Toyota Celica GT4 ST205 first modifications

Under construction - not yet accurate...

First 10 Mods ?

What's this all about?

This is my recommended list for your first 10 modifications to your stock car. It is a little difficult to know exactly what to do first and if this affects that, what does this do, does this mod work, what's the best thing to spend my money on etc...

Please bear in mind that opinions vary and that as I see things these are the first 10 mods I would do to my car if I was to start again on a stock car.

What is the aim of these mods?

The aim of these small 10 modifications are to be low cost, quick and "mostly easy", to provide a small foundation on which to build and to release a bit more power from the engine. They will also guide you around the car looking at engine bay, suspension and other bits and pieces. These mods tend to focus on the key weak areas, as well as being the cheaper ones!

One of the golden rules for modification is intake, exhaust, fuel and ignition. Something that is always worth bearing in mind.

Okey dokey, what is your list of first 10 mods?

1.   Maintenance
Before you start modding away the car needs to run well beforehand. If it's misfiring belching out smoke and generally misbehaving then get these things sorted first. If you don't it may well cost you dearly later. Things to address:

Cost - depends on the state of your motor...

2.  Replacement panel air filter
Get the K & N as they are relatively cheap, reliable and you'll probably never need to buy another filter! To clean it wash it through with soapy water, dry it and then re-oil it. You'll save money in the long term. Don't get a foam one cos they tend to disintegrate and if it does then foam will be drawn into the engine and turbo. The K & N is a cloth filter sandwiched between metal gauzes - much safer. Drawback - if you want a straight intake later then this will be redundant. There are induction kits available but they are expensive i.e. >£150.

Cost ~£35

3.  Boost gauge
You really need to now what is going on in the intake manifold, and if you are going to do further mods then you definitely need a boost gauge or it may go horribly wrong. TIM manufacture cheap and cheerful gauges, whilst not particularly good looking or highly accurate it is certainly a step in the right direction...More expensive gauges are electronic, can be linked together, have warning functions, replay functions etc etc expect to pay >£150 per gauge for these shiny bits!

Cost ~£30 (low quality and reasonable accuracy)

4.  Intercooler mods - these will depend on the type of GT4 you own...
The turbo heats up air as it compresses it. To cool this air down and reclaim some of the "lost" power the intake air charge needs to be cooled.

For WTA IC GT4s, insulate the underneath and sides of the IC to prevent it from heating up due to the engine and exhaust manifold temperatures and close proximity. Demon Tweeks and Fensport sell insulating material and tapes, see the links section for more shops. Modify the IC pump so that it runs continuously on the 165s and 185s - I wouldn't bother on the 205 as the control system appears to be better.
For ATA IC Wash the core, ensure the fins are undamaged and aren't clogged with dead flies etc.

For all ICs - wash out the IC with petrol to clean the interior to ensure it transfers heat efficiently.  Maybe worth a few bhp, and should help to keep your engine safer...

Cost - heat reflective tape ~£5. If your adventurous, heat shield ~£5 for aluminium and some of your time.

5.  Fit a Dump Valve
This will help to prolong your turbo life and help to keep the turbo spinning between gear changes improving driveability. Also makes you grin a little and feel like a boy racer...A popular choice is the Bailey DV26. The GT4OC offers a very competitive price for the valve and fitting kit! (only available to GT4OC members). Other more "fancy" dump valves are louder, different sounds, sequential etc. Expect to pay >£150 for some of these shiny bits. Drawback - the car will over fuel on gear changes. Not really required on the 205 as this comes with a DV as standard

Cost - ~£90 for the DV and the fitting kit from the GT4OC

6.  Replacement exhaust
Your stock exhaust is probably rusty and blowing, go get a new stainless one. At this stage just get the cat back exhaust to keep the spending in check. Performance exhaust probably good for ~15bhp. This also frees up the exhaust gas path for later power increases and helps to prevent this from becoming a big restriction later on. Get the largest diameter possible 3" is a good size. You might want to look at an Aussie exhaust as these are right up there with the best and are 3" systems... Watch out that the exhaust you get covers all three sections, (the Scorpion does), i.e. flexi section, mid pipe and back box.

Cost - depends on exhaust, Scorpion ~£350 (2.25", 4" tail pipe).

7.  Gut the catalytic converter
Gutting the cat will release approx 5hp and help the turbo to spin up earlier. If you can afford it then replacing the cat with a down pipe is much better. The 3" Aussie is considered to be the best ~£250, available from Fensport.

Cost - nothing if gutting the cat, just time.

8.  Relief Valve & TVSV
Firstly disable the TVSV so that you can run the same amount of boost in all gears, thereby establishing a common level, and taking away the ECUs input... Note - this will reduce boost in 3rd+ gears by approx 2psi...which isn't a problem cos you are going to raise the overall boost level with the RV.

To increase power the boost needs to be turned up. To do this cheaply fit an RV or alternatively called a Dawes Device. To obtain one contact Martin Farrell via e-mail or visit his website. For much better/more controllable/repeatable results fit an SBC ~£350 (ouch).

On your stock setup you need to watch what boost you run, or you will hit fuel cut, (a safety feature to help prevent damage). Guide levels for fuel cut are:

165 - 12psi
185 - 14psi
185 CS/RC - 17psi
205 - 17psi

Note - the exact fuel cut level varies from car to car.

Cost - ~£20 for RV, a little bit of rubber hose that you might need to buy ~£2, and use a couple of old bolts that are lying around to block off the TVSV pipe work.

9.  Fit Polyurethane suspension bushes
You have increased power by doing the above, now you need to make the car a little safer and also to sort out that bloody awful handling, (165). Fitting PU bushes will stiffen up the car. Don't forget to get the anti-rollbar bushes as these made a noticeable difference, as well as the front and rear suspension bushes. Click here for an article on how to replace the rear suspension bushes.

Cost - ~£180

10.  The list continues...

After that cheap lot it starts to get expensive, items you might want to consider are...

Summary

~£700 will set you on the right path and provide, (~40bhp - 165), and a lot more fun!

Blimey! Got any more info on that lot?

Have a look through the modifications section...

On the shopping list really should be a bigger turbo and some way of controlling all this lot i.e. a replacement o ECU.

A thought...

How much is the car worth? How much do you plan on spending on mods? Would you be better off putting that modding money towards a faster car?!? i.e. a 205? Bear in mind that the 205 already comes with 239bhp, better intercooler, different cams, larger injectors, metal head gasket, better pistons, different turbo, better fuel maps, much better engine management, bigger throttle body, revised intake manifold, revised oil filter location, better gearbox, better rear diff, mild head porting, massive brakes, much better suspension and is not so prone to rust! But it's not the original GT4!