engine ping: is it bad?
Gregg L. Kasten
Thanks for any info,
Gregg L. Kasten
gr...@cs.stanford.edu
Dan Roberts
I really don't think that engine ping itself is detrimental to an
engine..An engine shouldn't really ping unless it was my old chevy w/ 250K
on it. An engine may ping under a HEAVY load...Really I think that you
should really try to eliminate the ping...Try checking..the EGR value and
other Emissions control stuff..I am sure you will get PLENTY of net help!!
Dan Roberts
BRISTOL-MYERS-SQUIBB PHARM. RES. CENTER
Cardio-Vascular Biochem Dept.
PRINCETON, NEW JERSEY U.S.A. PLANET EARTH, MILKY-WAY GALAXY
<<<<INTERNET ADDRESS>>>>Robe...@BMS.COM
Richard O. Lindsay
is the sound of preignition. The cause is usually fuel with a flash point
too low for the compression ratio of the engine or a poorly operating engine.
Common causes are carbon buildups in the combustiion chamber. (They glow
hot and preignite the air/fuel mixture.) The most common solution is to
use a fuel with a higher octane rating. The octanes (ring shaped hydrocarbons)
are additatives that raise the flash point of the fuel. They DO NOT add
power. Yet I do have friends that claim that they get a lot more 'power'
from their hot rods using 'super-extra-quadra-octane-premium'. If spending
more money for fuel makes tham happy, it's a cheep thrill.
Now to your question, does it do damage? Think of the position of the piston
and associated hardware (rods, bearings, 'wrist-pins', etc.). The pre-ignition
usually occurs before the piston reaches the top of it's travel resulting in
incredible stresses being placed on the afore mentioned hardware. Extreme
cases result in fractured pistons, broken rods and damaged bearings. So yes
Virginia, avoid pinking whenever possible by using higher octane fuel and
by not 'pulling down' the engine in higher gears.
Rick
------------------------------------------------------------
Richard O. Lindsay / __ __ __ __
Senior Research Scientist / / /_/ /_ / / /_/ /_/
Amoco Production Research / / / / /_/ /_/ / / / \
/ /_/
/
My opinions are my own, until they're worth something, at
which point they become the property of my employer...
------------------------------------------------------------
Trond Vidar Olsen
thermostat cooling system is OK,try another gas dealer(with same
octane rating).
Pinging is bad for the hardware in the engine.
Some of my friend have high compression camaros mustangs etc. they
all use ONE SPECIFIC of the many gas stations availablein this area.
Buying the same octane fuel from different makers can have an effect.
trond
Eric Carr
Preignition knocking/pinging does have the potential for damaging engines
under severe and prolonged conditions. Common results can range from
cracked/fractured connecting rods to piston heads actually burning through.
How severe and quickly this occurs depends on the conditions of your
problem. Engine compression, tolerances of bearings, etc. The most common
reason I've seen knocking is because of carbon build up within the
combustion chamber - mostly on the piston head. How to clean? Well,
unless someone has come up with a very in-demand easy method I think
disassembly and cleaning is about the only real answer I've come up with.
I don't think taking your car out on the expressway to "blow the carbon
out" is a very good answer (and it usually doesn't work).
I just finished rebuilding the engine in my Caprice, and one thing I was
REALLY glad to see go was the preignition. It almost didn't matter where I
set the timing - it would knock like an s.o.b. anywhere above 4¡ initial
which subsequently made the engine a real dog. And I should add that the
guy I bought it from stored it for about 12 years without draining the
coolant which accumulated quite a bit of sludge in the bottom of the
cooling jackets which is probably another reason why the engine would get
very hot and subsequently have vapor lock problems along with preignition.
I'm running 10.5:1 compression with a 365 hp L34 cam and it's incredible
when I jump on this thing how it comes to life without knocking. Timing?
To be honest, I don't know - haven't checked it with a timing light. I
like to set it by engaging the parking brake while in drive at about 2-3k
r.p.m. and twisting the cap until it runs well (dwell angle is set to about
26¡). I can advance the timing so much now that it hesitates slightly
while starting because the timing is so far advanced, but it still won't
knock after firing up. And with unleaded premium gas rated at 92 octane.
_________
______| |_______
/ '67 Caprice /
/______ Sport Coupe______/
|_________|
396 cid 365 hp
Before the heartbeat o' America, they did make real cars.....
Lee W. Spencer
I have crushed ring lands in an 86 Escort for this reason. Now rebuilding it
Tom Leone
: I have but a short question: is engine ping detrimental to the engine?
The short answer is, yes IF the knocking is severe and/or prolonged.
Minor pings that only last a few seconds (when you first step on the
gas) are not harmful.
The long answer is below (from something I've posted before).
Tom Leone <t...@slee01.srl.ford.com>
------------------------------------------------------------------------
Engine knock is the audible pressure oscillation caused by a form of
abnormal combustion. Normally, the flame propogates smoothly from the
spark plug to the edges of the combustion chamber. As it does so, it
compresses the unburned gases ahead of it, which increases their
temperature and pressure. At these high temperatures, chemical reactions
in the unburned gas can lead to spontaneous, extremely rapid combustion
before the flame front arrives. This fast combustion can produce very
high (even damaging) pressures and temperatures.
There are many ways to prevent this:
(1) Slow down the pre-flame reactions--use a higher octane fuel.
(note: this does not slow down the normal flame)
(2) Lower the temperatures:
(a) Flush out cooling system, make sure thermostat, water pump,
and other parts are working properly. You can even install
a lower-temperature thermostat very cheaply.
(b) Check the ignition timing (too much spark advance causes
higher combustion temperatures and knock).
(c) Make sure that intake air "flapper" valve is not stuck (this
collects hot air from the exhaust manifold for cold starts).
(d) Do a general car "check-up" to look for things that might
be making the engine work harder (and hotter) than normal.
(e) Eliminate "hot spots" in the combustion chamber, like incorrect
spark plugs (these come in different "heat ranges") or burrs.
(f) Remove insulating deposits from the combustion chamber (piston
crown and cylinder head surface). This requires removal of the
cylinder head, which is a pretty big job on most cars. Some
people say you can clean them out by spraying water into the
intake air, but I've never tried this.
You may also be interested to know that engine design affects the tendency
to knock. An engine which "burns fast" gives less time for pre-flame
reactions, and therefore avoids knock. Some ways to get faster burning are
central spark plug location (and/or multiple plugs, like the Ford 2.3L
twin-plug), higher turbulence (from swirl or small-diameter valves), and
compact combustion chambers (such as the famous Chrysler "hemi"
hemispherical chamber, or pent-roof four-valve engines).
-Tom Leone <t...@slee01.srl.ford.com>
<-- Sunbird --<
>I'm running 10.5:1 compression with a 365 hp L34 cam and it's incredible
>when I jump on this thing how it comes to life without knocking. Timing?
>To be honest, I don't know - haven't checked it with a timing light. I
>like to set it by engaging the parking brake while in drive at about 2-3k
>r.p.m. and twisting the cap until it runs well (dwell angle is set to about
>26!). I can advance the timing so much now that it hesitates slightly
>while starting because the timing is so far advanced, but it still won't
>knock after firing up. And with unleaded premium gas rated at 92 octane.
Sounds like a fun machine. Are you using a vacuum advance distributor?
> _________
> ______| |_______
> / '67 Caprice /
> /______ Sport Coupe______/
> |_________|
> 396 cid 365 hp
> Before the heartbeat o' America, they did make real cars.....
>
>
--
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t...@slee01.srl.ford.com (Tom Leone) writes:
>Gregg L. Kasten (gr...@Xenon.Stanford.EDU) wrote:
>: I have but a short question: is engine ping detrimental to the engine?
>
>The short answer is, yes IF the knocking is severe and/or prolonged.
>Minor pings that only last a few seconds (when you first step on the
>gas) are not harmful.
>
>The long answer is below (from something I've posted before).
This assumes ping is due to knock, which is not necessariliy correct.
Knock is the spontaneous ignition of the unburnt gases ahead of the
flame front to produce an excessive rate of pressure rise. Knock and
pinking are the terms we use in NZ for that. I associate "ping" with
preignition ( the charge is ignited prematurely, usually from glowing
deposits or hot exhaust valve or spark plug ), and there is no direct
correlation of anti-knock quality and preignition. High temeperatures
favour both, and each can lead to the other in certain cirumstances,
because they both lead to higher temperatures if continual.
Note that knock that occurs only when you first step on the gas is
usually either poor engine design ( unlikely today ) or due
to poor distribution of octane throughout the boiling range of the
gasoline. When gasolines are produced they need to have high octane
components in the volatile "front ends" so they reach the combustion
chamber gaseous when you "step on the gas". If gasolines don't have
lots of octane in the less than 100C fraction ( gasolines 30 - 220C
boiling range ) then knock is experienced until the high octane
material volatilises and combusts. This was mainly a problem with
carburetted cars, should be less on fuel injected engines.
Other causes of knock, deposits ( can increase the octane number
requirement of an engine up to 8 above that of a clean chamber),
humidity etc. etc. depend very much on the drivers habits.
[ heaps of good advice deleted ]
Bruce Hamilton