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Naturally Aspirating a Subaru Impreza RX 1998
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Old 14 Oct 2009, 12:05 PM   #1 (permalink)
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Naturally Aspirating a Subaru Impreza RX 1998

Hey everyone, I was just wondering if it is possible for me to NA tune my RX to 200kW (268HP) from 92kW (123HP). If so, approx. how much would it cost and what parts would need to be upgraded. I was told that I would be lucky to get 210HP from a NA tuned 4 cylinder engine. Also I was told the engine wouldn't last long at such high compression.

I just want a second opinion. I'm not asking for a quote or anything that detailed, just a quick estimation. Thanks.

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Old 14 Oct 2009, 12:12 PM   #2 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

Hello n Welcome for starters


Hmmmm,to get a N/A scoob up to that power,you'd have take on some serious engine work,cam,crank,re-bore,skim,port,polish,pullies etc,you'd be well into the thousands to obtain that power(if your lucky),even if you dropped a turbo engine in there,you'd still have to uprate the gearbox,brakes,suspension,ecu/ecm,bushes etc,will be a massive job with huge expenses...
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Old 14 Oct 2009, 12:20 PM   #3 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

Oh right thanks. The reason I'm choosing to NA tune instead of turbo is because in Australia you can't drive turbo charged cars until you have held your licence for 3 years, I've only held mine for 8 months.

As far as costs go, would it be in the order of $10,000 or more for the necessary upgrades? Also, would 150kW (200HP) be a more reasonable target then?
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Old 14 Oct 2009, 12:25 PM   #4 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

it's a good possibility on the costing bud,but not too sure as to what power you would be able to get from the block,thinking about it,there is one way you could do it but then again costings and possible OZ law could cap it off completely..
Nitrous would be a quick and easy way to gain power like that,but obviously,suspension and brakes would be a very wise upgrade to make it safe..
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Old 14 Oct 2009, 12:34 PM   #5 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

Right I see. My budget would be $5,000 max. So I take it that wouldn't be enough for all the work that would need to be done.

Also would port grinding, full engine balancing and a performance chip increase the output somewhat?
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Old 14 Oct 2009, 12:40 PM   #6 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

when you start tuning scoob's it does become very expensive..
porting,ploishing and balancing should see some good gains,will also need to sort the exhaust system to make it a nice free flow,at a rough guesstimate i'd expect to possibly see iro 160-180 bhp max with the forementioned work..
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Old 14 Oct 2009, 12:44 PM   #7 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

So if I were to NA tune the car (not overly tune it), along with port and polish, engine balancing and performance chip I would be looking at about 180bhp? All that would give me approx. 180bhp?
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Old 14 Oct 2009, 12:45 PM   #8 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

at the most i would say..
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Old 14 Oct 2009, 12:51 PM   #9 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

Ok that's not to bad. Though I was wondering about acceleration. Would items such as a sports muffler, sports transmission, twin plate clutch, sports flywheel and a carbon driveshaft improve the acceleration much?

Sorry about all the questions... Just trying to weigh up if it is worth upgrading an RX
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Old 14 Oct 2009, 12:57 PM   #10 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

indeed they will help greatly(the twin plate will be very"heavy"and possibly too much for the car),but to gain full advantage to the rear muffler,you'd be better off adding a set of headers and a de-cat as well,as for the carbon shaft,thats a serious bit of kit,costs in excess of 1,000 over here,god knows what that equates to in OZ...


have a read of Aron in the USA has done with his N/A scoob,may well give you some ideas

link:- DirtyImpreza.com Project Rally RS (2001 2.5RS)
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Last edited by The Pilot; 14 Oct 2009 at 12:59 PM.
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Old 14 Oct 2009, 01:02 PM   #11 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

What do you mean by "heavy", would a high capacity single be better in this situation?

And I did some research for the carbon driveshaft and found it to be around 1,000 - 1,200, which in Australia equates to about $2,200 - $2,400 or there abouts. This is a project that I would more then likely be doing over the course of a year, I mean I'm not going to be buying all these upgrades at once.

Ok thanks for the link

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Old 14 Oct 2009, 01:11 PM   #12 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

"heavy" meaning the presure on the pedal,biting point,really only need a twin plate if your running massive power,and uprated Exedy fast road clutch should do you nicely....$2,400 for the shaft,thats almost half your estimated budget!!!

best way to tune a scoob,little and often,that way the changes are mildly noticable in the car and the bank balance
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Old 14 Oct 2009, 01:16 PM   #13 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

Ah I see, thanks for the help

Yeah I have around $5,000 to start the project, but then over the course of the year I'll be earning money as well (since I live with my parents I have next to no expenses to pay) and most of the money will go into the car.

Thanks for the advice, it really helped a lot
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Old 14 Oct 2009, 01:21 PM   #14 (permalink)
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Re: Naturally Aspirating a Subaru Impreza RX 1998

no worries fella,keep us posted on the progress and shove some pics up of the car when you get it
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