SCOOBYNIPPA

iTrader: (3)

Right im after a little bit of info and help lol

Im just building my v7 sti jdm impreza to 550bhp and want to know what bottom end is the best? The 2.0 or 2.5?

My mods are gt30/40 turbo rotated kit external wastegate, 1000cc injectors, simtek ecu, external fuel pumps etc.

I was going to go with my 2.0 and have it fully forged but have been offered a 2.5 fully built for a really good price.

I just want to know what you guys think?

Thanks in advance.

chrisdicko

iTrader: (21)

Make a 2.1 from your 2.0 block.

john banks

2.0 for strength but can you live with a laggy power band that will in many circumstances make it slower than a car with 400-450 BHP?

Can you get access to drive some Subarus with 550 BHP to see what you think? If you haven't, it might save you making something you don't like.

SCOOBYNIPPA

iTrader: (3)

That's what I was going to do but for the price all that would cost I can buy this fully forged 2.5 for well under half what the 2.1 would cost.

SCOOBYNIPPA

iTrader: (3)

I couldn't live with laggyness lol. I've had a couple of scoobys in the 420bhp range and this one I wanted to get at 550bhp and keep it lol

Infected by sti

iTrader: (6)

If its cheap is there a reason behind it? Can totally see the logic behind the thinking but you got to ask yourself are you buying somebody else's problems

If you know the full history of it, warrant the miles, know the owner etc then you could be on to a good thing for a good price, but dont just jump in head first would be my advice do your research first, and if poss go in both cars 2.1 and 2.5

Im running 453bhp on a stock 2.0ltr jdm engine with pure bolt on mods an can honestly say its a great car, will you be using it for track or road use? As 500+ in a road car is fun but i very much doubt you will use it to its full potential so would really be spending all that money and not being able to use it to its full potential, the speed you approach cars at in a 500+ car is scary tbh, stick your foot down and before you know it your riding the back end of the car in front lol

tubbytommy

iTrader: (20)

450 is about right, like you say it has bolt on mods and is not laggy and driveable as an everyday car.
this is the figure im going for.

chopperman

The 2.1 route would be the cheapest option for that power level. I have been in a 550+ bhp 2.5 and it was awesome with over 550ft/lb of torque. It drove like any other road car at low speeds and when the loud peddle was pressed it was mental with zero lag.
That 2.5 block had some serious money and engineering on it to get it to that level. It was the 2010 block which has thicker liners and was converted to CDB and cryogenicly treated.
Read Bob Rawles project thread for more info.

Bez300

iTrader: (2)

You will need inserts or pinning to get a reliable 550 from a 2.5
I am running a 2.5 with 487bhp & 480lb on a gt 30 at 1.5 bar of boost.
there is no lag with it, but have been advised by some very good mappers on here, not to go above 500 with it if I want to stay reliable
I was not aware about the 2010 block with thicker liners,
I think my engine will be coming out & having inserts in,
then fit a front mount, twisted kit and go for an aftermarket ecu
My engine with 487bhp has been in 2 seasons of sprints 2 nurburgring trips, a trip to spa, and still going strong, but its not running 550,
550 is pushing the std 2.5 block

Bez

SCOOBYNIPPA

iTrader: (3)

Yea the person selling the bottom end is a close friend of mine who as only had it in for around 3000 miles but as just brought a Evo mr 340 and is stripping his car back to stock so he don't lose to much money.

I've already brought the gt30/40 turbo and rotated kit with external wastage and all the other mods so the bottom end and a remap is all I'm missing.

I want the car to feel like its gonna rip your neck off lol

I got quoted by a big company £5000 roll in roll out with turning my block into a 2.1 stroker but have been offered this 2.5 bottom end fully forged for £1500 so it's a massive saving but I don't know what to do. I defiantly want over 500 so 550 would be my goal.

BlueBugEye

iTrader: (12)

2.5 will need the deck closing or pinning for 550 I'm just under 450 on mine and Simon doesn't want to take it much further, WMS the builder is happy up to 450 but over that he's not going to promise anything!

Infected by sti

iTrader: (6)

Oh its certainly fun lol and i would love to push for 500+ but when im at this point where the car is relatively safe shall we say, then to push for that extra 50+ bhp would cost near enough £1000 per 10bhp by the time the engine is built and upgrade this and that so its a reliable engine, so to me that i cant justify for a road car. If worse comes to worse and the engine did get unhappy then im prepared for that and will sort it when needed,, i could probably get near 500 with a 20% meth mix which is what ill probably do just out of curiosity so thats near enough your target and still on stock motor without the extra £££'s just a bit of food for thought maybe

If its the number your after then both routes will probably see you around the 500 marker but for reliability and the torque then 2.35 is your answer

stevebt

iTrader: (8)

I had a gt30/40 with .82 housing on my 2ltr and I loved it. It was bland until about 4000rpm then it was Mine was only running 490bhp and 1.7bar




I also moved to a gt3582 with a .63 housing on my 2.5ltr and again this was fun running your exact power figure but I was only running 1.8 bar but it was more fun that the above turbo

sonic93

iTrader: (16)

Steve was that on standard 2 litre new age engine ?

stevebt

iTrader: (8)

It was on a forged 2ltr. It was soo much fun booting it from 2nd gear onwards. I reckon 2/ 2.2bar on the same turbo would be fantastic


Ooops yes newage as it was in my car so yes avcs

TonyBurns

iTrader: (3)

2.33/2.35 and twin scroll, you will be laughing then

stevebt

iTrader: (8)

Don't do it as you will regret the spend as it does get costly

banny sti

iTrader: (68)

Standard newage 2 litre engine with sti 3 heads running a GT3076R on 15% meth

Bez300

iTrader: (2)

What boost was that running Banny

Bez

MartynJ

Built well, using the right components and if you're not power crazed, you can get a 2.1 to be a very usable road car and within a decent budget.

sonic93

iTrader: (16)

Martyn when do standard Sti 3 heads start needing work for more power? Or banny you will prob know?

banny sti

iTrader: (68)

Hi Bez it was just a touch under 2 bar

I would say around 550bhp would be the limit for the sti 3 heads as mine still had a little more in it according to Simon

SCOOBYNIPPA

iTrader: (3)

How long did that last banny?

SCOOBYNIPPA

iTrader: (3)

Who built your engine?

banny sti

iTrader: (68)

10K miles and engine was still going when I broke the car

stevebt

iTrader: (8)

Back then it was built by some idiot but the one I have now is built by SD motorsport. He has been working on my car for 5 years now and has virtually built the thing

SCOOBYNIPPA

iTrader: (3)

Was the bottom end totally standard then? If so think ill keep mine and Map it to 500bhp and see how it goes

SCOOBYNIPPA

iTrader: (3)

Ill have a look into them. Where they based?

banny sti

iTrader: (68)

Yep totally standard right down to subaru head bolts!

SCOOBYNIPPA

iTrader: (3)

Also what would the difference be with the v3 sti heads to the ones I have fitted?