Cavitation?

[forged00]

Pulled the long block (04 cobra longblock) out of my car after stretching the head bolts from too much boost (23-24psi). After pulling the heads I noticed the gasket on the drivers side looks burnt. (The drivers side was smoking the worst). The gaskets themselves don't look blown.

On pistons 7 & 8 there's a large amount of putting. Some on 7 and 8 is done for. Would this have been caused by the coolant being ignited in the cylinders?
Piston #8

Piston #7

Also, found this in my oil pan. Lol anyone have any idea what it's from?

 

[01yellercobra]

Coolant doesn't ignite. That's all from detonation. As for the piece of metal, are there any chunks missing from the bottom of your block?

 

[forged00]

Coolant doesn't ignite. That's all from detonation. As for the piece of metal, are there any chunks missing from the bottom of your block?

I know coolant wasn't flammable, but was just curious if it caused the cavitation from under pressure. What would cause just those two cylinders to detonate? And I haven't seen anything missing off the bottom of the block. I'll be able to get a better look tonight when I got home. I got to this point yesterday after it was already dark

 

[01yellercobra]

Cylinders 7 and 8 are known to run hot. That's why a lot of people run the cooling mod. Cavitation is a pump issue. Fuel won't cavitate inside a cylinder. What's your fuel system set up? I'm guessing race gas with your boost level?

 

[forged00]

Cylinders 7 and 8 are known to run hot. That's why a lot of people run the cooling mod. Cavitation is a pump issue. Fuel won't cavitate inside a cylinder. What's your fuel system set up? I'm guessing race gas with your boost level?

Unfortunately I didn't have the head cooling mod. Fuel wise I was running 93 plus torco, but I can't vouch for the previous owner. The car was abused before me so I'm having to take care of all the shortcuts he took.

So it looks like he was running this thing at high boost, on low octane, with no head cooling mod. Fortunately all of those will be fixed with the new shortblock. I'm assuming that those two pistons are trash?

 

[Blueline]

Yeah def detonation in those cylinders. When coolant passes into the cylinder, it will steam clean the tops of the Pistons and they will look shiny and new.

 

[01yellercobra]

Unfortunately I didn't have the head cooling mod. Fuel wise I was running 93 plus torco, but I can't vouch for the previous owner. The car was abused before me so I'm having to take care of all the shortcuts he took.

So it looks like he was running this thing at high boost, on low octane, with no head cooling mod. Fortunately all of those will be fixed with the new shortblock. I'm assuming that those two pistons are trash?

Ouch. That's a recipe for disaster. Yes they are. But the bright side is you can bump the compression now. Are you wanting to keep it at 23psi?

 

[forged00]

Plan was to sell this shortblock, build a teksid with a 10:1 compression, sell the blower kit and just drive it N/A for a while while I sell my daily and get a new daily and also I piece together a twin kit. Looks like I'll just have to salvage the crank and rods from this, get new pistons, and go from there. I've already picked up a teksid block

 

[01yellercobra]

If you're gonna end up boosting it again plan for it now. Are you going to run E85 or will you want to be able to run it on pump gas?

 

[forged00]

If you're gonna end up boosting it again plan for it now. Are you going to run E85 or will you want to be able to run it on pump gas?

I'll run both. The fuel system I have now will handle e85 once I get the injectors. I sold my 60lbs injectors so now I'm upgrading. Would 105's be too much for an NA motor?

 

[Lightning&Mach1]

That piece of metal looks to be off a secondary cam gear.

 

[forged00]

That piece of metal looks to be off a secondary cam gear.

I'll be home in a few hours. I'll give the whole thing a good look over

 

[01yellercobra]

I'll run both. The fuel system I have now will handle e85 once I get the injectors. I sold my 60lbs injectors so now I'm upgrading. Would 105's be too much for an NA motor?

They shouldn't be if they're good injectors. If you think about it you're running N/A when out of boost.

 

[forged00]

They shouldn't be if they're good injectors. If you think about it you're running N/A when out of boost.

True. I'm building this shortblock based on boost in the future. All forged with either 9.5-10:1 CR which will be perfect for a twin set up later on and will allow me to run N/A for now.

I noticed on my passenger side bank that I had some valve contact with the pistons, but only on the passenger side. I know if I bump my CR up it will also risk having more PTV issues. I'm only running stage 2 crower cams, so I shouldn't be having valve contact unless my timing is, or was off, correct?

 

[Steve@Tasca]

That piece of metal looks to be off a secondary cam gear.

Chunk of a timing gear was going to be my guess, I'm not that familiar with them hands on to be as specific as you though. :thumbsup:

-Steve

 

[01yellercobra]

Now I'm curious to see if that's a piece of gear and what side it's from since there's been PTV contact.

 

[forged00]

Chunk of a timing gear was going to be my guess, I'm not that familiar with them hands on to be as specific as you though. :thumbsup:

-Steve

I don't think this is a thumbs up type of situation. Haha
I thought for it to be a tooth off something as well, but haven't noticed anything.

Now I'm curious to see if that's a piece of gear and what side it's from since there's been PTV contact.

From what I could see there's no teeth missing off the cam gears or the crank timing gear. I only had about an hour to work on it last night and I spent the whole time fighting a stupid rounded off motor mount bolt (that I still haven't been able to get off)


Whenever I bought the car I was told it was a stock 04 longblock that was in the car. Whenever I was looking at it last night I noticed that it wasn't the the same pistons that I've seen in terminator blocks before and also the Manley rods didn't have the SVT writing on the opposite side of the H beam. They're still Manley H Beams, but I can't seem to find a part number on them.

Ran the part number on the Pistons and found out they're actually Wiseco.

Also found out that it had arp main studs as well

It's a shame I those two pistons aren't usable anymore, this thing was already stout to begin with!

 

[Steve@Tasca]

I don't think this is a thumbs up type of situation. Haha
I thought for it to be a tooth off something as well, but haven't noticed anything.

Thumbs up was strictly to recognize Lightning&Mach1's knowledge.

Obviously not a thumbs up for your situation. Since the engine was obviously apart before I wonder if that chunk of gear is from a previous failure and they somehow missed it when doing the work.

-Steve

 

[forged00]

Thumbs up was strictly to recognize Lightning&Mach1's knowledge.

Obviously not a thumbs up for your situation. Since the engine was obviously apart before I wonder if that chunk of gear is from a previous failure and they somehow missed it when doing the work.

-Steve

I was kidding. I know you guys are here to help, and I'm thankful for that.