In the Eco, as on most of the engines in this segment, the weak
point is the powdered metal con rods. It's been our experience
that 300 HP (engine) is a safe limit. 'Safe Limit' meaning: run
it as high as that, but do not exceed.
We are typically conservative in what we state as safe limits,
for, as mentioned in this thread, there are many external
factors that we cannot control (detonation, excessive RPM, poor
tuning, etc etc) that can all affect this threshold.
Nonetheless, this 300HP mark has proved to be a dependable
number for some years now. Some tuners can tiptoe very
effectively and exceed it, but they have the instincts and
knowledge to do so. On the other hand, some overconfident brutal
types can break an anvil! It's all in the execution.
GM's stock Ecotec 'engine
failure' rating of 288 HP was achieved using Nitrous as
compared to boost, so it
will be skewed low to a large
degree.
The essential difference between Nitrous and
Boost
are the way they produce power increases:
1. Nitrous is very
sudden in its application, whereas Boost
is gentle and
progressive in comparison.
Instant pressure rises are much
harder on parts than gradual ones.
2. Nitrous achieves most of its power gain via increases in
cylinder pressure, whereas boost increases power more by
increasing the length of the power cycle, thereby achieving
'work' on the crankshaft for a longer period of crankshaft
rotation.
Always remember, the combustion event is not so much an
'explosion' as a controlled burn. It moves away from the
point of ignition at the spark plug, and 'burns' throughout
the entire air-fuel charge until it reaches the piston,
which is when cylinder pressure falls away, and effective
power production on that cycle begins to ebb. The denser
charge of the boosted engine takes longer to burn than the
much faster pressure rise of the nitrous engine. They both
increase power, but in substantially different ways.
