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PostPosted: Sat May 18, 2013 7:37 pm 
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hi, below is a list of mods i intend to do to my stock gt4 (only upgrade at mo is exhaust). can anyone tell me if i can do all this with stock internals? or if there are any that arent worth it, or ones ive missed?

intake system
dump valve
stainless steel manifold
boost gauge
boost controller, boost to 1.1 bar?
grooved brakes, pads
road set up
mapping of ecu

also i wont be able to do most of these myself would a garage be a reasonable price if i asked them to fit the parts?

and do you think it might be around the 280-300bhp after the mods?

thankyou in advance


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PostPosted: Sat May 18, 2013 8:18 pm 
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Location: sunny sleaford- lincolnshire
Car Model: ST205
looks fine to me, its the usual mods list to be honest. :)


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PostPosted: Sat May 18, 2013 8:19 pm 
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Location: sunny sleaford- lincolnshire
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and price depends on who you take it too, your average jo who doesnt know what they are doing might take longer than someone who charges slightly more but takes less time.

Other than the boost controller and ecu you should try fitting all the rest yourself if you have the tools as it will save you a pretty penny and they are easy to fit.


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PostPosted: Sat May 18, 2013 9:06 pm 
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Car Model: ST205
intake system
Either fit a panel filter or leave stock - don't break what ain't broke

dump valve
You already have one

stainless steel manifold
Why?

boost gauge
boost controller, boost to 1.1 bar?
Good plan

grooved brakes, pads
Good plan
Try EBC yellow pads on stock diska

road set up
Of what? Geometry? Try parallel all round. Nothing else is adjustable

mapping of ecu
Not possible, you will need either a complete aftermarket ECU or a piggyback


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PostPosted: Sat May 18, 2013 9:38 pm 
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thanks for the good comments, so:

you wouldnt recommend say a hks flow induction kit then? is there no gain over the standard one thats fittted?

manifold: ive heard it helps with the air pressure and spool time, and less weight?

ive heard good things about ebc pads so ill get some of those on the stock discs like you said, good idea

the set up of wheel alignment etc my friend said he took his supra to get set up for "fast road use" and he said it made a lot of difference

mapping ecu: ive seen a company that says pre 2000 cars they take the ecu out and reprogramme it after going on rolling road and deciding what set up you want, does that sound wrong then?

comments much appreciated as dont want to waste money :)


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PostPosted: Sat May 18, 2013 11:02 pm 
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Location: Perth, Western Australia
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The HKS mushroom air intake filter has a smaller cross section than the stock panel filter and the filter element also tends to clog up with debris further reducing the air it can flow. The other disadvantage is that it is sucking in hot air from the engine bay. You could always build a cold air box but if you retain the stock intake system it pulls outside ambient air through the resonator intake in the wing. Toyota knew what they were doing!

While a fabricated tubular intake manifold of the correct design (e.g. equal length runners) may flow air more efficiently than the stock cast intake manifold they are more likely to suffer from fatigue fractures.

I have tried both TRD and EBC yellow pads and find that the EBC's have slightly better bite but they do produce a huge amount of dust. I will probably go back to the TRD pads when the EBC's need to be replaced.

As Steve has pointed out above there is not much you can adjust on the standard suspension. I would imagine the same is true of the Supra? The toe-in/out can be adjusted and if it is off-spec then the car may feel darty and unstable. It's worth getting it checked that it's in-spec. Not many places know how to adjust the rear toe. There is good info on this forum if you do a search so its worth familiarising yourself and/or printing it out before you take the car along to get the alignment checked.

Some older cars allow changes to be made to the ECU bu Toyota isn't one of them. You can fit a cheaper 'piggy-back' to the ECU. This fools the signal to the Toyota ECU and effectively adjusts the fuel and timing to compensate for engine/intake/exhaust mods. Other than that its a whole ECU transplant with all of the associated time and costs of getting mapped. This can cost many times more than the cost of the ECU hardware.

When I was running 280-300bhp I fitted an ERL Aquamist water injection system to keep the air charge temperature under 35degC while on 1.2bar boost. If the ACT is too high then detonation may occur and damage the engine. Not everyone likes WI but its a useful safety net so long as your engine doesnt depend on it.

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp


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PostPosted: Sun May 19, 2013 10:32 am 
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You don't say which model GT4, only the 205 has a dump valve as standard.

Induction kit:

Pros: Nice sucky noise if you like such things :)
Cons: Draws warm air from engine bay rather than cold air from outside. Filter surface area smaller than panel filter for std. airbox.

A few years back we were running some diagnostics on a standard 205 on a dyno, and since there was a bit of time spare we had a little playabout. First, we removed the upper airbox section and left the pipe open where an induction kit would fit. This showed about a 10BHP increase - the bonnet was open though so drawing cold air from the dyno fans. We then replaced the airbox lid but without the standard filter. The resulting line laid straight over the top of the +10BHP line. Conclusive proof that an induction kit is no better than the stock setup assuming the standard panel filter is changed for a decent aftermarket one.

Tubular exhaust manifold:
Pros: Shiney. Possible benefits from matched tuned lengths.
Cons: Prone to cracking. Have a large surface area to conduct heat from exhaust to engine bay, thereby both reducing turbo efficiency and increasing engine bay temperatures.
The heat issue can be reduced by lagging, but this will increase the cracking problem. Ceramic coating the INSIDE should reduce all issues.
In practice, unless you spend more than the cars value on a manifold, it will probably suffer all the above issues and probably won't have equal tuned lengths anyway.

Boost controller:
Running increased boost will probably shorten the engines life, especially if it's old and worn. Generally 1.1 bar is reasonably safe as long as it's not a 185 top mount air to air version, however a change to a front mount intercooler will pay dividends both in lifespan and power increase as the charge air will be much cooler.

Dump valve:
The 205 has one as standard, but it's a recirculating one back into the airbox. If you like the noise, it's easy to just take it off the airbox and screw a plate on the airbox in it's place.
There are 185's and 165's out there with atmospheric dump valves, but they do cause issues as they will screw up the mixture while open - especially as many open a little at idle. Using a recirculating one back into the intake pipe after the AFM will get round this problem but you'll lose the noise.

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PostPosted: Sun May 19, 2013 11:01 am 
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Sorry guys its a st205. Cant believe i got a car like this for less then 3500 im very happy with it!

Thanks for the advice everyone u all seem to have great knowledge so ill avoid the induction kit and manifold and continue with boost controller and brakes and look into how i can get the ecu improved.

I looked at inter coolers but cant tell whats worth it. There are ones for 200 and ones for ALOT more so i dont know if replacing it with a 200 quid one will improve anything? Or whether for that price its just same standard as the one on now.

I need to work out how to get a pic on so i can have it as my profile pic :)


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PostPosted: Sun May 19, 2013 11:08 am 
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mattworrall wrote:
I need to work out how to get a pic on so i can have it as my profile pic :)
The User Control Panel at the top of the page leads into customising your profile. Quick link is:
http://www.gt4dc.co.uk/forum/ucp.php?i=profile&mode=avatar

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1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp


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PostPosted: Sun May 19, 2013 1:32 pm 
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If I were you I would do the work on the brakes, maybe fit the boost controller and a boost gauge and then just spend some time enjoying the car.

I wouldn't bother with any of the ECU stuff or messing around with intercoolers quite yet. :)

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PostPosted: Sun May 19, 2013 7:47 pm 
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Sirius wrote:
If I were you I would do the work on the brakes, maybe fit the boost controller and a boost gauge and then just spend some time enjoying the car.

I wouldn't bother with any of the ECU stuff or messing around with intercoolers quite yet. :)



Agreed, boost controller and gauge, and brake pad upgrade. On the exhaust has it been de-catted, as if not, probably worth doin that rather than faffing with trying to get stainless manifold.

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1998 ford st24, 186hp 2.5 v6- sold
1997 bmw e36 318ti, mint hellrot red- sold
1992 celica gt4 st185- td04 340hp/330lbs
1998 mercedes E280- sold
1998 pug 1.9 td- mile muncher!
1993 rx7 542hp savage monster!!
2007 BMW 335i- in the shop gettin built!! :-)


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PostPosted: Sun May 19, 2013 10:23 pm 
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In theory you need a cat for the 205 to be legal. There is a loophole on JDM imports up to & including 95 where if it fails a cat test they can then do a non-cat test. This is because JDM cars don't have EGR so are not an exact match in the database. I believe they still need a cat fitted though.

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PostPosted: Mon May 20, 2013 12:05 am 
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Location: sunny sleaford- lincolnshire
Car Model: ST205
most people pretty much do what you have listed though to be fair, boost, etc.

The only one most dont do is the aftermarket ecu as it costs a fortune.

They do Nibbles for some garages, i had an argument with a tester once that my car wasnt the same as a uk spec.. they argued otherwise and said it needed a cat


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PostPosted: Mon May 20, 2013 8:04 am 
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If it pre 95 (k reg) I thought they get away without cat? Even if a legal requirement, I would take out as its huge and a massive restriction on exhaust gas flow.

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1998 ford st24, 186hp 2.5 v6- sold
1997 bmw e36 318ti, mint hellrot red- sold
1992 celica gt4 st185- td04 340hp/330lbs
1998 mercedes E280- sold
1998 pug 1.9 td- mile muncher!
1993 rx7 542hp savage monster!!
2007 BMW 335i- in the shop gettin built!! :-)


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PostPosted: Mon May 20, 2013 8:35 am 
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Agree that the cat is a big restriction however as its a 205 we are talking about you will need to refit the cat every year to pass tbe emissions tests. If you are lucky and know a friendly MOT tester you may be able to avoid this. I used to do that on my old 205 but I have reverted to a cat on my near-stock 205. Some people have fitted a bespoke 3" exhaust system and a motorsport cat which is more free-flowing. It also helps if it is located downstream of the downpipe. The WRC boys fit their cats in the muffler/tailpipe area to minimise the effect on performance. Given your objectives this is probably a bit extreme!

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Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp


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