Hi all,

Well, it's time for me to bite the bullet and go for it.....I think.

07 plate STi, 47k miles.

I'm perhaps going to go for Mahle pistons, ACL bearings, Cosworth head gaskets, and ARP head studs.

Will this pretty much bullet proof it?

Has anyone ever forged and (given the cost) regretted it?

Piston slap, is this really that nasty, or can it be lived with?
Is there always teething problems with any build?

Also, can my PPP ECU be programmed with a running in map and then mapped again for around 360bhp once run in? Or would my PPP ECU have to be replaced with another unit.

I'm wanting to keep standard turbo and injectors.

It's only a weekend car, but according to lots on here, a built 2.5 makes for a cracking road car?

I'm tired of in the morning after a blast, having to half empty the overflow coolant tank, and top up the header tank an inch or so!

Thoughts please......

Thank you

 

at 360-400 will be fine
if wanting more get the closed deck insert by as performance
i wld get it any way

 

Mine has SCD I think, do you mean pinning?

Would standard turbo / injectors see 360 bhp? I'd like to think they would.

 

If your only looking at 360 ish then you don't need to go to the expense of closed deck inserts which is what is being recommended above, pining is inserting dowels down the side of the bore walls to support them, not sure what it costs but it's cheaper than closed deck inserts, which costs about £650.

People say to go forged as it's a similar cost to oem parts so may as well fit better quality stronger forged parts, in the case of the 2.5 forged pistons are a necessity as they are the weak point.

David at API will do it for around £2.5k for that power level, how much more you want to spend depends on spec and power levels you wish to aim for, it will also depend on what damage has been done, ie if you need a new crank, I'd do it sooner rather than later so as to try and save some cash.

 

Thanks Ditch.

What are the symptoms of needing a new crank? The car runs fine, but I think the heads are lifting, causing the water to spew into the overflow tank.

Running temps are fine....according to the gauge and my PSi3.

 

If the big end bearings have gone, you need a new crank.

 

The spec you propose looks fine. I wouldn't worry about the stock block with the stock turbo, 360 bhp and around 390 lbs ft won't hurt it. Sorting out the head gasket leak won't be a problem with RCM or Cosworth stopper gaskets and ARP studs.
The OE pistons have a well known issue with ring land breakage, and we often find them broken when stripped for inspection even though no obvious fault has yet shown up. In which case you have to choose forged pistons anyway! Careful reboring and honing using a stress plate means they shouldn't be too noisy.
Stock rods are fine at your spec. We'd fully overhaul the heads as well, rather than just slap them back on.

The 2.5 clearly scores on torque, and that's what makes a car feel fast on the road. Your OE ECU will map up nicely.
We eliminate teething problems by running any new build for at least 50 miles before you'd see it back. We also map as well as build and install.

A properly built shiny new engine should look like this..

 

Thanks Alan, I remember these shots from a while back, lovely!

My ECU isn't OE (as such), it's a PPP one, would it still map up ok?

What do you offer when fully overhauling the heads?

 

Your ecu is oe its just had the PPP rom file flashed over it, api or any other mapper will be able to remap it no problem

Siv

 

Not according to the dealer who fitted PPP. I asked to keep my old one, but they said it had to be sent back....

I know where it is in the passenger footwell, but would it have a Prodrive logo on it?

 

The PPP package has a different map on the standard ecu, which is remapable. Your dealer is talking our of his ****.

 

I'm lucky enough to have recently had my 2.0 rebuilt by Engine Tuner to a forged 2.1 and have to say, its stunning!! The attention to detail is amazing. Mine isn't running yet, but a good friend collected his classic wagon on Friday and it is epic, still on a safe map for a while though.