I'm in the process of speccing up a replacement engine, and am currently undecided on whether to choose a later 2.0 engine or one of the 2.5 lumps.

A couple of people have said that the 2.5 litre engine is 'lazier' than the 2.0, and acceleration is a lot more progressive, but the 2.5 would give me more potential for future enhancements.

Any opinions would be appreciated!

 

go for a 2.1 stroker it still revs like a 2 liter and give you more ft and it will spool up quicker then a 2.0 but then a 2.5 is a option just depends on where you want to be power wise

 

Power-wise, I would like to get as close to 400 BHP as I can get without costs going too crazy, but this would require a tougher gearbox (I'm told).

The other thing: would I have a problem with my current UK Turbo 2000 manifolds lining up on a newer engine?

 

i would go for a 2.5 build. bags of torque and makes an execellent road car. the cylinder heads from your car will bolt up fine to a 2.5 block. so your manifold will fit fine.

 

Jap (JDM) 2 litre? They always keep the best stuff to themselves ...

TX.

 

For 400bhp i'd personally go for a STI7/8 bottom end

 

im in the same situation as you mate, i cant decide either. and have to make a choice soon

 

That was the original intention. A couple of people I've spoken to recently who have rebuilt/replaced their 2 litre lumps said that they now regret not taking the opportunity to go to the 2.5 litre units.

 

the 2 litre engine is stronger than a 2.5 and for that reason alone i'd stick with 2 litre and when i have enough money go for the 2.1 stroker

 

2.5 is far from lazy, it will work better with your heads on a budget build up to 400 BHP, it will however mince your box very quickly. The Version 8 bottom end mentioned above will work out cheaper, but your getting like for like for you money although capable of holding more power displacement is equal, spool up will be slower, toque will be down so ultimately it will be slower and less responsive than the 2.5.

 

You need to choose based on use.

2.5 will make a nice road car motor, but isn't safe to 400 bhp out of the box.

STI V7/8 bottom end is safe to over 400 bhp, but needs a few revs to really fly.

IMHO

dunx

 

See post 2, Why not stroke a 2.0 to 2.33

The basis for this engine

22B Bulletin Board: Cosworth 2.2 Build

Shaun

 

Standard EJ257 will run "up to" 400 BHP, 18 or 20G works well on a budget and keeps the block to a safe limit, beyond this point you need to upgrade internals.

 

We don't like to run a standard EJ257 over 350 bhp / 380 lbs ft.
The pistons just aren't up to it.
There is another issue, in that the 2.5 just isn't as efficient as far as some turbos are concerned, and it isn't unusual to get a whole stack of torque, but relatively little power from a 2.5. Bear in mind you're using the same heads on both engines. This is why we tend to offer the 2.1 for certain applications, which has improved torque over a 2 litre and works well all the way up.

 

I've had 3, 2.0l classics, and a 2.5 converted classic with uk heads and agree with Alan.

 

Thanks for everyone's input on this.

Based on the opinions above, I'm now leaning towards an STi7 bottom-end now. My Impreza is mainly a weekend toy with the odd smattering of weekends blasting up Santa Pod, so the strength issue is important for the road to 400/400.

 

I have an EJ257 and have driven a few 2.0's, Personally like the 2.5 better and drives well off boost too...

 

Got a 2.5 in my Type R running approx 400bhp and it is far from "lazy" Full boost is at 2900rpm on a 20G turbo, redline has been raised also to 8200rpm.

Compared to a previous Type R I used to have running similar power but with the 2.0, this one blows the other away.


If it were my money then I would bet the 2.5. You can still make a 2.3 out of it if thats they way you want to go eventually.

 

So are you looking for a standard block to drop in or willing to spend on adding stronger components?

 

At the moment, I'm looking at a standard block, but ultimately depends on how the financials pan out as I'm being stung uncontrollably by the Inland Revenue at the moment!

The next issue is whether to buy a new block from Subaru, or a cheaper low mileage one from a crash-damaged car.

 

This has been covered many times and the answer remains the same, for a street driven reasonable hp reliable car a 2.5 will feel better as said earlier a 2.5 will build more torque and its torque that accelerates you, 2.5 lazy???...as said many times by people that have never owned/driven one...ours revs like a demon and 600 horses on straight v power in an everyday road car dont lie...

 

How many have the budget to build such a tool ?

I could scrape up £3K for a 2.1 what point is there in comparing it to something twice the price ?

dunx

P.S. Daz-Davies has a V8 STI bottom end up for £750 IIRC....

 

Operating within the std limits of the EJ257 engine is more than enough for most, so go for the 2.5, as torque and boost threashold will be better than a 2.0 litre engine and that's what makes a road car IMHO

 

the point is just that 2.5,s do rev its just bs that they dont, Fact is a 2.5 will generate more torque, horsepower is pub numbers torque is what accelerates you more torque means easier to drive a forged 2.5 bottom end can be done for 4 k easily a standard 2.5 for a lot less
nothin wrong with 2 litre but the same mods on a 2.5 will give you more

and everyone wants more dont they???

 

2.5 will give you a right kick in the neck. 2.0l feels more like Vtec nowdays.

 

std EJ257 - easy.

If you want to future proof it a bit then put in some forged pistons.

2.5 torque and driveability all the way for me. Much quicker in the real world than a 2.0.

 

I wouldn't use uk heads for a 2.5 if i was you, source some sti heads if poss

 

I'm sorry but there has been no mention of budget.....

A £750 STI short motor with a reasonable turbo will make mid-300 bhp. for a couple of grand plus mapping, it will also be around 350 ft.lb. which a five speed box may manage for a while if not launched.....

A forged 2.5 with decent heads and a 600 bhp turbo is going way beyond £7K at a guess, with a six speed and a clutch being needed.

So I'd rather suggest something that can be done, rather than something that may be possible if the cash is available.

IMHO

dunx

P.S. I know a lad with a 2.5 in his Type-R and it is a fantastic car, but it lunched his rear diff and gearbox whilst "only" putting out 300 bhp.

 

Dunx, I think you may have got the wrong end of the stick, mate. I believe some, including me, were saying that a EJ257 std lump will provide 350bhp and be nicer to driver than a std 2.0 litre producing the same peak bhp, owing to the superior torque and better boost threshold of the bigger displacement engine.

Ns04

 

2.5 all day long ....no replacing cubic displacement , get the heads gas flowed/ported and its will rev like a 2 litre