ADY Compression Correction

[DoogyStyle]

Hwzt guys

Been seeing a lot of compression related question/issues being raised which also have been on my mind for a while.Case in point i have a golf velociti running the 2L ADy engine with a 288 degree cam correctly mapped MP9 ECU.Car is running fine with a hint of pinging ever present.I recall these ecus were mapped in the days of the good old 98 octane and the short block Motorsport 2L high compression MP9 engines. Im looking at getting the head worked( flow,port ,bigger valves etc).With this being said when head gets worked it will most likely be machined for a smooth flat surface.

Will this alter the compression drastically to aggravate the little pinging i currently experience .

Side note I had a 272 degree and mapped MP9 ecu on same engine previously and car ran flawlessly.

What do u guys reckon

[Jetta2]

If the head is skimmed it will result in a very slightly higher compression ratio which will make the pinging worse.
If the combustion chamber is modified by grinding bits away to make it larger, the opposite will happen.

Head flowing/porting, bigger valves and what not will not affect the compression ratio.

[DoogyStyle]

Hi Jetta2 .

This is a stock used Import engine so compression should be as per the manual No skimmimg was done.I think its 10:1 which does not seem relatively high.Its funny that this pinging only happened after the cam install.Question now is how do or can i drop compression enough to mitigate pinging without sacrificing power

[Jetta2]

Then the ignition timing is too far advanced. Possible cause is the intermediate shaft was not lined up correctly after the cam install, causing the distributor to be slightly too far advanced.
There are literally thousands of motors out there running the same setup as yours with no pinging issues.

Lowering compression ratio can be as simple as a thicker head gasket, or as complicated as reworking all the combustion chambers or pistons themselves, or both.

And the only way to calculate an accurate compression ratio is to measure a whole lot of stuff.

[DoogyStyle]

Head will be coming of next year so ill do calculations as to exact compression thn before and after head job..In the meanwhile ill check distributor in relation to timing marks and maybe get the car on a dyno.

[DoogyStyle]

So ... its been a minute and car is now running 8V performance head 298cam with 45mm Toyota ITB''s on standard @2L ADY bottom. Spitz EFI. As been the case quest for more power is non stop. I want to up compression to fully utilize cam potential. Bottom is still 100% so dnt want to scratch where it isn't itching.

Head was skimmed 0.5mm with head @ 28.5cc.Calculation have Static Compression @ 10.5
I understand a thinner head gasket can be made to order but here is my question.
What is the minimum thickness the head gasket can be made for this engine(Aiming to get around 11.5 compression ratio Mix fuel will b used)
What is the minimum space between piston and cylinder can be without piston touching.
As per the forum skimming the block so piston protrude no mote thn 0.9 mm is deemed ok. With that being said standard head gasket is 1.8mm meaning a 0.9 gasket will do the same trick as skimmimg the block.
Any input appreciated

[Quik-Trix]

Why don't chat to the guys at 8VP?

[DoogyStyle]

i would have thought since a zillion guys have build 8valves engines on the forum at least one would be able to advise but alas.