Factory "Squish" #'s

dastevoe

dastevoe

Wood Hacker
Joined
Jan 3, 2009
Messages
135
Location
Norwood Ontario,Canada
Does anyone have knowledge of any lists of factory squish #'s ? Or the technical specs. they shoot for at production ?
Or maybe someone has a working knowledge of them from their own experience.
These #'s I'm sure aren't "carved in stone",but there must be an average (tolerance) for each saw.
Just curious....
Steve
 
The volume above piston when piston is top dead center, As high as it goes just before it ignites and expansion push piston down.

It is in this space the air fuel mix is compressed and were expansion starts.
 
Trick is to get in as much fuel/air mix as possible to get a more powerful and faster expansion.

This volume should be as big as possible and filled up as much as possible with fuel/air mix.

Often if it is over filled you get a noice that we call "spikning", not sure what the eng term is... On turbo charged engines this is one of the first problems that we encounter. It is usually created when the fuel/air mix ignites by iotself and premature.

You would be amazed to see how much fuel/air mix that can be added to a stock saw before this happen.

A fuel with high octane (pressure ignition point) can be of use in some cases...
 
On most Stihls the top clearance or "Squish " is usually around 40-45 thou .Usually the base gasket is around 20 thou .
 
"spikning"...wow. It's generally referred to as "knocking", or pre-ignition, at least in the states, anyway.

Magnus, do dogs and cats go "bow wow" and "meow", over there? In my neck of the woods, the locals tell me that they go "won won", and "nya nya". I gave up trying to tell them that they've got it wrong. Oh yeah, chickens go "kokekoko" :roll:
 
Usually you won't experience pre ignition on a woods ported saw if the carb is set correctly .I suppose were it set too lean it might become a problem .

Automobiles for example use "knock" sensors which in effect through the engine control module controls the pre ignition by richening the fuel mixture and retarding the spark if it detects a knock .

Even older cars that ran a 4MC carb used knock sensors .The practice became more prevalent with the advent of no lead fuels . Which by the way was pretty bad stuff when it first came out in the 70's . Since then it has been improved considerably .
 
Not sure how I can explain it better.

It is a bit different from knocking (Knackning) but This is probably another of these very frequent language issues...
 
Detonation (knock) is what happens when the mixture is ignited by the spark plug, but before the flame front can traverse the combustion chamber pressure causes the mixture to be ignited at a different point. When the two flame fronts collide it causes the metallic "ping" that you hear. Octane is a measure of a fuels resistance to detonation.

Pre-ignition is when the mixture is ignited, usually by a hot spot, before the spark.

Either one is bad for engine longevity.
 
Ha,I had a '73 Olds Toranado with a 455 cu in engine .The thing would pass anything but a gas station .

That engine was made about the time of going from leaded to low lead to non lead gasoline . The damned thing would "diesel " with the ignition off for about a half a city block .

Ping ,pop, rattle .Smelled like a bucket of fermented butt holes too as it clanked away .The only way I could shut that land cruiser down was put it in gear and gas it .Basically flooding the engine .--Good riddance to that thing ,I missed it about like a toothache after it went bye bye . :lol:
 
Try posting it in swedish, I can probably translate it.
 
Hmm...

Spikningen är annat från motorknack.
Samma symptom men har olika ursprung.
Glödtändning innan tändtillfället kan va orsakat av för varmt stift. Glödande elektrod på stift, kan ge denna knackning med, har varit med om det vid ett par tillfälle o då är det bara o byta typ av tändstift. Inget annat funkar.

Man avhjälper dessa på olika sätt med... Det är två symptom olika från varandra.

Knackning kan avhjälpas så som de beskrivit, men det hjälper inte då det är spikning.

Hade stora bekymmer med en Fiat Uno Turbo som kom in på Bosch när jag jobbade där. Denna hade forit runt på en massa verkstäder o hos specialister hit o dit tills den kom dit eftersom det var Bosch bränsle o tänd styrnings system. Otaliga timmars tester o felsökning, många tim. prokörning o till sist visade det sig att squish volymen var sänkt för att få lite högre komp av en verkstad som skulle hotta upp den lite i effect.

Efter att detta konstaterats o avhjälp med lite tjockare topplocks packning än normalt o ny optimering av systemen gick den som den skulle med laddtryck på 0.9. den gick upp längre, men sattes där. Vid test upp äver 1,8...
Avsevärt högre än det var tänkt.

Med lite bättre oktan kan kompressions trycket ökas utan självantändning.
Oktan talet är en klassning baserat på hur hög ångpunkt i förhållande till flampunkt o i vilket tryck det är självantändande i.
Detta är dock den enda fördelen....

Here you go Stig.
Knock your self out!

:D
 
Magnus said:
Hmm...

.
Med lite bättre oktan kan kompressions trycket ökas utan självantändning.
Oktan talet är en klassning baserat på hur hög ångpunkt i förhållande till flampunkt o i vilket tryck det är självantändande i.
Detta är dock den enda fördelen....

Here you go Stig.
Knock your self out!

:D
Click to expand...
:O Damn ,you've got letters that haven't even been invented yet .Oh my ,it might as well be Chinese to me .I give up .;)
 
Welcome to my boat, ladies and gentlemen!

It is not easy to be correct in grammar and smelling good all the time... Or was it spelling?
 
OK Mange, I am going to take that and put it into that translator program you showed me once.
Hope you are not telling us where to stick it :lol:.
 
OK I am even more lost with the translator :O.

Spikningen är other från motorknack. Same sympathy but had various derivation. Glödtändning entrance tändtillfället able va caused of för warmly pegs. Glödande elektrod på pegs , able impart that knock with , had wherein with if the wide one couple tillfälle un då är the only un exchange creature of tändstift. Nothing other function. Husband avhjälper these på various sätt with. The är två sympathy various från each other. Knock able avhjälpas så as they describe , but the hjälper nots då the är spikning. Had superb worry with a Fiat Uno Turbo as enter på Bosch när self am working där. That had forit about på a mass verkstäder un with expert here un there until the arrived there as it was Bosch bränsle un tänd styrnings system. Countless hour test un felsökning många tim. prokörning un at last was guiding the themselves that squid volume each sänkt för that få few högre dense by an shop as should hotta up the few in effect. Behind that this ascertain un avhjälp with few fatter topplocks packning än normal un fresh optimering of systems was going the as the should with laddtryck på 0.9. the was going up längre , but seated där. Wide test up äver 1,8. Avsevärt högre än it was tänkt. With few bättre octane able compression burden ökas devoid självantändning. Octane digits är a klassning based på how hög ångpunkt in förhållande to flampunkt un in which pressure the är självantändande in. This är yet the conclude fördelen. Here you go Path.
 
TreeTrim said:
OK I am even more lost with the translator :O.

Spikningen är other från motorknack. Same sympathy but had various derivation. Glödtändning entrance tändtillfället able va caused of för warmly pegs. Glödande elektrod på pegs , able impart that knock with , had wherein with if the wide one couple tillfälle un då är the only un exchange creature of tändstift. Nothing other function. Husband avhjälper these på various sätt with. The är två sympathy various från each other. Knock able avhjälpas så as they describe , but the hjälper nots då the är spikning. Had superb worry with a Fiat Uno Turbo as enter på Bosch när self am working där. That had forit about på a mass verkstäder un with expert here un there until the arrived there as it was Bosch bränsle un tänd styrnings system. Countless hour test un felsökning många tim. prokörning un at last was guiding the themselves that squid volume each sänkt för that få few högre dense by an shop as should hotta up the few in effect. Behind that this ascertain un avhjälp with few fatter topplocks packning än normal un fresh optimering of systems was going the as the should with laddtryck på 0.9. the was going up längre , but seated där. Wide test up äver 1,8. Avsevärt högre än it was tänkt. With few bättre octane able compression burden ökas devoid självantändning. Octane digits är a klassning based på how hög ångpunkt in förhållande to flampunkt un in which pressure the är självantändande in. This är yet the conclude fördelen. Here you go Path.
Click to expand...

What is that, the Klingon version? :lol:
 
I'll tell you it would be tough to do .Most languages have a different sentence structure than English .Different usages of words, I suppose regional slang etc just like English .

Some like German ,Spanish and French I can get the general gist of by reading but fail miserably at recognizing the spoken version . I am totally lost when it comes to the Nordic types such as Danish ,Swedish etc .

Actually it comes as no surprise because I don't do real well at English some times .
 
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