To remap or not to remap?

Hi all, I'm looking for a bit of technical advice & informed opinions on remapping for piece of mind

I've had my 09STI from new. It's done 7.5k mls. Those helpful folks at Prosport told me it had the ECU reflash done by IM when it hit the docks - even gave me written proof - so if I read the other opinions / facts correctly IM's super safe map that this reflash loaded will prevent the most common cause of piston meltdown on the gr series STI. Phew However, that's also the problem. I can't get it outta my head - sooner or later I'm expecting the worst to happen. It's like the xbox - everyone gets the RROD, it's just a matter of time

So I'm considering a remap. Not necessarily for power, just more piece of mind, some mid-range oomph and no power fade beyond 5.5k rpm. Only a few horses and tortoises as well, I don't want to go mad (although I'm very envious of those who have - you know who you are ). A good panel filter, a good mapper & my miltek catback should be more than enough to put a smile on my face.

I can't afford the £2-5k cost of a re-build - either pre-planned or after denial of warranty claim due to tampering. But I'm also not happy staying where I am, constantly fearing the dreaded failure. I too have started to check the oil level every three days. What sort of relationship is that with my Ultimate Driving Machine?

Very very annoying that IM & Subaru have taken this approach - the pistons have been value engineered too far, so they water down the ECU to the point that it makes the exiting bit of the rev counter too short to enjoy but short enough to ensure the pistons don't fail. Then if the tuners fix it, or at least make it less likely to happen, they can deny any claims because the car was modified. It's beginning to sound like another certain Japanese car manufacture weaving a tangled web of their own

So back to the question - What does everyone think?

Remap knowing full well if it goes pop you have to spend £5k to fix it? If so, why - because it won't go pop if the map was done by a professional mapper for the individual car or because you have £5k put away just in case?

Or stick with it as it is, wait till it goes bang under warranty & let IM fix it.

Or trade it in for someone else to worry about.

I've always wanted an STI, and when they started making a hatch it ticked all the boxes for me. In every other way this car is a dream come true. But it's starting to feel like a pain in the butt, when it should feel like a rush everytime I press the loud button.

Please help...

It seems from the "experts" that the 2.5 is very safe at up to 360-ish. The risk increases as you exceed that with apparantly definite risk of breaking at 400. Mine was at 350 for 18 months and others too, some at more. I'd go for a 350-ish level with a safe rev limit built into the map so by mid 6k rpm its noticeably decreasing performance (so you notice !!) and change gear !!!

Dunc at RaceDynamix mapped mine, sticking to a max 1.2-1.3bar(Peak) and a boost cut set at 1.45 for added safety.

now running a healthy 340-350bhp and way smoother than the stock map.

Seems Dunc has visited quite a few of us hatch owneres and all with good results!

Midiclorian,

When I spoke to Dunc (about this ringland failure threat) He basically said the hyper'whatsit pistons on the 2008 STI were a great idea by Subaru, and in reality they are in fact an upgrade from the 2007 piston design... the only problem seams to be that Detination destroys them very quickly... So by mapping out any possible DET, you are in fact making the engine safer than stock...

I'm 150% happier now the car is running and fueling correctly. I was like you, thinking put up and wait for a possible ringland failure (yes covered by warranty, but also a pain in the ass) or do what Subaru should be doing anyway...and sort the problem out.

On the theory of piston detonation in the 2.5 engine, i have stripped & built quite a few now & have never seen any sign of detonation on the ringland failed pistons, in fact i have a 07 non turbo 2.5 legacy engine here with ringland failure.
I am still convinced its the piston design thats causing the failure of the ringland, the life of the piston might well be shortened by the fueling issue, but when you look at the design it does have a lot of unsupported area around where the ringland fails, its basically a 99.5mm version of the old 92mm piston.

OK that's good to hear another point of view on the matter.

We both agree DET significantly shortens any piston's life though, and these lighter hyper jobbies seam more fragile than others? The stock OEM map created a few lean spots plus a dreadful fuel cut at red line...I'm sure this caused a few to weaken if not fail in the 1st place.

If the piston design was at fault though, how come Rob's been running 380bhp for the last few months with no problems...surely if it was a piston design issue, he'd have grenade'd at least one by now. (Not arguing btw, just trying to fathom it all out!)

Guys thanks for the input! Keep the debate coming...

I just had a thought (pls shout me down if it's a useless one, I'm not an automotive expert I am a chemical engineer who builds shampoo & shower gel factories). If the failures may be influenced by piston design as well as det, would there be any clues on the failed pistons? More than just visual clues I mean. I have a contact in metallurgy whose expertise is in failure of alloys in severe conditions. Motors S-GT if you have any failed pistons maybe I could get him to look at them from more than just a visual perspective?

This has probably already been done by Subaru JP, didn't I hear they changed the design of pistons making up the rebuild from these ringland failed units?

Just my 2p

The pistons have been looked at in great detail, they have been through the metology depts of my old employer, Mercedes High Performance Engines, & through Cosworth's hands, there comments i won't repeat on a open forum.
They have been seen by various piston designers in the above company's, to satisfy my own curiosty.

All i will add is when i was in F1 engine development & build, when a piston went up in diameter even by .5mm it was a complete redesign, not as in Subaru,s case by simply going up 7.5mm & keeping the same support design as a 92mm piston.

As for Rob,s engine, it might be he has been lucky, or has a great deal of mechanical sympathy, warms & cools down after a blast etc, we shall see shortly as he is going to strip it down.
It will interesting to see if his has started to crack.

MOTORS S-GT wrote:

As for Rob,s engine, it might be he has been lucky, or has a great deal of mechanical sympathy, warms & cools down after a blast etc, we shall see shortly as he is going to strip it down.
It will interesting to see if his has started to crack.

24k today on it, Pesonally I know its started to crack a ringland, my car gets used and abused but does get warmed up and cooled down properly. Hence the reason for wanting forged internals. If I were happy with it I would just leave it alone but I have a thought in the back of my mind its fucked lol

The last two posts say it all really - thanks guys for your honest in-depth replies.

I wait with interest Rob's feedback....

Anyone like to venture an opinion - if a stock engine goes bang are IM likely to endorse replacing critical internals with better components (marginal cost obviously paid for by the owner)? Or have IM improved something in the re-builds their doing to prevent recurrence?

I know of one dealership that has fitted non OE pistons to a couple of replacement short motors & IM paid the cost, the cars were West Mid Police 07 Hawkeye's.

MOTORS S-GT wrote:I know of one dealership that has fitted non OE pistons to a couple of replacement short motors & IM paid the cost, the cars were West Mid Police 07 Hawkeye's.

It's great having you on here mate, just wish I had spoken to you earlier.

I begged the IM Group when my replacement short engine went in to let me fit 'better' forged pistons and they insisted that would invalidate the warranty so they would not do it...I even offered to pay for the price difference in parts and labour myself...still no joy, if only I had known this then. I would have stood my ground and put up a better fight The dealer said 'don't worry' Subaru Japan has re-designed the pistons in your replacement short engine...I did not see them myself (I only saw the packing case the new engine came in) or get this in writting from anybody (a before and after picture would have proved it), so I can't say if it's true or not...

Been running 355 for over a year and a bit (and another 25K) miles since the replacement short engine went in. Running 366 on a JGM re-map at the moment. I drive the car hard (after a decent warm up etc.) but run decent oil and change it every 5K miles. Nearly every time I floor it through the gears in the back of my mind I'm thinking...is it going to go this time...not good in a car that begs to be driven hard, but thats the price you pay for that lovely extra 50-60 bhp

I cannot afford/justify the cost of a rebuild with forged internals at the moment, but if the engine fails again or I find £3-4K under the bed I will get it done. Then also change the intercooler, turbo, fuel pump & injectors and look for around 400-450bhp