I did some figuring in my spare time.....

2.422 cc seperates 9.5:1 from the 9.0:1 soobs. that is very small changes. I jokingly thought "that is about what a spark plug crush washer takes up."

I wasn't even wrong.

.1476774 cubic inches == 2.422 cc (to gain a view on my ruler- that is just over 1/8th inch cubed. closer to 9/64)

▀<- about the size of this cubed.

 

So... it turns out to be double the width of the washer on an ngk to be removed to gain, unless you use a bosch platinum (which is different now than the older style I have lasting forever.) I put the ngk next to the slightly longer bosch and concluded... I only need to take this plug washer off somehow and still be able to seal it, to noticably gain even more than I have already, after swapping out the ngks that glowed in the dark.

is there a sealant for high temps that could be put on the root of the plug where it would seat on the head? I do not know of any off hand... a gasket <= 1mm would also be noticable and decnet for my pursuit.

I'm going to quote this from a thread earlier:

In a 9.5:1 EA82, Vtdc (V2 in the article) is 52.3 cc

In a 9.0:1 EA82, Vtdc is 55.6 cc

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3 CCs is actually quite large though. If you have an 18mm spark plug, the cross sectional area is 2.5cm^2. In order to subtract 2ccs, the spark plug would have to protrude nearly a centimeter, which from a picture you posted earlier does not look like it.

 

You have to decrease the combustion chamber by 3.3 CCs, which is actually quite large. In order to achieve this by just increasing the depth the spark plug threads in, you'd have get it to thread 1.3 cm deeper. Seems to me you'll need to remove a lot of washers to get that number.

removed

I'm going to quote this from a thread earlier:

 

 

You have to decrease the combustion chamber by 3.3 CCs, which is actually quite large. In order to achieve this by just increasing the depth the spark plug threads in, you'd have get it to thread 1.3 cm deeper. Seems to me you'll need to remove a lot of washers to get that number.

 

Thanks, that makes more sense than what I am coming up with. I was certain it was quite sensitive as my spfi pinged like crazy until high octane. A year later after tearing it down and finding the unburnable crud- it did not take much at all to change compression and see for myself it is a very tiny stroked sensitive engine. I have cleaned the seats a bit to drop plug closer to where I wanted, will stay with that until an all out project I hope to put together can be done. Another afterthought on the soob I want to do this to is the heads may have been reworked (so I am told- no reciepts, times, places to verify, except for the head gasket egdes not even brittle for a 20 year old car on drivers side). Thanks for input- "cubing" a distance (measurement) brought me back to an argument in high school with a teacher . To this day I do not understand how cubing a distance changes so much to visualize a measurement simply cubed..... theres a squared in there... to get to the cubed, and I am still confused thoroughly.