine loading

At any given rpm the ECU will select that RPM row (or the closest to it) and then move along the row until it reaches the column corresponding to the current load on the engine. It then uses the value from this single cell to determine how much fuel the engine needs (from the fuel map) and how much ignition advance it needs (from the ignition map)</TD></TR>

 Controller</TD>

 Usually refers to a <a href="#RV">Relief Valve</div></TD></TR>

</TD></TR>

</TD></TR>

 See the <a href="/website/faq/faq_wheels.htm">Wheel Primer</div> for a better 
 description</TD></TR>

 differential rotation speed between one wheel and the other<p>The advantage of 
 this on a road car is that it will go round very tight corners where one wheel 

The disadvantage is that if one wheel loses traction it will spin continuously leaving the other wheel with do grip to drive the car forward</TD></TR>

</TD></TR>

 past the piston rings when the cylinder fires. Left unchecked this will 
 pressurize the crankcase and place additional unwelcome load on all of the oil 
 seals in the engine<p>To combat this the crankcase is actually ventilated to 

Is standard cars this vent is actually connected back to the air inlet system to prevent the emission of harmful oil/exhaust fumes into the atmosphere.<p>As the engine becomes older and more work the PCV system can actually start to re-circulate fine oil vapors back into the inlet system. To overcome this a catch can may be fitted</TD></TR>

 specific meaning<p>A propshaft connects drive from the engine at the front of 
 the car to the rear differential at the rear</TD></TR>

</TD></TR>

</TD></TR>

 excess boost pressure is fed back into the inlet system rather than to 
 atmosphere<p>The ST205 uses a recirc dump valve as standard and all the other 
 ST1x5 models work best with recirc</TD></TR>

 blocking the turbo to wastegate line until a preset pressure has been 
 achieved. This is generally done using a ball bearing and spring mechanism. 
 When pressure is low the ball beating is held at one end of a tube by spring 
 pressure. As boost pressure increases the ball bearing will try to lift until 
 eventually boost pressure overcomes spring pressure opening the valve and 

While this is a very simple idea it can be a very effective and very cheap way of increasing boost pressure. The drawback is that they are prone to pressure variation over time and can often become clogged by engine oil vapour causing unwelcome boost variations</TD></TR>

</TD></TR>

 In turbo applications it is most likely to be used in a boost controller 
 solenoid context. This allows a boost controller to electronically control the 
 bleeding of pressure from the wastegate resulting in an increase in turbo 
 boost pressure</TD></TR>

 The main weight carrying part of the suspension. It is these springs which 
 actually hold the weight of the car. In simple terms it is a coil of spring 
 steel which compresses under loading.</TD></TR>

 Each strut is made up of two distinct parts - the damper assembly and the 

In all versions the strut can be removed from the car as a complete unit</TD></TR>

 front wheel camber constant during cornering and suspension travel to improve 
 the overall handling.<p>The system is quite complex and prone to wear over the 

Quite expensive to replace when it does eventually wear</TD></TR>

 springs and dampers, both described in simple terms elsewhere<p>The overall 
 suspension performance is determines between the interaction of these two 
 basic components which interact with each other<p>If the car was only 
 supported by springs, with no dampers, it would be very unsafe and unpleasant 
 to drive. If the spring is compressed (say by a bump) it stores that energy 
 then releases it when the compressing force is removed. However, the spring 
 will not stop at it's original length but will extend further than it should, 
 then compress again etc etc. This results in an extremely unpleasant 
 oscillating motion which makes the car very hard to control. You can actually 
 see this in action even on a damped car. If you press firmly down on a wing 
 for example you see the car sag then rebound, oscillate a little, but very 
 quickly settle back to it's original position. Un-damped the oscillation would 
 just keep going<p><p>This controlling or Damping force is provided by 
 the <a href="#Damper">damper</div>. The resistance from this damper will quickly 
 stop the oscillations<p>Suspension tuning is a very long subject and many 
 books have been written on this subject alone. One thing to remember is that 
 if your car is on the original suspension it is now likely to be very tired 
 and in need of replacement</TD></TR>

</TD></TR>

 This controls the flow of air into the engine. It basically consists of a 
 rotating flap in a pipe. When the flap is closed the engine is starved of air 
 and will not produce much power. When the flap is open the air can consume as 
 much air as possible producing it's maximum amount of power<p>On all GT-Four 
 standard cars it is attached between the inlet manifold and intercooler 
 towards the back of the engine bay. Easily identified by the control cable 
 connected to it (and the accelerator pedal)<p>The ST205 features a larger 
 throttlebody than other models</TD></TR>

 intercooler as used on the ST185 model. The air to air core is mounted on top 
 of the engine block, hence the name topmount<p>See also <a href="#Heatsoak">
 heatsoak</div></TD></TR>

 asking the engine for by measuring the position of the accelerator pedal. The 
 ECU can then adjust engine fuel and timing parameters accordingly<p>NB the TPS 
 sensor is actually located on the throttle body not the accelerator pedal</TD></TR>

 in the past with the ST165, ST185, ST205 and Corolla based WRC cars. Recently 
 involved in Le Mans and 
 currently they have a very successful  F1 team</TD></TR>

 Read the <a href="/website/technical/TurboOperation.htm">Turbo Primer </div>for 
 an introduction to turbo systems</TD></TR>

 simplified version of an EBC solenoid which allows the ECU to bleed pressure 
 from the <a href="#Wastegate">wastegate</div> to achieve it's target boost map.<p>
 In 1x5 models this appears to be an electronically controlled <a href="#BleedValve">Bleed 

In the 205 is actually is a boost control solenoid</TD></TR>

 It is a twin entry single turbo<p>What this means is that the path to the 
 exhaust turbine is actually divided into two separate channels with two 
 cylinders coupled together into a single channel into the turbo<p>The 
 principle advantage of this is that exhaust gas pulses are spread out better 
 reducing pressure in the exhaust manifold. In a "normal" system all of the 
 cylinders feed into a single manifold. As each cylinder exhaust there is a 
 spike in manifold pressure caused by the restriction of the turbo. 
 Consequently manifold pressure is relatively high and this can start to effect 
 the flow of exhaust gas out of each cylinder<p>In the twin entry system 
 cylinders 1&4 and cylinders 2&3 are twinned together. This means that there 
 will always be a cycle of non firing in each of the twin entry manifolds (the 
 engine fires 1,3,4,2) reducing average manifold pressure<p>Present on ST185 
 and ST205 models only with the ST165 having a normal "single entry" type turbo</TD></TR>

</TD></TR>

 to say whether they make any aerodynamic difference to the car or not. 
 Certainly UK spec cars have a scoop in the undertray to direct cold air at the 
 transfer case which may help cooling but it is not obvious that cooling would 

One thing for sure though, the trays do keep a great deal of road dirt out of the engine bay and removing them quickly results in an extremely dirty look under the bonnet</TD> </tr>

</TD></TR>

 electrically controlled open/close pipe switch very similar to a solenoid</TD></TR>

</TD></TR>

 system which allows the injection of small amounts of water vapor into the 
 inlet air system<p>The main purpose of this is to cool the inlet charge 
 reducing the chance of detonation and making the standard intercoolers 
 slightly more efficient. It also enables higher power to be run for longer 
 periods of time without charge temperatures climbing into the danger zone</TD></TR>

</TD></TR>

 obtainable today but cost prohibitive to say the least</TD>

</tr>

</TD></TR>

</TD></TR>

</TABLE>