Right the time has come, The engine in my version 4 wrx is tired and i want more power so new engine required (450+ bhp more in the future lol) and i would like to over enginer it to be honest because there is no point in doing it twice lol .. BUT where to start which engine is a better choice idea/stronger (can't make my mind up lol as i work with impreza's all day long and every one has there own opinion to impose on me lol maybe this is the wrong idea to post on here but i need some answers and 2.5LTR's weak or not)

i am looking to build either a

2.5 semi-closed desck block with a nitrated crank, ACL race bearings, forged rods (eagle any other recomended), forged pistons (CP/mahle), 14mm headstud conversion, cometic head gaskets (not to sure on size yet), 12mm uprated oil pump, with a set of STI 3/4 heads bolted to it (most likely ported/polished)

OR

2.0 semi closed deck block (or closed deck) with a nitrated cross driled v9 cranck, ACL race bearings, forged rods (eagle any other recomended), forged pistons (mahle), 14mm headstud conversion, cometic head gaskets (not to sure on size yet), 12mm uprated oil pump, with a set of STI 3/4 heads bolted to it (most likely ported/polished)

All ready got 6 speed sorted with complete r180 rear end with brembo's all round, coilovers, ARB's, so power can be handled. Also very large front mount fitted

HMMMM what turbo to used aswell was thinking a md321T not going twisted set-up yet lol

thanks scott

 

hows tricks bud? ive had a few now but the spec c is my 1st twin scroll and im well happy with it apart from the turbo seems to run out of legs in 5/6th so maybe a bigger turbo and injectors nxt

so what sort of power are you looking for?

 

If you work for Andy why arnt you asking him ??

2.5 is good for torque and can be reliable if built properly, I'd be pegging the liners if your doing the job right
Eagle rods well for get that they arnt good to be honest, go for something like manley/carrillo/cosworth
Mahle Pistons are spot on, theres a couple of choices though High/low silicon content.
sti v4 heads would be better on the 2.5 but get them machined to suit.

 

2.1 is a better choice isn't it as more torque than a 2 litre. MD321T (same as me) is good for 450hp.

TX.

 

I would go 2ltr CDB and stroke to 2.1, it wont have as much torque as a 2.5ltr but it will be a better car to drive higher up the rev range (4000RPM and above) and give good room for spec creep

 

Agree with TX 2.1 wil be mine choice(and is it in mine build) ..
Turbo SC46 or SC50


Jura

 

As above. Cdb 2.0 block stroked to 2.1 with nitrided crank and 14mm studs etc with a 321v. Sorted.

 

If you want to go north of 500.
Definately go for a 2.1 CDB as suggested by others above

Sub 500 with lots of torque 2.5 Semi CDB - properly built as mentioned above

Money no object 2.3

 

You work with subarus all day but haven't considered a stroked 2.2 cdb. The 2.35 is by far the strongest of the big power engines.

 

for starters i have asked andy obviouse, that is the first choice looking for other opinions/ideas as it is something i only want to do once lol

going for manley rods just been doing more research lol, forged eagle wondered why the were so cheep lol,

 

2.2 cbd ££££££ not at the moment maybe in the next one lol i know they are the best option but a bit dear at the moment, as i already have 2ltr abd 2.5 ltr block's


these 2.1's are very popular looking for lots of torque not going over 500bhp to be honest as it become's unusable on the road in my opinion forgot to mension want a reliable road car in post not asking for much lol haha maybe have to stick to 450 lol

 

I have those too

TX.

 

what are 2.1's like to drive, drove 2.5's and 2.0's. are they fast response with the old rev's cos 2.5 can be a bit sluggish lol

 

Best of both worlds tbh ... still have the mad top end + loads of torque just like the 2.5s

TX.

 

A 2.1 is a good all rounder, a nice extra chunk of torque, they rev very well and they are not that expensive.

Dont forget wiseco's, they are good pistons too.

 

Hey Scott, have you not spoke with Brian?

I believe the 2.1 is a great choice for a quick road car with track day useablitiy. It proabably bar the standard 2.0 forged the cheapest option out of the options available too. Some name that spring to mind, Pennie & EngineTuner that are relatively local.

As for the Turbo I assume your going standard plumbing? MD321, SC46, GT30, Some of the VF Ranges...

https://www.scoobynet.com/scoobynet-...t=400bhp+worth

Rob

 

[QUOTE=Scott@ScoobySpares;9931333]Right the time has come, The engine in my version 4 wrx is tired and i want more power so new engine required (450+ bhp more in the future lol) and i would like to over enginer it to be honest because there is no point in doing it twice

2.35 may be expensive but still cheaper than doing it twice or more.

 

wow 2.1's are being pushed lol wasn't too sure about them but sound good, always thought 2.5 better due to enine size lol but i have read up a bit on them now and i am impressed,

got a quick option on the cards i have been offered a 2.5sti short motor with forged RCM pistons sti 9 rods/crank (£1100) what is this good for power wise without pushing it too far what turbo to fit???

 

I would say no money object,i would go with 2.35..
EJ22 block you can pick up for good money etc.
But if its limited budget(like me) 2.1 stroker is good option...


Jura

 

2.5's I believe (stand to be corrected) are bloody good every day road cars, loads of torque and good for around 400bhp ish, past this point and it becomes dangerous, they are prone to bottom end failure (correct me if im wrong guys). The 2.5 rebuild from RCM needs to be put to RCM for answers imho. As for the choice in turbos, there is a good thread on here, i'll just have a quick search and get back....


Edit - Here you buddy.... https://www.scoobynet.com/general-te...ighlight=md321

Rob

 

A safe reliable 450/450.

 

Thanks rob read this thread hmmm help full

not too sure if it has been built by RCM don't think it has they have supplied the pistons, i know the person selling it well and all his stuff is good, also know the mapper who mapped this engine in the last car it was in and heard good reports

nice to hear that they are good road engines 2.5s don't want to track as i would rather build another car on a budget for track more fun as tracking something you have a lot of money has its worries lol if it blew it blew lol

 

I've a built ej257 which ran on a T @ circa 450/450 for 8k. It did the ring, KH many times, Cadwell, Snett, and various drags/events.

I have since ran the last 2k on a 35R which made circa 620bhp on sunaco 109 @ 1.65Barg held. Its also done some drag events in this guise. Its been reved to 8.5K at these events with out issue.

It gets used and abused and runs fine. It also revs as quick as many ej20 I have mapped, which seems to be another myth about the 2.5

There's no reason why a properly built ej257 with good quality supporting mods should not be as reliable as any other low capacity engine running at these power levels.

Cheers
Col

 

What power was/is in the seller of the block running? Also ask him what blower he is running, I assume Andrew mapped it?

Off Topic - Andrew will be mapping mine Early next week, my car is at his unit where Brain is undertaking the pre-map work

 

Good Lad, I'm running Manleys in my 2.5 Forged Motor. Had the base of the cylinders machined slightly to allow the larger rod bolts to pass without fouling the caseing when rotating. I've heard some shocking reports on the eagle rods to haha.

 

2.5 is quite cheap fun with a 20g

 

You do know that any choice on your list will destroy your gearbox...

And clutch...

dunx

 

erm well i hope it wont pal, as i stated in the post i have a full 6 speed set-up sorted whilst its out clutch will be replaced if needed

thanks

 

There's an awful lot of rubbish being said about the 2.5's here.

All this crap about them being sluggish and not reving well is utter bollocks.

Built right with the right components and they will be very very responsive and rev to 8K without issue!!

Their only shortcoming is block integrity at above 500bhp which can be tackled by pins around the bores.

600bhp and 585ft lbs from mine mine's just been stripped due to dropped valve and the bores are mint. It will soon see close to 650 - 700bhp I then hope to dispell any myths about the 2.5.

Here's a graph from my latest dyno run this is with standard heans and cams too.

 

Dazdavies - Am I right regarding the standard 2.5 bottom end being potentially unstable past 400bhp or thereabouts? I was considering this when I bought my last project car, and looked into putting a 2.5 STI Forrester engine in my 2002 STI, but was informed that 400bhp would be the limit, and even this would be pushing my luck?!?!? Obviously with the right aftermarket components its possible to push more, but then even the block in OEM form can be at risk beyond 500bhp?

Sorry for sounding thick, but when you believe all you read without having the knowledge or experience like yourself its all 'here-say'. Your motor is/was certainly proof in the pudding, and my dearest compliments to you.

It was a shame the last SSO was soaking as I would have like to have seen some better times, although despite the monsoon it was amazing to see the times you and many other were managing to plant down the 1/4.

Rob

PS, Scott - Im sure Dunx missed your info from the original thread, and yes im again 'under the impression' that a standard 6 speed box if not abused will take upto 550bhp, and maybe more.... I think I read someone pushing 603bhp.... Banny is running well over 500bhp on his 6 speed which is also a 2.0 STI lump if memory serves me correct?

Rob