Okay, I know I've only just got the car back from Neil but something he said got me thinking. Bearing in mind that my motor is supposedly capable of dealing with around 400BHP, If I basically just buy a turbo eg the mdx blah blah 400, does he just fit it and remap it and job done???

 

Nah you'd probably be in to FMIC and bigger injector territory if you aren't already. Not to mention clutch and possibly gearbox depending on what you've got already?

 

Don't forget the brakes and suspension.

 

Hopefully the brakes are already done!

 

Okay so let me rephrase that, the XTR 380 (to leave some headroom), presuming the pistons can cope with 400, I can sit and wait for anything else to go bang, but not too much strain on the engine??

 

Depends on what the op wants from his car!
Personally I say **** the brakes beyond uprated disks and pads!

 

Brakes and handling first power last. It's the tried and trusted way.

 

I learned this the hard way

 

Ok but my concern is if I put a 380/400 BHP rated turbo on my car which I am told the pistons will cope well with 400BHP as they are factory forged, the engine won't go bang???

I know that suddenly it will
Go forward quicker than it will turn or stop, but my main concern is damage

 

Again - fully dependant on what the OP wants from his car!

 

Upgraded discs/pads and drop links/ coil overs don't seem to worrying to me, however a new engine or rebuild does

 

Well if the the sum of all the parts used in the engine add up to a rating of 400bhp then maybe you should stay around 360/370bhp as a safety margin. Depends how hard you drive and how often!

 

Okay, therefore the XTR 380, theoretically buy the turbo, get a remap and job done? No other little bits to do to prevent a Big Bang? Obviously tjere is the strain of repeatedly punishing any engine, but theoretically it would
Be okay??

 

I don't think there's any anti-bigbang bolt on devices out there lol. Maybe thermostatically controlled oil cooling would be something to consider for when you do push hard? Better having parts that can cope with much more than you run them at, not pushing them to the limit if you get me. Anyway, I'm no engine builder/tuner but I'm sure the right guys will be on here soon with some better advice. What injectors and fuel pump you got?

 

maybe I missed the post, but what all is done to your car already - maybe that will help people advise you as to what else is needed to achieve 400 safely?

 

What? A car that he can't drive fast around corners or stop when has to. All boost no brakes! Comes to mind.A classic example of people getting BHP happy that is. You could have a car with a 1000 BHP but if the brakes and suspension are not uprated it ain't gonna be quick if it doesn't handle or can't brake properly in the corners. A decent 400/400 car set up properly would smash a 1000 BHP with standard brakes and suspension every day of the week.https://m.youtube.com/watch?v=koRYfURimAw

 

All I am asking is if I bolt a 380
BHP turbo and remap it to a standard JDM bug which is running well then (in terms
Of engine only) what other precautions should I take? Please be aware I am
Aware or suspension, clutch and brakes

 

No such thing as precaution when modding a engine power wise one will be fine another might go bang

 

Yes is what you want to hear ...


But you may discover that the injectors, or fuel pump, or intercooler, or exhaust, may stop you reaching your bhp goal.

Your tuner - once turbo fitted and mapped - would advise you what is holding it back etc. I run an XTR 2.5 Dom - great turbo. Prob too big for you.

Have you considered the SC 36 - prob v similar to what you r been looking at.

Enjoy 😎

 

As Apostle has said.

The three main retardants at that stage will be 1.) Injectors, 2.) Fuel pump 3.) Exhaust )Down, and up pipes, headers, Cat etc. If it's an STi intercooler you have should see you well up to the high 300's.

There is no safe point on any engine. There are people out there who've done the mildest of mods and it's failed. Then there are the uneducated doing things like bolting on massive cheap air induction cones and dump valves and the engine lets go. Then on the other scale there are people who have spent ten of thousands on massive builds and the engine has let go after not being maintained and checked.

During the mapping procedure the mapper should be able to detect any knock when pushing the car.

The SC36 would be ideal for your situation, very quick spooling turbo which is fantastic for road use. Don't chase BHP figures and join the p155ing contest. I've been lucky enough to be taken out in a few monster builds over 600bhp. Yes they are awesome but pretty useless on the roads.

 

I think your going about this slightly **** about tit.

You've only just got the car running properly and your already thinking about more power, just because the engine can take it.

I think you should live with the car for a while and discover it's short comings in terms of drivability with what you already have.

Just bolting on a big turbo is a mugs game as numbers mean nothing, drivability is king, sure once your big turbo comes on song you'll get a big shove in the back between 4 and 7k rpm but it's not going to be much use when the guy with the smaller turbo and better set up car has already gone you'll always be playing catch up.

The Bug STI is a decent starting point but it's by no means perfect and TBH I think All Imprezas are pretty **** out of the box until you sort the handling and breaking.

I suggest you spend some time reading tips on handling, set up, springs, roll bars, drop links , polly bushes and braces as well as good pad and disc combinations before you spunk £1500 on turbo Injectors remap etc.

And like I said above get to know the car and push it a little, I think you'll find it's pretty crap with 14yr old bushes and suspension.

No offence mate but if you think it's good and handles well as is then you've got no business going for more power because your obviously not able to get near it's limits as it is now, once you do you'll see that all the guys above were right.

 

Thanks for the advice guys, I have to say I like the handling although it doesn't take long
To find the limit get it under steering, this happens at a much lower speed than I would
Expect.

My plan for now is definately to run it as is, get a rolling road figure and enjoy for a few months. I'm thinking maybe start doing some bits in the Summer. As aforementioned the handling would need to be addressed as would the brakes. Currently I have a bigger fuel pump and a decat with the downpipe so would happily go down the sc36/38 route along with maybe some pink injectors. I understand the concept of having a fully balanced car with regards to putting the power on the road, I just wondered with my spec whether much else would be necessary on the power side to aid the turbo/injectors. But definately gonna live with it running so nicely for now, as you said I am
Still getting to know it. Maybe the satisfied feeling never lasts long enough???

 

A 1000bhp Impreza will stop just as fast as a 220bhp Impreza from any given speed. They will also handle the corners the same also at any given speed. What I'm getting at is that maybe the OP likes to come off a roundabout, get in a straight line and feel the boost. Maybe he doesn't like hammering into corners and breaking at the last minute. Let's face it - if you are getting anywhere near to the limits of a standard Scoob then your are simply driving too fast for the public highway.
If I was to buy another Scoob then i wouldn't think twice about taking the power to or beyond 400bhp on the standard suspension and brakes as I simply wouldn't get anywhere the limits of the standard items.
Not everyone wants the same thing

 

Well said

 

Erm, NO and NO.

Speaking as someone who has had both standard and modified I can tell you for sure that there is no way my mapped WRX equipped with standard suspension and brakes stopped or went around corners like my PPP WRX with AP 4 pots on the front stops and with the springs I have just fitted along with a few other handling mods there is no way on this earth it could corner like it does now.

I agree not everyone wants the same thing though, I'm not interested in top end as I very rarely go over 100mph and I have no interest it revving the **** off my car, so small turbo that starts spooling @ 2250 rpm and pulls to 6250rpm is perfect for me as I'm interested in getting off the line quickly and mid range pull / drivability in 2nd 3rd and a touch of 4th without it screaming to the red line.

I definitely don't want to wait until 4k rpm and have all hell break lose but I can see the appeal of that for some people, I like to drive my car on twisty country roads, brake late and hard then get on the power asap and always have something there without murdering it to do so, In fact most of the time I barely go over 5k rpm and try and carry as much speed as possible through the corners, my old standard suspension didn't do this very well but my new set up sees me going round the same bends at speeds I could only dream of previously.

So yeah sorry but have to take issue with your first two points but agree about the last one.

 

Think you missed my point! Of course a car with suspension and brakes done will destroy a car on the standard items. My point was that an Impreza with 220bhp will stop from 70mph (or whatever) on standard brakes just as quickly as a 1000bhp Impreza on standard brakes. Both cars will handle the corners the same on standard suspension at the same speed. Obviously if you use the extra power In the corners or going into corners then mods to the brakes and suspension might just save your bacon.

My Impreza ran 313/300 on standard brakes and I never once got close to a situation where the brakes couldn't cope but that was down to how I drove, not down to the amount of power I had.

 

HAHAHAHAHAHAHAHAHAHA

 

Blimey, think I'll pass on the turbo........

 

Good choice, by the sounds of it you're already experiencing a bit of lag, just bolting a bigger turbo on will only increase that, it's not fantasy, it's fact.

You can reduce some of it through mapping, but if you want to do it properly you'll need to spend a lot more than £2k, the next step for you would be something like an SC 36 which is the modern equivalent of a VF34 but it's a fair bit of outlay, I'd be more inclined to take the VF34 route if you can find a good one, very similar end result for a lot less outlay, I ran one in my fantasy and it gave me a stiffy every time I dreamt about it.

More cc or twin scroll is really the way to go if you want to go into 400+ territory with either a 2.1, 2.35 or 2.5, I wouldn't bother taking a 2.0L non twin scroll much above 350bhp (you'll also note that it's the reason Subaru went twin Scroll, weight loss and handling at that point well it was around 320bhp but lets not split hairs) as you lose responsiveness which is what you really want in a road car, which is why cars like the S202 run the VF34 ball bearing turbo, a fair bit of weight loss and special handling package and are pretty much considered the pinnacle of your particular version of the Impreza, you'll not go far wrong trying to make yours a little more like an S202.

For 400bhp Subaru turned to Cosworth and a built 2.5L.

My advice would be don't take anyones advice work out what it is you want from your car then do your research and move forwards from there as mistakes are costly, just be-cause some guy on the internet said so doesn't make it right for you.

 

I've cleaned this thread. Any more petty arguing will result in an instant ban. Thanks.