StickyMicky

they are fackin brilliant


60 miles now done and only a 4krpm limit, but its awesome

going for a long drive after work at 2.30pm

Peanuts

iTrader: (15)

if you can work the heads and do the valve train some justice then yes, I agree.
If you bolt standard heads on then no, you are wrong.
They are big hulking lazy engines and they compensate very well for poor quality driving due to the increased torque.

StickyMicky

bugger the heads, i simply can not remember the last time i ever took my car over 5.5k on the road, the last time i ever did was probably at elvington about 5 years ago


i always wanted the low down stuff, and actually prefered driving my car the most "around the doors" when the vf22 blew up and i fitted a td04 as a stop gap

besides, the hulk is baddass

Peanuts

iTrader: (15)

good man

triplesix

My standard STI V valve train seems to cope OK. (452bhp) It also revved very well indeed for a stock EJ257 bottom end.

I'm sure the closed deck 2.5 rotated GT30R engine I'm building now will reach the limit of these heads though.

scoobysmiff

iTrader: (2)

[quote=Peanuts;8187285]if you can work the heads and do the valve train some justice then yes, I agree.

If you bolt standard heads on then no, you are wrong.

Can you please expand on the 2 above statements? I am building a 2.5 into my V4 Sti and would like to know everything i can before i get started

StickyMicky

stock heads can be "bored out" or machined to make them the same size as the 2.5 bores

if you don't do this, you need a fatter head gasket, the general rule is, if you want to rev the knackers of your 2.5 then its best to sort the heads.

personally i did not, i don't want to scream the engine, i just wanted a less laggy drive.

1 bar of boost by 2800 is fine by me

bighead

iTrader: (1)

no Peanuts is right (apply on the 2 litres as well ), ports the heads will give you a very smooth engine that will rev!!
I had mine ported on my forged 2.5 and its revs better than my old P1 2.0

ps........... stickymicky its is great with all that torque low down, but after a while you get use to the power and you will wants more !!!

triplesix

Some sweeping statements there.

I threw together a stock EJ257 with some standard STI 5 heads and put a rotated GT30R into the equation for good measure.

The heads weren't touched (just re shimmed) I used a 1.6mm head gasket.

It made 452 bhp @ 1.4bar and revved to 8k no problem.

It was not a lazy engine and was every bit as punchy as my 360bhp 2.0L was.

I think saying that 2.5's can't rev is nonsense.
I think it's all to do with what else is bolted onto it.

I'd imagine people that use standard UK heads with over bucket shims are the ones saying the engine doesn't rev well.

Mine does and the heads were completely and utterly standard albeit STI 5 items.

I'm now building the proper engine now. It's a closed deck sleeved 2.5 with RCMS wrc rods and Omega Pistons. We'll see how standard heads (now with stronger springs) cope with 2bar from the Rotated GT30R (0.82)

Peanuts

iTrader: (15)

triplesix, dont confuse power with efficiency

triplesix

Peanuts its Daz (serving an infraction ban )

We're discussing what a 2.5 revs like not its efficiency.
452bhp a 1.4bar I would say is a fairly good result.
What i'm disputing is people saying that 2.5 engines don't rev. Speaking from my own personal experience I think that's rubbish. I think its the quality of the build and the parts used to bolt onto the 2.5 that make the difference.

As stated I used a stock EJ257 bottom end STI 5 heads and a GT30R

I bounced off the limiter with it numerous times and it still delivered power right upto the redline.

turboDean

iTrader: (4)

agree 2.5's rev just fine, i've got STI 5 heads on mine, only worked done is the bores opened to match the block.
Took a mate out in it who wanted to build a 2.35 (coz 2.5's don't rev) he's now bought a 2.5

stevebt

iTrader: (8)

What do you mean don't rev ??? I can take mine right up to the 8k limiter on my car with my tiddly turbo

l70byb.

iTrader: (5)

Mine seems to be abit lazy when revving . But i've only got a 18g fitted and pre96 wrx head that have been gasflowed .Which i've been told the heads can struggle on a 2.5 at higher rev's. Has anyone suffered from this ?

StickyMicky

you don't have a tiddly little turbo,

i have a tiddly little turbo

ported 16g

its boosting as soon as i pull away, i love it mighy get bored with it tho once i raise the rev limit over 4k, will have to see lol