# VRT Melted a piston, starting an investigation but anyone got any guesses?



## TwinScrew20v (Dec 25, 2003)

So a good high speed run was the death of my VR6T #6 piston...Started smokin from the crankcase about a week later (and got progressively worse, so I'm guessin it wasnt an isolated incident)









I need to check the injector wiring and spray pattern once its together, it had a slight misfire at idle, and I havent checked the plugs yet. But heres the quick list and details.

T04 60-1 P-trim on a .83 hot side
3in DP 2.5in exhaust
Stock pistons with a 9.5:1 spacer
Stock intake mani
MS1 extra
42 lb injectors
13psi
Stock coilpack/plug wires

So obviously the piston overheated, but theres no damage to the crown, I dont see any evidence of detonation (no sandblast lookin marks). And theres no damage to any other pistons. I did however turn the timing up two degrees up top and by my best guess this happened during an extended 4th and 5th gear run at up to 5500. The melted ring and ring land doesnt make sense without any of the tell tale detonation marks. Am I losin it and this is purely detonation? (BTW I never looked at the EGTs or AFs...given the closed course conditions )


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## radoman57 (Jan 16, 2007)

Happened to me too, only it was 4 pistons with broken ring lands with 1 piston looking like yours.
I think but not sure is that it is not enough ring gap for boost and some wear on the cylinder at the top end of the bore.


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## TwinScrew20v (Dec 25, 2003)

Yeah Id expect to see that with detonation, plus some sandblasting on the crowns. The more and more I think about it, Im going to have teh injectors sent out for cleaning testing and balancing. Its sounding like its a bad injector...Or the pump is giving up the ghost at high revs (and Im gonna wasp it too).


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## vr-vagman (May 15, 2010)

... strange! Always rear bank injectors get faulty!?


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## 'dubber (Jun 15, 2004)

How was it running after it melted, but before you took it apart, besides the crankcase puffing? How bad was vaccum fluctuating? What did the afr's do at idle? Sounds? I just want to know, if you can remember. 

Do you know what kind of max egts normally you had before changing the timing?

I know that advancing timing will raise combustion chamber temps pretty fast. 

(I just learned that last week on the internets. =). )


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## TBT-Syncro (Apr 28, 2001)

i'd guess egt, but thats just a guess.


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## HidRo (Sep 19, 2003)

What AFR were you running? 
I'm placing my money on lean condition, either injector faulty or lean mixture+high temps due to good high speed race


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## TwinScrew20v (Dec 25, 2003)

Well its been all figgered. The pump tested good...And it should have been performing fine for a 3bar FPR at 13psi...But there-in lie the problem. I had a 4bar installed. End of the rail ran out of oomph. Explains a lot of the wierdities Id been having with timing tho.

In the gran scheme it felt like had a mild missfire and ran a bit low on boost, and about 1-2in short on vacuum. But otherwise it was pretty consistent. The crankcase was the only signal anything was wrong (and then I beat it until other symptoms showed). Now its all a question of tossing in the Walbro I have or just goin for the 044. Either way itll get a surge tank...Its just all about funds now.


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## TwinScrew20v (Dec 25, 2003)

And EGTs were pretty constantly around 1250 tops (when it was safe to watch em...So up to 3rd )


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## HidRo (Sep 19, 2003)

TwinScrew20v said:


> And EGTs were pretty constantly around 1250 tops (when it was safe to watch em...So up to 3rd )


 Real man stare at gauges for at least 5s :laugh::laugh::laugh:


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## vr-vagman (May 15, 2010)

Unless you have 6 egt sensors, watching the average egt (before the turbo) is just for your.... comfort. Also if you have 6 egt probes installed they should be very carefully placed on different distance to head for the front and rear banks of cylinders. 
IMHO you also have made a mistake rising the advance... just like that! You need a dyno for/when changing the advance table. The temperature of all surfaces inside cyl go high during the long run on higher gear/load. The NA piston material and construction just cant accumulate and conduct so much heat. The piston face gets overheated. I guess the detonation initially just broke the ring land and then the ring bending has led to poor seal and combustion leak and melting. 
MS1 is not a good choise for VR engine. I'd advice to switch to MS3X at least. Even with te OEM manifold and compensated runner lenghts, your injectors still squirt fuel on different places for the front and rear banks and rear bank inlet runners are heated by the coolant/head temperature. Also there could be some small cooling isuues with rear bank cylinders, especially the farthest ones (4 and 6th) from the cooling pump. That's why using the MS3X with VR6 is very advisable, becuse you could trim the fuel and the advance individually on every cylinder. I believe the rear bank needs definitely correction in fueling and spark to avoid such damages. 
Hope that helps.


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## simple_man (Jun 18, 2006)

vr-vagman said:


> Unless you have 6 egt sensors, watching the average egt (before the turbo) is just for your.... comfort. Also if you have 6 egt probes installed they should be very carefully placed on different distance to head for the front and rear banks of cylinders.
> IMHO you also have made a mistake rising the advance... just like that! You need a dyno for/when changing the advance table. The temperature of all surfaces inside cyl go high during the long run on higher gear/load. The NA piston material and construction just cant accumulate and conduct so much heat. The piston face gets overheated. I guess the detonation initially just broke the ring land and then the ring bending has led to poor seal and combustion leak and melting.
> MS1 is not a good choise for VR engine. I'd advice to switch to MS3X at least. Even with te OEM manifold and compensated runner lenghts, your injectors still squirt fuel on different places for the front and rear banks and rear bank inlet runners are heated by the coolant/head temperature. Also there could be some small cooling isuues with rear bank cylinders, especially the farthest ones (4 and 6th) from the cooling pump. That's why using the MS3X with VR6 is very advisable, becuse you could trim the fuel and the advance individually on every cylinder. I believe the rear bank needs definitely correction in fueling and spark to avoid such damages.
> Hope that helps.


 That's some quality reply. WTF do you do for living? :thumbup:


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## vr-vagman (May 15, 2010)

Thanks man! Nothing special. That's my hobby.


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## TwinScrew20v (Dec 25, 2003)

Yeah MS3x is the better bet...But Im not shooting for a flawless every inch HP squeezed motor. MS2x is goin in once Im sure all is well after the run. The EGT is a rough estimate for proof of state...NEVER the end all be all for tuning. Sadly the timing table isnt even what killed the motor (Ive even got a similar reference car running 3 degrees more over 4500...But hea got more pump)...But the loss of fuel flow at my conditions. In the grand scheme of things, a LOT can be changed in the VR. Even the OEM fuel system is crap for the motors design, but its all rough fueling for power.

In the grand scheme...A new intake mani with a dual plenum, a front and rear bank fuel rail, and a length adjusted exhaust manifold is needed to make it all happy. But its a cheap toy (Sadly I have designs for the rails and intake mani...But my motivation is on an FSI Mk2 project that actually shows more promise for fun). But keeping the motor in the rough range is plenty on MS1x and MS2x. To dial in the cylinder trims also requires either 6 O2 sensors and EGT probes (think data logging an something like LabView) or bouncing the sensors to each cylinder after a rough tune to get the cylinder trims in line. Something thats not worthwhile on a street car that will never make use of 400hp.


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## vwflygti (Sep 11, 2002)

To much timing. Lower it or do like I do and run water meth. Timing friendly ;-).


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## TwinScrew20v (Dec 25, 2003)

vwflygti said:


> To much timing. Lower it or do like I do and run water meth. Timing friendly ;-).


Failing fuel pump did it. Makes sense seeing as theres no sand pitting on the crowns. No fuel means not setonattion and high temps under compression would deffinitely melt metal. And Ive been running water meth for two years on this car ;-)


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## vwflygti (Sep 11, 2002)

TwinScrew20v said:


> Failing fuel pump did it. Makes sense seeing as theres no sand pitting on the crowns. No fuel means not setonattion and high temps under compression would deffinitely melt metal. And Ive been running water meth for two years on this car ;-)


Ouch. Do you monitor your afr or lambda target?


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## Big_Tom (Aug 19, 2007)

HidRo said:


> Real man stare at gauges for at least 5s :laugh::laugh::laugh:


:laugh::thumbup:


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## _muppet_ (Aug 5, 2004)

vr-vagman said:


> MS1 is not a good choise for VR engine. I'd advice to switch to MS3X at least. Even with te OEM manifold and compensated runner lenghts, your injectors still squirt fuel on different places for the front and rear banks and rear bank inlet runners are heated by the coolant/head temperature. Also there could be some small cooling isuues with rear bank cylinders, especially the farthest ones (4 and 6th) from the cooling pump. That's why using the MS3X with VR6 is very advisable, becuse you could trim the fuel and the advance individually on every cylinder. I believe the rear bank needs definitely correction in fueling and spark to avoid such damages.
> Hope that helps.


The features of ms3x are cool, but certainly aren't needed. It's only been out a couple years and people have been building vrts for a long time. In cases like this it wouldn't have helped anyways, for two reasons. One is that I am sure he didn't know that his piston was melting until the damage was done, just having features available doesn't mean your tune is spot on. If you're tuning on the road by yourself it can be hard to focus, and hard to hear small knocks here and there. The other obvious reason is that piston six is not a rear bank piston.


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## TwinScrew20v (Dec 25, 2003)

vwflygti said:


> Ouch. Do you monitor your afr or lambda target?


Yeah. I actualy do regular data logging since Im into fine tunig, but 1st thru 3rd pulls dont run long enough to obviously show the early stages of pump failure. Explains some issues but its a hard thing to catch. At least it didnt happen on a forged bottom end Hahahaa


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## TwinScrew20v (Dec 25, 2003)

_muppet_ said:


> The features of ms3x are cool, but certainly aren't needed. It's only been out a couple years and people have been building vrts for a long time. In cases like this it wouldn't have helped anyways, for two reasons. One is that I am sure he didn't know that his piston was melting until the damage was done, just having features available doesn't mean your tune is spot on. If you're tuning on the road by yourself it can be hard to focus, and hard to hear small knocks here and there. The other obvious reason is that piston six is not a rear bank piston.


All true statements. It was a situational failure thwt took out the motor, not a poor tune or ECU issue. DieGTI and have have been runnin MS1 extra for 3 years on a VR (I think his is more like 6-7). Theres some nice benefits to MS2e, but nothing thats a need over MS1e.


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## vr-vagman (May 15, 2010)

Guys, you're free to do whatever you want with your engine until.... next damage due to... something you'd like to be. OK, it is not detonation. It is due to bad water in the WM injection
C'mon! Everybody spends a lot of money in these turbo projects. Why you decide to save few bucks on most important step- engine control and dyno tuning? Of course you could use MS1 with VRT for years. But of course you can be down on power(but boosting at the same or higher level) and low on MPG for years too. It's up to your decision. 

@_muppet_, you're right about piston 6 but it is still farthest from coolant pump. Obviously I've made a typo. Tuning on the road *with just a WB* is waste of time and money imho. 
Regards to all!


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## TwinScrew20v (Dec 25, 2003)

vr-vagman said:


> Guys, you're free to do whatever you want with your engine until.... next damage due to... something you'd like to be. OK, it is not detonation. It is due to bad water in the WM injection
> C'mon! Everybody spends a lot of money in these turbo projects. Why you decide to save few bucks on most important step- engine control and dyno tuning? Of course you could use MS1 with VRT for years. But of course you can be down on power(but boosting at the same or higher level) and low on MPG for years too. It's up to your decision.
> 
> @_muppet_, you're right about piston 6 but it is still farthest from coolant pump. Obviously I've made a typo. Tuning on the road *with just a WB* is waste of time and money imho.
> Regards to all!


So then youre the guy running a full data logger with six EGT taps and preturbo widebands at each end of the mani? Because thats the rit way to fully dial in one of these motors on. Chassis dyno to reach the ultimate power mark. But lets be totally honest...5-600 hp in a FWD VW? Theres your waste of time and money.

And low mileage? Shiet I went down 2 mpg from stock fueling to boosted MS1e after it got dialed in. Two different languages to reach the same end goal. An average running quick, but not fast street car. Feel free to tell people their doing it wrong...But make sure youre on the same page and realize theyll tell you youre in the wring boat also. MS1e does its job and it does it well. Are there better systems out there? You bet. But youre well into hte multi thousand dollar range.

Honestly Im done with this convo. My system does exactly what I need it to. The tune matched mysetup. And a failing fuel pump proved to be my problem (removed and tested). The end.


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## vwflygti (Sep 11, 2002)

TwinScrew20v said:


> So then youre the guy running a full data logger with six EGT taps and preturbo widebands at each end of the mani? Because thats the rit way to fully dial in one of these motors on. Chassis dyno to reach the ultimate power mark. But lets be totally honest...5-600 hp in a FWD VW? Theres your waste of time and money.
> 
> And low mileage? Shiet I went down 2 mpg from stock fueling to boosted MS1e after it got dialed in. Two different languages to reach the same end goal. An average running quick, but not fast street car. Feel free to tell people their doing it wrong...But make sure youre on the same page and realize theyll tell you youre in the wring boat also. MS1e does its job and it does it well. Are there better systems out there? You bet. But youre well into hte multi thousand dollar range.
> 
> Honestly Im done with this convo. My system does exactly what I need it to. The tune matched mysetup. And a failing fuel pump proved to be my problem (removed and tested). The end.


:thumbup: opcorn:


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## FlatlanderSJ (Oct 4, 2007)

TwinScrew20v said:


> Failing fuel pump did it. Makes sense seeing as theres no sand pitting on the crowns. No fuel means not setonattion and high temps under compression would deffinitely melt metal. And Ive been running water meth for two years on this car ;-)


Im not so sure of this, I think the vr just runs hot on 1 and 6. The latter being the hottest. I just lost compression on 6 and low on 1. I haven't torn it apart quite yet but this is want I'm expecting to see. I was watching my plugs the whole time with tuning and the fronts were black and rears a nice dark brown. 

35r @22 psi
9:1 spacer
Stock intake manifold
Stock fuel rail
60lb injectors
Walbro inline 
Front mount
Watched gauges for:
AFR (12:1 full boost)
Pre turbo EGT on #5 1100 or lower in boost (EGT's would cool down when boosting?)
Fuel pressure steady at 4bar

Timing never touched up top from Paul's turbo base map (11-12* maybe?)

I think It's just time for forged pistons.


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## TBT-Syncro (Apr 28, 2001)

FlatlanderSJ said:


> I think It's just time for forged pistons.


the outcome would have been the same.


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## FlatlanderSJ (Oct 4, 2007)

you really think so with larger ring lands and stronger material. i really think this is an odd place to melt a piston from a lean condition.


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## [email protected] (Jan 2, 2009)

95% of the JE / Wiseco / Mahle single replacement pistons I sell are for VR6 rear banks. I'm not even exaggerating, it's like once a week. I would never build a high boost vr6 without individual cylinder fuel trims. 

I don't see how one could conclude that rail pressure dropped at #6. The rear pistons we sell are random- sometimes all 3 at once. There's really no data to conclude anything more specific then that the rear bank got too hot. 

You could upgrade your pump, but I'd start by getting some data- why don't you weld a bung on the #6 end of the fuel rail and add a sensor. You can get a generic pressure sensor in 1/8" pipe pretty cheap- it's handy to have a spare one anyways, you can move it around and learn a lot.


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## FlatlanderSJ (Oct 4, 2007)

[email protected] said:


> I don't see how one could conclude that rail pressure dropped at #6.


maybe because that's the one that melted and it not being a rear bank cyl one would have to wonder why the "colder" piston failed first.



[email protected] said:


> You can get a generic pressure sensor in 1/8" pipe pretty cheap


I would like to know where you can get one for less than $100.


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## need_a_VR6 (May 19, 1999)

http://www.ebay.com/itm/Pressure-transducer-or-sender-100-psi-for-oil-fuel-air-/250799543734

Enjoy.


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## FlatlanderSJ (Oct 4, 2007)

awesome, thanks


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## ncsumecheng (Nov 1, 2005)

You said throw in the Walbro you have or buy an 044?

Does this mean you didn't have a pump other than the tank pump? Or did you just have a Walbro fail?


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## DieGTi (Jun 19, 2001)

We could start a coffee table project of melted pistons instead of a BBS wheel.


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## Boost112 (May 8, 2002)

ncsumecheng said:


> You said throw in the Walbro you have or buy an 044?
> 
> Does this mean you didn't have a pump other than the tank pump? Or did you just have a Walbro fail?


 x2...also i know that the UM tunes have a 10% increase of fuel on the rear bank because of this issue...is it possible to adjust the table for the rear cylinders...in the MS application?


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## cosmicmkII (Apr 20, 2006)

I have been through 12 stock VR6 pistons in the last 2 years. All rear bank cylinders. 

Different boost levels every time, but the same result on every piston. Wrecked ring lands. I have not skimped out on tuning either. I run Lugtronic with maps done by Kevin, and verified the timing and Air Fuels with my local Tuner on a Dyno. 

The stock pistons are not designed to take boost pressure, simple as that. 

I have decided the VR (and it's headaches) are not for me. So I started buying parts from one of Integrated Engineering Dealers up here on the East Coast of Canada. 1.8T for me. 

I like what Pete and the guys there are doing for the 1.8T and am going that route. While I am sure i will do my fair share of wrecking on the 1.8T before I am where I want to be, the aftermarket support isn't slowing down and its cheaper to replace 4 pistons, than 6.  

VR is awesome, I am just done with it.


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## DieGTi (Jun 19, 2001)

Boost112 said:


> x2...also i know that the UM tunes have a 10% increase of fuel on the rear bank because of this issue...is it possible to adjust the table for the rear cylinders...in the MS application?


 Yes, you can run separate fuel tables for the front and rear banks. You get a different fuel table for each injector in MS 3.

-Andrew


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