|
The A4 is such low compression I doubt it would be an issue.
What you get with the light is the ability to check the advance over various RPMs as well as set timing accurately. I am pretty sure a 6:1 A4 could run on 80 octane gas if you could still buy it.
From Wikipedia:
When unburned fuel/air mixture beyond the boundary of the flame front is subjected to a combination of heat and pressure for a certain duration (beyond the delay period of the fuel used), detonation may occur. Detonation is characterized by an instantaneous, explosive ignition of at least one pocket of fuel/air mixture outside of the flame front. A local shockwave is created around each pocket and the cylinder pressure may rise sharply beyond its design limits.
If detonation is allowed to persist under extreme conditions or over many engine cycles, engine parts can be damaged or destroyed. The simplest deleterious effects are typically particle wear caused by moderate knocking, which may further ensue through the engine's oil system and cause wear on other parts before being trapped by the oil filter. Severe knocking can lead to catastrophic failure in the form of physical holes punched through the piston or cylinder head (i.e., rupture of the combustion chamber), either of which depressurizes the affected cylinder and introduces large metal fragments, fuel, and combustion products into the oil system. Hypereutectic pistons are known to break easily from such shock waves.[2]
Detonation can be prevented by any or all of the following techniques:
the use of a fuel with high octane rating, which increases the combustion temperature of the fuel and reduces the proclivity to detonate;
enriching the air-fuel ratio which alters the chemical reactions during combustion, reduces the combustion temperature and increases the margin above detonation;
reducing peak cylinder pressure by decreasing the engine revolutions (e.g., shifting to a higher gear, there is also evidence that knock occurs more easily at high rpm than low regardless of other factors);
decreasing the manifold pressure by reducing the throttle opening, boost pressure or
reducing the load on the engine.
|