Head Gasket/ATR header ????'s

[mr go fast]

The following pics are the aftermath of a run that I did over the weekend. The gasket blew on a pass. I launched the car (felt real good) then hit second (felt the power dropping off) and then boom. The gasket blew pissing out white smoke everywhere. I got temps pretty high. The temp was around 220 when I left the line. It shot passed 230 and when I lifted it was too late. I didnt hit more than 15lbs (cause I was on 91 octane) and it never spiked. I have been sharing some reason why I blew it with some local cats. I can agree that it ran lean and let go. Does anyone else have an idear as to why it might have went?

LEFT SIDE HEAD GASKET

LEFT SIDE HEAD

RIGHT SIDE GASKET

Is it normal to not have exhaust gaskets at the head if you have ATR headers?

 

[Slow91z]

1st and foremost I would never race a Buick that was showing 220 on the temp gauge. Just asking for it to knock.

Stock didn't have gaskets on the headers and I don't run them on ATR's either...Others do, but with no gasket there's nothing to blow out, smear a little high temp copper silicone on em before you bolt them up and you're good to go.

 

[davidf]

220 at launch? I would've uturned for the pit.

 

[mr go fast]

Yeah it was a jack ass move. Lesson learned.

 

[XXQUICK6XX]

For ATR's I run fel pro 1400 exhaust gaskets.

Steve

 

[Nick Micale]

Well, I see a couple of reasons for this disaster.

To start a high timing chip burned for race gas and you had crap, alleged 91 octane gas, temp way higher than normal at the line, probably heat-soak from other runs and driving to the track.

This is an excellent recipe for pre-ignition which is more damaging than detonation, and you are lucky the safety valves, head gaskets, gave away instead of pistons. Hard to believe the rod bearings did NOT get hammered too.

We see detonation on an almost stock street car with junk 91 octane gas at 14 #'s of boost in cool weather.

Hard lesson to learn, but many of us have been there, so go at it again when it is together, BUT use race gas so you have a margin of error in your favor!

 

[charlief1]

Um...Pre-ignition is the same as detonation Nick.:biggrin:

 

[Nick Micale]

Um...Pre-ignition is the same as detonation Nick.:biggrin:

Sorry Charlie, but where I went to school for 4 years and specialized in automotive and engine design, we were taught they are 2 different situations brought on by different conditions.

I will not define or discuss them here, as this is easily verified with a simple internet search.

 

[Nick Micale]

Here it is for those that do not care to search:

Knocking (also called knock, detonation, spark knock, pinging or pinking) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front. The fuel-air charge is meant to be ignited by the spark plug only, and at a precise time in the piston's stroke cycle. The peak of the combustion process no longer occurs at the optimum moment for the four-stroke cycle. The shock wave creates the characteristic metallic "pinging" sound, and cylinder pressure increases dramatically. Effects of engine knocking range from inconsequential to completely destructive. It should not be confused with pre-ignition (or preignition), as they are two separate events.


Pre-ignition (or preignition) in a spark-ignition engine is a technically different phenomenon from engine knocking, and describes the event wherein the air/fuel mixture in the cylinder ignites before the spark plug fires. Pre-ignition is initiated by an ignition source other than the spark, such as hot spots in the combustion chamber, a spark plug that runs too hot for the application, or carbonaceous deposits in the combustion chamber heated to incandescence by previous engine combustion events.


The reason pre-ignition is so damaging is that occurs before the spark when the piston is moving up, and the pre-ignition explosion hits the piston like a giant sledge hammer.

 

[mr go fast]

youtube.com/watch?v=fL20phTQW6w

 

[charlief1]

Knocking (also called knock, detonation, spark knock, pinging or pinking) in spark-ignition internal combustion engines occurs when combustion of the air/fuel mixture in the cylinder starts off correctly in response to ignition by the spark plug, but one or more pockets of air/fuel mixture explode outside the envelope of the normal combustion front.

engine knocking, and describes the event wherein the air/fuel mixture in the cylinder ignites before the spark plug fires.

I know they're diffined differently but this sounds like the exact same thing to me. Both are ingintion that occurs not because of the spark plug.

 

[Nick Micale]

Well Charlie, like life experiences, timing is very important.

In the case of detonation, the spark ignites the mixture at the proper moment, but due to a hot spot in the combustion chamber, after it starts to burn, another flame front ignites. Most common cause due to lack of octane in the fuel.

Pre-ignition means just that, the mixture ignites BEFORE the spark, and BEFORE the piston is in the proper position to accept the timed combustion. This unplanned explosion hammers the piston/rod and tries to stop it from continuing it upward travel. This is why pre-ignition needs to be avoided, as it usually results in catastrophic failures.


Pre-ignition can be precipitated by not enough octane as it will cause hot spots in the cylinder/cc area. Only takes a split-second at 5-6000 RPM for multiple "hits" to do damage.

With the engine in question here, there is no normal signs of detonation. The piston tops would look like there were sandblasted or have small pits in them if so.

The safety valves, head gaskets, in this case really saved the engine from serious pre-ignition damage.

The pic below illustrates what happens when 14 bolts do not allow the head gasket to blow. But since there was so much force the weakest link broke - no. 5 and no. 6 rods. Took out the block, cam, valves, converter, trans and other parts.

Over the years, damage like this has been brought to, and discussed with many engineers and experts in the field to determine how and what happened.

In the case of this alum block, the unanimous opinion is pre-ignition. My opinion, same goes for the head gaskets here. My guess is that over the years, I have seen and been involved in MUCH more engine damage that you have, not all of it mine!

On a side note, that block has been repaired, machined, rebuilt and is a car being tested. :biggrin:

 

[pdzz]

Well Charlie, like life experiences, timing is very important.

In the case of detonation, the spark ignites the mixture at the proper moment, but due to a hot spot in the combustion chamber, after it starts to burn, another flame front ignites. Most common cause due to lack of octane in the fuel.

Pre-ignition means just that, the mixture ignites BEFORE the spark, and BEFORE the piston is in the proper position to accept the timed combustion. This unplanned explosion hammers the piston/rod and tries to stop it from continuing it upward travel. This is why pre-ignition needs to be avoided, as it usually results in catastrophic failures.


Pre-ignition can be precipitated by not enough octane as it will cause hot spots in the cylinder/cc area. Only takes a split-second at 5-6000 RPM for multiple "hits" to do damage.

With the engine in question here, there is no normal signs of detonation. The piston tops would look like there were sandblasted or have small pits in them if so.

The safety valves, head gaskets, in this case really saved the engine from serious pre-ignition damage.

The pic below illustrates what happens when 14 bolts do not allow the head gasket to blow. But since there was so much force the weakest link broke - no. 5 and no. 6 rods. Took out the block, cam, valves, converter, trans and other parts.

Over the years, damage like this has been brought to, and discussed with many engineers and experts in the field to determine how and what happened.

In the case of this alum block, the unanimous opinion is pre-ignition. My opinion, same goes for the head gaskets here. My guess is that over the years, I have seen and been involved in MUCH more engine damage that you have, not all of it mine!

On a side note, that block has been repaired, machined, rebuilt and is a car being tested. :biggrin:

You saved that block?? WOW!!! That thing looks like scrap metal. Nick, you are the man!!! Phil.