Modification Title
Here you will find a list of the Modifications done to my Toyota Celica GT-Four ST185

 Click on any of the mods listed below for a summary of that modification. For more information and pictures on a particular mod, click on the "DETAILS" logo.


Addition Of An Intercooler Fan
PCV Routed To Catch Can
Short Shifter Modification
Bosch Fuel Pump Upgrade
G-Force ECU Upgrade
Stillen Crossed Drilled Rotors & Pads

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ERL System2 Water Injection

Details Logo

Manufacturer: ERL Limited,  Address: Iroko House, Bolney Avenue, Peachaven, E.Sussex, BN10 8HF, England. Telephone: 44 1273 581007, Fax: 44 1273 581555. Web Site: http:www.aquamist.co.uk/e-mail: erl@aquamist.co.uk

What Does it Do?: The System2 Water Injection kit is used to inject water directly into the charge air. The System2 is capable of controlling water delivery by a 2D map (amount of water injected dependent on rpm), or if used in conjunction with a MAP (Manifold Absolute Pressure) sensor, can control water injection by a 3D map (amount of water injected dependent on boost and rpm). Why inject water into the charge air? Simple, because of water's high latent heat of evaporation, which results in charge air cooling, and lower peak temperatures in the combustion chamber. Water injection is great for detonation control, allowing higher boost pressures. It can also be used for detonation prevention in the case of low octane fuels and hot ambient temperatures.

Installation: The System2 can be installed and setup by anyone with reasonable mechanical experience. It's not an extremely difficult install, but can be time consuming on the ST185. A detailed installation procedure for the ST185 is outlined in the "Details" section.

Opinion: I am very satisfied with this modification. I have always had problems with detonation since I got the car, even when it was stock, I would get occasional detonation, mostly because of the poor quality fuel here, the very high temperatures, and the fact that the Japanese market ST185 has a higher compression ratio. Since adding the water injection, the little men with the hammers in my engine have retired.

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Autronic SMC Programmable ECU

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Manufacturer: Autronic

What Does it Do?: This replaces the factory ECU with a programmable ECU, which gives total flexibilty to tuning and modifications

Installation: In order to install this system you will need to have some experience with the electronics in a car, a basic understanding of wiring. You will also have to able to perform minor fabrications in the engine bay. After reading the "Installation" page, you will be able to determine whether you feel you can handle this installation.

Opinion: As with the water injection I am very satisfied with this modifaction. The power delivery is now smooth, and consistent. It has allowed me to raise the boost from 1.0 bar up to 1.2 bar, where the car never perfromed very well before. With a system like this, the limiting factors are now mechanical, as this can handle the fuel and ignition, basically every fuel injection need, any modifactions you make require. It also allows you to change things that you couldn't with the stcok ECU, like injectors, switching to direct fire igntion etc. The system also controls many other functions, for example, controlling boost by rpm, coolant temp and throttle position. Note: You will have to have experience tuning engine management systems to programme the Autronic. If you don't you will have to get the car tuned by a professional.

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Custom Enclosure For Air Filter

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Manufacturer: Custom design.

What Does it Do?: By building an enclosure you stop the filter from sucking in the hot air inside the engine bay.

Installation: Some skill with cutting, filing and working with wood plus cutting and bending aluminum is required, plus a lot patience. For a decent look and reasonable performance, this will be a time consuming job.

Opinion: As anyone who has opened the hood on a GT-Four would know, the engine bay gets very hot, and I noticed that the filter itself was very hot to the touch, probably due to it's location right below a vent for letting heat out of the engine bay. Now the filter sucks air from under the fender.

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HKS EVC III Electronic Boost Controller
 

Details Logo(The HKS EVC lasted for almost two years, and then stopped functioning correcly. However I can't
                                   blame the unit or HKS, as the actuator was mounted in a bad location exposed to a lot of heat, which
                                   HKS does not recommend, and I never got around to moving it. I no longer need one, as the Autronic
                                   now controls the boost.)

Manufacturer: HKS Company Ltd. Web Site: http://www.hksusa.com

What Does it Do?: This unit allows you to change your boost pressures from the drivers seat, even while driving. The EVC also shows a real time display of your boost pressure.

Installation: The EVCIII was relatively simple to install, but some understanding of turbos is necessary. The "Details" section has some hints about ST185 specific install techniques.

Opinion: I am very happy the HKS EVCIII, it has performed flawlessly since I installed it over a year ago. The convenience of being able to change the boost at the touch of a button is fantastic, not to mention the many other features, along with the unit having a very appealing look.

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Passion Automotive 2.5 Inch Downpipe

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Manufacturer: Passion Automotive, email nathan@gtfour.com

What Does it Do?: The downpipe will replace the turbo elbow that comes straight off the turbo, as well as the main CAT. It allows the exhaust gases to flow much better directly out of the turbo.

Installation: Not recommended for novices. Anyone from the moderate to very experienced Do-It-Yourself type should be able to perform this installation.

Opinion: The downpipe itself is of excellent quality and finish. Fit is near perfect, although some minor adjusments were neccessary. I highly recommend getting one of these if you are looking for good exhaust flow.

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Malpassi Adjustable Fuel Pressure Regulator

Details Logo(Details for this mod not ready yet)

Manufacturer: Malpassi, I got mine from Select Sales in Miami, Tel: 305 888 2828

What Does it Do?: The malpassi adjustable fuel pressure regulator is a fast gain type, which means that it makes the pressure changes faster than the stock one, from what I have read they are usually 1.7 times faster than most stock regulators. It also allows you to increase your fuel pressure, which can help if a richer mixture is needed, or if you are close to maxing out your fuel injectors.

Installation: Not recommended for persons with very limited mechanical knowledge. Remember you are now dealing with fuel, and under pressure, so mistakes can lead to a fire hazard. The stock fuel pressure regulator will have to be removed and replaced with a straight through nozzle, which a machine shop will have to make up for you.

Opinion: Before I would get very mild detonation when first accelerating hard, the Malpassi unit cured this, as well as allowing me to increase the pressure which helps to lower the duty cycle of the injectors (an adjustment must be made in the AFM, unless only a slight increase in fuel pressure has been made).

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Intercooler Fan Added

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Manufacturer: Unknown (the fan came with no name or model no on it)

What Does it Do?: The fan keeps the intercooler cool by always supplying it with outside air. It will eliminate the heat soaking process that takes place when the car is stationary in traffic or moving at low speeds.

Installation: Not a very difficult install when it comes to know how, but it can be a little time consuming if, as in my case the fan needs modifying to fit the limited space. There is some electrical work involved, as a relay must be used to engage the fan.

Opinion: One of the best low cost mods you can do in my opinion. The fan only costed me U.S. $70.00, and you can pick up a 30 amp relay for less than U.S. $10.00. Before I could actually see the heat escaping out of my hood scoop in traffic. This meant, of course, that all the heat from the engine and exhaust manifold, which the intercooler sits right above, was soaking into the intercooler. With the addition of the fan, this no longer happens and acceleration out of traffic feels just as good as accelerating while you were cruising. Overall performance has also improved.

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PCV Routed To Catch Can

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Manufacturer: Custom design.

What Does it Do?: The PCV system on the ST185, and most turbo cars, routes the crankcase gases back into the intake. This system causes the intake to get dirty over a short period of time, which includes the intercooler, cutting down on it's effeciency. By routing the gases to a catch can, the intake remains clean for much longer periods.

Installation: Very simple, anyone can do this mod.

Opinion: It keeps the intake and the intercooler clean, which is good for more than one reason. One reason is effeciency, the other is if you ever see oil in your intercooler, you will know it's not from the PCV.

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Shifter Modification

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Manufacturer:Custom design.

What Does it Do?: This modification to your shifter will reduce the length of travel of the stick as well as the height, making it feel more like a quick shifter.

Installation: This modification requires the removal of the shifter stick, as well as welding.

Opinion: For anyone who likes the short stick feel of a performance car, this is a must. Another alternative would be to purchase a Quick Shift Kit from TRD.

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Bosch Fuel Pump Upgrade

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Manufacturer: Bosch (I should have more info on this pump shortly)

What Does it Do?: This upgrade replaces the stock fuel pump with a high capacity Bosch fuel pump to ensure adquate fueling at high boost levels on an upgraded turbo.

Installation: Not recommended for novices. Because of the dangerous nature of fuel, I recommend that only the experienced Do-It-Yourself type should perform this installation.

Opinion: The car was running lean at high boost/high rpm with the stock pump. The new pump supplies more than enough fuel. It has already been proven to supply a mixture as rich as 10.0/1 A/F at high boost/high rpm. Note: This is not a desired mixture, it just shows the amount of fuel the pump is capable of providing. I recommend anyone running upgraded turbos that they upgrade their fuel pump. Another option would be the Supra fuel pump, which would probably be much easier to install.

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G-Force ECU Upgrade

Details Logo(I never got around to doing the write up on the G-Force, and no longer have one, however I still
                                   recommend this mod for those that are content with running 1.0 bar)

Manufacturer: G-Force Engineering,  Address: 2311 West 205th Street, Suite #102, Torrance CA 90501, U.S.A. Telephone: (310) 782-8278, Fax: (310) 782-1611. Web Site: http:www.g-force-engr.come-mail:gforce@g-force-engr.com

What Does it Do?: G-Force reprogrammes the ECU to ensure you have the right fuel and igntion up to about 16 psi. They also take out boost fuel cut, speed cut (if the car has it), and can raise your rev limit.

Installation: Realtively easy job that anybody can do. The ECU is located on the floor behind the centre console. Before removing the ECU connectors, it is very advisable to disconnect the negative cable of the battery.

Opinion: This mod makes a very noticeable change in the cars performance, and also adds the safety of having the correct maps.

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Stillen Crossed Drilled Rotors & Pads

Details Logo(Details for this mod not ready yet)

Manufacturer: STILLEN High Performance Brake Division,  Address: 3176 Airway, Costa Mesa, CA 92626, U.S.A. Telephone: 714-755-6688, Fax: 714-540-5784. Web Site: http://www.stillen.com

What Does it Do?: Crossed drilled rotors (brake discs) allow for the gas that is created between the brake pads and the rotor to escape, which reduces the chances of brake fade. Another configuration used for helping with out gasing of the pads is slotted rotors.

Installation: For anyone with even a little mechanical knowledge, this is not a difficult job.

Opinion: I used to get brake fade after a short time at high speeds, but since installing the crossed drilled rotors, I rarely get brake fade anymore.

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 TO BE CONTINUED

This page was created by Dennis Heath.
If you should wish to ask a question about the GT-Four/All-Trac, you can join the GT-Four Mailing List, where I, and many others with GT-Four's, might have your answer. For information on joining go to http://www.onelist.com

Please note that I am not a mechanic by trade, and that any information offered on this web page is free and without guarantee. Should you choose to perform any of the procedures listed on this site, you will be doing so of your own free will, and I will not be held responsible or liable for any damages that might occur from using information obtained here.