spark plug gap smashed under high boost and rpm?
Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
spark plug gap smashed under high boost and rpm?
hey guys,
i have not posted here in a long time...but anyways there was always a quesiton on my mind i could never get an answer for.....
here is the situation
one day i was doing some hot laps in the vette and in high boost 15psi and compression and rpm and when i got out of it the car would not run right and it even died...well i got it home and pulled the plugs and some of the plugs where closed like if the piston hit the plug and shut them or smashed them? so i regapped the plugs and cleaned them and the car ran fine?
but what could of caused that to happen? to high of a rpm or what? to much pressure in the cylinder? could there be bigger problems to the piston...etc things i will never know till i pull that motor and tear it apart? but the motor still works great and runs fine but i thought i would post.
Thanks Kevin
i have not posted here in a long time...but anyways there was always a quesiton on my mind i could never get an answer for.....
here is the situation
one day i was doing some hot laps in the vette and in high boost 15psi and compression and rpm and when i got out of it the car would not run right and it even died...well i got it home and pulled the plugs and some of the plugs where closed like if the piston hit the plug and shut them or smashed them? so i regapped the plugs and cleaned them and the car ran fine?
but what could of caused that to happen? to high of a rpm or what? to much pressure in the cylinder? could there be bigger problems to the piston...etc things i will never know till i pull that motor and tear it apart? but the motor still works great and runs fine but i thought i would post.
Thanks Kevin
Drifting
Joined: Nov 2003
Posts: 1,637
Likes: 2
From: Honeoye Ny
wow, kev. I must say that doesn't sound good. It could be 2 things
-foreign material went thru the motor.
-extreme detonation can smash the gap shut. But Im talking catastophic detonation, the kind she doesn't start back up over.
Id do a leakdown test and see if the downstairs took a hit. Was there alot of aluminum on the insulators?
-foreign material went thru the motor.
-extreme detonation can smash the gap shut. But Im talking catastophic detonation, the kind she doesn't start back up over.
Id do a leakdown test and see if the downstairs took a hit. Was there alot of aluminum on the insulators?
Melting Slicks
Joined: Jan 2002
Posts: 3,293
Likes: 79
From: Jackson MI
I'm pretty sure that too much timing/detonation will cause the plugs to be blown open. I've never herd of plugs being closed though. If you've re-gapped them and the engine ran fine after that I'm not sure what to tell you. couldn't be the piston hitting them or it would keep hitting them.
i'd almost say chalk it up to the underwear gnomes if it doesn't happen again. But that could be a bad thing in the long run.
i'd almost say chalk it up to the underwear gnomes if it doesn't happen again. But that could be a bad thing in the long run.
Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
Originally Posted by Baldturbofreak
wow, kev. I must say that doesn't sound good. It could be 2 things
-foreign material went thru the motor.
-extreme detonation can smash the gap shut. But Im talking catastophic detonation, the kind she doesn't start back up over.
Id do a leakdown test and see if the downstairs took a hit. Was there alot of aluminum on the insulators?
-foreign material went thru the motor.
-extreme detonation can smash the gap shut. But Im talking catastophic detonation, the kind she doesn't start back up over.
Id do a leakdown test and see if the downstairs took a hit. Was there alot of aluminum on the insulators?
as for aluminum on the insulatros the is a negative...just closed shut and dark carbon build up it looked like? i hope that is the right term?
but u know now that i think about it the car does have a very fant tick tick tick but you really have to listen my girlfriend thinks i am crazy cause i am like "CAN YOU EHAR THAT?? I HEAR A TICK TICK TICK" she is like your crazy
Drifting
Joined: Nov 2003
Posts: 1,637
Likes: 2
From: Honeoye Ny
Maybe there was such a carbon buildup on your pistons that they contacted the electrode. Pretty unlikely though. Did you check your whole intake system for anything missing/open?
The leakdown test is as follows
remove all plugs, remove all valve tension (thats right pullin the valve covers) it's a far better reading, and then you dont have to constantly turn the crank for the compression stroke.
One by one go thru the cyl (hot if possible) and record the reading at both tdc and bdc. then throw a few squirts of oil in the hole and do it again. If you get a drastic reading change then she's wore.
With the engine hot it should be <5% any serious engine damage will be obvious like more than 30% It will also tell you where it's leaking crankcase,intake,exhuast, etc.
The summit leakdown guage set is cheap and accurate. I ve got one it works great.
mn- I dunno man I had a 14-1 piston in my 200x, anytime Id mix the racegas/swill too weak it close the plug up on me. Perhaps it has more to do with the shape of the chamber. After all, detonation is an explosion that didn't start at the sparkplug gap.
The leakdown test is as follows
remove all plugs, remove all valve tension (thats right pullin the valve covers) it's a far better reading, and then you dont have to constantly turn the crank for the compression stroke.
One by one go thru the cyl (hot if possible) and record the reading at both tdc and bdc. then throw a few squirts of oil in the hole and do it again. If you get a drastic reading change then she's wore.
With the engine hot it should be <5% any serious engine damage will be obvious like more than 30% It will also tell you where it's leaking crankcase,intake,exhuast, etc.
The summit leakdown guage set is cheap and accurate. I ve got one it works great.
mn- I dunno man I had a 14-1 piston in my 200x, anytime Id mix the racegas/swill too weak it close the plug up on me. Perhaps it has more to do with the shape of the chamber. After all, detonation is an explosion that didn't start at the sparkplug gap.
Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
Originally Posted by lead foot 85 vet
what plugs are you running? sounds like there too long...if the piston was hitting the heads it would be more then a tic tic. were you been man?
As for where have i been i have been around i sold the blower off the vette and rolled that money into other things...But i am back on the forum and hoping to do bigger and better things like F-1 blower customer bracket and stand alone system.
but yeah i could never figure out how that happened i think that night the car was running super good i mean very mean and when the boost shot from 11psi to 15psi and going up i think the pressure was to great and it detonated and straight crushed the plugs and killed the car from starting....
cause after that i really never ran it hard like it did and the plugs are denso's i had for a long time and never had a problem with them and now that i think about it at the time i was running low octane and high timing and lots of boost and i would usaully run 100+ octane but for some reason i was running 85
but i will get that gauge from summit and do a leak down and see how things pan out!
Instructor
Joined: Apr 2005
Posts: 198
Likes: 0
Originally Posted by krivera
hey guys,
i have not posted here in a long time...but anyways there was always a quesiton on my mind i could never get an answer for.....
here is the situation
one day i was doing some hot laps in the vette and in high boost 15psi and compression and rpm and when i got out of it the car would not run right and it even died...well i got it home and pulled the plugs and some of the plugs where closed like if the piston hit the plug and shut them or smashed them? so i regapped the plugs and cleaned them and the car ran fine?
but what could of caused that to happen? to high of a rpm or what? to much pressure in the cylinder? could there be bigger problems to the piston...etc things i will never know till i pull that motor and tear it apart? but the motor still works great and runs fine but i thought i would post.
Thanks Kevin
i have not posted here in a long time...but anyways there was always a quesiton on my mind i could never get an answer for.....
here is the situation
one day i was doing some hot laps in the vette and in high boost 15psi and compression and rpm and when i got out of it the car would not run right and it even died...well i got it home and pulled the plugs and some of the plugs where closed like if the piston hit the plug and shut them or smashed them? so i regapped the plugs and cleaned them and the car ran fine?
but what could of caused that to happen? to high of a rpm or what? to much pressure in the cylinder? could there be bigger problems to the piston...etc things i will never know till i pull that motor and tear it apart? but the motor still works great and runs fine but i thought i would post.
Thanks Kevin
im guess you have forged pistons. i hhad this same problem on a 383 with a wieand roots blower on top. motor made 650 hp at 14lbs. it was my track truck. i use to smash the plugs shut when i would shut off the water injection. actually when it ran dry, it is from detonation for sure 100%. im new at this site so i know im not very creditable but ive had 4 blower setups in my c1500 truck and detonation on a mild level(not enought to break a forged piston but would of already melted anything less) causes the plugs to smash. two ways to fix it, go colder with the plugs. i ran ngktr10s. or you can lower boost and or timing. id go as cold as possible on the plugs first. it worked for me. goodluck with it
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Safety Car
Joined: Apr 2001
Posts: 3,525
Likes: 2
From: Houston TX
Originally Posted by krivera
... and when the boost shot from 11psi to 15psi and going up i think the pressure was to great and it detonated and straight crushed the plugs and killed the car from starting ...
Aaron
Melting Slicks
Joined: Dec 2000
Posts: 2,719
Likes: 60
From: Fremont Oh
Originally Posted by AKS Racing
What caused the boost to jump? If I remember correctly, you were running a D1 on an L-98 with a 6 rib. Many on this forum would love to know what you did to gain an additional 4 psi.
Aaron
Aaron
He took it up to 9000 feet!
Just kidding ... Hi Kev!
Mo
Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
Originally Posted by Mo_Bandy
He took it up to 9000 feet!
Just kidding ... Hi Kev!
Mo
Just kidding ... Hi Kev!
Mo
just kidding
and yes D-1 on a L98 383ci...i swapped out the belt and took some VHT and placed it on a new sticky belt and had that tensioner as tight as possible and first run.....
ZZZZZZZZZZZZZzIIIIIIIIIIPPPPPPPPPP what the 15PSI holy crap! wait car is dying what the hell, belt must have broke.....
it only did it maybe 3 times and yes i have forged internals....oh and yes i called denso and they said a colder plug would of fixed the issue from being to much pressure in the cylinder and causing dentonation and pre ignition
oh i got extra psi because i put in Mo-s intercooler!
man that was a nice intercooler loved that thing! thanks MO!
So tight **** 6 rib with vht and new belt got me 15psi at 6700rpmso that would be 19psi at sea level.
Melting Slicks
Joined: Dec 2000
Posts: 2,719
Likes: 60
From: Fremont Oh
Hey Kev
I love my friends on this forum....
~quickly scribbles notes~ So if I get an earthmover, pull 1400 feet of earth from the street I could get at least another 2 pounds that would put me at 13
~If I steal back the intercooler from Kev, that should put me at 14.5
Good to see you back my friend!
Mo
I love my friends on this forum....
~quickly scribbles notes~ So if I get an earthmover, pull 1400 feet of earth from the street I could get at least another 2 pounds that would put me at 13
~If I steal back the intercooler from Kev, that should put me at 14.5
Good to see you back my friend!
Mo
Supporting Vendor
Joined: Oct 2004
Posts: 761
Likes: 68
KRIVERA, My opinion you detonated. Detonation will close the plug gap everytime. Take a hard look at the plugs under a magnifier and I'm pretty sure you will see the telltale signs of detonation. If you were running the cast pistons you'd be smokin' !!! If you tear the engine down at some point the upper half of the rod bearings will tell the story. Regards Greg
Race Director
Joined: Dec 2004
Posts: 14,172
Likes: 30
From: Millet Alberta
St. Jude Donor '17-'18
Originally Posted by BlowerWorks
KRIVERA, My opinion you detonated. Detonation will close the plug gap everytime. Take a hard look at the plugs under a magnifier and I'm pretty sure you will see the telltale signs of detonation. If you were running the cast pistons you'd be smokin' !!! If you tear the engine down at some point the upper half of the rod bearings will tell the story. Regards Greg
I just had to rebuild my motor... Number 8 plug was smashed, leakdown led to a rebuild... Upon removal of the heads we found SEVERE detonation pitting of 3 pistons, with number 8 piston missing a chunk off of the top (between the top of the piston and the top ring). $11,500 CAN later, she's running strong again...
PS: I was running a small (100 hp) shot of nitrous...
PPS: I was also over-revving at around 7000 RPM
Last edited by mtnman; Sep 21, 2005 at 10:27 AM. Reason: Missed some data...
Le Mans Master
Joined: Oct 1999
Posts: 6,366
Likes: 34
Originally Posted by mtnman
I just had to rebuild my motor... Number 8 plug was smashed, leakdown led to a rebuild... Upon removal of the heads we found SEVERE detonation pitting of 3 pistons, with number 8 piston missing a chunk off of the top (between the top of the piston and the top ring). $11,500 CAN later, she's running strong again...
PS: I was running a small (100 hp) shot of nitrous...
PPS: I was also over-revving at around 7000 RPM
I lost power and had issues with keeping the car running one day out of no where. I was not even getting on the gas. first thing I did was remove a spark plug and saw it was smashed into the center. I though oh ****. Pulled the intake and found metal in it. pulled the heads and saw #1 lifted the ring land, and fed it to all the other cylinders. my bores look perfect, pistons are all pitted, heads are in need of some serious work.
Thread Starter
Drifting
Joined: Feb 2002
Posts: 1,937
Likes: 2
From: Arvada CO
Originally Posted by bill mcdonald
I lost power and had issues with keeping the car running one day out of no where. I was not even getting on the gas. first thing I did was remove a spark plug and saw it was smashed into the center. I though oh ****. Pulled the intake and found metal in it. pulled the heads and saw #1 lifted the ring land, and fed it to all the other cylinders. my bores look perfect, pistons are all pitted, heads are in need of some serious work.
that looks pretty ugly...but yeah i hear you! yeah i had a friend with a N/A motor that had the same thing on a Super high compression motor and bad tuning i will have to pass the information on to him! thanks agian and yeah i really need to start giving my vette some love and show these new guys in there C6 who is boss hog dog on the block!
