Then drop the putty into a graduated beaker filled to a known level with oil.  When I dropped the two pieces of putty into my beaker the oil level rose about 1 cc.  So, each valve relief has a volume of 0.5 cc for a total of 1 cc.

The volume of the cylinder above the flat top is easy to calculate.  The bore is 3.819” and the height of the area is .095”.  Pi x the radius squared x height = volume.  That works out to 1.088 cubic inches (17.829 cc).  Subtract the piston top volume of 5.5 cc and we should have a final volume of about 12.3 cc.

So, with the piston locked in place at .095” below the top of the cylinder, I sealed all around the top with grease.  Then I installed the clear plastic and filled the area with oil.

We are now ready to use the calculator.  The pop-top for the 94 mm Wiseco is identical to the pop-top for the 97 mm Wiseco, so we can use the same piston top volume (negative 6.3 cc) for either piston.

Use the following values in the RB calculator:

Bore: 3.703” for 94 mm, 3.819” for 97 mm
Stroke: 3.701”
Head Gasket: .028”
Deck Height: .143” (Wiseco is a bit taller than stock)
Piston top volume: -6.3 cc
Combustion Chamber: 56 cc

With the Wiseco 94 mm piston you end up with a compression ratio of 9.2:1

With the Wiseco 97 mm piston you end up with a compression ratio of 9.5:1

These values fall well short of 10.5:1, but keep in mind that the Wiseco we are using was intended for the DR650.  I assume that the DR engine brings the piston much closer to the top of the cylinder, which in turn results in less negative deck and a higher static compression ratio.

I am currently running a 94 mm Wiseco.  The cranking pressure is about 30 to 40 psi higher than stock, and it runs a lot better than it did with the stock CR.  Now I have a better idea where I stand and what I must do to bring the CR up to an honest 10:1.

I hope this report serves as a useful reference.  Knowledge is power.

Mike  

 DMB, If you're still using the head where you modified the intake passage ,you may have a higher compression due to higher VE, maybe somewhere between 9.5 to 10:1, how much compression are you really willing to try considering that you said your oil temp had been running 340F.  While on that subject , rather than running 20w50 , I would think that you might try Rotella 5w40 instead, decreased pressure = increased flow which carries away more heat and the SAE Conference stated that if you can decrease oil temp by 20 degrees in a motor that the oil would act as the next higher grade (50w) . It seems worth investigation .

Once again, well researched and documented!
I've always just assembled the top end with a bit of grease around the top ring land and filled oil in thru the spark plug hole til it hit the bottom of the plug threads. I get it that with an engine in the frame, this is often impossible.
Any reason not to do it that way with the Savage?
Were you really seeing 340F oil temps?!?!
thanks

Actually, Fast, on a well tuned motor the intake doesn't close til ABDC and the incoming charge continues to some in. You can actually get more than 650ccs of mix into a 650cc motor.

Batman, that's a good point regarding dynamic compression ratio.  The RB Racing website also has a calculator for that.  You need connecting rod length (6.573") and intake valve closing point (depends on cam).  I haven't had much success with that particular calculator.  Wallace Racing also has one.  I get different values depending on which calculator I use.  This particular exercise is geared toward gathering the data needed to determine static CR.  Based on my personal experience with the LS650, I'm gonna shoot for 10:1 static CR for my next project.  BTW, that 340F was cylinder head temp not oil temp.  I'm fiddling around with some ideas for an oil cooler so I'm planning on doing some testing on the two oils (10W-40 & 20W-50) to get some baseline data.  Versy's report of 50 psi at the crankcase port threw a monkey wrench in my plan so I'm back to the drawing board.  I think I have some good ideas.  Just need to turn them into hardware.

Hey Armen, I've used your technique a time or two.  It's kinda messy when it's time to get the oil out, but it certainly gives you a good number. One of those fancy engine stands like you have would come in handy for that.  Measuring the different volumes gives more flexibility but also can introduce errors.  Now I know the volume of each key part in the mix.  I have more choices when it's time to adjust the squeeze.  I can also figure out the weight of the pop-top so I can get a feel for how much it will affect vibration if I lob the top off to make a tight-quench setup.

It's all good.  

Thsanks both of you,, and yeah,, the General explanation first probably was better. I do understand a column of air moving, too,, but IM glad we didnt start there