Dynamic Compression / Cranking Compression - good reliable calculator available?

[360duster]

Hi Guys, i´m planning some upgrades to my 408, including new pistons for higher compression ratio. I´m a little bit confused with the existing dcr / cranking compression calculators. Some say add 15° to the IVC @.050" value, some not.....so what´s the best calculator to use for correct results?

I´d like to play around with the cr and IVC data to see what works and how to adjust the cam timing.

Thanks in advance!

Michael

 

[273]

Here's all their calculators
Wallace Racing - Automotive Calculators

 

[PRH]

Anything other than the actual point where the valve closes against the seat is an “approximation”.

 

[360duster]

ok, now i got it....i use the .006" data from the cam card to calculate the IVC at this valve lift, then i can use this data to calculate cranking compression.....simple....should have read the instructions before

Now that calculated data makes sense.

Thank you!

Michael

 

[PRH]

A good starting point to validate the calculator’s accuracy for your combo would be an actual cranking pressure test…….. and see how the results compare.

 

[mopowers]

ok, now i got it....i use the .006" data from the cam card to calculate the IVC at this valve lift, then i can use this data to calculate cranking compression.....simple....should have read the instructions before

Now that calculated data makes sense.

Thank you!

Michael

If it's a .006" number, you may even want to add another degree to that IVC at .006" to get closer to the actual closing event.

 

[TurboGLH]

I like the UEM one vs wallace, it asks for cyl head cc. gasket dia/thickness, piston dome, etc and will calculate CR and dynamic CR vs wallace that asks you to figure out your CR and input it.

Compression Ratio Calculator | UEM Pistons

uempistons.com