mrx

Hallo,

just for information, what can cause a blown headgasket?

- Too high coolent temps (overheating)?
- knock/pre-ignition?
- too lean mixture in boost?
- too lean mixture in vacuum? (if yes, how lean is bad?)
- exhaust gas temp? (is there an indication to look for?)
- oil temperature?
- headlift during boost?

hope to get some nice infos about this topic...

purpleh22

And - - head or block surfaces that aren't true to begin with. - also- Always use ARP or other after market head bolts on boosted engines.

RyanEJ8

I've been trying to figure out what is causing mine to keep blowing for a year now.

oscarmayer

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">I've been trying to figure out what is causing mine to keep blowing for a year now.
</TD></TR></TABLE>

install error in YOUR case.

oscarmayer

also bad products. very few companies can best a stock oem gasket. Cometic is one of those few. They are awesome products.

RyanEJ8

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oscarmayer &raquo;</TD></TR><TR><TD CLASS="quote">

install error in YOUR case.</TD></TR></TABLE>

Oh yeah? And what was my install error?

purpleh22

In this case it would be listening to oscarmayer.

oscarmayer

you touched it

nowtype

Increased cylinder pressure will be the most common cause of this. Detonation causes dramatic increases in cylinder pressure. This is why detonation will cause headgasket failure. Running more ignition timing than you need to will also increase cylinder pressure thus causing head gasket issues.

mrx

So when i understand this right, a too lean mixture (i.e. 16:1) in part throttle can't hurt the headgasket - IF - the engine isn't detonating with the settings - right?

because from what i've understood is, that a leaner mixture burns slower, so with the same ingition advance it makes peak cyl. pressure later in the process and therefor less stress to the engine and because leaner mixture means less pcp it makes less torque when the ign. isn't changed.

another question, is it even possible to get an engine detonating with i.e. 16:1 AFR and i.e. -0.5bar vacuum? or does it at least only misfire because of the lean mixture?

oscarmayer

lean mixture will not cuase detonation. it WILL or "can" cause overheating of the chambers and thus leading to parts meltdown or "softening". That's how you get hole sin pistons, melted head chambers, valve seats that fall out and cause valves to break.

14.5-15.2 is an ideal NA oem mixture range. leaner can cause issues "if" it's ran that way all the time.

it's not the mixture, it's the timing, heat, and firing of the camber that causes detonation.

mrx

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oscarmayer &raquo;</TD></TR><TR><TD CLASS="quote">lean mixture will not cuase detonation. it WILL or "can" cause overheating of the chambers and thus leading to parts meltdown or "softening". That's how you get hole sin pistons, melted head chambers, valve seats that fall out and cause valves to break.

14.5-15.2 is an ideal NA oem mixture range. leaner can cause issues "if" it's ran that way all the time.

it's not the mixture, it's the timing, heat, and firing of the camber that causes detonation.</TD></TR></TABLE>

Ah ok i understand... but is there any way (maybe via EGT's) to see whats going on with my combustion temperature? ok i will see it at the water/oil temperature, but when oil and water are overheating most things are allready melted i guess :-)

is there any way to determine if i've gone too far?

remember, its all about vacuum here. atmosphere or boost is a totaly different story.

i.e. i have a stock B16 engine, a stock B16 ignition map and 95 roz octane fuel which is standard recomented from honda for this engine. when i not turn off closed loop and lean the mixture out to ~16:1 without changing the timing - what will happen from the point of physics?

- will the 16:1 mixture burn hotter (bring more heat in the combustion chamber) then the stock 14.7:1 mixture?

- from what i know, the 16:1 burns slower then the 14.7:1 so ignition timing in relation to the 14.7:1 should be a bit too retarded, but that should not hurt the engine or am i wrong? egt's will maybe rise a bit but nothing serious i guess.

- but when thats true, what scenario will do things like you described in your post?

Best regards