Originally posted by bigx01
Uh, D/D, by the time “ping” or “knock” can be heard over the noise of a moving vehicle, you are already damaging the bearings, pistons and
valves of your engine. The reason most of us do not become aware is we trade our cars often enough to miss the “last gasps” of an abused engine.
todays computer controlled engines, the timing is advanced to the edge of knock and then backed off a bit. it's not as easy with auto trans to get
it to knock but it's real easy to get a manual to do it no matter what grade you put in.
thats because the computer and the auto trans are linked. but the computer can't predict what i will be doing with my clutch and gear selection. it
only does it when i'm stopped since it's under idle conditions and probably advanced as far as it can with the little fuel and no load that idle
[edit on 2-5-2006 by bigx01]
Granted, by the time you hear pinging there has been an opportunity for damage.
I haven't had any trouble in the damage dept with the carbureted engines I build.
Forged pistons, good rods etc. along with reasonable driving habits as far as lugging the engine goes.
Proper ignition timing enters into it as well.
The engine has been opened up and inspected several times as well as gone through several camshaft profile changes as well as intake system
No damage noted on pistons, valves or crankshaft bearings.
The engine runs an amplified ignition system advanced a couple of degrees from the stock all-in timing figure.
No vapor lock problems with electric fuel pumps.
The same was true with my brothers mechanically fuel injected drag racing Henry J.
At one time he ran a 463 cid engine with 15/1 CR.
The high C/R ratio ran fine on straight alcohol, but some cool mornings the car would be difficult to start.
That cured by putting a gallon or so of racing gas in the fuel cell and starting the engine on 105 octane + racing gasoline.
Started with no problems, but it rattled and pinged a whole lot.
After the heads got a little heat in them, the engine was shut down, gasoline drained, filled the tank with alcohol and the car started easy the rest
of the day.
The HJ's engine was inspected internally on a regular basis and we found no damage from detonation.
More than likely due to the low loads on the engine during the 1000 rpm idle warmup.
I would argue the point that a modern, computer controlled stick shift can be made to ping moreso than the same car/engine with an automatic would.
In either case, the knock sensor hears what's going on and backs the timing off to compensate.
The knock sensor is much more sensitive than the human ear.
My roadster is driven regularly, although it does sit through some of the colder weather.
It does get out in the winter with 16 degrees F. being a personal best.
I've had no problems with winter gas when we experience a sudden heat wave.
Higher gas mileage in such a situation hasn't happened either.
The roadster is a light car - 2400# - with a big engine (462 cid) and the CR is 9.0/1.
I run it on 87 octane summer and winter with no ping problems and advanced to the point of best performance.
My Mustang GT (5 speed stick) with computerized, injected 5.0 liter engine got 89 octane in winter and 91 octane in summer due to, I didn't want to
have the timing backed off to the point where mileage would suffer or have ping rear it's head.
A penny-pinching co-worker bought a similar Mustang and ran 87 octane in it with no problems.
He got good mileage in it, better than mine, but he drove the flat Central California highways at 55-60 mph in cruise control and 5th gear.
He reported no detonation problems.
(Edited quote to get the post under 5000 characters.)
[edit on 3-5-2006 by Desert Dawg]