Small Problem at Sandown Raceway

[1NRO]

Not what you want to see in an engine, nasty. My sympathy

[jimnielsen]

yes, its a bit of a mess. As to the specific cause, i'm not exactly sure, but there are a number of possibilities....

You can see on the attached pic from the data logger - the problem occurs 13 seconds along the graph (time is the x axis..) Boost is normally controlled to approx 1.05 bar to 7000 rpm but as the car (in 3rd gear) passes 6700 rpm boost starts to rise again - as an 'artifact' of the failure of the engine.

the cause is probably either one, or a combination of these things..

1. generating too much heat into the inlet manifold from using a turbo / intercooler combination that does not work efficiently enough at these revs. causing detonation.

2. failure / overload of an injector. causing detonation.

3. failure of the head gasket, causing mixture problem, causing detonation.

4. general problems with the air fuel ratio - causing detonation.

[arjunior45]

can't say - see much from this graphic.

Don't you monitor the AFR? I think you mast do it, as long as you use the car in the track. A wide band one is the best and there are certain one with data logger too.

Too much heat into the inlet manifold should have caused other problems before {less boost increase is one of them}.

try to clean the injectors and see how they work and if they spray the same amount of gasoline.

Failure of the head gasket? I think you should have a head gasket with broken rings and yours is just melted - as far I can see from the photo attached.

Any way, you have a lot to do with your engine for the moment but I believe you should consider {seriously} to mount a wb AFR meter, an exhaust temperature meter, a 'detonation detector-warning lamp' and maybe an 'inlet temperature sensor-reader' too.
From my experience, AFR meter and exhaust gas temperature meter can help you a lot to avoid problems at a track - as long as you keep an eye on them.

Wish you the best for the engine at the moment.

Nick

[Evodelta]

yes, its a bit of a mess. As to the specific cause, i'm not exactly sure, but there are a number of possibilities....

You can see on the attached pic from the data logger - the problem occurs 13 seconds along the graph (time is the x axis..) Boost is normally controlled to approx 1.05 bar to 7000 rpm but as the car (in 3rd gear) passes 6700 rpm boost starts to rise again - as an 'artifact' of the failure of the engine.

the cause is probably either one, or a combination of these things..

1. generating too much heat into the inlet manifold from using a turbo / intercooler combination that does not work efficiently enough at these revs. causing detonation.

2. failure / overload of an injector. causing detonation.

3. failure of the head gasket, causing mixture problem, causing detonation.

4. general problems with the air fuel ratio - causing detonation.

No. 2 can be ruled out as it has happened on more than one cylinder, No. 3 can be too as a blown gasket would cause decompression. It's 1 or 4 or a combination of the two. Poor quality or old fuel can also cause or contribute.
The logging stuff is great btw, a great help and very interesting.

[Juan AR155Q4]

Sorry to hear/read this Jim.
Anyway nothing that couldn?t be solved.

When I melted a piston, was #3 too (weakness design maybe), but just on the intake side.

No. 2 can be ruled out as it has happened on more than one cylinder, No. 3 can be too as a blown gasket would cause decompression. It's 1 or 4 or a combination of the two. Poor quality or old fuel can also cause or contribute.
The logging stuff is great btw, a great help and very interesting.

It looks just to happened in #3, can?t see any marks in the others cyls.


As Nick said, it would be great to monitor and log AFR and EGT, that would tell you a lot of what happens in the engine.


Now the positive side: time for forged pistons, flowed head and beasty cams!!!

[Juan AR155Q4]

Nice stuff !!!
How are the main caps tightened? Have you got a sided pic?

Maybe we could split this in a new thread so as not to hijack Jim?s.

[jimnielsen]

I have been using a wide band lambda sensor, the Innovate Motorsports LC-1 - and i was logging its data as well - however I wasn't using it last weekend at Sandown because it has failed (yet again..) Its been a pain to work with - I wish I had bought the LM-1 instead.

Question . Where can I purchase a new exhaust valve - needs to be somewhere that does mail order, you can't buy them from Alfa Romeo here.

cheers, jim.

[wrinx]

Should be able to get one from Alfa UK I think, c.?20 last time I read a price (Alfajack?).

7650916 - EXHAUST VALVE

Edit: 2005 price is ?50!!! Sure AJ said they were less...I'm happy to help with sending one over if needed.

wrinx

[AlfaJack]

Afraid not, they were ?50 each - sodium filled type

[jimnielsen]

50 Pounds - that's about 6 billion Australian Dollars!

[jimnielsen]

For the sake of completeness... I did make many full throttle runs with using the wideband lambda sensor.. here is a typical one that show AFR's of approx 12.5:1 at full boost. the AFR graph looks lumpy because I haven't bothered to 'smooth' the data - this is just the raw output of the sensor.

[arjunior45]

well, my notes for the AFR are:

- "12.7 at the spool-up turbo zone. 12.5 at midrange and 12.4 at top end. The usual suggestion on turbo cars is between 11.5 and 12"
- "Optimum power is considered to be at around 12,5AFR for a turbocharged car and 13AFR on a N.A. one. While optimum economy (on cruise) seems to be in the 15-15,5AFR. Leaner than that you'll experience bad throttle response when cruising (typical hesitation when pressing the throttle). Below 11,2AFR you are loosing power so I never target below this point. I target 13AFR in atmospheric pressure up to +0,2bar then go to 12,5bar up to +1,0bar. If I were to boost very high (like +1,7/+1,9bar) I'd bring it to 11AFR".

As for just one exhaust valve I can not help you that much.

Nick

[na15575]

im going to check on monday if i can find one used valve

[jimnielsen]

I think this piston may almost be beyond repair

[wrinx]

Quick rub over with some emery cloth and it'll be fine....

wrinx

[arjunior45]

I'm afraid I must agree with you.
Check the rest of the engine before you decide anything.

Nick

[mindus]

How is the engine block looking?... That could be a problem. It's not very expensive to get new piston and conrod here in Europe...

[jimnielsen]

is this the correct part number to use - 71719060 ??

does one use 'standard' alfa romeo bearings?


http://212.187.114.126:7080/navi?VER...D=1&GUI_LANG=3



Rods - these are made here in Australia. I think i will use them.

http://www.pureperformancemotorsport...f4013e9f996d07

pistons - I was thinking these...

http://www.jtechmotorsport.co.uk/index_Page1326.htm


thanks, jimn ~

[1NRO]

It's the cheapest way of doing it Jim for sure, but is cheapest best? China forgings would have me worried. The Wossners aren't IMO much good, they must have a very low CR with all that milling on the crown and word on the street is they are less than well made. Ready for the big bore clearance they require?

The ones I've shown you are more expensive (about 50% more) but many times better. The very best I could muster for myself. Maybe the import would kill that possibility though.

[Steve Webb]

Slightly off topic here Jim, but is there any reason why you are using such high rpm? Have you found it gives you better times? Might be the way my engine is set up, but I found that using lower rpm and the midrange torque gives just as good lap times/speeds.

Steve

[jimnielsen]

No, I haven't found that Steve, however I am using the standard cams. At Phillip island and Sandown where the straights are long, I tend to use 4th as long as possible to avoid 5th! But as you can see from the attached data power begins to fall off sharply after 6200 rpm. I have found that faster lap times do result from pushing the car out to 7000 rpm in both 2 & 3 gears, but now I have the car lapping faster, I haven't actually been back and tested it of late...

[RMB-Racing]

It's the cheapest way of doing it Jim for sure, but is cheapest best? China forgings would have me worried. The Wossners aren't IMO much good, they must have a very low CR with all that milling on the crown and word on the street is they are less than well made. Ready for the big bore clearance they require?

The ones I've shown you are more expensive (about 50% more) but many times better. The very best I could muster for myself. Maybe the import would kill that possibility though.

Well - I?ll say that you have a slightly small agenda by recommend your product - because it?s your product, and you sell it for a living.

I haven't heart bad about W?ssner pistons - at all, and to the pries they come - I cant see why they shouldn't do the job.

I appreciate your professional comments - but please - let it be objective. Otherwise our decisions of what to buy, could be wrong and to expensive.

If you are being objective - I?ll hope I haven't offended you - but I needed it to be said.

[1NRO]

Indeed you are right, it is maybe wrong of me to shoot the Wossners down. They are after all a piston that will fit. My own products are indeed just that too. What I'm trying to point out is that the Wossner piston are someway short of ideal, they have a design of crown that must be low compression, far lower than origional. They have massive valve cuts and a deep dish. This in my opinion is the wrong way of building a turbo engine. Straight away you are creating a lag ridden car. Yes, wind the boost up you might say but with that comes more problems (heat and induction problems) you'd from the very start be chasing problems. The valve cuts do a job that they are required to do but thats all they do, the ones I have are also valve cut but various troughs and sculptured details do a very delibrate job of manipulating the combustion charge (also the exhast stroke) in a manner that promotes a fast and even burn with a mechanical assistance to producing power and exhaust evacuation.
The very sharp machined edges of the crown will not help in the fight to keep DET at bay, more likely that it will give it a helping hand.
A good visual way of seeing this is to use a blow lamp to heat a square edged metal bar at the same time as heating a round bar. Same with riven kindling and something like a round brush shank.
I'm trying to not mention mine (difficult without using them to compare to the Wossners) but on this point they are on a winner, the man who has them made for me (he designed them) gets them from wiseco but before he sends them to me he hand finishes the crown in a manner used in cylinder head porting. No sharp edges at all.
The Wossner pistons come with a normal set of rings, fine, but to me I'd prefer to fit something that has modern high spec rings that reduce the rotational friction. Why leave power on the table?
The market up to date for these engines has only had rods to suit a standard piston compression height (that and the market is littered with China forgings that would cause me sleepless nights, ever wondered why there is no manufacturers name mentioned), there is so much more to it than that IMO. A longer rod has many benefits (albeit small improvements) which can be ignored but thats not my style, I want every small improvment that I can get. When in Rome. I won't go on about this point as it will turn into a massive reply, another time maybe.
The point I supose is I'm hell bent on dragging this engine into the modern era and have spent a massive amount of time (and money) researching whos door to knock on and what I want them to do for me when they answer. The sum total of lots of small improvments can only be a good step forward IMO. This is one of the reasons why I don't like to discuss price openly, not because this stuff is massivly expensive (quite the opposite) but rather I'd like to have people understand why. I'm no expert I admit just an obsessive enthusiast that wanted this for myself and I've had to put the effort in to achieve it. Quality is my obsession, I demand it. I have a highly sensitive bullshxt sensor and use it, I don't believe the first thing I hear but more likely log it as a small piece in a bigger jigsaw that someone mixed with another jigsaw.

Nik

[#84]

I haven't seen the Wiseco pistons 1NRO sells (please show us a picture or two!), so I can't say anaything about them besides that it sounds serious when you describe them. An alternative, which I have mentione in previous threads, is Italian CPS pistons http://www.pistonispeciali.it/index%20pistu1.htm. The cost €150 each and you can have the compression ratio you want. The pistons looks good in general but I don't remember the piston ring design and I know the valve pockets are quite sharp edged.

/A

[jimnielsen]

What are the "BBB" 's that are on the side of the block here supposed to signify?

(yes, I HAVE taken the engine out....I have decided to have it bored to an exact size for the new pistons.)


** AND **


how do you remove the front pully/gear that drives the timing belt from the crankshaft - is this thing sort of like a 'slide hammer' that they are using in the manual to get it off?? - see pic..



jimn~