Post-Thruxton Post Mortem

[JohnD]

Nick, Holy Grail, eh?   And I'm not even using coconuts!

I'll get it cleaned up and have closer look.

RogerG, would your method salvage that bearing cap, please?

John

 

[JohnD]

Worse news.   I didn't do the PM very well.   Seeing inside a dark crank case is never very eas, but a bright torch has shown me that the side of No.1 bore has been shattered by the loose cor rod.    This block is unusable scrap, and it really is a restart from zero.

Ho hum.

John

[Escadrille Ecosse]

Not good news at all John. Very philosophical.

Did you get that other block along with the crank? Hopefully that will do the job although it does mean a lot of extra fettling.

[PaulAA]

2 hours ago, JohnD said:

This block is unusable scrap

John, this is uncharacteristic pessimism!

According to the vigilant Mr Google, a Triumph 6-cylinder block has yet to make it into the public realm as an eye-catching coffee table.

What an opportunity!

Paul

[PeteStupps]

3 minutes ago, PaulAA said:

 

Whilst I admire the workmanship, a cast iron 6-pot would surely be impractical in the front room. Imagine trying to move it out of the way to vacuum the carpet, or stubbing your toe on it!

[Nick Jones]

4 hours ago, PeteStupps said:

Imagine trying to move it out of the way to vacuum the carpet, or stubbing your toe on it!

Yeah. Stubbornly immobile! Not actually bolted down but might as well be!

 

[rogerguzzi]

Hello All

              A nice set of rubber casters or even better a nice little electric trolley or better still rebuild it so it can move its self?

Roger

[Escadrille Ecosse]

23 minutes ago, rogerguzzi said:

Hello All

              A nice set of rubber casters or even better a nice little electric trolley or better still rebuild it so it can move its self?

Roger

Needs a regrind though. I think the big ends might be a bit tight

[flatter4]

Cross drilled crank.  Nice, but why?

(I'm looking for a debate here....!)

I think early production would use it because the accuracy of the long gun drilling would not necessarily be set up in a refined machining process.  The cross drilling could allow some error (drill 2 ways: main into the big end journal 'well' and big end surface into the 'well').  I'm not sure it was done for performance reasons?

....but it does give some performance advantages.  As I see it this would be nice perpendicular oil feed from a 'well' in the centre of the journal.  Plus oil feed for the big end could be placed at the optimum radial position.  Can't recall all the science here but you would feed the oil in just before the point of maximum pressure (a bit after TDC).  Not sure that that is what has been done here?

Perhaps the main oil drillings are one long straight drilling all the way from main to big end which trashes my theory......

 

Any other thoughts?

It leaves you with a nightmare cleaning job though John!

Cheers, Will.

[RogerH]

Hi Will,

 the TR   4 pot engines started life with TDC drilling (early TR2).

This gave possible oil starvation due to centrifugal forces. This was soon changed to a cross drill design.

This cured the oil starvation. BUT!!!! the TR     6 pot has TDC drillings in the Big-End journal.

I suspect the oil pump was the main issue all those years ago,

As for deep drilling etc - the workshops could do almost anything.

However one oddity - When they changed over to cross drilling they adapted the original oil gallery drilling which gave an awkward dog leg.  The new TR 4 pot crank has a new drilling design which removes the dog leg

 

Roger

[mpbarrett]

John

All that work gone so quickly.
Its all good to try to understand what has happened, at least you then have a chance not to repeat it.
I guess it all happened too quickly to notice any change in oil pressure? In future is it possible to put some data logging onto the car? If you had a log of the oil pressure, temperature you could probably work out if you had a gradual (bearing failing) or catastrophic (oil pump broken) oil pressure failure.
You would need an electronic pressure gauge and and a simple acquisition system. Not sure what's out there,  but not difficult to do these days with an Arduino/PI and a decent size USB stick.

Mike
 

[JohnD]

Mike,

I did my dissertation on torsion vibration using the instrumented engine rig and a significant part of my course was on datalogging, but I'm still an electronic numpty!    But you have a very good point, as I have tried to promote my damper testing service under the slogan, "Measurement for Motorsport"!      So I'll take your point to heart!

But a "little electric trolley" (rogerG)?      Maybe that's what I should be building, to get about in my old age!

John

[thebrookster]

Yeah, Mike has the nail bang on there.

To progress any further theories we would need data, and obviously triumph engines, indeed all car engines simply do not have that level of data logging installed.

The other issue as Clive has said is the sheer speed of car engines. Problems occur and develop at remarkable speed. So from that point it probably is not worth fitting multiple sensors, as by the time you register a problem most likely the engine is already caput!

Phil

[Nick Jones]

Data logging higher speed machinery tends not to save the machine in question completely, though it might minimise the damage. However, knowing what killed the first one may well save its successor from the same fate.

[Escadrille Ecosse]

55 minutes ago, Nick Jones said:

Data logging higher speed machinery tends not to save the machine in question completely, though it might minimise the damage. However, knowing what killed the first one may well save its successor from the same fate.

Sometimes. Buy depends a bit on the cycle rate of the logger as you can just end up with an alarm flood and not be any better off than the old days. Been there, got that multi- tens of millions worth of kit t shirt. 

[spitNL]

Quite a destruction, John.

I can't go into details too much, but at work we regularly run engines past their maximum rpm, but just short of destruction.
To this end thermocouples are installed under every bearing shell, even the big ends.

Normally the bearing temperature increases linearly with increased load, but past a certain point the load becomes too much and the temperature skyrockets in a fraction of a second.

A human wouldn't be able to react fast enough, but the software/control system is quick enough to catch it and prevent major destruction.
The key is to remove the load and return the engine to idle asap and keep it running.
If you do stop the engine, the bearings will melt to the crankshaft.


 

[Escadrille Ecosse]

44 minutes ago, spitNL said:

Quite a destruction, John.

I can't go into details too much, but at work we regularly run engines past their maximum rpm, but just short of destruction.
To this end thermocouples are installed under every bearing shell, even the big ends.

Normally the bearing temperature increases linearly with increased load, but past a certain point the load becomes too much and the temperature skyrockets in a fraction of a second.

A human wouldn't be able to react fast enough, but the software/control system is quick enough to catch it and prevent major destruction.
The key is to remove the load and return the engine to idle asap and keep it running.
If you do stop the engine, the bearings will melt to the crankshaft.


 

Poor John. This is all starting to sound a bit like the four Yorkshiremen for engines.

Realistically who is going to build a fully instrumented engine for club racing? And install a control system purely to monitor it all and have executive action over the driver? 

It reminds me of that line by Jeff Goldblum in Jurassic Park, the one about 'can' vs 'should' .... 

There's another thread about NOT using inertia switches on the fuel pump to avoid spurious trips on race engines. Even at the potential cost of immolation of car and driver 

It's all good fun but it's not the space shuttle  having seen some of John's creations I'd argue that it's better......

Good luck John 

 

Edited May 13, 2021 by Escadrille Ecosse

[mpbarrett]

analysing the data and look for potential failure to stop the destruction is very difficult if you want to make it reliable. I spent a lot of my career trying to do in the oil industry ie trying to predict oil well drill bit wear by looking at torsional vibration at the surface.

But I was thinking of just monitoring some parameters not just to find out why something has broken but for predicating possible failure by looking at trends  in the data. 

Still a lot of work to make it useful.

Mike

[Hamish]

John

i really feel for you on this one. 
 

but you can rebuild it. You have the knowledge and the skills, and I hope the budget. And plenty of support on here and elsewhere.

I wouldn’t over think this one. Even the very best have engines let go. 
 

select the most common protection upgrades as these will be mitigating the most common faults or weaknesses.

and go for the performance spec that you know.

if it happened to me I would have to go to TR Enterprises and say “make me another” and remind my long suffering wife that I don’t drink and don’t smoke and that we don’t need a new car!!!! The 10 year old ones are just fine.

[Bumblebee]

When all is said and done the way you use engines John is always going to highlight even minor flaws. Component failures happen in F1 with cutting edge kit and engineering, and you are operating in your garage with 40 plus year old kit and engine parts which are either NOS from the year dot or modern stuff of dubious quality. 

Most of us can get away with it though, take the twink my lad built. Who knows if it has a fault that will make it grenade at sustained high rpm. I certainly dont, and doubt I will ever find out, because its a street engine, and will never be redlining for sustained periods.

You can but build to the best you have available. Select the best parts you can find and measure everything is the best you can do, after that it is just quality management in your build, and hoping the parts you picked are fault free and up to it. 

You built an engine that made good power on the rolling road, but were unfortunate and by the looks of it suffered a catastrophic component failure of some kind.

I am sure the next one will be fine and once we can come out to play I will come to a meet and give you the support you deserve. 

A 

 

 

[Escadrille Ecosse]

1 minute ago, Bumblebee said:

I am sure the next one will be fine and once we can come out to play I will come to a meet and give you the support you deserve. 

A

[JohnD]

Well, Gosh!     Thnak you all for your kind words and expenditure of brainwork and experience!

There will definitely be another engine.      I have been the lucky receiver of concidence before, for instance when SofS appeared on ebay, only a few days after Silverback rolled over on the 'Ring.     To find an engine with a crossdrilled crank, and only a few miles away from me, makes me want to use it, but it is badly worn, so the sensible thing to do may be to scrub that, and use one of the complete engines I have stashed away as the bases for the rebuild.   They are unknow quantities as yet, I'll have to pick one and dissect it.

Meanwhile, here are some pics of the thrust washer area of the cross drilled (CD) crank:

A profile vew of the front face of the rear flange:

That forward face should, I think, be vertical, not sloped, and the rim should be twice the height.

 

Here's the No.4 bearing cap, rear face and profile views, showing the wear rings, and previous 'repair' by brazing:

 

 

What d'ye think?    Recoverable?     By welding, brazing, or other technonology?

I must owe the Common Room of Sideways U a whole box of biscuits for all the excellent advice I've had.     I will see if I can make up some stickers for the car to acknowledge that!    But meanwhile, thank you!

JOhn

Edited May 14, 2021 by JohnD

[Bumblebee]

Would you not be better finding an endcap from a donor and line boring it. That looks tat! The face should deffo be vertical  and much thicker at the top as you say. I know this as there is a 2 litre one on the floor under my desk! (dont ask!) 

 

 

 

[Nick Jones]

Ohhhh.... that's ugly......

That engine ran along time without thrust washers, got "fixed" then did it again.

Possibly could be fixed properly if you were determined and had the right kit, though looks like there is an awful lot gone from the crank face in particular - would need a specially made thrust washer for sure.

Sorry to say that I think you'd do much better to start with better parts!

[rogerguzzi]

Hello John 

                  If it was me I would take the sumps off both the spare engines and remove both rear main bearing caps and hope you find an undamaged one.

Unless there is is something super special about that engine? other than the crank!

I do not think it would warrant the machining costs and I could just machine the bearing cap to take a thrust washer.

Then you are just into a rebore and crank grind plus balancing.

As RogerH said they stopped cross drilling TR6 cranks but they fitted the bigger pump.

That's my 2 penneth for what is worth.

I still think the half circle thrust washers are just a CHEAP job but they did not build them to last 50years!!! 

Roger