Melted a piston - unsure why.
06-29-2018, 09:07 PM
#1
Teching In
Thread Starter
Join Date: Jun 2018
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
Melted a piston - unsure why. Hello, new to the site and I need some help. I have a single turbo 78/75 billet camaro, 3 bar factory computer setup. Had the car running 3-4 months now on 6#, and then 9# and all was well. Turned it up to 11# and melted the top edge of #1 piston and it blew down through the side of both rings and through the whole piston.
timing was 11* through peak tq up to 5k then ramped up to 14* to shift point.
Iat was 102 at the start of the pull and ended at 152*
11.2 afr but it did creep to 11.5 around 6,000 rpm and the. Start to go back to 11.2 at shift point.
Pump gas 91 octane, 3” exhaust dumped, 2.:5 hotside
did it do it because it went slightly lean coupled with high Iats? Help me out here. Will post a picture tonight. 9.8:1 comp
timing was 11* through peak tq up to 5k then ramped up to 14* to shift point.
Iat was 102 at the start of the pull and ended at 152*
11.2 afr but it did creep to 11.5 around 6,000 rpm and the. Start to go back to 11.2 at shift point.
Pump gas 91 octane, 3” exhaust dumped, 2.:5 hotside
did it do it because it went slightly lean coupled with high Iats? Help me out here. Will post a picture tonight. 9.8:1 comp
06-29-2018, 09:08 PM
#2
Teching In
Thread Starter
Join Date: Jun 2018
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
Hello, new to the site and I need some help. I have a single turbo 78/75 billet camaro, 3 bar factory computer setup. Had the car running 3-4 months now on 6#, and then 9# and all was well. Turned it up to 11# and melted the top edge of #1 piston and it blew down through the side of both rings and through the whole piston.
timing was 11* through peak tq up to 5k then ramped up to 14* to shift point.
Iat was 102 at the start of the pull and ended at 152*
11.2 afr but it did creep to 11.5 around 6,000 rpm and the. Start to go back to 11.2 at shift point.
Pump gas 91 octane, 3” exhaust dumped, 2.:5 hotside
did it do it because it went slightly lean coupled with high Iats? Help me out here. Will post a picture tonight. 9.8:1 comp
timing was 11* through peak tq up to 5k then ramped up to 14* to shift point.
Iat was 102 at the start of the pull and ended at 152*
11.2 afr but it did creep to 11.5 around 6,000 rpm and the. Start to go back to 11.2 at shift point.
Pump gas 91 octane, 3” exhaust dumped, 2.:5 hotside
did it do it because it went slightly lean coupled with high Iats? Help me out here. Will post a picture tonight. 9.8:1 comp
also my first thought was an injector, since it hurt #1 piston but not 7, had them flowed and #1 injector is flowing 9cc more than #7, so I’m at a loss.
06-30-2018, 03:47 PM
#4
06-30-2018, 04:08 PM
#5
Teching In
Thread Starter
Join Date: Jun 2018
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
Hey guys, thanks for the replies. I’m running br7ef plugs, and factory ls1 intake and rails. I’m skeptical that too little ignition timing could have caused this, but I’m not a professional tuner. I’m not sure what to think here.
06-30-2018, 04:46 PM
#6
Completely disagree. You need low advance at peak torque, especially on 91 octane, it melted a piston I.e. the combustion temps were too high.....I think 11 psi, 91 octane, 15 degrees and 11.5 AFR on 91 octane, I'm not surprised it blew. Too lean and too much timing for that boost and octane.
Trending Topics
06-30-2018, 08:11 PM
#9
Teching In
Thread Starter
Join Date: Jun 2018
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
Yes stock ls1, I should also mention it bent the connecting rod slightly, so I’m certainly leaning towards detonation. 14* at 11# is too much for 91 octane? The internet sucks, I sure see a lot of conflicting information and it makes it very hard to decide on who to believe. I’m trying to stay away from meth, I might buy a Garret intercooler to help.
06-30-2018, 08:37 PM
#11
Yes stock ls1, I should also mention it bent the connecting rod slightly, so I’m certainly leaning towards detonation. 14* at 11# is too much for 91 octane? The internet sucks, I sure see a lot of conflicting information and it makes it very hard to decide on who to believe. I’m trying to stay away from meth, I might buy a Garret intercooler to help.
06-30-2018, 10:07 PM
#12
With only 91 octane, you would really benefit from water/meth. I run 18* @13-14 lbs on 93 with 50/50 water meth with no knock. This is on a gen 4 SBE. My compression is only 9.6 to1 though. I think your a full point higher .I’m able to do this because of the water lowering combustion temps. Also my IATs are low. 25* over ambient.
Buddy of mine has a 99 c5 with a vortech 15*@10lbs boost running 93 with an alky control 100% meth
Buddy of mine has a 99 c5 with a vortech 15*@10lbs boost running 93 with an alky control 100% meth
06-30-2018, 10:57 PM
#13
Staging Lane
Join Date: Jul 2016
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Low timing and rich mixture melts pistons. Low timing builds heat in the cylinders. I run 19° timing and any lower than 11.7afr and I get a rich miss. What does the plug show? Excessively rich will burn between the rings, lift lands, and melt the heads, pistons and burn gaskets.
07-01-2018, 11:36 AM
#14
Iats a pretty high and 91 pump prob the issue. 93 pump and I run 16-17* at 10psi and spray 50/50 or wiper fluid and a FMIC.
Sounds like your intake cooling is not up to the task. My IATs are in the 90-115* range with 80+ outside temps before the meth even kicks on.
Sounds like your intake cooling is not up to the task. My IATs are in the 90-115* range with 80+ outside temps before the meth even kicks on.
07-01-2018, 01:03 PM
#16
FormerVendor
iTrader: (1)
Join Date: Nov 2008
Location: Santa Ana, CA. USA
Posts: 2,157
Likes: 0
Received 16 Likes
on
16 Posts
High EGT = Piston Damage Hi Loud Mouse, yes YOU are correct AND a measurement of EGT is easy.
NO AFTERCOOLER ???
This too ADDS EGT increases.
SURE detonation can be a result of a bad tune AND the added information provided by the OP points to that broken piston, NOT a MELTED piston. ( OP's Question)
BUT/INSTALL an EGT Gauge.
A HIGH EGT is a result of a too low Spark Instant.
WHAT is your EMAP at 11 .lbs ?
WHERE is your EGO/UEGO sensor located ?
MY tune target is from .866 -.902 Lambda AND finding the lowest EGT, found with CORRECT Spark Advance.
Lance
NO AFTERCOOLER ???
This too ADDS EGT increases.
SURE detonation can be a result of a bad tune AND the added information provided by the OP points to that broken piston, NOT a MELTED piston. ( OP's Question)
BUT/INSTALL an EGT Gauge.
A HIGH EGT is a result of a too low Spark Instant.
WHAT is your EMAP at 11 .lbs ?
WHERE is your EGO/UEGO sensor located ?
MY tune target is from .866 -.902 Lambda AND finding the lowest EGT, found with CORRECT Spark Advance.
Lance
07-01-2018, 01:43 PM
#17
Teching In
Thread Starter
Join Date: Jun 2018
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
I didn’t change my timing from 6# all the way up to 11#, so if it’s because it was undertimed, why didn’t it hurt anything when it was only on 6-8#? Plugs I can’t tell, they are old. Will do some checking with a new set. I also believe it was from 91 and high iats, but here also , I literally have to pick who I believe and hope it works. 19* on pump gas 91 sounds a little silly unless it’s kind 4# to me...
