12) COOLING (Engine) Rating 10/10
Info:
(i)5 main components is the radiator, coolant, radiator hoses, thermostat+fan switch and radiator cap.
(ii)For radiator, bigger is better and wider surface aids better cooling.
(iii)For coolant, use any type u like but make sure u dun run on pure water.. Yr coolants must have anti-rust properties.. or else u risk damanging the internal part of your engine block.
(iii)For radiator hoses, DOHC EG/EK/DC are bigger size then SOHC EG/EK.
(iv)For thermostat & fan switch, all EG/EK/DC are same.
(v)For radiator cap, oem comes in 1.1bar for all EG/EK/DC.
(vi)All SOHC ESI/LSI radiators come with single fin.
(vii)For EK3 and all DOHC EG/EK, the radiators come with double fin.
(viii)For DC2, the radiator is single fin, aluminium and long type. Best radiator among all.
(ix)Auto and manual car radiators are different so make sure u get the right radiator before u buy. Auto comes with extra piping outlets to cool transmission oil.
Upgrade:
(a) ESI/LSI in (vi) is beri prone to overheating. Easiest way to upgrade is to swap in a stock SOHC EK3 twin fin radiator. However, the DOHC radiator is more common but inlet and outlet sizes is slightly bigger. U have to force in yr stock rubber hose. I have previously used this set-up for a year without any problem with crack piping or leaks.
(b) Generally double fin radiators (vii) are good enough. There are many 3-fin thick aftermarket radiators for more coolant capacity or aluminium ones for lighter. Juz make sure you take note of point (iii).
(c) For upgrade to DC2 long radiators, u need to use the dc2/aftermarket air-con condenser that goes under the front mounting bracket. The mounting points to hold the radiator also need to be cut off and relocated to fit the DC2 legs.
(d)Radiator caps are also important to ensure enough pressure within the cooling system to circulate the coolant. 1.1 bar cap would be sufficient but for those who want improvements, u can upgrade to the 1.3bar caps.
(e)Silicone Radiator hoses are mainly for looks. But if u are using 1.3bar radiator caps, it may be good insurance to invest in silicone hoses.
(f)The stock thermostat and coolant fan switch are set to activate at higher coolant temperatures. If u want a cooler engine, u can upgrade to a Mugen/ARC low temperature thermostat and fan switch. It is important that both muz be changed together (thermostat+fan switch).. juz changing either 1 alone wont be as effective.
(g) For those stuck with single fin radiators with no budgets, a simple way to improve yr car cooling system is to put yr coolant fan to turn on direct/permanent. However, the set back is yr fan motor will wear out faster. All u need to do is plug out the socket from the fan switch and use a wire (paper clip) to connect the 2 points in the socket head. This will make yr fan run continuously whether the coolant is cold or warm.

13) THROTTLE BODIES (Engine) Rating 6/10
Info:
(i)There are 2 common oem types. The older version TB comes with the MAP sensor separately mounted on the engine firewall. The later/newer version come with the MAP sensors mounted DIRECTLY on the top of the tb.
(ii)SOHC ESI & EK3 have 56mm (measured at butterfly) throttle body.
(iii)DOHC EG6/EG9 from 1992 have 58mm (measured at butterfly) throttle body.
(iv)All DOHC EG/EK except those from (iii) and B20B, H22A have 60mm (measured at butterfly) throttle body.
(v)DC2R have 62mm (measured at butterfly) throttle body.
(vi)All oem TB are compatible (including the MAP & TPS sensors).
(vii)EG throttle bodies come with attached idle valve but EK throttle bodies do not have the idle valves. It is perfectly ok to bypass the coolant pipes if using a EK throttle body for an EG.
(viii)Bigger TB wont get u HP gains unless yr existing TB flow have become restrictive for your engine set-up. However, bigger TB makes yr car feel more responsive as for the same percentage of throttle opening, more air is flowing through.
Upgrade:
(a) For (ii) and (iii), Easy way to upgrade is to swap in a 60mm or 62mm throttle body. Just take note of point (i).
(b)If upgrade to a bigger throttle body, it is a must to port match the intake manifold inlet with the bigger throttle bore. Port matching the manifold could costs between $50-80.
(c)Typically if upgrade your engine (bigger cc/ higher compression) u need a bigger throttle body.

14) SPARK PLUG CABLES (Ignition) Rating 5/10
Info:
(i)All SOHC EG/EK spark plug cables are same.
(ii)All DOHC EG/EK/DC spark plug cables are same.
(iii)SOHC and DOHC spark plug cables are not compatible.
(iv)OEM cables are black-colored from NGK and gd enough.
Upgrade:
(a)There is little need to upgrade the cables if the ignition system is stock. If u need slight (i mean really little) gains, u can change to the blue NGK cables or apexi red cables.
(b)If you have upgraded to aftermarket ignition system, you have to be careful with the type and resistance level of the cables u using. Typically, if u using aftermarket ignition system like MSD, it would be a safer bet to use the MSD cables.
(c)AVOID unknown brands that are unheard of.. there are high chances of current leakage which can affect your car performance.

15) SPARK PLUGS (Ignition) Rating 6/10
Info:
(i)All SOHC and DOHC EG/EK spark plug size is the same.
(ii)SOHC and DOHC EG/EK typically use heat range 6 plugs.
(iii)EK9 and DC2r use heat range 7 plugs.
(iv)The applicable heat range usually correspond to the engine compression levels. For high compression or turbo engines, its appropriate to use a higher heat range (meaning "colder" plugs).
(v)Using plugs that are too "cold" for your engine will result in poorer engine performance and u risk fouling the plugs easily. Using plugs that are not cold enough will cause engine detonation.
Upgrade:
(a) Get the right spark plug heat range is more impt then the type of plug u use.
(b) Iridium plugs (denso, iriway, NGK) are the best but expensive.. follow by platinum plugs then the stock plugs (NGK R).. gains are really minimal too.

16) DISTRIBUTOR (Ignition) Rating 7/10
Info:
(i)SOHC EG & EK distributors are same except for the connecting electrical socket.
(ii)DOHC EG/EK/DC2 distributors are same except for the connecting electrical sockets. EK and DC2 is same socket type.
(iii)SOHC and DOHC distributors are not compatible.
(iv)Honda distributors are well known for the weak design as the ignition coil sits inside the distributor and prone to high temperatures.
Upgrade:
(a)For highly modified engines, it may be neccessary to upgrade by using an external ignition coil mounted outside the distributor. The common external coils are bosch from inter-continental cars or the aftermarket MSD from usa. The important factor is to ensure that u use an appropriate distributor cap (avail fr MSD) and ignition cable to connect to the coil.
(b) the distributor can be manually adjusted to adjust yr ignition timing. If u want abit more response to yr low-mid end, u can ADVANCE the timing by lossening the 3 bolts securing the distributor.. turn away fr u (when u are facing the engine bay from the front of the car) is advancing and turning it the other away is retarding. However, u wont want to advance too much coz u can coz yr engine to "ping"=knocking=bad situation. Always be alert for pinging shd u advance yr ignition.. coz pinging=blown engine=$$ fly away.

17) INJECTORS (Fuel) Rating 7/10
Info:
(i)SOHC and DOHC EG injectors are OBD1 & compatible.
(ii)DOHC EK and DC2 injectors are OBD2 & compatible.
(iii)All SOHC (except from LSI) and DOHC EG/EK (except from DC2r and EK9) injectors flow @240cc.
(iv)DC2r and EK9 injectors flow @280cc.
(v)It is relatively easy to mod OBD2 injectors to fit into EG OBD1 injector sockets.
(vi)Although DOHC injectors flow the same rate as SOHC, the spray pattern is differerent as the DOHC and SOHC engine head are different design.
(vii)Bigger injector doesnt mean better. The most important is to meet yr engine needs and to be able to control it. ie. through piggybacks or standalone ECUs.
Upgrade:
(a)It is common for mod engines of up to 230hp to use DC2r/EK9 injectors.
(b)H22a injectors flow higher rate but is peak & hold design so you must install the H22 injector balast or u will fry your ECU.(c)Older version EVOs injectors are much higher flows and use OBD1 sockets so it is also direct fit for EGs.
(d)Aftermarket injectors like RC engineering are common. Typically, the 440cc injectors can support almost 300hp.

18 ) FUEL PUMPS (Fuel) Rating 7/10
Info:
(i)All SOHC and DOHC EG/EK/DC2 fuel pumps are compatible.
(ii)The flow rates are SOHC EG/EK < DOHC EG/EK < DC2R & EK9.
Upgrade:
(a)It is generally not necessary to upgrade the pump unless ur fuel requirements have change with modified engine set-ups.
(b)DC2r, DC5 and EK9 pumps can support most NA set-ups. For the more extreme, just go for the Walbro 255 pump but make sure your have the proper means to tune yr engine.

19) FUEL REGULATORS (Fuel) Rating 6/10
Info:
(i)All SOHC and DOHC EG/EK/DC2 fuel regulators are compatible.
(ii)Only the DC2R & EK9 regulators flow higher pressure.
Upgrade:
(a)Adjustable fuel regulator are available and the most common brand is SARD. Try get a regulator with pressure gauge attached (No gauge=no readings on yr fuel pressure=how to adjust yr pressure??). Usually u need to get an adapter to fit the regulator on yr stock fuel rail (no adapter=no fit).
(b)When mounting aftermarket regulators, be wary of the mounting location and the rubber fuel line attached. There are many known cases of fuel line leaks which can expose yr car to fire.

20) FUEL OCTANE (Fuel) Rating 9/10
Info:
(i)The applicable fuel type (octane level) usually correspond to the engine compression levels. For high compression or turbo engines, its appropriate to use a higher octane range.
Upgrade:
(a)Use appropriate fuel. On highly modded engines, use the highest octane level to avoid pinging/knocking. Dont waste $, pumping high octane fuel (the most expensive range at petrol kiosk) if yr engine compression is normal.

21) AIR INTAKE (Engine) Rating 9/10
Info:
(i)Stock air intake pipe+airbox seems to be very restrictive for air flow but it does provide good shield over the engine bay hot air.
(ii)See section 13 on throttle body sizes. Stock DOHC air intake rubber pipes will be bigger. Stock DC2r intake pipes is the biggest.
(iii)Only the DC2R oem air intake system uses an open pod filter design and is the best among the oem intake system.
(iv)Cold air to engine = free HP gains. So rule of thumb is to get cold air to the engine.
(v)Typically for aftermarket air intake system is 4 components namely the filter, the intake pipe, heat shield from engine bay and Cold Air Intake pipe to engine bay.
Upgrade:
(a) For filters, K&N and many aftermarket open pod air filter are gd. BUt K&N tends to leave oily residue in the throttle body if not oiled properly.. steel mesh filter tend to leave dusty residue.. "cotton" material filter tend to "break off" and leave greenish residue when used too long.. Apexi have shown 1 of the best dyno results.
(b) For intake piping, there are fat tummy, simple 3" aluminium pipes etc. I wont be so concern about these except for Cold air intake pipings (eg. iceman) that lead directly to the bumper.. have to be careful with those when it rains.
(c) Make sure u get proper heatshield to avoid sucking the engine bay hot air if using open pod filter. There are replica mugen design or juz use industrial foam material to block off the heat.
(d) To get cold air into the engine bay, its common to use a flexible rubber hose/aluminum piping to connect from the front bumper up to the engine bay where yr open pod is located.
(e)There is alot of stuff like air chargers and "e68" thingy that are attached to the air intake. I have tried these on a dyno and the answer is.. CRAP!!!. dont waste yr $..
(f)Some ppl add washers to Lift the rear of the bonnet to cool the engine bay.. i think that is only useful when car is stationery.. bur hardly make a difference when car is moving. Further, u risk catching the attention of TP/LTA easily.

22) OIL CATCH TANK (Engine) Rating 6/10
Info:
(i)All SOHC & DOHC EG/EK/DC2 have oem oil catch breather tank behind the engine block to release crank pressure and divert air back to the engine via the PCV valve & to the intake manifold.
(ii)All SOHC & DOHC EG/EK/DC2 cam covers come with outlet to release head pressure back to the air intake pipe.
(iii)(i) & (ii) can leave oily residue in the intake manifold & intake pipe causing poor air flow.
Upgrade:
(a)Use oil catch tank to filter the oil vapor and release cold air back to the engine.

23) EXHAUST (Engine) Rating 9/10
Info:
(i)There are 4 components to the exhaust system, namely the extractor/header, the CAT, the mid pipe and the muffler.
(ii)For extractor/header, all SOHC EG/EK are compatible.
(iii)For extractor/header, all DOHC EG/EK/DC2 are compatible. However for those with b16b/b18/b20 blocks, the extractor/header length is longer to clear the block
(iv)Except for extractor/header, all SOHC and DOHC EG/EK/DC2 CAT and mid pipes are compatible. For mufflers, there is differentiation between 4dr or 3dr.
(v)Size of the mid pipes are: SOHC EG/EK < DOHC EG/EK < DC2/EK9. Design for the DC2 & EK9 mid pipes are unique and design for improved flow.
Upgrade:
(a) Aftermarket extractors come in 4-2-1 or 4-1 design. Generally 4-2-1 gives gd gains from mid-high rpm range while 4-1 improves mid range more.
(b)For the CAT, DC2 and EK9 are high flow cats. Cheapest way is to knock thru for straight flow or buy an aftermarket CAT. If u decide to knock thru, make sure u have the "fake" CAT mounted or u risk failing ur annual inspections. Avg price is about $70 to knock thru the CAT.
(c) the size of the mid piping is impt.. too thick car will feel laggy on low rpm range but feel super on high rpm. Too thin car will feel gd on low rpm but will not be as ideal on the high end. Prices range between $120-150 (no brand type) including labour.
(d) For the muffler, if U want big mufflers with nice bassy sound.. there are only 2 common legal choices.. the remus and supersprint. Make sure u buy with the original certificate for the exhaust. U need to go to the agent to document the transfer of the muffler to u (pay transfer fee). then go to the authorised workshop to install the muffler (pay labour charge abt $15-30). then go to any inspection centre for inspection (pay inspection costs abt $50+) but make sure that other parts (got CAT) of yr exhaust are "legal". If u pass, a letter will be issued to u and u have to keep it in the car in case kana spot check by TP/LTA.