Lets say you take a brand-new engine and drop it into your SRF and go
racing... If you choose to race a fresh
engine, you will build up significant temperatures in the cylinder head and pistons. Foot-
to-the-floor treatment creates load on the engine and consequently heat in the combustion
chamber. This heat has to be dissipated somewhere. The only way the pistons dissipate heat
is through the rings...into the cylinder walls and from the cylinder walls to the coolant.
But, the issue here is, your "fresh"
rings are only partially contacting the cylinder walls. Heat builds up in the crown of the
piston and tries to escape -- however the only escape is through the rings -- and the
limited running surface area of the "un-seated" new rings only builds more heat
in the rings.
Now, the rings are not transferring this excess
heat, and , as metals will do when exposed to very high temperatures, lose their temper.
In short, the rings will lose the tension pushing them outwards toward the cylinder wall.
The lower tension on the rings causes combustion
sealing to decline and horsepower falls off. Glazing of the cylinder wall occurs and
ultimately, ring sealing goes completely away.
So, you ask: "How do I break in my
engine?"
First, whatever you do, DO NOT USE Synthetic oil
during break-in. Some factions expound the use of non-detergent oil for break-in purposes.
If you choose to use non-detergent oil, drain it after 60 minutes running time, and use a
conventional oil.
"How long is break-in?"
"Good question", I answer, but I know
you will not like my reply. Engine "break-in" is best accomplished by driving
the car under various loads (none too major) and RPMs...for, perhaps, 18 hours.
These are the facts of life in our context. This procedure allows for the best ring
sealing and best heat transfer from piston to cylinder wall and thereby, to coolant
(water) jackets. Ultimately, this should lead to best performance. Do Not, I Repeat, Do
Not race a fresh engine. There are some who believe there is a theoretical horsepower
gain, involving crossover between ring drag losses and sealing compromises, but at this
moment I have no answers for this equation.
Unfortunately, 18 hours of non-race break-in time
is not acceptable for most amateur racers. I have to say though, that these are the facts,
and, for best performance, my research leads me to believe 18 hours is a reasonable
number. Sorry if I have told you things (times) you did not wish to hear. This is only my
best recommendation.
It must be understood that we (the SRF community)
use a mass production-based engine. In this light, we must be aware of and live
with the limitations of racing a mass production-based engine. |