Rover 200 BRM - 1.8 K-Series turbo project
Discussion
Stuballs said:
227bhp said:
That was det damage 100% and only the OP has the hard facts on how it happened and he isn't saying much.
I don't really know much more you you at this stage so not much to say to be honest. I'll get the pistons out and share what I find.I used to work somewhere where they f
ked things up regularly, the motto in the workshop was "We make it nice, because we do it twice"So there is hope for you yet
227bhp said:
I was referring to my rather pointed questions. I don't think there will be much of use to see at the side of the piston, but It would be good to see and hear more. It's such a shame after what looked like a lot of care and diligence went into it for it to fail on something minor and possibly not even engine related, but i'm glad you're remaining upbeat and having another go.
I used to work somewhere where they fked things up regularly, the motto in the workshop was "We make it nice, because we do it twice"
So there is hope for you yet
This issue does highlight the obvious problem with being a novice. I simply don't have the experience to avoid problems before they occur and diagnosing faults after they have happened is so much harder!I used to work somewhere where they f
ked things up regularly, the motto in the workshop was "We make it nice, because we do it twice"So there is hope for you yet
I do really appreciate everyone's contributions.
I've just been having a look at exhaust design as a possible contributing factor. Someone suggested to me (can't remember who, when or where) that the log manifold can cause reversion which becomes a particular problem when upping the power and using wilder cams. This could in theory be causing cyl 1 to run hotter than the others and explain why it was the one that let go. No way to know for sure but worth bearing in mind. Maybe a good excuse to splash out on a tubular manifold! Or maybe the answer would be to go milder on the cams - not a bad idea anyway if I'm going for an even smaller turbo.
227bhp said:
They are known as 'anti-det grooves' or 'minimum contact grooves' and are not stress raisers as they are machined in with smooth contours, no sharp edges. If they were an issue then no-one would use them
Well, any reduction in section area is a stress raiser whether sharp-edged or not. Calling them grooves this thing or that makes no odds. If you section the piston through the ring land at the valve pocket, you'll see just how much these super special grooves reduce the section area - exactly where the piston has failed, BTW...Oh, and the standard K-series pistons don't seem to have them...
AER said:
227bhp said:
They are known as 'anti-det grooves' or 'minimum contact grooves' and are not stress raisers as they are machined in with smooth contours, no sharp edges. If they were an issue then no-one would use them
Well, any reduction in section area is a stress raiser whether sharp-edged or not. Calling them grooves this thing or that makes no odds. If you section the piston through the ring land at the valve pocket, you'll see just how much these super special grooves reduce the section area - exactly where the piston has failed, BTW...Oh, and the standard K-series pistons don't seem to have them...
The piece of the piston broke away due to the shockwave caused by det', it broke away from the base of the ring groove upwards which is the weak point. It has nothing to do with the other shallow grooves which sit above it, nor do they ever break there.
It has occurred either outside of the mappers reach due to failure of something else or unsafe map, or on the dyno if he wasn't wearing det cans.
It's a bit like pointing out the Titanic wouldn't have sunk if it had been built stronger, well actually if you hadn't driven into an iceberg it wouldn't have either....
Edited by Evoluzione on Tuesday 19th April 11:29
just a thought, might it be simpler to transplant something else with a higher power output and scope for simpler methods of tuning rather than developing your own solution ?
I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
RumbleOfThunder said:
Technical bods..
1. Det cans are like a doctors stethoscope with earmuffs, just for for listening for detonation?
2. Are knock sensors no longer in the loop with builds like these?
1. Basically yes, but they use a knock sensor and headphones, not a stethoscope and muffs.1. Det cans are like a doctors stethoscope with earmuffs, just for for listening for detonation?
2. Are knock sensors no longer in the loop with builds like these?
2. When actually mapping the car you need to be listening quite intently and act accordingly, you can't sit there and expect the car to do it, that wouldn't be mapping.
The knock sensor is used after mapping is finished as safety device should something unexpected happen.
J4CKO said:
just a thought, might it be simpler to transplant something else with a higher power output and scope for simpler methods of tuning rather than developing your own solution ?
I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
Not the first person to say that. Problem with that is I couldn't do that myself and would have to pay someone else to do the fabrication and fit. And a lot more would need rethinking like gearbox and driveshafts too I would have thought. I won't lie and say I haven't considered it though! But I've learned so much from this that I can take forward to the next build. I'm confident the next iteration will be bigger and better!I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
I'm looking into somewhere I can take the engine and have it run in and mapped on an engine dyno before I fit it to the car. Possibly Emerald themselves. It strikes me that that's a much more consistent and controlled environment and easier logistically.
Just ordered the pistons
ime, enough "det" to knock the land off a piston leaves tell tails in the piston, bore, head gasket or head!
Over a huge number of cycles, mild det can do the same without leaving as much trace, but this engine is pretty new is it not? (ie it hasn't done 1,000s of miles / hrs ?)
The same with excessive thermal loading, as the pistons are scrap, you may as well section a few for a look!
Over a huge number of cycles, mild det can do the same without leaving as much trace, but this engine is pretty new is it not? (ie it hasn't done 1,000s of miles / hrs ?)
The same with excessive thermal loading, as the pistons are scrap, you may as well section a few for a look!
Stuballs said:
J4CKO said:
just a thought, might it be simpler to transplant something else with a higher power output and scope for simpler methods of tuning rather than developing your own solution ?
I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
Not the first person to say that. Problem with that is I couldn't do that myself and would have to pay someone else to do the fabrication and fit. And a lot more would need rethinking like gearbox and driveshafts too I would have thought. I won't lie and say I haven't considered it though! But I've learned so much from this that I can take forward to the next build. I'm confident the next iteration will be bigger and better!I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
I'm looking into somewhere I can take the engine and have it run in and mapped on an engine dyno before I fit it to the car. Possibly Emerald themselves. It strikes me that that's a much more consistent and controlled environment and easier logistically.
Just ordered the pistons
As an ex BRM owner, I see the charm of the actual car, if not bloody K series engines, which have their good points but mine went bad, my uncle still has one which has had a later engine fitted, when they work they are great, gearbox is a delight and it offends conservative Audi owners.
Stuballs said:
J4CKO said:
just a thought, might it be simpler to transplant something else with a higher power output and scope for simpler methods of tuning rather than developing your own solution ?
I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
Not the first person to say that. Problem with that is I couldn't do that myself and would have to pay someone else to do the fabrication and fit. And a lot more would need rethinking like gearbox and driveshafts too I would have thought. I won't lie and say I haven't considered it though! But I've learned so much from this that I can take forward to the next build. I'm confident the next iteration will be bigger and better!I know its not as interesting but K series engines always seem like an expensive and shaky foundation for big power.
I'm looking into somewhere I can take the engine and have it run in and mapped on an engine dyno before I fit it to the car. Possibly Emerald themselves. It strikes me that that's a much more consistent and controlled environment and easier logistically.
Just ordered the pistons
Plenty enough for front driver with out nobbling a fine engine.
Max_Torque said:
ime, enough "det" to knock the land off a piston leaves tell tails in the piston, bore, head gasket or head!
Over a huge number of cycles, mild det can do the same without leaving as much trace, but this engine is pretty new is it not? (ie it hasn't done 1,000s of miles / hrs ?)
The same with excessive thermal loading, as the pistons are scrap, you may as well section a few for a look!
Engine had covered 800 miles. There are no signed off det anywhere (other than the melted piston ha!) - I mean none of that characteristic pitting. The other 3 pistons are spotless although as I say they do have the same very slight bending in at the valve cutout. Even the broken piston shows no det damage.Over a huge number of cycles, mild det can do the same without leaving as much trace, but this engine is pretty new is it not? (ie it hasn't done 1,000s of miles / hrs ?)
The same with excessive thermal loading, as the pistons are scrap, you may as well section a few for a look!
Cylinder 1 is very badly scored all around but theres no material transfer from the piston so I suspect the ring may be part of the problem, whether causative or just caught up in the chain reaction. Maybe I got the gaps wrong. Maybe the gaps are marginal and that cylinder ran hotter by enough of a margin for it to be a problem (going back to the design of the stock manifold and possible reversion raising temps in that cylinder).
jdwoodbury said:
Great read, I had a love for Rovers early on having a 200vi at one point which is like a BRM without the smiky face ??
There was a parade of these on the M42 on Saturday, was it you?
That was a convoy on its way to "Pride of Longbridge" - an annual pilgrimage to the home of Rover on the anniversary of the closure of Longbridge. Very well attended by all the models built there over the years. Always get a good turnout by the ex-workers and their families too which is nice. There was a parade of these on the M42 on Saturday, was it you?
I would have been with them if not for my engine failure.
Evoluzione said:
You seem intent on pushing a point for no real reason other than just to argue for the sake of it, consider the facts:
The piece of the piston broke away due to the shockwave caused by det', it broke away from the base of the ring groove upwards which is the weak point. It has nothing to do with the other shallow grooves which sit above it, nor do they ever break there.
Not arguing for the sake of it at all. You don't seem to be able to visualise the situation in 3-D. Take a look at the piston crown and note carefully where the valve pockets nearly intersect with the top ring land. Now stick a radial groove or two in the ring land and tell me with a straight face that the section thickness at the valve pocket hasn't reduced? Oh, it has! The piece of the piston broke away due to the shockwave caused by det', it broke away from the base of the ring groove upwards which is the weak point. It has nothing to do with the other shallow grooves which sit above it, nor do they ever break there.
And you're going to tell me the ring land failed first at a much thicker point at the base of the ring groove...?
AER said:
Evoluzione said:
You seem intent on pushing a point for no real reason other than just to argue for the sake of it, consider the facts:
The piece of the piston broke away due to the shockwave caused by det', it broke away from the base of the ring groove upwards which is the weak point. It has nothing to do with the other shallow grooves which sit above it, nor do they ever break there.
Not arguing for the sake of it at all. You don't seem to be able to visualise the situation in 3-D. Take a look at the piston crown and note carefully where the valve pockets nearly intersect with the top ring land. Now stick a radial groove or two in the ring land and tell me with a straight face that the section thickness at the valve pocket hasn't reduced? Oh, it has! The piece of the piston broke away due to the shockwave caused by det', it broke away from the base of the ring groove upwards which is the weak point. It has nothing to do with the other shallow grooves which sit above it, nor do they ever break there.
And you're going to tell me the ring land failed first at a much thicker point at the base of the ring groove...?
I am that other chap running those pistons in a supercharged K in a Elise.
It just knocks a tad earlier that I would expect.
This MAY BE down to two things one being related to that piston valve cut-out thing, the other to something different.
I have inspected 2 out of the 4 with a video endoscope and found no traces of any bending.
It is correct that that thin area should have been removed. Too late for me as I do not want to remove the Pistons just for that.
But as I use methanol water injection, I found the affected area plus the same on the opposite exhaust side being blank alloy coloured vs the crown being covered with the thin black layer of carbon. The fluid cools the affected areas.
The engine runs approximately 250HP and has done a dozen trackdays plus road use. Boost peaks at around 13 PSI at 7300 rpm.
I don't have a exact number as I have never been on a dyno. It is all street and track tuned by myself.
The HP number is dervied from some driving in a group of three in Spa and the straight line acceleration being slightly faster than a Honda K20 NA Elise S2 with some 230HP and a tad slower than a JRSC K20 Elise S1 with 280HP.
I have since improved charge cooling and the amount of ADI injected so should see a tad more HP this year.
The colour of that failed piston is very light. Maybe it takes time to build up the carbon, or the turbo engine was running lean? It definitly became very hot at the crown. Annealing temperature of 4032 is a tad over 400C. Otherwise it would not have bend.
On top of the water meth injection, I also use a J&S safeguard vampire knock control system. It pulls up to 10 deg of ignition timing within a single revolution for individual cylinders.
Fueling is controlled through a wideband lambda sensor running closed loop injection at all times, even under full boost. I do this for many years now with excellent results.
Looking at the broken piston picture, I agree that the material thickness is not that high on the inlet side.
Having used the same Wössners blank as the 12:1 version before, I know these are much more meaty and heavy.
That thin section should have been removed by the supplier before delivery. There is no excuse for that.
I did not know at the time and just did the weight matching. These Pistons are very light with 222 g minus rings, clips and gudgeon pin. I am also not sure the valve pockets do need to be that deep for 10.6mm of lift.
A few comparison pijctures of the 12:1 vs the 9:1 Pistons. They are machined from the same forging.
Points of improvement of this piston could be machining of the thin section of the valve cut-out and leaving more metal on the ramp to the piston crown between the valve pockets. It will add a few cc of volume, but make the pistons much stronger.
It just knocks a tad earlier that I would expect.
This MAY BE down to two things one being related to that piston valve cut-out thing, the other to something different.
I have inspected 2 out of the 4 with a video endoscope and found no traces of any bending.
It is correct that that thin area should have been removed. Too late for me as I do not want to remove the Pistons just for that.
But as I use methanol water injection, I found the affected area plus the same on the opposite exhaust side being blank alloy coloured vs the crown being covered with the thin black layer of carbon. The fluid cools the affected areas.
The engine runs approximately 250HP and has done a dozen trackdays plus road use. Boost peaks at around 13 PSI at 7300 rpm.
I don't have a exact number as I have never been on a dyno. It is all street and track tuned by myself.
The HP number is dervied from some driving in a group of three in Spa and the straight line acceleration being slightly faster than a Honda K20 NA Elise S2 with some 230HP and a tad slower than a JRSC K20 Elise S1 with 280HP.
I have since improved charge cooling and the amount of ADI injected so should see a tad more HP this year.
The colour of that failed piston is very light. Maybe it takes time to build up the carbon, or the turbo engine was running lean? It definitly became very hot at the crown. Annealing temperature of 4032 is a tad over 400C. Otherwise it would not have bend.
On top of the water meth injection, I also use a J&S safeguard vampire knock control system. It pulls up to 10 deg of ignition timing within a single revolution for individual cylinders.
Fueling is controlled through a wideband lambda sensor running closed loop injection at all times, even under full boost. I do this for many years now with excellent results.
Looking at the broken piston picture, I agree that the material thickness is not that high on the inlet side.
Having used the same Wössners blank as the 12:1 version before, I know these are much more meaty and heavy.
That thin section should have been removed by the supplier before delivery. There is no excuse for that.
I did not know at the time and just did the weight matching. These Pistons are very light with 222 g minus rings, clips and gudgeon pin. I am also not sure the valve pockets do need to be that deep for 10.6mm of lift.
A few comparison pijctures of the 12:1 vs the 9:1 Pistons. They are machined from the same forging.
Points of improvement of this piston could be machining of the thin section of the valve cut-out and leaving more metal on the ramp to the piston crown between the valve pockets. It will add a few cc of volume, but make the pistons much stronger.
Edited by Ive on Sunday 24th April 14:18
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