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...