gravelexpress

Due to the inherent problems of engine failure on many turbos. I was wondering if it would be less expensive fitting upgraded rods, pistons, oil pump etc. BEFORE an engine experiences a failure.

The Fixer

Fitting stronger / competition internals before a blew up is a better idea because when blew ups occur you often get further damage to other items like bores, heads, valves etc. Plus you get the added bonus of planning the job in rather than being thrown into it because you have to. Try Mark @ Lateral Performance for Rods, Forged Pistons ETC.

Conrad

greasemonkey

To a certain extent what you are asking is a bit like bolting the stable door while the horse is still out in the field.

If you are planning an upgrade programme for your car, you should ask yourself what your ultimate performance target is, and, if it's going to push some of the standard components beyond safe limits, yes, it's much better to choose the right parts and change to them before the failure rather than as a result of it.

However, by the same token, there's little point shelling out a stack of money on an expensive rebuild if you're only planning on a mild performance increase.

john banks

What are the safe limits please?

Not found them yet on a Subaru engine, but then I've only run 406 through a UK one and 434 through a US one

They seem to be quite strong engines IMHO.

Tempting fate

dowser

The inherent problems with engine failures you're talking about are not necessarily due to engine weaknesses. I'd suggest that failing MAF's and bad tuning play a much larger part.

What is your target? You can make a very strong package using standard internals, assuming timing, fuelling and in-cylinder temps/EGBP are all suitably controlled.

Richard

gravelexpress

I suppose I would be looking less at pushing performance but more towards a stronger engine.

I have read so much over the years on oil starvation, and conrod failure that you nearly feel paranoid especially with the MY 99 sti. version 5 engine. Some posts suggested an inherent weakness in the engine component or engine design.

Dowser which steps would you recommend to improve the strength of the engine.

regarding tuning, fuelling etc. which specialist companies offer this service. I have already experienced the CHECK ENGINE light as per my previous post.

The MAF was replaced at SVA stage. I understand that the tell tale sign of a failed MAF is the idle hunting between 500 - 1000 revs is this correct?

John Banks - I am impressed with the high state of tune that can be achieved, I would not be looking to achieve anything like that power. However, It appears that more or less standard cars have suffered major engine failure - something I really wish to avoid.

My thoughts are that I will be using this vehicle fairly infrequently (it is not a daily drive) but I do want to drive it hard when I choose and I am looking at track days.

greasemonkey

This seems to be part of the problem in your case. Seems as though you're scared of something bad happening, and allowing that to dictate what you do with the car. If you don't want the car to blow up, the answer is simple - sell it and buy something that runs with a much lower stressed engine.

There's a lot of rot talked about this. The EJ engine design has some specific design features - such as relatively small big end bearings - but these are common to all of them, and not just the STi5. The main specific issue that affects the STi5 and 6 in particular is the MAF sensor design used on those engines.

Have a read around the forum, there are plenty of tuners around with good reputations. BRD, Pat, TSL, Power Engineering etc. etc. etc.

Erm, yes and no. The first thing you need to understand is that these sensors rarely "fail", in as much as it's not like they're fine one minute and f**ked the next. They tend to degrade over a period of time.

Unstable idle is best described as one possible symptom of a failing MAF sensor. Unfortunately, the sensors can degrade in a way that they can cause engine damage without obvious symptoms - like the idle - manifesting.

The most accurate way to pick up a degrading one is to fit a data monitor such as the SECS, which you then use to check the WOT air flow readings, and make sure they don't reduce over time, or (indirectly) via an AFR meter and a KnockLink, where a failing MAF will likely show a weakening mixture accompanied by an increase in noise. Even with all this kit fitted though, it's possible for a sensor to degrade without you spotting it.

Modified cars suffer failures too. Don't get into thinking that spending a stack of money on a supposedly "stronger" engine will guarantee it against failure. As John has illustrated, you can do a lot on standard internals if the car is properly (and safely) mapped, while an unsafe map will still eventually blow an engine no matter what bits are inside it.

gravelexpress

Some helpful responses Grease - except your first point. Of course im worried about something happening to the engine. However, my previous impreza JDM Wrx my 96 I ran for 3 years before selling. Every week it appears someone pops an engine - so it is obvious to have concerns.

If you dont the car to blow up sell it? Not really constructive.

But I think I may look to mapping as you have suggested - and something that i didnt consider to be honest. I will have to do more research obviously.

RRE

I was thinking of upgrading my internals on my 99 GT with forged pistons and rods, but are there no downsides with forged pistons? Is everything better? And is the idea of the forged pistons a hopeless choice if you stay on the original main bearings?

Rasmus

dowser

That's my point, it's not necessary to improve the strength of the engine if you're after ~350 bhp. You just need to make sure that all inputs to ECU are accurate, the ECU can deal with these inputs optimally and the bits controlled by the ECU are up to the task.

Your best bet is to find a decent tuner in your area and follow whatever path has worked for them in the past. Certainly, a remap should be part of your solution if you want peace of mind, as should at least a knocklink in terms of passive problem detection.

Finally, don't worry about the engine going bang - it may happen, but you'll likely trash many other components first (brakes, clutch and gearbox are all likely candidates). Buy a Porsche if you want to jump in and drive it hard without worry

Richard

greasemonkey

It was constructive, just not what you wanted to hear. It was a cold reflection of the fact that there is no cast-iron guarantee against engine failures in the context you are talking about. If you simply don't want to take that risk, buying a car with lower performance is a practical, constructive solution.

Of course. This is a large online community so it goes without saying you'll read the occasional sad story. Don't forget though that for every person who posts here about a blown engine, there will be hundreds, maybe thousands of Subaru owners who experience thousands of miles of trouble-free motoring, but don't post here to tell you that. Thus while sensible risk management is a good thing, unwarranted fear/paranoia/"just in case" modification isn't.

Yep. As I said up top, you need to consider the desired end result and then work out the best way to achieve it. John has ably illustrated that the standard engines are able to produce a lot of power without falling to bits, provided they're mapped properly.

There's no point at all shelling out on a rebuild using expensive pistons, rods or whatever simply "to make the engine stronger", as, if the engine is running outside safe parameters, it'll still blow up. The only difference would be that it'll probably take a little longer. When it does, you've obviously ruined a set of aftermarket internals rather than the standard ones...

Think about what you want to achieve (or to put it another way, how much you want to spend), and the practical considerations should slot fairly simply into place.

Gidney&Knowlesy

Top Lad You "greasemonkey" always offer sound advice......

911

He sure does, bit blunt, but hard to ignore the advice!
It amuses me about the Porsche comment.
Before my troublesome (because i abuse it) Sti v3, i hill climbed a well tweeked 911, still have it, and only lost one clutch and a second gear (crap hurried driving) in 9 years of thrashing.....
I think now it is possible to find a reliable route to bhp/torque:

350 bhp/300 lbft do abc mods
400 bhp abcdef
450+bhp the alphabet!

The first costs about £4K DIY
The last about £10K proffessionally.

I think this is where Grease is coming from.(?)

I'm scared at what he's going to say now!

911

harvey

iTrader: (48)

Mark: If you would like to buy me a beer over the week-end we can talk through what you are aiming for, the most reliable way to do it and the budget required.

gravelexpress

beers on me Harvey!!

Gidney&Knowlesy

Do you know how much Harvey can drink?

RRE

When people say that you don't need uprated internals, does that then go for both the standard turbo and the STI? How much stronger is the v5 STI compared to the non STI v5?

Rasmus

greasemonkey

Nobody's saying you "don't need" uprated internals, you've got a bit the wrong end of the stick there. Even under ideal circumstances there will still come a point where the durability of the standard bits will become curtailed by the amount of power you're trying to extract from them, and, if you want to spend the money, there are performance advantages to be gained from some aftermarket internals. Lighter rods and pistons lower the reciprocating weight and allow higher engine speeds for example.

What I was saying is that there's little point going for an expensive engine rebuild simply in an attempt to prevent your engine going pop. If it's mapped and running properly (and you're not going for silly power), chances are it won't go pop on the standard bits, while if it's not mapped and running properly, chances are it's going to go pop whether you rebuild it with stronger bits or not.

As I was saying up above, you should consider the internals (and whether or not you change them) as part of the overall program, and only change them if there's something worthwhile to gain from doing so.

Anyway, in response to your question, there's no such car as a "non STi v5", did you mean the model year 1999 UK/European cars? If so, John's given you an idea what can be done without having to change stuff. What sort of power are you looking to get?

dowser

How many miles did JB put on at 400+ bhp?