Short story:

Car: '05 JDM Sti.

Decided on some mods before a(nother) remap. Went for an uprated actuator and s/h RCM induction.

Fitted the actuator - found it overboosted big time, drove like a granny until a few days later...

Fitted the induction - car wouldn't idle, but once running was OK, but got a CEL (P0171 - running lean). Eek - brown trousers; didn't have any, drove it really really carefully 80 miles to the remap...

Could not get any meaningful timing advance, mapper suspected problems. Booked car in to get sorted...

Then find induction is an 80mm intended for "big" builds, although not incompatible with my car, but ideallly should only have been fitted immediately prior to the remap

Now, compression really low (95-ish psi 1 and 3, 120 or so 2 and 4)...

Am told could "just" be head gaskets, or could be pistons/rings . Might be related to my mods, or just bad luck.

Any suggestions/comments/words of wisdom? What am I likely to have fooked?

 

Evening mate, my 2.2 went the same way on same cylinders after the injectors failed somehow and went lean in cylinders which created a gas torch style cutting effect on the rings, and snapping the ring landing, take the oil filler cap off and watch for chugs of oily smoke and pressure from engine crankcase breather, place your hand over filler neck and the pressure shouldnt be too much as to blow your hand up!! if you have next to no blowby from crankcase then i would say not your rings/pistons,white smoke and high water temp with cool heaters/oil emulsification spells a head gasket
pheew essay done!!

 

You broke my engine... b*stard

For what it's worth, I know just how you feel, having just picked up my rebuilt P1 from API. David seems to enjoy providing words of comfort to people whose engines have just let go, you could do worse than to give him a call.

 

Thanks guys. Already dropped David at APi an email to see what he has to say/offer, and waiting for S4U to take heads off to determine the extent of the damage.

Given the CEL, and that there were no obvious signs of headgaskets having blown, I'm preparing myself for the worst and am assuming knackered pistons/rings.

If that's the case, the question will be whether to uprate stuff to future proof the engine in readiness for any further tinkering, or to maybe consider a recon short engine...or any other suggestions anyone has.

Bang go any thoughts of trackdays this year

 

Sorry mate

It's well looked after other than that though - honest!!

 

Initial prognosis is that pistons and rings are OK, but one head is cracked. It's off to be pressure tested, then we'll know if that's the cause of the problems.

 

Update - head is still believed to be cause of low compression, as well as worn rings. Bought a pair of 3000km-old '05 Spec C heads and decided to push the boat out...I'm going for a brand new built 2.5l as follows, with the intention of getting around 450bhp, using the standard STi TMIC if at all possible.

• New 2.5 block
• 2.5 crankshaft
• 2.5 Mahle pistons
• Manley conrods
• ACL Race series shell bearings
• Oil control baffle, or baffled twin scroll sump TBA
• New Modine
• Modified oil pump
• Kevlar timing belt
• Kakumei twin scroll headers/uppipe, ceramic coated along with down pipe
• Spec C heads, which have more aggressive cam profiles with bigger exhaust and intake porting. Reworked to suit 2.5l
• ARP head studs
• Cometic multi layer steel head gaskets
• Twin plate clutch and lightened flywheel
• Uprated FPR (TBA)
• 650cc injectors
• The new Turbo Dynamics/Litchfield twin scroll turbo, good for 500bhp we hope
• Manifold spacers
• Parallel fuel lines (TBA)

 

Do they think that the overboosting did that? How strong was the actuator spring rate?

 

It's believed to be a combination of things:

• car has overboosted for several years in 1 specific case - off boost, 6th gear, floor throttle, >2bar when it comes on boost. Generally tried to avoid it, but inevitably happened sometimes
• Had a split pipe to the 3-port, but it took many months before it finally split. As it was splitting I was getting more knock link activity but couldn't explain why. With hindsight I should have paid more attention
• When I fitted the uprated actuator (1.2 bar) it overboosted immediately, so I then kept off boost as best as I could. A week later I discovered I'd almost certainly knocked off the manifold pressure pipe to the fuel pressure regulator when refitting the TMIC - actually, for all I know it could have been like that for months as I've had the TMIC off several times.
• After fitting the large RCM induction I got a lean-running CEL. That would have caused cylinders to run hot, despite driving like a granny
• Car has always suffered piston slap - I imagine that, in combination with the above, would cause ring wear. The pistons show definite wear on their shoulders - there should be, I understand, a low friction coating but the shoulders are really quite shiny.

So, all in all, I think it is a combination of all the above and I have no option but to put it down to experience really. Goes hand in hand with tuning an engine, as well as 6 or 8 track days.

Thankfully, I can turn it to my advantage and now get the engine I've always wanted

I will have the 2.0l re-assembled and sell it on as a 50k mile short engine, once bores have been inspected for wear and we decide exactly what needs to be replaced. I may still pay for the cracked head to be inspected as it might be OK for a standard build after a skim - I certainly was not going to risk it for a build capable of 500bhp!

 

Self induced then, ouch.

 

Was it ever mapped for all of those mods before 'trying' it?

I'd definitely say self induced (shame as it is) but fitting any of those mods without adjusting the map to suit is suicide.

- decat needs mapping for
- 3 port solenoid needs mapping for
- bigger induction needs mapping for
- uprated actuator ....

Expensive lesson but hopefully the new engine will get properly mapped before giving it some beans.

 

Not that stupid

Decat/panel filter and 3 port were fitted two years ago by PowerStation and immediately mapped by them. The occasional det, plus the split(ting) pipe to the 3 port occured subsequent to that.

The uprated actuator and then induction were all fitted 1 week and 12 hours, respectively, prior to a remap and car was never given beans in that week - in fact it was only driven once, and then an 80 mile trip to Surrey Rolling Road for the remap.

It was during the remap that the damage became apparant as JGM was unable to map in the usual amount of advance. The subsequent dismantling revealed the worn rings and cracked head.

The list above is an (obviously poor ) attempt to explain that there were probably a number of things that led up to the final death of the head. Subaru heads are prone to cracking, I suspect it had ben slightly cracked for a while, but it was probably the lean running that finished it off and caused the det that was seen during mapping.

I could also have added to the list the possibility of stretched head bolts.

Bottom line - engine could probably have been put back together with just new rings and either a pressure tested/skimmed head or, at worst, one new head, but I have seized the opportunity to get a new engine.

When I looked at the cost of a new head casting from the UK (£1000) vs a pair of fully assembled Spec C heads/cams etc from Japan at the same price...then the labour cost to reassemble my engine vs the cost of having a new one built...the cost of a new clutch while the engine was apart vs an uprated one...cost of replacement rings/pistons vs uprated...I knew it made sense to go forged 2.5

 

Ah. Fair point then

Unlucky.

2.5 is the way forward - hope you are going to treat it to a good turbo, would be a shame to not do so

 

Plan is to use the brand new Litchfield/Turbo Dynamics Twin Scroll I am in pretty much daily contact with Iain getting status on it, as it is only just being manufactured.

Car is a JDM so already has the twinscroll setup and I really wanto to stay with that it possible...and the cost of a single scroll up and downpipe would bust the already busted budget

 

Cool - handy that you dont have to do the up/down pipes.

 

All in all sounds like a good excuse for an upgrade, then. Does all that kit actually qualify the car to wear a Type 25 badge, or is it a different spec?

 

Sounds like lean running was caused when the fuel pressure was always at atmos (3ish bar) when it needed to be 3ish bar + boost pressure, due to disconnected pipe.

 

No - it's a different spec. To qualify as Type 25 would need the full Cosworth 2.5 - with hindsight perhaps I should have considered this as the costs are similar, but it's a lot of fun specifying this myself

 

How much is Iain charging for the turbo?

 

No firm price as yet, but expected to be a few £100 more than an MD555