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what is BAR??


Hakeem
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Hi Guys,

 

I new to this forumn and have been reading a lot on different Subaru models. I currently own a 3.2 V6 Vectra and considering a 3.0 Legacy or WRX Impreza. I have never owned a turbo car before but considering one as I am mainly big engine 6 cylinder NA man.  maybe some tuners here can help me out. what does it mean if one says their Impreza is running 1.0 bar or 1.5 bar boost? does this mean the 2 litre engine is now working like a 3 litre engine and can bar be increased to make more power? sorry to be daft but turbo charging is all new to me.. Thanks in advance

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In a N/A engine the air going into the engine is under atmospheric pressure, ie it's not compressed. Engines with a turbo or supercharger will compress the air before it goes into the engine. This gives more fuel/air mix in the combustion chamber, and thus a bigger bang when it sparks and more power.

The amount of boost is just how much the air in the inlet manifold has been compressed, and air pressure is measured in either PSI (imperial) or BAR (metric).

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Thanks for the Welcome Jay :)  

 

Thanks Adam.. I see so does this mean a WRX making around 240bhp at the crank is compression or sucking in as much air as the equivalent 3.0 engine legacy? I have read a couple of debates in google about say NA being better in terms of power than turbo if both cars make the same or similar bhp at the crank. as the 3 litre legacy makes around 245 and 2002 WRX with high octane fuel will match it in terms of performance. this is a guess so say if your GTB is running 280bhp at 1.5 bar does this mean the air being compressed into the cylinder is equivalent to that of  a bigger engine NA making roughly 280bhp which will be around 3.5 litre V6? I amjust working this out by adding 1.5 bar to the standard engine size of the imprezza which is 2 litre = 3.5 . is this how its calculated?

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The calculations dont work as simply as that due to numerous other factors that all affect the flow rate of air in and out of the engine plus inertia of components and compression ratios.

 

Ill try and break the statements and answer individually for clarity.

 

The NA vs turbo debate for equal BHP (power) relates to how the power is delivered. The power for the NA engine is there straight away so giving drive earlier. An equivalent power turbo engine has a delay while the turbo comes up to speed (spooling up) and thus pressurising the air intake - this increases the air fuel mixture (due to density) crammed into the chamber giving a bigger bang, this is how smaller capacity engines with a turbo can generate the same power as larger capacity NA engines.

 

The engine characteristics between the legacy and the impreza are different not only because of the size but also because of the turbo setup and the tune, they are designed to be different drives, nice fat torque spread against a more active driver engagement to stir the gearbox and keep the motor buzzing - the Spec R legacy though could be some what more of a beast so dont count that in this train of thought.

 

I would advise driving both as I believe (having driven a couple of vectras) you will find both cars really enjoyable to drive but I think you will struggle to draw theoretical comparisons when you start to take into consideration power to weight ratios between the vauxhall and the subarus - its not just about the individual numbers but the sum of all parts

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haha I like that Gambit.. one more question ..how long do turbo's last on a stock WRX engines as I have read stories of turbo's needeing replacing often which I read are not cheap.. £700 -£1500 if they go and take some other parts with them in the process. reason why I have driven NA cars is fact that they don't have turbo so one thing I wont have to worry about, they don't have lag so I put my foot down and am gone, the engine internals last longer due to less stress/heat but I am considering a turbo WRX vs Legacy 3.0 R Spec B. and I once read some where 'regardless of how its generated power is power'  hence am torn between these two models.

 

WRX:- will have turbo lag, will need turbo replacing after a while, will be quicker to 62mph 'but 0-62mph' acceleration does not give the clear performance of vehicle. will have a flatter torque, will draw too much police attention, interior looks basic.

 

Legacy : will not have lag, no turbo needs replacing, about half a second slower to 62mph but can live with that, valve timing and lift will help it maintain flatter torque across the rev range, wont draw police attention and more toys and more luxury interior.

 

so am being swayed towards the NA Legacy for its benefits outwaying the WRX stock for stock. but also want a turbo car for once.. cant make my mind up. :mellow:

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My wrx last time it was checked would 0-60 in 4.1 seconds I have a mate of mine who rides  motor bikes and even he started to lift his legs up when I did a stand and start launch. But mine's been modded but only runs 300BHP. And only time I've heard of Turbos failing and taking the engine with it is if it gets starved of oil. But as long as you let it warmed up and cooled down and service it more than you would any other car should be fine. I've know 2 people with Audi a3 and an Astra VXR both blew their turbos with in 20k miles. My bugeye I would say from when I had the engine rebuilt and bigger turbo fitted I've done 70k+ now still going. I know when you read up on these things you find all the horror stories and rightly so. But as I pointed to before if it's been well looked after and these cars need it :D they would just about last forever. :D

 

And with turbos you will always get turbo lag depends on the size of the turbo no matter what car it is. but when it does spool you know about it :D

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Some Legacys do have turbos - so you could have the best of both worlds.

 

Turbos can be reliable if maintained / looked after as Gambit said - warming up / cooling down etc.

 

WRT the WRX and police attention there is the spec D model with is very understated - also it tends to be how you drive and where you are which can attract the attention not necessarily the car

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I see what you saying guys.. if you take good care of a car be it turbo or NA mainly Japanese cars they will last a life time and yes you right about being how you drive and not what you drive which attracts police attention. but for some reason Imprezas and Evo's are top of their list.. my 3.2 V6 can clock 160mph where permitted but most don't know and some BMW guys have been taken by surprise.

 

4.1 secs to 62mph is very quick was this on stock 225bhp WRX or was this with the 300bhp upgrade? thing is 0-62 figure sells cars but not so import in real world as I have seen some cars run a quicker 0 to 62mph due to their 1st and 2nd gearing but slower time in quarter mile to a mile against another car as they keep going up the gears.. thing is I will prefer to leave my engine in stock form as I don't know much about turbo cars more so tune one lol.. I was under the impression all Legacies officially sold in UK were non turbo's and only turbo models sold were the 2.5 GT in US and maybe Japan?

 

just had a look in autotrader and cant see a turbo legacy from 2003 onwards. reason why am being drawn to the 3.0 legacy more is it will only require oil  spark plug changes and that's it but the WRX will require the same and potential of turbo/ intercooler replacement which is an extra cost I can avoid if i take the legacy but wont loose on performance as they make roughly similar power and grip due to AWD layout.. 

 

maybe I should just get the WRX for the turbo experience and if its proving too much to run I will just stick with what I know best which is big displacement 6 -8 cylinder NA engines.

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No that was it being modded the Blobeye thats stock still pulls well but can feel it's slower from when you have been in the bugeye. And I would say it will be the same for the Legacies if it's in the right range its power all the way through the gears. But if you was doing drags more mods would make it even quicker with the likes of antilag and so on, but know you're not after that type of thing from what you have said. 

 

So I'm guessing you are either into dogging or need to transport murder victims or drug smuggling  :lol:  with not wanting police attention and big boot  space ;) But joking a side I think once you have test driven either one, and once you have decided which is the right one you would be very happy with it they drive like nothing else I've driven. It's just making sure you get a good egg really with them. :)  

Cost wise if you can keep off the money pedal and not keep boosting it everywhere you can get good mpg but just be warned it's hard not too ;)

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:lol:  would be using it for night Bank jobbies  hence I need the space and not too much attention...haha just joking! will keep a look out and not rush with the purchase whilst test driving both models in the process...

 

this one is definitely out of my league in terms of budget but gosh it looks good. maybe one day.

 

http://www.autotrader.co.uk/classified/advert/201310179331990/sort/default/usedcars/make/subaru/model/wrx_sti/page/1/onesearchad/used%2Cnearlynew%2Cnew/postcode/mk160ay/radius/200/body-type/saloon?logcode=p

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Best way mate both the Scoob's in the garage I spent ages looking for them and even traveled to get both of them, Just so I could get ones that felt right for me :) 

 

And I agree very nice cars and out my budget range too :) But if I did get one I would want one with the rear spoiler already fitted. If you don't you have to buy a full new bootlid with the spoiler :(

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