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Broken TFS head ??

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Old 04-08-2018, 08:19 PM
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Default Broken TFS head ??

Anyone ever seen this **** before ? lol

I'm not knocking the heads, I've had these same TFS 225cc heads for over 10 years, but this is ******* mental. Head stud/washer/dowel etc were all still intact, although I screwed it out for the photo.
Current build has been running fine for a little over a year, although only recently got it running again after some winter work.

Head damage is one thing...but it's looking like some alloy beside the liner has been knocked out too. I guess this means liner replacement ? 1 or a full darton type setup ?

I do not want to have to replace the block if at all possible, as it already has billet/pinned caps and oil squirters fitted. And I do not want to have to buy new pistons, so need 4.005" finished bore.
It's bad enough I might have to buy a new head or possibly pair of heads. Being outside the US, all of these options can get very expensive.

In the threaded hole you can see, normal bolt hole I've always had an earth point bolted here...same bolt for those years. No changes there. One part of the head is actually still attached to the bolt but I cant reach it yet

Photos just with a cheap USB bore scope camera, engine still in car etc
Attached Thumbnails Broken TFS head ??-stillsnapshot000001.jpg   Broken TFS head ??-stillsnapshot000002.jpg   Broken TFS head ??-stillsnapshot000003.jpg   Broken TFS head ??-stillsnapshot000005.jpg  
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Old 04-08-2018, 08:50 PM
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It's hard to tell from those pics though the carnage is graphic, is a piece of the end of the head broken away? is that #2 cylinder could it be what happened with the liner that broke up the head.

I seen bad stuff happen to heads like chunks blown away but this is different, hopefully you can save the block good luck to you.
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Old 04-09-2018, 06:23 PM
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Well..even if nobody else is, I'm impressed lol ( fucked off, but impressed )

Somehow it must have ingested water and hydraulic pressure has tried to blow the head apart. It's cyl8. I think it's also bent that rod slightly. Although from what I can see in the car the block itself looks ok.
It's cracked right through to cylinder 6. Not sure if the head stud threads have sustained damage, but obviously they'll have seen some huge forces.
Attached Thumbnails Broken TFS head ??-dsc00232-large-.jpg   Broken TFS head ??-dsc00238-large-.jpg   Broken TFS head ??-dsc00239-large-.jpg  
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Old 04-10-2018, 04:06 AM
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That's some hydrolock. Did it crack the block too?
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Old 04-10-2018, 10:09 AM
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Originally Posted by Jontall View Post
That's some hydrolock. Did it crack the block too?
I bloody hope not !!

At a glance it does appear it may be ok.

But I'd need to measure the bore for distortion. And I'm not fully convinced one of the stud holes has good threads. A stud will screw in, but not as easily as I'd like. But again, need to get the engine out for a better inspection.

Pretty sure it has bent the rod on that cylinder too.
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Old 04-10-2018, 10:20 AM
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As we say in the racing world...... Boy you blowed her up goooooood!
I don't think I've ever seen that on any engine short of diesel or blown alky/nitro engines.
Might have been weakening over time and finally let go. Best of luck on the rest of the engine, If it was cumulative damage the block might have faired better.
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Old 04-10-2018, 10:22 AM
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Was it pushing water prior to this event?
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Old 04-10-2018, 10:41 AM
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Engine was running just fine, was just doing a little tuning as over winter I'd changed intake, entire fuel system, gearbox so just ensuring everything was going to be ok for a 1/2 mile event this Saturday. Clearly it wasnt lol

And as I mentioned...I dont even believe this happened at full/open throttle.
Absolutely no signs of abnormal pressure in the cooling system on the couple of 4th gear pulls prior to this, nor right up to this incident. But I'd let off the throttle about 1sec when it lost all cooling system pressure and dumped the water out....and perhaps even because of closed throttle it was more inclined to suck the water in, rather than perhaps on power/boost where it might want to spit it out.

Something may have happened under power, but this damage occurred after letting off and perhaps some knock on damage as I had to drive a mile or 2 to get off the main road.
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Old 04-10-2018, 11:01 AM
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Hi Steve, I find this very interesting, to find the root cause.

I have observed "steam cleaned" combustion chambers, not observed in your case.

I would like to see a picture of the Ring Lands ?

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Old 04-10-2018, 11:19 AM
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Was the rivet in the corner of the gasket?

On some of the TFS heads, the rivet will interfere with the corner of the head. I used to grind or mill the corners to clear.
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Old 04-10-2018, 11:19 AM
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I'd like to find the root cause too !! lol

I'll get the engine out over the next few days.

There was a very small degree of cleaning..but bare in mind again, I do not believe the major damage occurred under open throttle, but I did then drive about another mile or 2 to get off the road to stop. With obvious loud noises and water/steam everywhere. At that stage of course...there probably wasnt much if any water in the cylinder simply because of the size of the hole.
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Old 04-10-2018, 11:31 AM
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Originally Posted by KCS View Post
Was the rivet in the corner of the gasket?

On some of the TFS heads, the rivet will interfere with the corner of the head. I used to grind or mill the corners to clear.
Although it has been together a few times, last time around I did drill a little dimple to clear the rivet. This is right at the outer corner so not an area of concern
I think the rivet must be in a slightly different place on the LS9 gasket vs others ?

And the head dowels, could literally disappear into the head, so it's not that which was another thought.
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Old 04-12-2018, 12:45 PM
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Surprisingly, the piston looks ok. Little bit of scuffing, but just the same as all the rest. Bore likewise with light scores.

but bore itself seems to measure up ok, nothing of any concern to me anyway and certainly nothing visible that resembles a crack or damage.

The rod on No8 is definitely bent, just slightly but it is bent.

Pin came out of piston/rod just fine, rings are all happy and free to move so I've no concerns that the piston has suffered any harm from this incident. Which has to be a testament to Diamond !

But sequence of events ? What caused the start of this ? Whilst the HG is blown, I'm not convinced it was the start of this.

Where the head burst, there is a line quite similar to when you torch a head.... COuld that have been the start even though it's on the chamber rather than head/block interface ?

Could there be a material or age concern ? Is it just a simple and unfortunately HG failure ?

Are current 225cc Trickflows just the same as these 10+ year old heads ? Or would new heads be a better CNC profile and better materials ?

I'm going to upgrade to 1/2" studs anyway...but would be nice to know if there was an avoidable cause
Attached Thumbnails Broken TFS head ??-zoom-head.jpg  
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Old 04-12-2018, 12:54 PM
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Gotta say, the "torchline" DOES look interesting, though I suspect it is a RESULT rather than CAUSE of the ensuing carnage. I would bet once it cracked, there was a combustion leak and the flame front found it!
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Old 04-12-2018, 01:30 PM
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As said, pressure in the cooling system never rose. This is odd given what happened. Although I guess if the head fail was sudden and large enough, maybe it can make some sense as the sensor is located in the header tank to keep it remote from the engine. Obviously I'd never expected a huge blow out like this lol.

I was on throttle when this happened, but let off within around 0.5s. All mixtures, timing etc fine, nothing really any different in terms of tuning than there has over the last several years of running
Oddly there was a strange hiccup which probably was this happening. Large pressure spike seen in the intake followed by water loss and a drop in cooling system pressure.
Immediately after the hiccup, boost also dropped....not a huge surprise there though, from 20psi to around 12psi. One turbo lost a cylinder and probably took some water.

But this engine has been together for around a year without any concerns about health.

Although in 2015 I did have the heads skimmed. Not for any reason, other than it was apart and I decided to before changing to LS9 gaskets for the first time.
Whilst there is a nice shiny surface....there was also a considerable amount of black spots which would almost make you think of a porous casting ? This was across all of the machined surface. Probably nothing though

I've de-cluttered a log to try and make a screenshot easier to view.

AFR's both banks pretty much identical around 11.5, EGT's both banks almost identical. Occurred around 100mph, 4th gear.
Blue shaded area on lower graph is Engine Cooling System Pressure in mbar. Actual timing when it happened was around 7deg, pulled back from 13deg base by traction control so if anything under less pressure than if there had been grip.
Altogether, nothing unusual whatsoever.
Attached Thumbnails Broken TFS head ??-head-casting-large-.jpg   Broken TFS head ??-logheadfucksimple.jpg  
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Old 04-12-2018, 03:33 PM
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Hi Stevie, we'd be happy to look at it. PM me you email and I'll get in contact with you. Get some high quality pictures that can give us the whole story. We generally see what was going on in one cylinder is going on in another. If you bent a rod, that's almost certainly hydrauliced...but we'll know more when we see it.
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Old 04-12-2018, 04:15 PM
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Thanks for the interest Trickflow, PM sent.

Absolutely the engine has hydraulic'd ( quite impressively lol ), but given the info to hand, quite how it got to that point is still a bit of a mystery.

And most importantly if there are measures that can be taken to prevent it.

Of other note. There is bubbling on the layers of the head gasket around cylinders 1 and 8. Actually a tear on cyl 1
This seems odd given no pressure increases were seen in the cooling system. Unless the gasket was compromised slightly and just leaking into those specific layers ?

Other gasket around 8 is pretty badly exploded in that corner so less visible info I think. But it exhibits the same bubbling around that cylinder.

It is not present on any of the other cylinders.
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Old 04-12-2018, 09:47 PM
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What are you using for head fasteners?
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Old 04-13-2018, 05:05 AM
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Just normal ARP2000, same studs for last 4-5 years or so.
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Old 04-13-2018, 06:42 AM
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Iíve never seen anything like this before, thatís for sure. Iíve seen engines hydro and break rods, but never do this to a head. Glad to hear that your block is ok.
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