DCR is a nice easy way to show how the late intake valve closing point changes effective compression ratio. Sure with the right cylinder head the VE% still gets at or over 100% at some RPM. But with late IVC that RPM is always higher right? (big cams turn more RPM). The higher the RPM, the less prone the engine is to detonation.

Meaning without a doubt... late IVC (lower DCR) is better for detonation resistance.

This is a GREAT article about detonation if you have time to read it. That being said... some excerpts below about DCR DOES mean ZIP.

https://www.sciencedirect.com/science/article/pii/S0360128516300764

From section 5.1

"Conventional knock is a race between the flame in the engine and the thermal auto-ignition of the unburned “end gas” [1]. The principle for avoiding engine knock is that the time of flame propagation to the end gas (τ1) is less than the time of the end-gas auto-ignition (τ2)."

Obviously the faster the engine is turning, the shorter the combustion time, and the less time the end gas (part of the mixture away from the plug) has to auto-ignite. Since big cams have late IVC, they naturally want to turn more RPM. They also naturally bleed off pressure at lower RPM where detonation is most likely.

Again as stated in the paper above...

5.1.5.3. Lowering effective compression ratio [110,127,258,262,317–321]
Variable valve timing (VVT) is a practical way to change effective compression ratio at relatively low cost for the different engine operating regions. Late intake valve closure (LIVC) is commonly used at high load to achieve a lower effective compression ratio to avoid knock.


Again... from another SAE paper... Experimental investigation on early and late intake valve closures for knock mitigation...

The application of Miller cycle through Late Intake Valve Closure (LIVC) or Early Intake Valve Closure (EIVC) for knock mitigation at high load on a turbocharged downsized spark ignition engine was experimentally investigated. By reducing the effective compression ratio due to a shorter compression stroke and hence achieving lower charge temperatures inside the cylinder, significant mitigation of knock tendency could be obtained.

Don't get me wrong... being at the track and trying things is VERY valuable. People want to discredit science based findings because "they saw once" or "I heard once", or "I knew a guy who" type single events in an uncontrolled environment. We as racers have a lot of opinions on technical things based on VERY limited experience compared to the OEM's and universities. These guys are looking at knock at 240,000fps cameras, spending MILLIONS of dollars trying to prevent it to improve horsepower and efficiency.

If you look around for these types of published papers, you will see that it's basically common knowledge that a late IVC helps with detonation. Yet here we are still arguing about it...