Can these cylinders and heads be repaired?

[Mike930Euro]

Had a major failure during Dyno tuning last week. Still unsure of the exact cause. Appears that #6 ran lean. Blew a chunk out right between the barrel and head. Can these parts be saved or will they need to be replaced? Any recommendations? Any help will be greatly appreciated. Thanks in advance.

[Tippy]

Was cylinder 5 cleaned up, or did it appear that way after disassembly?

If untouched, cylinder 5 looks like it went lean.

Which cylinder shows aluminum speckling? That's your lean cylinder.

Anything is reparable, but is it worth it? It will have to be PERFECTLY clean during welding, machined, then related X's 2.

[billybek]

Wow, that sucks...
No input on this but will be interested to hear what the experts say.

[SoyRacer]

The cylinders are good for kitchen ladle/spoon holders. (They're wasted)

The cylinder heads could be welded and machined but to have them properly tig welded and then machined would be more expensive than just buying a pair of heads.

A shame too. It looks like they were nice heads. Check the fuel pressure regulators as it looks like you were running a Carrera manifold.

[boosted79]

Ouch, sorry to see that. I think the heads could be built up with TIG and machined but the welded section would not have the strength of the rest of the RR350 alloy used in the turbo heads. I don't know about the jugs, they could be TIG'd ok and machined, not sure if they would still be dimensionaly correct after though. Both would have to be preheated in an oven prior to welding so as soon as the arc is struck the pool forms. The #6 plugs def. look lean, what intake manifold do you have?

Looks like the 930 pancake manifold based on stud length?

[Mike930Euro]

Originally Posted by Tippy

Was cylinder 5 cleaned up, or did it appear that way after disassembly?

If untouched, cylinder 5 looks like it went lean.

Which cylinder shows aluminum speckling? That's your lean cylinder.

Anything is reparable, but is it worth it? It will have to be PERFECTLY clean during welding, machined, then related X's 2.

Nothing was touched, just removed and put aside. The reason why I believe #6 went lean is because the spark plug is melted.

[Mike930Euro]

Originally Posted by boosted79

Ouch, sorry to see that. I think the heads could be built up with TIG and machined but the welded section would not have the strength of the rest of the RR350 alloy used in the turbo heads. I don't know about the jugs, they could be TIG'd ok and machined, not sure if they would still be dimensionaly correct after though. Both would have to be preheated in an oven prior to welding so as soon as the arc is struck the pool forms. The #6 plugs def. look lean, what intake manifold do you have?

Looks like the 930 pancake manifold based on stud length?

I do have the stock pancake manifold. The jugs are Carrera 3.2 matched with JE 8.0:1 98mm pistons.

[boosted79]

"because the spark plug is melted."

That's what I thought but wasn't sure. The ground electrode is gone on the right plug and bits of metal on the head around it?

[boosted79]

Does the #6 head have the same miles on it as the other two? If so that has been running lean for a long time based on how clean the chamber is compared to the other two. were you just doing a pull or tuning ? How much boost were you at when it failed? I'm interested because I am looking at 3.4 twin plug also with 8:1. Did you CC the chambers to verify it was truly 8:1 with the 3.2 pistons and 930 heads? How about ignition timing?

[tctnd]

Have the injectors tested.

[Tippy]

Originally Posted by Mike930Euro

Nothing was touched, just removed and put aside. The reason why I believe #6 went lean is because the spark plug is melted.

It looked like it torched 5. That is wild!

[Mike930Euro]

Originally Posted by boosted79

Does the #6 head have the same miles on it as the other two? If so that has been running lean for a long time based on how clean the chamber is compared to the other two. were you just doing a pull or tuning ? How much boost were you at when it failed? I'm interested because I am looking at 3.4 twin plug also with 8:1. Did you CC the chambers to verify it was truly 8:1 with the 3.2 pistons and 930 heads? How about ignition timing?

Please excuse my ignorance on knowledge about the specifics but I am the owner of the car and not the mechanic who has done the work nor tuning. I will tell you as much as I know about it..

The engine was rebuilt less than a year ago. The stock heads were sent out to JB racing in Tavares, FL to be machined and twin plugged. The 3.2 Carrera jugs were sent out with one of the new Pistons to be matched up. I don't remember the name of the place they were sent to at the moment. I had put roughly 800 miles on the car when I noticed oil leaks on cylinders 5 and 6 at the seals where the jugs meet the case. The car was in much need of a tune as it has not been tuned since 8 years ago when it was converted to EFI. The heads were torqued down and the next day the tuner came up from S. Florida to tune the car. He checked everything on the car and we did some tuning on the highway before taking it to a local Dyno later that day. There were some issues with the Dyno shaking and vibrating and not giving accurate readings. He did 3 to 4 pulls at 1.0 bar and everything seemed ok. The boost was set to 1.2 bar and on the second pull is when it blew the cylinder.
The tuner is telling me the cylinder shifted and it could've been a bad head stud since it was leaking oil at the base. My mechanic is telling me it could be due to the tune or injector failure. That's all I know at this time. Hope that helps. All this has me so stressed it's not even funny. [sigh]

[Mike930Euro]

Originally Posted by tctnd

Have the injectors tested.

That's the next step. I will be taking them to get flow tested tomorrow. The funny thing is, they were cleaned and tested while the motor was being rebuilt.

[boosted79]

That would stress anyone out. Your best bet i think is find a couple used 3.2 jugs and call Xtreme Cylinder Heads in Palm City and send them the pics and see what they say about the heads. If #5 and #6 were leaking oil at the base that would have contributed to the destruction at the jug/head surface. It looks like the heads were O-ringed too. How much experience does your tuner have with turbo Porsches? Get the injectors checked too, that #6 is most likely plugged some or not firing right. Good luck, it's only a hunk of metal. (easily said until your are the one with the hunk of metal)

[Alan L]

I see your P/Cs are a bit unusual, but I just bought a new single 3.3 P/C from EBS Racing (to complete a set). You could try them. Frankly while anything is possible I don't think it is worth the stress trying to repair those bits - especially with the stresses you are putting on that engine - long way from stock.
Comiserations.
Alan

[dap930]

I hope the tuner pulled some timing after going to twin plug. If the tuner did not pull timing that could have lead to detonation at the higher boost levels. But the failure looks more like a pre-ignition failure (melted parts) which might have been the result of the lean mixture and a hot spot. Detonation usually results in broken ring lands.

[Tippy]

Good point, not pulling out timing would have been a death sentence.

[cgarr]

I have welded up a lot of heads with bad sealing surfaces but nothing like this, would be interesting to try and bring them back to life, would have to surface all 6 after the repair:

[Mike930Euro]

Originally Posted by dap930

I hope the tuner pulled some timing after going to twin plug. If the tuner did not pull timing that could have lead to detonation at the higher boost levels. But the failure looks more like a pre-ignition failure (melted parts) which might have been the result of the lean mixture and a hot spot. Detonation usually results in broken ring lands.

I remember him checking timing before we went to the dyno. All he said was "timing looks good". Whether it was where it should have been, I do not know. I wish I did.

I would also like to add, both my mechanic and the tuner are no amateurs when it comes to Porsche. My mechanic has rebuilt quite a few motors with no problems like this and he's telling me my engine is possessed. He even offered to give me back what I have in labor and give someone else a shot at it. He can't seem to wrap his head around what's going on with it.

I have been waiting on the tuner for over a year to come from Pompano Beach. I had several people tell me he's excellent when it comes to these engines and he knows his stuff and it's worth it to spend the extra money and have him tune it.

Either way, I guess none of this really matters because either one or the other is probably responsible for what happened here. It's really frustrating when you spend $1200 to have a tuner come spend a day on your car and at the end of the day you end up with major damage and no idea who's at fault.

[boosted79]

This is probably a dumb question but was the tuner aware it's twin plug? Did he talk to the mechanic beforehand re. the mods?