Getting this forum back to TECH!

While on track I was on the back straight off the gas talking to my passenger and I hear a miss fire...
Well I thought it was a plug wire that fell off, it happened once before at Expo4... So I immediately turn the key off and cruise to the access road on the track.
I wait for the tow truck to pull me off the track.

Now in the paddock there are 20+ people asking what happened...
A few knowledgeable people come over and are thinking ring lands and ring failure. so I pull the plugs and Jack uses his thumb to check the compression. His thumb told us that #4 had low, if any compression...

At that point Brad, Bradstard steps in and offers to take me under his wing and tow my car to his house and offers me a bed until a reasonable solution is figured out. With in a few days he towed it to a dealer and they said the part just failed and the extended warranty Co. also said it was a part failure and they would cover it. Cool!!!

Now here is my question. if the valve in the pic had no contact with anything and the only damage was that part in the pic, WHAT HAPPENED ?



There was no miss-shift, proper amount of oil, nothing out of the ordinary. Just like that.

Without making a big mess... and lets try to keep this on topic... Toss up your theories.
But try to back them up with some sort of proof. No off the wall ideas, Wacky thoughts and comments not needed.

This is a tech question, not your "which muffler should I buy"...


Modified by Bbasso at 10:53 PM 12/15/2005

 

Seems like detonation to me but I could be wrong.

Edit: backing it up. There is a GS-R in my garage right now with the exact same thing. His car has a JRSC but there was no contact in his either. His was run without any kind of engine management. So that is why my guess would be detonation. Car seems like it may have been out of tune, thus leading to this failure. Again though, I could be wrong.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dave_B &raquo;</TD></TR><TR><TD CLASS="quote">Seems like detonation to me but I could be wrong.</TD></TR></TABLE>

Explain

 

IDK.

But, is your caR still smoking? Take that thing back to them and tell them it smokes now!! I'm sure they'll buy you a new block.

 

curious how much gas you had in the car?

 

At least 3/4 tank

 

Walker... I can not tell a lie.

 

I dont lie either, but if it comes to a new block for free, Id come up with all kinds of ****. lol

What octane were you using?
How did the plugs look?
Stock fuel pump?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by itr206 &raquo;</TD></TR><TR><TD CLASS="quote">I dont lie either, but if it comes to a new block for free, Id come up with all kinds of ****. lol</TD></TR></TABLE>

Oh no!

 

Also Rob when was the last time you had a vavle adjustment prior to it going?

 

I wouldnt call it lying. You "use" the car, I would say it smoked a bit before, they supposedly fixed my problem, but it still smokes like a pig. There is nothing wrong with that. I drive the **** out of my car with 105k on it and it doesnt smoke like that.

 

have you ever run without a filter?

is it possible that a small rock or some debris got caught in between the valve and the valve port causing it to bind and break off a piece of the valve?

 

I called it from the beginning. mad props to myself

 

93 octane
Plugs looked used but all there.
Stock fuel pump
Last valve lash Adj 10k prior
Always used a filter.

Btw Guys this is the Exhaust valve.

 

Maybe it got soft from all that oil

Just kidding, it could have just been a freak accident. Maybe the orginal valve had a small hair line crack in it and it finally let go?

Did you ever get the numbers from the leak down test? Are you running a cat? Look on the cat for loose pieces maybe that will tell the story.

 

taken apart the bottem end yet?

how's the cylinders look?

ring land or ring chunk?

 

Burning oil... Yeesh...
Not cat, So I'm sure it blew right out of the tail pipe.
The dealer never got back to me with the #s for compression or Leak-down.

I did not have the chance to look at the motor personally, the dealer said that all four cylinder walls looked fine and the top of the pistons were normal looking and the top rings were intact.

 

Rob, after talking to my old man he seems think that maybe the valve was to tight. He's seen a few of them and it's always the exhaust. He had a civic about a year ago where the exhaust valve was to tight and it did the same exact thing. Who did the valve adjustment?

 

I did all of the valve jobs... But each time I do them at 15k I find they are (most are loose) So I really doubt that was too tight.

The dealer said the other valves were lashed within reason and called for no concern.

 

Hrm, well back to the detonation theory I guess. It's possible to have a some trash in the fuel, clog an injector, thus leaning it out and causing detonation. Did you get a change to look at the old injectors?

 

I thought I chipped a valve, but turned out it was just burned up. yours looks almost identical to my valve. I would definitely be leaning toward fuel/detonation/spark issues. You are running a VAFC right? I know its tuned, but Im wondering if that caused an fuel issue for that injector?

 

that was definitely caused by excessive heat in the combustion chamber. doubtful it was detonation tho, the pistons are almost always the first to go. looks like there wasn't enough timing and not nearly enough fuel, causing combustion to happen in the exhaust manifold over heating the back side of the valve and melting it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SecretAgent &raquo;</TD></TR><TR><TD CLASS="quote">that was definitely caused by excessive heat in the combustion chamber. doubtful it was detonation tho, the pistons are almost always the first to go. looks like there wasn't enough timing and not nearly enough fuel, causing combustion to happen in the exhaust manifold over heating the back side of the valve and melting it.</TD></TR></TABLE>

With this theory would you assume then an exhaust valve was to tight?

 

it's possible, but they in no way would be related. the valves have to be extremely tight to cause damage. and to get them that tight, you will notice a very rough idle immediately after the valve is adjusted. but to check if there's signs of damage from the valve being tight, examine the valve seat and see if the wear is any worse than the others.

 

I chipped two valves at the drag strip, but that was because I was sprayin' NOS yo.

Were you sprayin' down the back stretch?