Engine Failure - Reasons/Causes

Would like to compile some info on why engines have failed.

Preferable 20vt engines under tune.

What power was it running? What let go? Why did it let go?

Ross

you probably already know mine

There was a thread like this a while ago - think it was started by Bockers

I dont know the final reason. I remember u said 3 pistons were down on compression. What was the final diagnosis?

Ross

Oo oo. That would be good.

Ross

the pistons cracked around the ringlands, think it was down to too much heat, thats what Accralite said anyway!

are you getting worried already Ross

Well.... Im just wondering.

Supposedly running a turbo outside its efficiency creates LOTS of heat. So technically running a bigger turbo within its efficiencies is gonna produce less heat and hence more power for safer.

But i know that the engine might still let go.

If it does, its off the road and forged. But just wanna see what else i need to watch for.

Ross

If your worried about that then check your inlet temps, if your cooler is good enough it will bring them down enough for the engine to be happy.

What should i hope for them to be at?

I have fitted Aquamist to combat the heat aswell. As far as i know this will buy me some needed safety.

Ross

Did you break down the other day? Somebody said they seen a yellow coupe at the side of the road which was stripped out inside.

Unless you look at the EGTs it will tell you nothing, inlet temp can be super but the engine is pinking and the exhaust gas temps are at 980C or whatever.

You know the std problems
350-360BHP - pistons are starting to get marginal, ring lands are brittle and will break. Ring land damage may have started 5 years ago and compression might be fine but they will go eventually unless your car has never pinked or somehow yours are stronger than everyone elses
350lbs/ft - rods are extremely marginal and over time will probably bend like I saw, like Nigel saw on std rods.
@Ross -
No amount of banter on here about anyone running 380BHP on std pistons and rods will make any difference; with your mods you are pushing your luck with an RSR at full pelt and something will go, just a question of when.
There are plenty of cases of blocks or cylinder heads getting damaged when engines go so don't try it. Run 350BHP absolute max and no more than 340lbs/ft torque unless you fit forged internals.

I totally agree with John. My car was running 350bhp with standard internals. When Eldhino's engine went, I realised that I then had the most powerfull coupe with standard internals, so I had it all checked.

Guess what I found? The ringlands had gone on one of the pistons. So, I bought forged internals and had the engine rebuilt. I was running with a pro alloy intercooler and Aquamist with 50/50 water methanol, and my inlet temps were good.

I had been running with that power for little over a year, but had only done 8k miles. So, anyone running over 300bhp should start saving for forged internals, because IMO it WILL go bang eventually.

Well i've been running over 300bhp for 15k miles. 310-320 for the first 8-9k and 330bhp+ since then.

But what turbo were u running squid?

Ross

GT28RS - 325bhp at the wheels, which is over 350bhp at the fly on most dynos and 320lbs of torque.

What boost were u running?

Ross

Here it is. Probably needs expanding a little concerning tolerances of standard internals etc...

Agreed. Maybe an idea for JohnS to add a section?


Ross

hello squid you told me you had done under 3k on the turbo that i bought off of you well if not that will explain why

my seals are going already and mine as only just been mapped 4 weeks ago

There has been an open discussion about stock pistons vs. forged pistons on a Danish tuning forum, but the conclussion was that stock pistons from a turbo engine should hold up to the same power as forged pistons - only thing forged pistons can do is take alot more detonation and lean mixture, because of the heat tolerance.
I know there is an issue with the 20vt pistons cracking at the ring lands, but i believe it's a matter of correct tuning. Monitoring EGT, AFR and listening for detonation, backpressure etc.
Jari has been making ALOT of hp on stock internals for quite some time now - so has some other of his mates. Vas has told a couple of stories to...

We have danish guys running +400hp on stock 16vt, and +500hp on stock corolla 4agze.
But we lack people with 20vt's, but some have tried and most of them have failed over 330hp on stock internals (although most of them has just plugged in a chip and cranked the boost). I am gonna try and push it a bit over 350hp, but with EGT and wideband AFR. Heard to many good stories from Jari and Vas to just let the opportunity pass by :-)

Mine went at 330bhp and it was live mapped, ringlands cracked, running forged pistons now and all seems well.

You cannot compare different engines stock pistons, there are a bunch of different designs, manufacturing techniques and different processes as well as different size of ring land and proximity to the squish band etc. etc.
This is a well known problem with 20VT pistons that doesn't mean no stock piston can take that power. There may be a pinking or det relation to all the failures yes, but it is probably more symptomatic of how the knock circuit works in the first place. At 350BHP the amount of knock detected before the advance is backed off may be wholly inappropriate for that amount of power.

Yes Jari is running more power, but it still is a question of when not if his pistons or rods will fail.

I'm sure you'd like to think that for you it will be fine, but there are so many people on here who it wasn't fine for, and it is better to either not run the power or switch pistons and rods then it is to see a failure that takes out your crankcase/block and cylinder head

really you can say I was lucky my engine went the way it did, as in nothing else got damaged!

I would also suggest that people who get their cars mapped should ask for a less aggressive ignition map. Sure you may loose 5-10bhp but it will make a significant difference to your chances.

Some mappers are very aggressive with their ignition timing, to what end I don't really know. All things being equal i.e. mechanical setup etc, when one mappper claims they can get X amount more power than Y mapper you have to take a step back. The only way to get more power from the same setup is to run closer to the ragged edge... air, fuel and spark timing that's all there is.

Not forgetting boost too ^^^

Also remember that the stock ECU can only back off 2 degrees, which is not always enough.

If the car has been mapped properly, i can't see why the knock sensors should have to retard timing - detonation should not occur!
And why would the maximum hp number be 330-340hp? It should be a matter of combustion heat, not hp. So if the timing is less aggressive, and the engine is getting enough fuel, it should be cooler with 350hp than a badly tuned engine with 300hp... But we'll see how it goes - i'm not saying all of you are wrong. I'm just an ignorant man who needs to learn from my own mistakes. If i trash the pistons i have en excuse to buy forged pistons
I have faith in my tuners expertise, so if the thing goes pop, i know it's because we have gone beyond the limits of 20vt stock capability.

Does any of you know if there has been made a new revision of 20vt pistons at some point? I saw replacement numbers in ePer awhile ago, and i just installed new, stock Fiat 20vt pistons. They were black on the skirts with some kind of coating...

Have you ever thought about the pressures that happen within the cylinder as well? If you increase the power, you're going to increase the pressure in the chambers. We ar talking around 18,000psi here, and with has been said with the ringlands, they will break.

I see what you mean about pressure - i'll look a bit more in to it, but it's a good point! But there must be product tolerances - meaning that some pistons may be able to withstand 350hp and others more or less. They cant all be 100% alike... But i guess that a safe number is around 340-350! I will think about it more, but right now i'm running 1,18 bar and will probably turn it up to 1,3 and make a bigger exhaust. So should end up at around 350-360hp...

You’re asking for trouble especially if you miss shift a gear. Squids engine had broken ringlands at 320WBHP.

http://jayman.bulldoghome.com/photos/bdres/jayman_bulldoghome_com/DSC00524.JPG
(Hope you don't mind me posting this one Squid)

That piston doesn't have the same coating, as mine do... Just worn off, or do i have a never revision?

if we wanted an engine rebuilt, who would do it? and where would we get the uprated internals from?

Because your pistons are new. This coating has worn off don't know how many miles they have done. Anyway that coating aint gonna mean jack as it is applied to the skit and no amount of any coating it gonna save a cast piston from destruction. As people have said and I show proof the ringlands are the weakest point.

That's not really how a knock circuit works. It is true that if the max advance is some way off any pinking it should be ok, but that's not always the case particularly when people up the boost and are running larger turbos than std.

JohnS is correct in saying its a matter of time....

the reason for this is that a piston with ringland damage will be down to fatique but will have little to do with detonating

if you run any engine lean eventually the pistons will fail but forged pistons have more tollerence to it than cast items.

Lars_DK you are wrong and you are right at the same time, yes a cast piston will take the same amount of BHP as a forged piston(to a degree)the problem is fatigue, they will fail

What you need to do is have a word with a metalurgist (spelling?)

he will be able to explain better than i can via a forum but if you told him the enviroment that a piston has to work in and then told him that you think a cast piston could do the same job as a forged piston i am sure he would burst into laughter

Trick

Thats OK Jay. I looked through the invoices and it does indeed appear that I had only done 3700 mile on the GR28RS with the remap.

But why would you run your engine lean? That is my point excactly. It seems that alot of you have slapped on a Gtech2, had the fueling checked (Through the exhaust backbox?) and then drove with that. That cant be the right way to do it, and hard to calculate for different fuel qualities, weather conditions etc. etc.

I'm not saying my engine will hold up to the 350-360hp - but there is a good chance. I believe it'll work, and others have shown it works - but only with a very good tuner that knows what he is doing. My tuner has shown that, with 3 hours of work got the 20vt ECU running with 440cc injectors! No UK tuner has been able to do that yet?

Although im not posting (apart from this) im watching this very carefully.

Ross

my car had been on many RRs to check the fuelling including mapping, was running WI and also had a egt gauge to check cylinder temps! but the pistons still went!

@ Lars
I personally think you are running a risk, as mentioned earlier the cylinder pressures are extremely high so you run the risk of piston or rod failure. I think the mapping does play an important part but any tuner/engine builder should know that you really should be forged at that level of tuning. The mapper should not have to worry about these things whilst mapping you should be able to take the car to them and just say “Map this please”.
Look at what happened to yellow coupe although it was narrowed down to rods bolts and possible a bad build.

Whilst were on the topic of engine failures it has also been known that the EGT of a certain cylinder think its number 4 can cause heat build up causing the spark plug to fall into to bore anyone know any more info on this?

How long did the car run like that tho? Thinking back, it was a testiment to the way it was mapped and maintained that it lasted that long.

Ross

probably about a year or so I think!

I have had my standar ecu mapped for 440 injectors now too but it does take a good bit of time and perserverance on the dyno and a very knowledgable tuner to do it.

I don't really want to post in here but i reckon if the engine is tuned properly then you should be able to see more power for a longer period of time before failure occurs than if you just bolt bits on and up the boost. All engines that are in ahigh state of tune by their nature unless being built purposely for a sepcific BHP will be liable to a failure iinternally of some sort sooner or later.

Im not saying that you should run a engine leaner or even that you would

What i am saying is that its quite evident that the common failure in the 20vt engine is the ringland breaking up and that has nothing to do with tuning/running lean, its down to metal fatigue and this is where the forged pistons come into there own.

Remember that fatique does not happen when you start the car for the first time, it takes time, this is why F1/WRC engines have a hourly life for each component, E.G: piston 20 hours, rod 10 hours, rod bolts, 5 hours and so on, in most cases you cannot even measure wear on the formentioned components but they can and do fail after there life cycle


To put it simply if you want the engine to last then you are going to have to improve the matierial/design of each component in the engine or it will eventually fail form fatigue and the more BHP you put through each component the shorter that life cycle becomes

you also keep going back to saying that a good tuner (Mapper) will be able to make this work, i dont know the Mapper your talking about but im afraid it doesnt matter, he will not be able to bend the laws of physics no matter how good he is.

Tricky

I generally agree (although I did mention of some Greek cases running extreme power on stock internals - mind you few failed on ringlands in the meantime...) but another issue has to be counted (and I've not seen anyone mention it)
Length and frequency of abuse!
I mean you may have an engine that on dyno produced 420bhp on stock internals (don't laugh we have a few...), if you're more or less driving miss Daisy (on the fear that something will break) then yes, engine may last an eternity!
If you only go for short blast of 3-5sec at 6+rpm and then relax, then I guess it will last

I've also notice that a few of the failures happen on new owners (short after they bought a car already prepared/mapped/dynoed etc) Maybe the fact that on the enthousiasm of the ownership you're overdoing it a bit, pushing trying to find the car's (and their) limits and failures occur...

V.

Agreed, the life of the engine is very much dependant on how its driven, if its a road car you are far less likely to damage it compared to a drag car

unfortunatly its almost impossible to tell how long the life cycle of each engine component is as differing power levels and different driving styles change it a lot

What if you'd had an engine built by barbz with brand new pistons and rods that were balanced and lightened?

Ross

Unlikely, unless severly over reved or used for a lifetimes racing the ringland damage is due to detonation. IIRC the pistons are hyper eutectic which are fairly brittle, detonation spike is like a center punch hitting the piston easy to see why such a small bit of aluminium could break off. Heat and pressure causes the detonation, higher boost on a lean setting will increase both significantly.

As for fatigue, kept at normal rpm the loads will be well within spec for the pistons, damn sure fiat didnt miss that step out in the design. Materials dont fail humans in their design and application do. Change the engine spec -> change the material spec/design, look at an S/N curve for alloys or any metal (aluminium alloys dont really have a defined fatigue limit like ferrous alloys), increasing the loads severly reduce operating life(cycles vs load) - I'd attribute rod damaged after ruling our oil issues to that, but for cracked pistons - detonation for sure.

btw, do we have any case of forged pistons failing in the ringland or elsewhere in that matter???

After all it pays to have forged pistons of decent(ish) quality installed...

V.

Hello,

I myself drove about 20tkm with an engine with stock internals and about 400HP
Boost with "big" GT2871R (and head work) was 1,6Bar at top power.
Only modification of the parts:
- lightening and shot peening of the rods
After 20tkm I dismantled the engine (installed a 2,4l).
I could not see any signficant abrasion... the engine was ok!
I think you have to look for a good tuner who creates a good map...
Moreover the original rods are quite heavy... better to lighten them.
Note: The original rods ARE FORGED ones!
Juergen

look at this pattern and tell me what is wrong

take a chip with a more aggressive ignition map
Run more boost
generate more heat

The answer is that with more boost generally you can run LESS ignition particularly at the top end. but a lot of people using a chip with the same or more advance then standard. Yes there is some leeway because of decent quality fuel but running a chip with more advance takes some of that leeway out.

So the knock circuit is probably working all the time backing off when it sees pinking or at least you aren't far off it.
Bearing in mind the temp sensor is extremely slow to react to inlet temp differences there is a good chance that you car will have pinked at some point.

Yeah, me.

Burnt 5 lovely holes in 5 lovely CP pistons

Cause? Quality det!

sorry to jump in but would a 252bhp coupe be in any danger of being to hot inside and melting/cracking???????

Its all to do with gettin adequate fuelling Paul, have you had your fuelling checked on a RR?

What are you running to get 252?

252 is not pushing the car too much, but thats not to say if its not done properly its safe!

nice one!
how can you possibly have 5 holes? All happened together???
can we have photos plz?
Was it long after fitting? did you have a custom chip or somesort of mapping?

cheers

V.

There was a hole in each one, couldn't have done as good a job with an oxy/acetelene torch

No pics, think i sent some back to Barbz to turn into ashtrays or sommat

It turned out that the problem was caused by ECU not reading crank position sensor properly and as soon as it hit boost, it was 25deg out.
All sorted now though

If you ask Ross nicely, i'm sure he'll post up a nice pic of a remaining piston with some rather unique markings!

in normal cercumstances i would probably agree but in this i do not

you see i have pistons removed from a 20vt that had ringland failure on piston no:4 and none of the pistons showed any signs of detonation

here are some pics i have of one of the pistons from that very engine

[img]http://img2.putfile.com/thumb/4/9717551946.jpg[/img]
[img]http://img2.putfile.com/thumb/4/9717551934.jpg[/img]

as you can see there are no det marks what so ever

this engine was live mapped and was absolutly spot on.

I agree that the extra heat and pressures that are present in a tuned engine would be a contributory factor.

But you never saw mine!

you could clearly see where the det had started to hot spot and then concentrate the heat til it totally melted through the crown.

just a gtec1, bacbox k&n 57i, and turbosmart boost tee set to 16psi.

the main reason of my rr was to check fueling, he said it was fine but a little lean around 3-4k, but he personally wouldnt bother changing it as its spot on further up he rev range all the way over.

but my grap only has bhp&torque curves.

cp pistons are good quality, i would guess that your problem was caused by an extremly lean mixture but i have never heard of all the pistons failing at once, very odd

that was in response to JIM O.

sorry not sure what you are saying, the pictures in the links i put up are there to show the lack of det marks.

http://i19.photobucket.com/albums/b176/h2ypr/20080406_164418.jpg

Here is the effect of broken ringlands... the coupe leaves its mark

Ross

Wrong again.

27 pages of datalogging showed perfect temps, AFR, etc.
it was purely a problem with the ecu being unable to retard sufficiently as the boost increased.

Is it just me that picked up on this comment

And you know what that sounds like. Please tell me if I’m wrong but the word DTA P8 PRO comes to mind. You can't argue with Trickey as you both have completely different issues. Trickey is talking about ringland failures due to fatigue yours is detting due to timing. It’s like you guys are arguing what is better Kg or Km.

spotted it but it has been beaten to death over the years...
iirc, verdict is that they're not.

Similar thing with cranks as well. Not sure there was a verdict there though

V.

Believe me - the rods are forged ones!
I always did NOT believe Hartmut Lohmann (a former F1- engine builder in the age of Turbos).
He was responsible for the rods and the cylinder head of the BMW-F1, which became world champion 1983!
He always stated to me, that the original rods must be forged ones regarding to the metallurgy, which could be seen.
The evidence for this was done in the laboratory of my automotive company. We analyzed a broken rod - our LAB- engineers stated the same: The rods are forged ones according to the special metallurgy, which could be found...
Therefore Hartmurt did the proposal to strengthen the rods by removing material (from the area around the connection to the crank) and to to do shot peening to improve the durability.
What we have seen as well were a lot of blowholes within the analyzed rod. This rod simply was already scrap at time of installation. Apparently Fiat did not really much quality checks regarding the rods.
Also because of this Hartmut recommended to investigate all rods regarding blowholes.
I am no "street racer". Nevertheless I can remember that there was a date with a Yamaha R1 on a German Autobahn, which tried kidding me (close driving to the rear of my car).
I allowed to pass the R1 and then I tried to stick to it...
What I realized was that below 250km/h I did not have any chance, BUT from 250 up to 300km the R1 became MUCH slower in acceleration than my car...
What I try to tell: I drove about 20minutes with almost WOT on a German Autobahn (it was a cold night, EGT- Temp was about max. 930°C) and there was no problem with the original reworked rods or the original pistons...
The rods and the psitons are not bad.
I have to agree Johns completely:
It is the map which has to be right, to get sane durability...
If you drive more advance than series, than knock circuit is probably working all the time backing off when it sees pinking. This in combination with a high ET will kill the pistons.
Best example: cylinder No. 4 - if this cylinder fails then this is a very good sign for too much heat or pinking!
Unfortunately I refueled a bad fuel (should be 100 Octane, but it never was) from my stay in Czech Republic with my new 2,4l engine... Result: I got a burnt down sparkplug in cylinder No. 4 and slight abrasion in cylinder No. 4. The compression now differs slightly from the other cylinders...
Juergen

In my engine rebuild, i found that the ringland was cracked at cyl 4 - AND piston on cyl 1 was melted due to detonation. Cyl 4 showed signs of that to...

I still believe that it's down to detonation - but i guess we'll see! And yes, a good tuner means the world when mapping your car... You can spend 5000£ on an engine, but if your tuner lacks knowledge and skills, he can still break the engine or just not have it tuned to optimum performance and reliability.

God i love the forum and these contentious topics.

It is not just fuelling, that's the point of this thread!

Yes I know, but my response was to Paul205 who just popped in to the thread to ask a question that was "slightly" related to the overall post

I understand now,

What ECU, standard??

Did this happen on the dyno??

i agree 100% that a mapper can make or break an engine but that was not my point

infact knowing how awkward the 20vt can be, i think that any mapper/engine builder that is getting more than 300bhp at the wheels on standard guts reliably is doing a good job

you have to remember even at that low bhp figure your touching nearly 50% more power than it was designed for

and looking at your sig with your stats for your engine, (331bhp) i think thats a testiment to how good your tuner is, he has done a good job!!

@Stichl - If you are saying the rods are already forged, but we have seen examples of them failing at high torque loads, why is this happening? Balancing of the original rods? Whats different with the cunningham rods (or alternative) which makes them last longer?

Ross

just because they are forged doesn't mean they are any good. The quality and density of the forging makes a big difference. That's part of the reason why not all forgings are created equal. There are also multiple manufacturing methods and techniques for rods.

balancing of original rods just improves the distribution of load across the engine it will not increase how much power they can take.

Bottom line is believe that your rods were designed for 220BHP with plenty of headroom not for 350BHP where there is no headroom whatsoever. I bent 5 std rods all balanced, one broke, Nigel bent 1 that was balanced, trevor had one fail that took out most of his engine. So of cars over 400BHP who have tried std rods there is very very high failure rate. Look at what torque we were making - mine was 400lbs/ft, but nigel and Trevor were both closer to 350lbs/ft
And our rods might;'ve been quite a lot better than others - the rods are really varable in quality to begin with. Mine were brand new rods BTW that were then balanced. So had not fatigued through a long hard life.


The rod bolts are not good for the power either IMHO, if it isn't a rod failing it will be a rod bolt.

Well looking at the rods it would appear to be cast as I see casting marks and air pockets within broken rods. FIAT would do this as mass production requires cheap parts to be able to deliver the complete car at a reasonable price. I can't see why the rods would be forged and if they were what are they bending under load? Are they crap forged? What about crap rod bolts? Why have I paid for Pauters? Did I get bumped?

Haven't you guys spotted a constant reoccurrence of cylinder no4 being the problem cylinder. It makes me wonder that the EGT for that cylinder is a problem. I think it could be a problem with the exhaust manifold design not being able to expel the gasses quick enough as no4 primary is shared with 3 and 2 at a poor design of a collector. I personally have always thought that the 5 cylinders major floor was making a decent manifold as 5 point at a turbo collector is one cylinder too much. What do you guys think?

Can't blame the manifold design for the two engines I've lost to snapped rods as I'm running bespoke tubular manifolds (and a different one for each engine that let go)

Basic problem here as JohnS has alluded is that too many people want to take short cuts to decent power and then wonder why their engine let go

If you want to increase power in the region of 20% or so, then fine. You'll probably not need to change anything, but even then the additional stresses will shorten the life of the components. Maybe enough for them to fail, maybe you'll get 50k miles out of them after the increase in power

If you want to take the risk, then fine, but you have to accept the consequences if/when it goes splut. Last engine snapped a rod with everything having been modded, but a diet of nearly 600bhp, 8000rpm and race use means its going to get a bit more stressed than even the track day/occasional 1/4 mile Coupes

Lets see how long engine number 5 lasts for me - I keep monitoring on here in case any other weaknesses show up

I have been running on standard rods for 1½ year now after the tuning job, running 1.1 bar daily and 1.6 on "special" occasions, and still no problems. Keyword = "STILL"

I agree with regard to the manifold, only way to be sure is to have a egt sensor on the outlet of each exhaust port

As for the rods being forged or not doesnt mean a lot

there is much more to a con-rod that just that

being crack tested and the material being used will be just as important as being forged

does anyone one know what its made from??

most forged rods are made from 4340/EN24T/EN24V

the american manufacturers seem to prefer 4340 chromolly, like Pauter/Eagle/Cunningham and the british manufacturers prefer EN24T and V, E.G: Arrow/Farndon

The way i understand it is the Price of the EN steel is much more expensive than the 4340 hence the the price difference between the manufacturers

At the same time the general view with regard to the materials is that Arrow/Farndon make the best rods in the world and a lot of that is down to the material, saying this though no-one unless they are in the upper levels of motorsport would be pushing there rods to the point that the material being used would make any difference

the hardening seems to very important as well and they all have differing levels of hardening that they work to

My point is its unlikely that Fiat would of gone to the extra cost of the better materials and better forging/hardening processes as its simply not necessory for the power figures that this engine was designed for

Its also worth mentioning that most people agree that Turbo charged engines do not need a rod as strong as a N/A engine as they generally do not rev as high

Ricky

Nyssa7 I completely agree with what you’re saying however I was referring to the manifold causing high EGT on cylinder no4 causing piston/spark plug failure not rod failure.

agreed, a man talking from experience, and good luck with number 5.

I am also of the view that while you have the engine out and your rebuilding you may as well go the whole way and not skimp on things like rods as it will cost you more in the long run

Ricky

Tricky is right in this case, you can forge many types of steel, but it could be a poor grade carbon steel or a high grade 41xx alloy steel. Forging is the process and not the material, this cr@p coming out of cina is a precise example of nice looking forged monkey metal! Fiat engines have used a number of different materials over the years but on looks alone you'd be hard pushed to see the difference in some cases.

Incidentaly the only evidence on a piston of detonation could be a the cracked pieces as soon as it occurs the pressure will be reduced in the cylinder, while robs CP probably held toegether long enough to keep the heat an pressure up to oxy-acetalyne levels!!

That last point is a very important one.

When doing the rebuild, it makes sense to use the best components and renew as much as possible as a few pounds scrimped and saved during the rebuild could easily cost you dear later.

I know of one forum member who rebuilt his engine with forged pistons but just used standard, although slightly hardened rods. He subsequently bent a rod and destroyed his engine. He ended up selling the car, I believe.

I believe it really is just a matter of time until the engines on the rest of the coupes with 320+ bhp on standard internals fail.

Dr Frag maintined his car very well indeed and his car lasted a couple of years with that sort of power, many will not be that lucky.

Incdently, it was piston number 4 which failed on my car too.

I had a piston ring failure also, believe on nr 4.
I had the engine rebuilt with forged pistons, but opted to leave the rods standard, it has worked well since, and it has been 1½ years since, but then again I might be just lucky. I am also mapped for 1.6 bar or so, or 400 hp or so.

I've lost an engine running under 300 bhp due to poor fuelling - no 4 went. My fault for not having it mapped properly. You have to consider that on the road the engine would most likely have been fine - 3 laps of Bedford and the top end of fourth gear was the issue. There may well be a lot of unmapped coop that will never know what would happen in that scenario. You can use bhp as a guideline only, and you have to bear in mind that different rolling roads will give as much as 30/40 bhp difference.

Doctorfrag's engine was well mapped - but 1.5 bar of boost on the standard pistons is most likely what caused the problem, though it ran well for quite a while....

You also have to consider that as far as the rings are concerned 340 bhp at 1.0 bar on a GT2871 and 340 at 1.4 bar on a GT28RS are going to put different stresses on the engine. (apart from the rods which are suseptible to torque)

If you want a car to run safe on standard internals then you have to get it mapped well, and conservatively - and dont run a turbo bigger that a GT28R or at the most an RSR - even screwing the boost up over 1.4 bar on those turbos is going to create issues. People should also remember that having forged internals does not make the engine bullet proof - the same mapping principles apply, but there is more margin availiable, and depending on the piston design you can raise the boost more.

Also remember most tuned 20VT's (in UK anyway) may be correctly mapped, but with no control over the boost whatsoever.

If pinking occurs the ECU can only back of the timing, not the boost - which may not be enough!
Worst thing is, the driver hardly notice what's happening until the piston's go bang.

My theory / 5 cents..

I for one will certainly never use anything other than ECU-contolled boost. And it works! I have around 275hp now with std turbo.

Is there any way that the coupe's built-in knock sensors could be made to trigger a warning light if pinking was detected?

I cant see why not, i have this on my R32 GTR but i have after market engine management, (power FC)

If anyone could do that, it would be Neil (Barnacle).

Is the signal transmitted down a specific ECU pin? if so I dont see why any auto electrician wouldnt be able to hook an LED up to it.

I know I know, probably way more complicated than that...

Get a knock link if you want to do that, the knock sensors are not in the best place for performance, only in the best place for economy. Anyway the signal requires complex filtering.

Anyway the ECU will try to back off if it sees major trouble, only problem is if it is still pinking at full retard then it will retard the boost but in most peoples infinite wisdom they have disconnected the ECUs boost control.

Has anyone here lost an engine due to the engine having been previously run low on oil? I have a past history of owning Alfa's and on some of those its quite common. The coupe also seems to use oil at a similar rate, and if someone were to not check it regularly enough some problems might occur.
Or is the Coupe more robust to this treatment than the average Alfa engine?

I lost my previous engine through this.. supposedly

Ross

running low on oil is slang for not checking the oil enough

I check mine at least every week although my coupoe doesn't seem to use much since I fixed the leaking rocker cover gasket.

If the worst does happen though there is a cure available..

http://cgi.ebay.co.uk/ALFA-LANCIA-ENGINE...1QQcmdZViewItem

I am sure it works wonderfully.. Not.

about as useful as scraping the fat off a donar kebab and slapping that in your engine.

He's done it already
Current widget will report knock (at least it does on mine due to some earthing probs... )

like I said on the 20VT the knock sensors are in the right place for engine efficiency and the wrong place for tuning. So the barnacle widget will tell you something but it won't help you to avert an engine failure

Thanks John, I think I'll get myself a knock link along with an electronic boost controller

Still got a bit more to learn about how all the different variables such as boost, ignition advance, fuelling, and temperatures all effect each other but getting there

Was the knock link useless unless it was properly setup on the rollers?

Ross

It is by far best if set up on the rollers but you need someone to actually make your car pink as well so it isn't just a case of going to your average rolling road and asking them to set it up.
Reason it is best set up that way is that there is a lot of background noise and it is making sure it is not just showing you that.

Is it possible to get something to read the ebv signal from the existing ECU with aftermarket boost controlers, to allow them to back off when the ECU thinks there is a problem?

the actuall ebv signal from the ECU is a PALSE.
It's not (what I initially thought) a signal that comes when the ecu wants the wastegate to open and vent.
It works with short pulses and their frequency changes (as in increases) when ecu wants to lower boost.

Now, even when you're driving normally with a bit of accel this thing pulses, so it's impossible to decipher (sp?) the moment that ECU thinks there's something wrong. So, forget that.

HOWEVER, I guess one of these companies could come up with an improved version of their kit that comes bundled with knock sensors and on tuning them (fck knows how though...) it would be able to lower boost when it senses know.
How about that?

Personally I'll stick to the adelco ebv

V.

I wouldnt want anything messing about with my boost, I'd rather stick an LED on the dash somewhere, if it comes on I'll know theres a problem and deal with it myself

by the time you notice the LED then damage may have occured anyway.

+1,
you'll need a big bugger 1W high power LED and beeper on top if you want to be sure...

V.

Nothing escapes my eye (although I suppose if it did I wouldnt know about it )

I'd notice it as soon as it came on if it was located in a conspicuous place, I always see the fuel light as soon as it flashes on for the first time...

Sure it pulses it during normal boost control, but when it thinks there is a problem, I would think it would just hold the vave open to try and knock the bost back as much as possile

To me though I think keeping an upgraded EBV with good mapping is a safer solution - was just thinking of the people that prefer boost controlers

Yea, I agree there

The Adelco, is that the "GM" Ebv?

yep, that's the one!