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Hatchback STi


Jord
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Hi guys,

I have a hatchback STi currently running the prodrive performance pack (330bhp) and would really like to see 400bhp. Is this possible without upgrading the engine internals? What mods do i need to do to get to 400bhp?

Regards

Jord

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Hi, I am not sure but, downpipe and exhaust will help de-cat or down to single sports cat then a remap should see some power gains.

Not sure if you will need to change the turbo.

I have a wrx so the list for that is exhaust, turbo, fuel pump, injectors and remap

So the sti starts out with more power so should just need a few improvements. I know you will get 350+ without to much work but it's getting into the 400's that might be costly.

But I am no expert.... One should be along soon.

--

I make Films and Website for people

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I was thinking of injectors, updated fuel pump, induction kit, exhaust, and remap?? Not 100% certain where this will get me. I have looked around at parts which seem reasonably priced. Was thinking of refurbished injectors as well??

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Found this its for a hawkeye not the newer hatch but should give an idea of power for mods:

 

Hawkeye 2.5 litre STi from 2006 – 2007 ….

In std form they are 265bhp give or take and have boost at about 1 bar peak dropping to about 0.8 bar at the top end.

so… choices icon_smile.gif .. (all based on using vpower)

1. Keep the car std but just remap for more oomph and better fuel economy.
A full custom remap will bring boost in much earlier and hold higher boost levels for longer but the map will be geared to running much more efficiently ( which is also more economically) as it wont be possible to push too much boost with both cats in place. Typically a Green/K&N/Cosworth air filter and a backbox are fitted at this stage but not essential – the backbox just adds some burble to the quiet hawkeye exhaust.

With a custom remap on the standard car typically this would get the car to around 310-320bhp with significant torque improvements.

2. Sports cat in downpipe – plus remove centre cat
A full custom remap will bring boost in much earlier due to the lower back pressure and hold much higher boost levels. The remap will also aim to get it running much more efficiently ( which is also more economically).
Typically a Green/K&N/Cosworth air filter is fitted at this stage (on top of the sports cat downpipe and exhaust system). A walbro 255 fuel pump is highly recommended.

It is also advisable to change to NGK 7 grade spark plugs at your next service.

This would get the car to about 340 – 350bhp but a huge boost in torque figures in the mid range.

3. Fully Decat Exhaust
The low back pressure from removing all the cats reveals the true characteristics of the boxer engine and really sets the 2.5 free. A remap is needed to bring it under control and stop overboosting that will happen enormously with the 2.5 engine. The remap will bring boost in as smooth as possible and most likely get full (and higher ) boost at around 2700 rpm and hold higher boost right through the rev range. The remap will also aim to get it running much more efficiently ( which is also more economically).
Typically a Green/K&N/Cosworth air filter and possibly a 3 port solenoid are fitted at this stage (on top of the decat downpipe and exhaust system).

This would get the car to about 350-360bhp on the std turbo but a huge boost in torque figures in the mid range and transform the way the car drives on the road. I remember this stage well on my own and it is a fantastic car to drive on the road.

A walbro 255 fuel pump is essential.
It is also advisable to change to NGK 7 grade spark plugs at your next service (ILFR7H).

4. 350bhp – 400bhp

You may be one of the lucky ones and have a car that wants to produce power with the std turbo – the VF43 on the std car can get to around 360-370bhp tops but if you want to get to up closer to 400bhp there are a number of turbo options and rather than list them all here – gimme a shout and see which of the many turbos around could fit your requirements. There are lots of suppliers of turbos and they are changing all the time.

The car’s engine, gearbox and clutch (just) can cope with this power.

It is adviseable to fit a larger diameter MAF housing by way of a good quality cold air induction kit.

 

 

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1st of you'd have to check if it has forged internals otherwise you probably won't last long pushing 400 on standard components, if not your looking at pinning the block and going forged.

As far as I'm aware the 2.5 is just bored out to 99mm so the cylinder walls aren't that thick hence why most people either go for a closed deck stroked & bored 2l block for big power applications

Sent from my SM-G850F using Tapatalk

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Also do you need 400bhp? I know HP is like ram you always need more, but with a few simple mods you should get into the 350-370's that should be a very rapid car and faster than most stuff on the road.

--

I make Films and Website for people

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As previously said you wont get a reliable 400 with stock internals the cs400 has forged internals. If that is what you want though look at a rebuild first then fuel pump injectors replace rest of exhaust back box should be ok if it has been changed from oem

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