Don’t buy that nonsense. As I already said, the dyno has limitations and that’s one of them.
Most of the guys spouting percentage gains from compression ratio increases get that from one (maybe more) of Vizards books. I’ve seen similar charts and graphs and they all say the same thing.
BUT…they never read the text under the chart/graph and if they did they would know that that percentage is the MINIMUM gain to be expected. Not the maximum.
If you are building something like the “Mission Impossible” engine, then I’d run bigger heads and live with the compression ratio I get.
If I’m building something that isn’t limited by rules or the constraints of some self imposed engine building flagellation then I put compression in it.
One last thing Dan. If you want to learn this stuff then you have to keep learning for the rest of your life. You should learn something every day and then apply it to validate what you’ve learned.
The learning curve is very steep, but today this information is out there from far more reliable sources than myself.
Verify everything, trust nothing until you PROVE it out.
To that end, spend some time learning about expansion ratio and how it affects engine performance. Once you get a grasp of that you will wonder why some many are willing to give up compression for old wives tales and fables.
That doesn’t mean you can build a 4200 pound car, use a 2200 converter and a 2.75 gear so you can run 95 MPH down the freeway and use 11:1 compression.
You have to apply some common sense and have a pretty decent grasp of ICE theory. But most guys can run quite a bit more compression than they do with very minor changes to the build.