Hi there again ;)

I am trying to assess how reliable Flanged Cylinder Liners (i.e. Top Hat Liners) are. Let me start with the main question (as the text to explain why I ask may be long):

???
does anyone of yall know anything about that issue, resp. if <> why <> when flanged liners could fail and if so, how to be avoided.
???

___________



Well, I felt really sure that they are an excellent means of repairing Rover V8 blocks that failed due to slipped liners or cracks behind the liners. Most V8 specialists nowadays use the flanged liners. The advantages are obvious - the cannot drop down, provide a much larger contact area for the head gasket to seal on, no chance for the V8 (as before) to let pressure escape (of water come in) between the aluminium and standard liner (as standard blocks do - because on the original block the sealing contact area not including the liner´s top). Putting flanged liners into a well used, seasoned block be advantage as the block will not "flex" any more. And that is exactly what I wanted to do if the pressure test of my short block was not fine.

Wildcat engineering use then since 10 years and are said to have not to report any failure, I´ve spoken to them and they still assure me that flanged liners are a fine - and the only solution to repair bad blocks. Lundengines.com uses them, as do automotivecomp.com, turner-engineering.co.uk (who provide a statement to the material of the liner, saying they use a superior grade), v8developments.co.uk and dunno who else. Westwoodtrading.co.uk offer such liners. Nowhere you can read something about failures. The excellent book by Des Hammill ("How To Power Tune The Rover V8") tells you everything about that issue. Probably his information is largely based on interviews with some of the abovementioned companies.

Now, if you look at the liner from the side, there is a small groove just below the flange. May be this is turned into the side of the liner to remove an area where stress cracks could develop (like there is a radius on crankshafts where the bearing shell area goes into the side of the counterweight). Or it´s got sth. to to with temperature expansion. Dunno. But this on the other hand is an area where the material thickness of the liners tube is reduced (ok, doesn´t necessarily need to make it weaker).
There is one engineer (rpiv8.com) who do report of these liners crack. They have one example to prove. I´ve seen a picture. That was a shock to see.

I have tried to find more about cracked flanged liners with google. But with no success. Now that I´ve spent almost an hour trying with many different variation of the keywords, I´ve given up. Ok, there is nothing as perfection on this world. Question is the likelyhood of sth. to happen.

Kind Regards !!

The best liners are centrifugally cast nodular iron.

They have proven themselves on high hp LS1+ series engines. It depends on the overbore but both wet and dry liners are used. The biggest name for that engine is darton.

The best installation method for dry sleeves is a cryogenic process. It is not for treating the metalurgy but creating a tight fit. When very cold the sleeve shrinks in OD and can be made to fit tighter.

The interference fit + the flange + the strength of the centrifugal cast nodular sleeve make it very strong.

Here is one source.

http://www.anandenterprise.com/index.htm

What about the poor heat transfer in nodular iron as compared to grey or even vermicular?
Are these aftermarket liners thinner than the originals to retain heat flow at the same level?
Perhaps the cooling system design in these dry liner engines rely more on cylinder head cooling than the wet liner engines I have more (professional) experience with?

T

my last two RV8s both have had top hat liners installed on both of them. First supplied by turner engineering (a 4.0 self build) and the second being a blueprinted high CR block built by Steve Lund at Lundengines.

Had no problems and the first one has done over 120,000 miles with no hint of mayo in the oil! Second one went to a another life in another car and i haven't heard of any problems.

next block is a 4.8 semi-race engine which will also have top hat liners. This is actually a very low mileage block (only just seasoned in reality) cross bolted- some people seem to say that the latest engines don't need liners but i think that is total rubbish.

Just in ref to the above comments- i don't think that top hat liners can actually be installed without some sort of cryogenic process- otherwise you get rotating liners.

I have to say that chris Crane at rpiV8 is not reknowned for his engineering imho. Sales yes, supplies yes, engineering- no! if you think how many people have had liners fitted then one failure really isn't a problem- actually my first block had to be remanufactured as they had managed to press the liner in whilst trappping some swarf between the block and the liner- this created some tensions in the liner which then cracked!!!!

frankly i think the risk of any problems is such a tiny one- and the risk of porosity so high without top hat liners, that not having an engine linered is a very silly idea!

my last two RV8s both have had top hat liners installed on both of them. First supplied by turner engineering (a 4.0 self build) and the second being a blueprinted high CR block built by Steve Lund at Lundengines.

Had no problems and the first one has done over 120,000 miles with no hint of mayo in the oil! Second one went to a another life in another car and i haven't heard of any problems.

next block is a 4.8 semi-race engine which will also have top hat liners. This is actually a very low mileage block (only just seasoned in reality) cross bolted- some people seem to say that the latest engines don't need liners but i think that is total rubbish.

Just in ref to the above comments- i don't think that top hat liners can actually be installed without some sort of cryogenic process- otherwise you get rotating liners.

I have to say that chris Crane at rpiV8 is not reknowned for his engineering imho. Sales yes, supplies yes, engineering- no! if you think how many people have had liners fitted then one failure really isn't a problem- actually my first block had to be remanufactured as they had managed to press the liner in whilst trappping some swarf between the block and the liner- this created some tensions in the liner which then cracked!!!!

frankly i think the risk of any problems is such a tiny one- and the risk of porosity so high without top hat liners, that not having an engine linered is a very silly idea!

What about the poor heat transfer in nodular iron as compared to grey or even vermicular?
Are these aftermarket liners thinner than the originals to retain heat flow at the same level?
Perhaps the cooling system design in these dry liner engines rely more on cylinder head cooling than the wet liner engines I have more (professional) experience with?

T

Bah! WhaddaYOUknow about metallurgy?:flipoff2:

What about the poor heat transfer in nodular iron as compared to grey or even vermicular?
Are these aftermarket liners thinner than the originals to retain heat flow at the same level?
Perhaps the cooling system design in these dry liner engines rely more on cylinder head cooling than the wet liner engines I have more (professional) experience with?

T

I thought a better insulated cylinder was better (closer to adiabatic and all that).
Of course that's up to when things start to melt.

I thought a better insulated cylinder was better (closer to adiabatic and all that).
Of course that's up to when things start to melt.

In the real world, isn't the goal to remove the heat and stabilize the system at a temperature that the system is tolerant of for indefinite periods of time? Hence, a consistent predictable thermal transfer would be preferred.

Well, to take PT's bait I work with high power density, wet liner truck diesels.
I'm not into cooling, but foundry metallurgy, so only have cursory info on cooling issues, but definitly know that cooling is now one of the most difficult things to optimise in that part of the industry. Keeping temperatures down to acceptable levels in stressed parts of the engine structure.
The Rv8 is a different bird, far from high power density!
But talking about cracks in a heated engine component and at the same time change into a material with worse heat transfer does not sound right to me.
The fatigue strength ("crack resistance") of any steel or iron decreases with rising temperature.

Enough metallurgy lesson for today...:flipoff2:
T

In the real world, isn't the goal to remove the heat and stabilize the system at a temperature that the system is tolerant of for indefinite periods of time? Hence, a consistent predictable thermal transfer would be preferred.

Well I'm not an engine designer either, but it is the heat from burning fuel that does all the work in an engine. More heat in the cylinder and less in the block has got to be a good thing. Within reason of course.

I know it's a little different being a diesel, but my 4BD1T with it's chromard liners has most of the cooling galleries in the head.

The heads get "hotter" than teh cylinder walls, mainly because all the hot gasses pass through it, on their way to the exhaust.
At leat on our heads (and all other heavy duty diesels) the exhaust channels in the head are completely surroounded by cooling galleries as well as injector spear and as close to the cylinder top as possible. Here is introduced an interresting compromise. The thinner you make the cylinder roof, the cooler you get the sensitive bridge between the two exhaust walve seats. The thinner you make it the weaker and less stiff you make it...
Where do we find the optimum for maximum engine life?

The strive for hotter combustion has been effectively quenched by the exhaust legislation maximising the amount of NOx in the emmissions.
The hotter the combustion the more NOx.
some competitors use catalysts and Adblue (Urea) to counter NOx, but we manage without it, only using EGR and some other tricks, but the caalysts in these engines have limited performance so until we see the combustion systems of a few generations in the future we will strive to have "cool" combustion.

Is not the heating of the engine's structural components that makes the work, but the thermal expansion of the combustion gasses and the generation of gas from liquid fuel.
We still need the structural part's integrity a few strokes down the line so we can not let their heat run away.

T