PSA 1.6 16v engine problem

Competition engines and 'live' projects only. Good photos to illustrate your post are expected.
Guy Croft
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Re: PSA 1.6 16v engine problem

Post by Guy Croft »

OK, understood.

Back to spark plugs, I rang NGK UK Race Div for you.

For your engine type, Peugeot 206 1600cc 16v TU5 JP4 the standard NGK plug for your motor would be LFR 6B and your plug (with P prefix for platinum center electrode) is PLFR5A11 which as Nabih correctly stated earlier is one grade hotter even than a standard plug. That is not a good idea. The gap on that plug if you chose to run them (which I would not) should be 1.1mm. Those standard plugs have a projected nose (a very prominent one) which typically places the spark plug as close as piston dome will allow to the center of the chamber. I am sure that is a very good thing on a standard road car for emissions etc etc but it is something I would avoid on a competition engine because it just picks up more heat than a plug with a short nose and of course the bits hanging off the end of the plug are exposed to more vibration.

I cannot say it will cure your problem but I would avoid the direct NGK Race plug equivalent R7437-8 (NGK stock code 4901) which has a projected nose and instead use R7438-8 (stock no 4905) - that plug has a solid platinum ground electrode and is not projected nose and you should fit them as supplied by NGK and NOT attempt to alter the gap as you will simply mess them up and snap off the ground. All NGK race plugs come pre-gapped.

It not be the absolute answer to the problems you have had but as I said before you can 'cross the plugs off the list' then as contributory cause of the problem which you certainly cannot do at present. And unfortunately race engine construction and fault diagnosis sometimes can be a bit 'hit and miss'.

GC
nabihelosta
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Re: PSA 1.6 16v engine problem

Post by nabihelosta »

All I have to say is to recommend you use the spark plugs Guy listed above, and DO a compression test as soon as possible.

I was never allowed to use over 11:1 CR pistons (listed) on BMW race engines, along with stock or near stock intake and exhaust setups, so it is vital to determine the engine's true static compression figures, with an accurate gauge (I would advise Snap-On). Even 280 degree camshafts ran with 60 deg of overlap, won't drop the compression dramatically, so do the test.

And one more thing, when you sort the problem and re-start the engine again, please start your tests with conservative ignition advance. Somewhere between 0 and 5 degrees at idle.

Nabih
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Guy Croft
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Re: PSA 1.6 16v engine problem

Post by Guy Croft »

Nabih - maybe I have misunderstood your point but really all you will learn from a compression test is the state of valves and rings. I've just hot run 2 16v 1800 Fiat-Abarth engines and have recorded the cranking compressions on all 4 cylinders at 18bar (hot wide-open throttle), on fairly agressive Abarth Gp4 cams. These engines are both 11/1 CR +

Do I expect them to exhibit detonation/firing problems? No. I have bought NGK race plugs costing over £37 + vat each for them though..

G
Attachments
this is one picture you cannot easily you just cannot fake...
this is one picture you cannot easily you just cannot fake...
_02 comp hot wot all 18 bar.JPG (137.25 KiB) Viewed 10139 times
nabihelosta
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Re: PSA 1.6 16v engine problem

Post by nabihelosta »

Oh! Interesting bit of information here, Guy! 18 bar? 265 PSI?? I always thought that at this compression any engine won't even crank!

Anyway, I think on that 1600cc Peugeot unit, with original intake and exhaust setup, you can go nowhere beyond 200 maybe 210 PSI (13.6-14.3 Bar).
Always, CORRECT me if I'm wrong Guy.

Thank you.
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FACTOR_LAMBDA
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Re: PSA 1.6 16v engine problem

Post by FACTOR_LAMBDA »

Guy Croft wrote:Back to spark plugs, I rang NGK UK Race Div for you.
Thank you very much you for taking your precious time.
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FACTOR_LAMBDA
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Re: PSA 1.6 16v engine problem

Post by FACTOR_LAMBDA »

After I talk to Wössner.
It appeared the engine problem.
Installed on this engine pistons incorrect.
More volume in the head, and the shape of the piston head totally different.
Piston installed
Piston installed
piston saxo.jpg (25.48 KiB) Viewed 10186 times
piston correct
piston correct
pistones correctos.jpg (19.15 KiB) Viewed 10186 times
The effect of this form of piston surely help all the problems. Plugs incorrect , compression ratio incorrect....
Result, a disastrous engine and money and time lost!!!!

When I fix it I will put here the results.

thank you all for your help!
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Brit01
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Re: PSA 1.6 16v engine problem

Post by Brit01 »

Glad you found the issue.

But what a mistake!! Who's fault was that?

Look forward to hearing about the results soon.
Guy Croft
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Re: PSA 1.6 16v engine problem

Post by Guy Croft »

yes, intruder volume too big. When I saw your piston dome I thought you might have gotten the CR wrong hence my asking you about the CR earlier.

Well done for getting in touch with the supplier, finding the cause and having the courage to ID the problem here.

Let us know if you find evidence of detonation in the bores and rings, it is important to many readers to learn these things.

GC
nabihelosta
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Re: PSA 1.6 16v engine problem

Post by nabihelosta »

It's good for you that you found the problem, although what happened is a waste of time and money. I'm really sorry. And glad to know that decent companies like Wossner (and CP-Carillo in my case) have a good feedback and follow up system with their clients. I had a slight problem with some CP pistons once, which are my regular providers, and I was amazed how much they followed and helped me. Such companies deserve a hat trick.

Guy: from your experience, such error couldn't have been found by the way of a static compression test? Or whatever the result will be, it will tell us nothing? Just a thought.

Thank you

Nabih
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Guy Croft
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Re: PSA 1.6 16v engine problem

Post by Guy Croft »

no, it would not show.

You have to cc the head and the dome and do the math see attached.

G
Attachments
doing the cc'ing (as it's called in the US) or rather more slavishly called 'buretting' in good old Englande
doing the cc'ing (as it's called in the US) or rather more slavishly called 'buretting' in good old Englande
buretting Jag.jpg (107.11 KiB) Viewed 10175 times
head vol
head vol
buretting Jag (1).jpg (112.62 KiB) Viewed 10175 times
measuring the piston dome - easy if you know the formula for volume of a cylinder
measuring the piston dome - easy if you know the formula for volume of a cylinder
buretting Jag (2).jpg (112.02 KiB) Viewed 10175 times
CR_MASTER READ ONLY.xls
(21 KiB) Downloaded 393 times
FACTOR_LAMBDA
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Re: PSA 1.6 16v engine problem

Post by FACTOR_LAMBDA »

I find Another difference ,in the engine.
cylinder head installed
cylinder head installed
miculata.jpg (56.01 KiB) Viewed 9928 times
The pistons I have are for this cylinder head SAXO 16V
The pistons I have are for this cylinder head SAXO 16V
The pistons I have are for this cylinder head SAXO 16V
culata saxo16v.jpg (39.8 KiB) Viewed 9928 times
The piston (will put pictures soon), apparently have no symptoms of pre-ignition. Rings, correct.
The number 3 has his head crushed. But it seems a problem in the remains of the spark plugs.
Only strange, all pistons, black skirts. ¿?
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FACTOR_LAMBDA
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Re: PSA 1.6 16v engine problem

Post by FACTOR_LAMBDA »

psitons fhotos
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WhizzMan
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Re: PSA 1.6 16v engine problem

Post by WhizzMan »

With pinging/knocking the pressures get so big, that the rings will no longer be able to hold the pressure in. You will get a lot of blow by, resulting in soot on the side of the piston as well. It could be (hard to tell) that the scoring you see on the piston walls is due to deformation of the piston because of pinging/knocking as well.
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Guy Croft
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Re: PSA 1.6 16v engine problem

Post by Guy Croft »

Other possibilities for the scuffing include:

1. Excessive expansion of piston due to abnormal combustion - close to seizure
2. Over-rich and bore-washing
3. Lack of oil-retention due to impaired honing and cleaning techniques

There is excessive carbon impact damage around the upper land indicating either very over-rich or high oil consumption - the latter could of course be caused by (3) above.

GC
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