Engine tech - liners

A technical question.

Are there any advantages to using liners on performance orientated engines?

Have they been used in motorsport?

Thanks!

Alex

Do you mean cylinder liners ? If so 2-stroke kart racing engines have been using cast iron liners for years. They allow you to have an all ally block, head and crankcase while having a strong cylinder barrel surface. Its also useful to be able to replace in the even of a major engine seizure where the bore is very badly scratched. I'm sure there are other more scientific benefits that I'm unaware of too.

Er, don't all engines have liners?

Er, don't all engines have liners?
No, for example not cast iron blocks.
Goran Malmberg

yes I mean cylinder liners...

For example an A Series is a cast iron block, usually the pistons run directly in the block.

Would a linered block have any advantages? Or even disadvantages bar cost?!

Alex

I always understood it to be related to weight saving. A cast iron block is very heavy, particularly for a racing car.

Alex,

Liners have been used in racing engines for decades with great success. As noted above, most aluminum-block engines traditionally used iron liners, though that has changed in recent years. Many current production aluminum engines use high tech hardening treatments of the cylinder bores to permit the piston to run directly in the block. F1 engines do this, so it's fair to say it can be done.

Do you have a specific example in mind?

Regards,

I always understood it to be related to weight saving. A cast iron block is very heavy, particularly for a racing car.
As I heard even F1 engines where using cast iron blocks. At least not long ago. New thin wall casting tecniques made it possible. Cast iron has some advandages over aluminium.
Goran Malmberg

Many current production aluminum engines use high tech hardening treatments of the cylinder bores to permit the piston to run directly in the block.
I think it is more common for coatings to be used, eg Nikasil

The main use for liners in a cast iron block is to recover a cylinder that has split the bore, or been bored out as far as possible previously. Another possibility is often you find cylinder wall thicknesses are not uniform (casting not centred) which might restrict overboring capacity, using a liner here would help.

No, for example not cast iron blocks.
Goran Malmberg
Well the cast iron blocks on my three cars have liners.
Timothy Falce

Timothy, I suspect Goran was referring to 'from the factory'... ;)

Did your iron block engines come from the factory with liners? If so, that would a first for me.

theres no real benifit to having liners in a cast iron block, unless used as a way to reclaim a block that cannot be bored further oversize, or to repair damage, in some cases they are needed as massive overbores leave cylinder walls too thin.

Timothy, I suspect Goran was referring to 'from the factory'... ;)

Did your iron block engines come from the factory with liners? If so, that would a first for me.
No idea :Shrug:

I think it is more common for coatings to be used, eg Nikasil.

Funnily enough, the larger kart engines, i.e. 125cc and 250cc superkarts, have been using Nikasil linings directly on the ally casing for over 25 years too. It seems that kart engines are more advanced than people give them credit for. Nikasil coatings were not as user friendly as the liners though as if the motor seized it was a real pain to get a recoating done.

This level of sophistication in kart engines may be related to the very high operating revs. They also have short running lives [2-3 hours] and high risk of major failure / seizure. 100cc rotary valve kart engines, of the type pervasively used in the 1980s, develop maximum power at close on 20,000rpm, use cast iron liners and teflon coated pistons. You could often expect to have to replace the liner, particularly if the seizure was a bad one.

Some engine, despite being cast iron, still use liners because the block doesn't have a proper wall to make a bore out off.

These are generally 'wet' liners, the coolant touches the outside.

A lot of two stroke bike engines used/use a nikasil coating. However most two strokes only last 10-20,000 miles anyway (if you are lucky!) so wear isn't so much of a problem.

Liners are used on aluminum blocks as a cheap way of getting the required wear resistance. Porsche have been using Nikasil since the late sixties/early seventies but it is a complex process with some production yield issues. On iron blocks, as mentioned previously, liners are used as a production rework to reclaim bores machined oversize. eg when I had the engine taken apart on my Midget when it was standard, it had liners. As I was going oversize on the bores, the block was thrown out and replaced with a Marina van block.

Cast iron is very good for liners. I have a Hemi engine myself and those ar used in topfuel racing where steel liners are used as cast iron will crack. Those steel liners are not as good as cast iron for gasoline and street use. Just a comment...
Goran Malmberg

Weren't liners used as standard on some Rootes Group engines, for example Imp engines? I seem to recall they had some 'pros and cons' on those engines

Chris, the Imp engines were alloy block (& head) and had cast iron liners. I think they may have been the first volume production alloy car engines made in the UK?

They also experimented with a linerless alloy block using cast iron rings instead. Prototypes gave very good results including the testing they did for wear, but the precision in machining needed for it to be successful was not economically available in the mid sixties.

On the mention of Rootes, some of the Humber/Commer engines had chrome-plated cylinder bores (in a cast iron block), these as long as they were not overbored lasted virtually forever.

ford . . .cast iron, bore the block direct, I'm still looking for a good std bore block to use my Cossy pistons, and I don't want to liner a block, its cheaper to get pistons made !!!

Triumph TR3 etc have wet liners I think ?

most hot 2 strokes use nicasil coated ally bores, I think some cars do as well ( posh race engines though) I've read about an old Lambretta 2 stroke engine ( cast iron barrel) with a chromed bore which worked very well at high revs . . but didn't last long !!!

I believe the Chevy 4 cylinder Vega all alloy engine was the first production engine to run pistons direct in the alloy bore which was specially treated. From what I have read the thing was a bit of a dog and had a very short life and could not be rebored. They even made a multi valve cosworth headed version.

I have had a liner put in one of my chevy v8 blocks due to a bit of water damage I could not hone out and it all seems to work good.

You pretty much have it right about the Vega, Al. Virtually all of them in this country have been sleeved if they are still running.

Is it ok then to just line one piston? Or is it a good idea to do all of them? Would it make any kind of difference?

The reason I didn't say much about why I was asking is I wanted to open a bigger discussion on the subject.

I currently tune A-series engines (nothing much new in that I know) but they are turbocharged which changes things alittle.

Many blocks came from the factor with liners, and it is report that this was down to production issues and concequent reqorking of the blocks. Now days as other "good" blocks are becoming harder to come by there is interest in these linered blocks. Many engine builders will not accept a linered block in exchange or for modification!!

So what are your thoughts!

Alex

Chris, nearly all liners are installed one at a time AFAIK. Sometimes more are done if other cylinders are marginal and the block is in for another sleeve anyway, but there is no real imperative to do them all at once.

No just one cylinder as required, I have done this twice now on differnt blocks and had no problems, find a good machinist who knows what he is doing though. Ithink it cost me around Ģ150 plus vat but saved an otherwise good 4 bolt mains block.

Denis mentioned wet liners in an iron block - common in diesels (truck & agricultural).

I've had a liner fitted in a block that damaged one cylinder, never used it for racing, so I can't comment on what it would be like. I have heard of them moving under extreme duress.

And as AlexF said, BL did fit liners to some of their A series blocks, I bet it was due to a strike at the casting plant or something like that! - use some reject blocks, fit liners, and make some more dreadful engines with lousy machining tolerances.

Zef - the TR3 - I think that had the Ferguson engine, so yes, 'tis probably wet liners.

Rob.

And as AlexF said, BL did fit liners to some of their A series blocks, I bet it was due to a strike at the casting plant or something like that! - use some reject blocks, fit liners, and make some more dreadful engines with lousy machining tolerances.


Rob.

yep i've seen factory linered A series blocks, its rather like when Ford used to machine a block badly on the mains, and so instead of chucking it, theyt remachined the mains housings oversize, requiring bearings that have a thicker back to them whilst being STD size as far as the crank is concerned, whilst both are a bodge, its works well for the manufacturers, and the public never knows until theres a problem at engine rebuild time, by which its so many years later the manufacturers doesn't care anyway

Zef - the TR3 - I think that had the Ferguson engine, so yes, 'tis probably wet liners.

Rob.

Eye, oww arrh, they was at that ,TR3 block was straight from a tractor

Is it ok then to just line one piston? Or is it a good idea to do all of them? Would it make any kind of difference?

thers no problem with fitting just one liner, although depending on the block, fitting a liner can distort the other bores, so although you might have to fit only one liner to reclaim a damaged cylinder you could have to rebore the whole lot including the new liner to get a set of round bores

The reason I didn't say much about why I was asking is I wanted to open a bigger discussion on the subject.

I currently tune A-series engines (nothing much new in that I know) but they are turbocharged which changes things alittle.

Many blocks came from the factor with liners, and it is report that this was down to production issues and concequent reqorking of the blocks. Now days as other "good" blocks are becoming harder to come by there is interest in these linered blocks. Many engine builders will not accept a linered block in exchange or for modification!!

So what are your thoughts!

Alex

Sorry to digress off topic slightly... but I would really discourage anyone trying to develop or tune A-series engines in 2005. There are so many better motors around for modification today. I spent a huge amount of time, effort, research and money in developing a very highly tuned, full race 1340 motor for a space-framed modsports MG Midget in the 1980s. I can honestly say that it broke my heart. It really did. I know thousands of people have modified them in minis etc... but most of those that I know were experiencing similar levels of despair to me.

I saw something recently in Autosport I think saying that Austin Rover spent almost GBP1M developing that Computervision Group A turbo Metro, so it appears that even they had huge problems with it.

I know its not constructive, but I would whole-heartedly recommend developing a motor other than an A-series.

I know its not constructive, but I would whole-heartedly recommend developing a motor other than an A-series.

but maybe your stuck with it ? like I am with a precrossflow Ford. I can't and won't pay someone thousands of pounds to build an engine for me so I develop and build my own . . .ok not everything works as well as I'd hope, but theres enough information available for free, and coupled with my own knowledge and experience that I'm heading in the right direction, have had no unexplained catastrophies and I'm still saving money ! at least thats what I tell the wife :rofl:

Zef, I too was stuck with the A-series, because the GT regs at the time said you had to keep the same block/crank assembly as the original [although you could modify them], everything else was more or less free but 16v heads weren't allowed. At least yours sounds reliable. Almost every time I sat in that car, the motor lunched itself... a different major thing every time :-) It brought me to tears :-( Still it was a long time ago I guess and can look back on it and have a laugh now. Glad to know your's is going well.

A-series is cheap and easy to tune... unlike MANY other engines.

besides. REGS ARE REGS! Its not a mini without an A-series.

Alex

Quite right Alex. Definitely not a mini without an A-series ;)

I do assume, if you're turbocharging, that we are talking about an A+ block here. You really are pushing the envelope if you are doing it on an A block :eek:

Anyway, back to the original question. Liners.... ok, I don't have any actual data, so this is personal feeling, but I would go for a linered block over a plain one, even a cast iron one. Fundametally it allows you make the liner from a higher grade material (say bolt grade nodular cast iron, or even a forging) and fully stress relieved it before insertion into the block. That should allow considerably higher stress in the liner without risk of cracking. Additionally it would allow the block to be machined to create a "wet" liner (as mentioned above) which should give better cooling.

Would need lots of calcs I'm not up to, or lots of experimentation which I couldn't afford to prove though :(

Didn't get that from my Vizzard book either ;)

as long as the liner doesn't move!!

which can happen in a block that is marginal on strength, coupled with a big overbore, by the time you have bored an A series to take a liner theres not a lot of the origonal block left to support it, this is made even worse if you need a big bore size, as you now have a thin liner and an even thinner block, personally i would try to avoid linering an a series unless your going to stick to the origonal bore size and aren't going to rev it very hard,

other blocks well thats a different kettle of fish.

I saw something recently in Autosport I think saying that Austin Rover spent almost GBP1M developing that Computervision Group A turbo Metro, so it appears that even they had huge problems with it.

.

hardly suprising, didn't the A series start off life as an 803cc side valve lump before going ohv 850,1000,1100,1300

its a long way from 35/40 bhp upto 200 that the metro racer had!

as long as the liner doesn't move!!

which can happen in a block that is marginal on strength, coupled with a big overbore, by the time you have bored an A series to take a liner theres not a lot of the origonal block left to support it, this is made even worse if you need a big bore size, as you now have a thin liner and an even thinner block, personally i would try to avoid linering an a series unless your going to stick to the origonal bore size and aren't going to rev it very hard,

other blocks well thats a different kettle of fish.

I wouldn't suggest a plain liner. For this application it would have to be shouldered or at least pegged. You're right that this doesn't leave much material on large overbores, but I'd personally still have more confidence in a few mm of high grade liner backed by a few mm of block unless I was very sure of the quality and integrity of the block itself.

Does the block have to be an original BMC/Leyland part, or can you have copies cast?

Does the block have to be an original BMC/Leyland part, or can you have copies cast?

Isn't that going to be expensive?

Out of interest, what is a safe cylinder wall thickness in cast iron?

Isn't that going to be expensive? It's been many years since I was last involved in getting pattern and casting prices at a foundry. At the time, though, we were very pleasantly surprised at how low the prices were. These sort of things are very much volume dependent though and probably wouldn't be worth it at an individual level. Either way, I guess patents would be more the problem that making patterns.

Dunno about liner thickness.

on a 70.6 (stock)1300cc engine you donīt find the place to have a shouldered liner,on a overbore 73.5 (as you have with1340) the liners would actually touch already.
So for the A series 1300 liners are what they are -a repair method for a stock engine,not more.
I actually lost a stock engine with a factory fitted liner ,due to the liner working loose after 10k miles.....
oh and btw a-series engines are really cool to work with I won two championships in a row ...without liners.

Isn't that going to be expensive?

Out of interest, what is a safe cylinder wall thickness in cast iron?

Liners are cheap as chips - it's fitting and finishing them that costs money!!

Thickness - Denis - remember that 1760 engine I built for 1997 season, only for the BRSCC to change the rules... well that's a standard stroke Nova GSi lump, which had a 79mm bore for 1600. I opened it out to 83mm!

I think Rizla comes to mind!

It worked happily. I still have it, and was going to put it in a road car!


Rob.

Unfortunately my block starts at 81mm and you start hitting water jacket somewhere between 83.5 and 84mm. Hence I am following this thread with interest!