hello and welcome to this thread! First off I would like to start off with all final calculations should be confirmed by a machinist before ordering the parts to match you exact parts. The numbers I used in this are going to be based off stock and aftermarket parts. The engine I'm going to you as a reference is the H22a4 engine.
First your going to need a millimeter or (mm) to inch calculator
this will work just fine.
https://www.google.com/webhp?sourcei...+inch&safe=off

The second tool we will be useing as another reference is this. Keep in mind they have this for every honda engine out there.
http://www.zealautowerks.com/hfseries.html

Now for the parts I'm going to use for this demonstration.
Mahle Gold 11.5 compression pistons part #H22220425D10
87mm bore
1.220'' compression height
10cc dome height

the second part i will be using as a reference
100mm Brian Crower Strocker crank
100mm stroke now on a stock h22 the stroke is 90.703mm. This will make the H22 a 2.4 liter engine instead of a 2.2.

Before i go any further I should tell you why i picked these products. this in sense is a budget stroker build. Yes there is full kits, but due to I'm not going to be sleeving this block only after market pistons I can use is the mahle gold

So now that you know the parts I'm going to be using, Now I can figure out what size rod I will need you use to have the ideal rod/stroke ratio made just for this setup; or the setup your going to be doing.


Now that you know how to measure your block height, lets get started
So my block height is 8.633'' and a stock untouched h22a block is 8.643'' thats .01'' decked or shaved off the original block. now what we do next is figure out the crank stroke in inches we know that that crank is 100mm so we convert it to inch with our fancy calculator provided by google and that calculates to 3.937'' the next thing your going to want to do is divide the stroke in half so 3.937''/2=1.968'' Then we are going to figure out what size the rod and piston need to be. your going to need to use you block height and the half stroke numbers for this so 8.633''-1.968''=6.665'' All these calculation were made at the top dead ceter (TDC) marks on the engine.

Now we can calculate the actual rod size needed for this setup. First let me show you how to measure a compression height on a piston. if you dont know already. In my case i know the piston specs.


So my compression height is 1.220'' we are going to subtract that to out rod/piston length witch was 6.665'' so 6.665''-1.220=5.445''
so now that we have successfully calculated what size rod to use we take what we came up with back to the machinist and they can further blueprint you engine block. so it can be confirmed that you calculations are 100% accurate..

now lets get started on the actual compression ratio. this step is if you already know the amount of cc you piston is mine happens to be 10cc. before we get started on the compression ratio part we are going to need to know the elevation of the area you live in to compensate the actual compression ratio.
http://www.whatismyelevation.com/ this link will tell you just that. all it does is calculate how far you are from sea level basically just is your air pressure each area has a different one.

Lets put all of our measurements into our compression calculator.
first lets do our stroke and deck witch we know is 100mm and 8.633'' or 219.3mm after we put that into the calculator lets move on to the pistons
so we know my dome height is 10cc and my compression height is 1.220'' or 30.98mm. Then we can put our rod measurements into the calculation to finish this up. We know that the rod length we need is 5.445'' or 138.303mm

So now that we have all out calculations put in our compression calculator we now know what out compression ratio will be with the new stroke.

so i will need to contact a connecting rod manufacture about getting a custom rod for this application. you will need to tell them the wrist pin diameter and get the specs from you blue print for the exact size of you rod journals. just so they know what they can make the proper sizes for you.

If you were wondering what my compression ratio is for this setup is. The compression ratio is 13.25:1 effective compression ratio. would not run on a 91 or 93 octane fuel.. i will be shooting for e85


Thanks for taking you time to read this post.i hope this has helped you in you engine building needs. Have a nice day!