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1.4 Twincharger Cylinder Compression - what should it read

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Newbie69,

so to cut a long story short,

 Does the results you got from a Compression Test mean you now go ahead to Stage 2 with your engine?

What plans are afoot other than the new Map?

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  • Did mine today at last. All cylinders very consistent as you can see. I was testing them from 1 to 4. The only difference between them, cylinder No.1 needed 6-8 cranks to reach top pressure while cyl.

  • Yes, one can calculate the theoretical maximum, good info and appreciated. I was more after the "normal" values for this engine, what is to be compression figure expected from this engine having taken

  • Could look at it the other way around, cylinder 4 could be the good one, and 1,2,3 have lost compression.

Is there anyway to do a visual inspection of the cylinders via a camera and light put through the spark plug hole? Compression tests are great and all but they don't tell you about imminent failure do they?

Reason why I ask is in my country all we have is RON 95. You guys see damage even on engines running RON 98-99 so I'm a little wary. My car is stage 1+, spark plugs changed at 68,000 km and the car is now at 83,000 km.

Yes, with a Borescope.

 

Which country are you in?

If you car runs OK, and does not use excessive oil, why worry?

 

Edited by goneoffSKi

Is there anyway to do a visual inspection of the cylinders via a camera and light put through the spark plug hole? Compression tests are great and all but they don't tell you about imminent failure do they?

Reason why I ask is in my country all we have is RON 95. You guys see damage even on engines running RON 98-99 so I'm a little wary. My car is stage 1+, spark plugs changed at 68,000 km and the car is now at 83,000 km.

I can't see why 95 ron will cause premature or excessive ring wear. It will just make slightly less power and the ECU will adjust the ignition timing slightly to compensate for the fuel change and to avoid detonation.

I can't see why 95 ron will cause premature or excessive ring wear. It will just make slightly less power and the ECU will adjust the ignition timing slightly to compensate for the fuel change and to avoid detonation.

I was thinking this as well but I see members on here swearing that nothing less than 98 should be used.

When you were remapping it and taking it to Stage 1 + you know the fuel you are going to use and the Octane.

 

?

Who was the MAP Written by?

 I assume they knew what they were doing and the Fuel Octane/ RON / MON available.

 

Nobody says nothing less than 98 should be used,

95 RON is the Minimum as available in the UK, and then 97 & 99.

 

But there are cars having issues on a standard Factory MAP running 95 RON in the UK.

But then UK fuel can be pretty rubbish, while meeting the required minimum standard.

'Crap Standard'.

http://en.wikipedia.org/wiki/Octane_rating

Not up to date, or necessarily accurate.

Edited by goneoffSKi

  • Author

Absolutely! Leakdown is far more useful than compression

 

Indeed, however it is far simpler and quicker just to start with the compression test to see if any further investigation is warranted.

 

RON 95 fuel is perfectly fine and no harm will come to your engine using it!

Indeed, however it is far simpler and quicker just to start with the compression test to see if any further investigation is warranted.

RON 95 fuel is perfectly fine and no harm will come to your engine using it!

Provided the equipment and method used is accurate

A mate of mine would check a suspect compression with his finger over the plug hole , no compression meant strip down and some compression meant leakdown.

He knows his stuff as he holds a Bonneville speed record :)

  • Author

Provided the equipment and method used is accurate

A mate of mine would check a suspect compression with his finger over the plug hole , no compression meant strip down and some compression meant leakdown.

He knows his stuff as he holds a Bonneville speed record :)

 

LOL, I do not mind sticking my fingers into holes but perhaps a spark plug hole is not one of them ;)

I know a a Consultants that does Prostate Examinations. (he is a medical practitioner, it is not a hobby.)

He wears the same type of rubber gloves as my mate the mechanic, that is all they have in common,

i know which i will have checking my bores.

 

PS.

Neither have a 14" long finger anyway!

Edited by goneoffSKi

Newbie69,

so to cut a long story short,

 Does the results you got from a Compression Test mean you now go ahead to Stage 2 with your engine?

What plans are afoot other than the new Map?

 

Yep. Hardware-wise there's not much other than the full TBE, and the GFB Diverter valve which has gone on already. Plugs look ok so they'll be staying.

 

Regarding the extra cranking used for #1, I don't know if it is something worrying. I remember reading "crank over as long as it takes for the pressure to stop rising" so as I understand it, how quickly you will get to max pressure is a rather random process affected by different factors. Then, regarding evaluation, the important thing is consistency. The only case where the instructions said: investigate further with a leak-down test was only in case of one cylinder reading lower than 5% than the others, didn't mention anything about time required to get there.

 

I'm away currently, but maybe when I get back I repeat the test starting from 4 > 1 just to see if all cylinders behave the same as during the first test or the situation is inverted.

  • Author

ELSA would not tell you everything I am afraid...

You can quickly tell whether it is piston rings letting the compression by, just put a spoon of fresh engine oil in the suspect pot, turn it over without the plug in few times and then do the compression test again. If it goes up to max pressure straight away it means your rings are not 100%. If it doesn't it is valves or piston or head gasket or cracked block/head.

With your readings I do not think you have anything to worry about really :)

  • 2 years later...

Discovered this old thread and just had my compression readings done, These are within each other which is a good reading like for like.  Car is 7 years old and Stage 1 tuned. Running very well but here were the readings taken :

Cylinder 1 = 164

Cylinder 2 = 164

Cylinder 3 = 162

Cylinder 4 = 162

I posted in your Project thread.

Those spark plugs you just fitted new are what VW / Skoda stopped using in 2012/13 in Twinchargers when they changed to 

03c905601B / SIZEFR6BEG

  • 7 months later...

Sorry to bring up a dead thread but what difference does pulling the fuse out make as when I tested mine I never pulled it out and only got 8 bar then I pulled the fuse out and achieved 11 bar doing a compression test doesn't involve anything electrical?

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