Pulling back the Magic Curtain
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Sucks, I hope you get it resolved. I don't get the valve clearance issue. The car would've made some terrible noises and not been really driveable with the valves hitting the pistons. But I agree, the engines should be built and run well from the get go.
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Quite sure the marks on the pistons are not valve strikes. Looks machined,.. just a tad rough at the bottom (as if he took 3 passes at varying depths?). Not smoothing it out leaves the compression higher,.. but opens the possibility of hot spots forming at high load. Not sure if this is an issue here or not.
As for the valve stem seals,.. it could also be the case they they are the wrong ones. If they don't fit snugly over the valve guides,... they could get more "grip" on the stem than the guide,.. and work their way up the stems when the engine is run.
As for the valve stem seals,.. it could also be the case they they are the wrong ones. If they don't fit snugly over the valve guides,... they could get more "grip" on the stem than the guide,.. and work their way up the stems when the engine is run.
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Sorry to hear about this, op.
This is another reminder to me that digging into the internals in this car is not a "no-brainer" by any means. I'm having my engine dropped for coolant line change and a few other things. I was then toying with the idea of pinning the camshafts. Then I started toying with the idea of changing rods. There's a local guy who looks after the engines for the Porsche cup cars and has some expertise. But after reading this thread it seems like expertise isn't necessarily enough to guarantee a good outcome. At this point I figure my power needs don't really justify going beyond the basic repairs I'm doing so I'll leave the block alone, unless I did actually damage the head gasket but hopefully not...
This is another reminder to me that digging into the internals in this car is not a "no-brainer" by any means. I'm having my engine dropped for coolant line change and a few other things. I was then toying with the idea of pinning the camshafts. Then I started toying with the idea of changing rods. There's a local guy who looks after the engines for the Porsche cup cars and has some expertise. But after reading this thread it seems like expertise isn't necessarily enough to guarantee a good outcome. At this point I figure my power needs don't really justify going beyond the basic repairs I'm doing so I'll leave the block alone, unless I did actually damage the head gasket but hopefully not...
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Quite sure the marks on the pistons are not valve strikes. Looks machined,.. just a tad rough at the bottom (as if he took 3 passes at varying depths?). Not smoothing it out leaves the compression higher,.. but opens the possibility of hot spots forming at high load. Not sure if this is an issue here or not.
As for the valve stem seals,.. it could also be the case they they are the wrong ones. If they don't fit snugly over the valve guides,... they could get more "grip" on the stem than the guide,.. and work their way up the stems when the engine is run.
As for the valve stem seals,.. it could also be the case they they are the wrong ones. If they don't fit snugly over the valve guides,... they could get more "grip" on the stem than the guide,.. and work their way up the stems when the engine is run.
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997TT SilverSpool - 210.8 mph 1/2 Mile WR Apr 2019, 9.2 @ 168 mph 1/4 Mile Manual World Record , 3.15 60-130 mph , 2.72 100-150 mph , 1400whp E85
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#TeamAIM
997TT SilverSpool - 210.8 mph 1/2 Mile WR Apr 2019, 9.2 @ 168 mph 1/4 Mile Manual World Record , 3.15 60-130 mph , 2.72 100-150 mph , 1400whp E85
996TT SpoolBus - 204.6 mph 1/2 Mile 996TT WR Aug 2018, 9.5 @ 154 mph, 3.23 60-130 mph, 2.5 100-150 mph Manual Porsche World Record, 1400whp E85
997TT SlowBerry - 205.0 mph 1/2 Mile WR Nov 2018, 9.7 @ 170 mph 1/4 Mile , 3.2 60-130 mph , 2.4 100-150 mph , 1420whp E85
ESMOTOR | DO88 | TPC DSC | SYVECS | COBB | IPD | KLINE | XONA | AMS | ID | ERP | SACHS | TURBOSMART | CSF | DODSON |
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I'm sorting through the nightmare of the heads as we speak. John has reached out to me, but an assessment of exactly what is damaged is still being done. A full heads rebuild needs to be done.
It's not a question of "if something" was hitting the pistons. I know what they looked like before they went in, and what they look like now. The valves WERE hitting the pistons and IT IS because of how the reliefs were cut. I will fix the pistons, but they should have been done right when the clearancing was done.
I will update this thread with details of everything that was done incorrectly. It's important for everyone to know. I wish I had this information when I was doing my engine last time.
It's not a question of "if something" was hitting the pistons. I know what they looked like before they went in, and what they look like now. The valves WERE hitting the pistons and IT IS because of how the reliefs were cut. I will fix the pistons, but they should have been done right when the clearancing was done.
I will update this thread with details of everything that was done incorrectly. It's important for everyone to know. I wish I had this information when I was doing my engine last time.
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So that roughness at the bottom of the relief was not there before putting it all together?
They do look strange, like why weren't they cut to the same depth as the original or why they didn't follow the lines of the original reliefs?
I am very curious about the valves. Did they show damage on their edges? And I wonder what you will find as far as bends when you get the head evaluation finished.
They do look strange, like why weren't they cut to the same depth as the original or why they didn't follow the lines of the original reliefs?
I am very curious about the valves. Did they show damage on their edges? And I wonder what you will find as far as bends when you get the head evaluation finished.
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Zero, but about 20+ working on engines. I understand these cars well. The car should work well day 1 period. Little issues aside (understandable), it's an engine. What the OP posted clearly isn't a case of "these motors are never right the first time".
You don't build your own no?
You don't build your own no?
Last edited by s65e90; Jan 3, 2018 at 03:29 PM.
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Zero, but about 20+ working on engines. I understand these cars well. The car should work well day 1 period. Little issues aside (understandable), it's an engine. What the OP posted clearly isn't a case of "these motors are never right the first time".
You don't build your own no?
You don't build your own no?
The engine was not built by John, I think he just supplied the heads and machined the valve pockets. In the end it is the responsibility of the one building the engine. He built it hemself, he might have set the camshaft timing wrong or something different, Who assembles an engine with out checking clearance.That is a huge amount of trust to put into a machine shop And yes any 1000hp+ build on any platform will have problems to be sorted out. From a small water leak to fuel system problem to more severe issues like head sealing or defective turbo. A simple connecter kept me baffled for days. Why is there a misconception that you can just get the parts and throw them together and have a perfect build. You can do that but you also have to do your home worke by religiously checking every part No professional builder would assemble an engine before checking every part he gets from a machine shop for fittment and size. This guy assembled his own engine but surely did not do it professionally
Last edited by Shadigt3; Jan 3, 2018 at 05:02 PM.
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The engine was not built by John, I think he just supplied the heads and machined the valve pockets. In the end it is the responsibility of the one building the engine. He built it hemself, he might have set the camshaft timing wrong or something different, Who assembles an engine with out checking clearance.That is a huge amount of trust to put into a machine shop And yes any 1000hp+ build on any platform will have problems to be sorted out. From a small water leak to fuel system problem to more severe issues like head sealing or defective turbo. A simple connecter kept me baffled for days. Why is there a misconception that you can just get the parts and throw them together and have a perfect build. You can do that but you also have to do your home worker by religiously checking every part No professional builder would assemble an engine before checking every part he gets from a machine shop for fittment and size. This guy assembled his own engine but surely did not do it professionally
That was my only point. Doesn't matter if it's a Porsche big HP build or a lawn mower engine, checking clearance is rudimentary. I sincerely hope you get it sorted. The man seems to have a good track record as evidenced here.
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John has built over 100 996/7TT engines and let's not forget the 1800hp that broke bunch of records. I recently got my Cayenne turbo with full engine build 5L back from John and the car runs flawlessly. It did take longer then expected but I shipped him the car to handle all aspects and couldn't be happier. I'm sure that it will all get sorted out op. There is a reason why everyone that's worked with him is backing him up. Your car will be a monster soon!