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Following on from the 'Block Mod' thread and thinking about things overnight I've come up with a few inomolies and have raised a few questions. First up are the liners:

Alot has been said about the RS liners being 'Plasma Coated'. Not something I personally believe. My reasons are:

The processes I've looked at are more to do with giving aluminium a hardened coating to enable it to deal with stresses/forces/heats it normally wouldn't. With the RS and ST liners being iron (afaik) there is no benefit in giving this an additional coating.

The process of 'Plasma coating' refers to the process in essence of spraying a molten material on to the face of another (as said usually aluminium) to give it extra strength. The processes I've seen quote thicknesses in excess of 100 microns. This is important as it's a greater thickness than the human hair. Therefore if Ford were to spray a liner with an alloy, were it a steel or aluminium coating, it should be easily seen- dark brown of the iron vs. silver for the steel/aluminium.

On top of this there would be the additional space the coating takes up, over 200 microns in diameter. If this were on the inside then I am cirtain the RS internals (they would have to be smaller accross their diameter) would be too small for the ST, something we know isn't true, and I cannot see a benefit in doing this (hardened coating etc).

If the liners were coated on the outside, again I can't see any benefit. Again your looking at nothing more than increasing the thickness of the liner wall by 100 microns+, something Ford could achieve by simply speccing thicker liners and would be cheaper.

Then there's the cost. A new ST3 would have cost around £19k, an RS around £25k. In that difference you would need to factor in the additional cost of the bodywork, clutch (we know is exspensive), diff, turbo, seats, the different suspension parts inc Revo Knuckle etc. So therefore I simply cannot see Ford employing some space age and highly probable, costly technique, to coat the liners for minimal benefit. From the outset Ford said the Mk2 RS had to make a proffit.

My question is this though, is there any evidence from Ford that the liners are coated in some way? I'm guenuinely interested so any links would be appreciated, as at the moment I'm just reading internet hearsay. I would love to read something about the processes Ford used and the benefit it has given.

Next up is RS internals and compression ratios:

It's widely said that instaling RS internals and lowering the compression is a good thing. Reading various bits of information basically shows that the reverse is opposite. With my basic understanding of what the Compression Ratio is- The difference between the displacement of air when the piston is at the top of the throw and when it is at the bottom. From what I have read the compression ratio is a measurement of combustion efficiencey, with the higher the CR the more efficient. Most manufacturers aim for 10:1, some petrol engines run up to 14:1 and some diesels up to 22:1.

The RS is booked at 8.5:1 whilst the ST is 9:1, so the difference is minimal at best.

So why is it viewed that lowering the CR in the ST is a positive thing? From what I have read lower CR's actually produce more heat (at the exhaust) than high. Surely this should lead to more issues not less? Again when I have looked at low compressions it tends to point to issues such as poor valve seats and O rings, issues not present in high CR's.

A Bugatti Veyron Supersport is booked with a CR of 9:1.

So why aren't RS's and ST's wih RS conversions splitting their liners? Is it something simple like the bigger oil cooler making the oil run at a lower temperature or displacing more heat? Is it perhaps the RS has a much better radiator? The ST is water cooled therefore a bigger and better cored radiator would displace more heat making the RS (and ST when instaled) run cooler?

Any help understanding these questions is greatly appreciated.
 

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Your .cr quote relates to na engines ,not turbo engines.
Also the plasma coating from what i have read is on the outside of the liner.

Engine Hardware -Plasma sprayed liners

Plasma sprayed liner technology:
The cylinderblock is high pressure die cast in aluminium EN46000 with open deck design cast-in, aluminium coated, grey iron liners.
The liner is manufactured by centrifugal casting process with a thin plasma coated aluminum sprayed layer on the outside which bonds to the cylinder block material during casting.
The bonding between the grey iron liner and the thermal sprayed aluminum coating is a mechanical adhesion bond.
The bonding between the thermal sprayed aluminum coating and the block aluminum is an intermetallic bonding due to re-melting of the plasma sprayed aluminum layer.
The bonding is a key factor for the mechanical properties such as block strength, fatigue and deformation of the cylinder bore during running engine condition.
The improved bond also improves heat transfer, hence cooling performance.
 

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I spoke to JamSport last year, it was a very detailed discussion about upgrade paths for the ST. When we got onto the subject of liners I was informed, in no uncertain terms, that plasma coating does nothing to protect the liners and was "bull twaddle Ford PR used".

Take from that what you will.
 

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Hopefully that clears up exactly what the plasma coating is, where it is applied in this particular engine (on the outside of the liner) and just how it brings benefits to the 'RS' engine in terms of added strength and enhanced heat transfer properties

One of the other points made in that Ford presentation was that the larger KKK turbo runs with higher EGTs which brings fuel consumption benefits along with leaner burn.

Also the benefits of a larger rad..

Don.
 

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Discussion Starter · #7 ·
Hopefully that clears up exactly what the plasma coating is, where it is applied in this particular engine (on the outside of the liner) and just how it brings benefits to the 'RS' engine in terms of added strength and enhanced heat transfer properties

One of the other points made in that Ford presentation was that the larger KKK turbo runs with higher EGTs which brings fuel consumption benefits along with leaner burn.

Also the benefits of a larger rad..

Don.
Cheers for the info Don. What are your thoughts on compression ratio with the RS being only marginally lower than the ST, but higher CR's being more favourable?
 

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Discussion Starter · #8 ·
Ford allowed Nissan to use the plasma technology in their car.it was ford and a company called flame spray industries who developed it.

Why not just ask ford directly ?
Have ever tried getting information out of Ford? You get two answers to every question so your no better off ,and I'd never get through to an engineer who has the correct knowlege.
 

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Ive answered your questions about plasma coating a few times already so will ignore them! On the compression ratio though you need a lower compression ratio to run more boost! You say 8.5/1 isnt much different to 9/1 but it is a lot of difference in the tuning world! Lets bear in mind that that is the compression ratio of the cylinder at atmospheric pressure! Try them adding the amount of air thats present at 1.2 bar of boost and things look a bit different! To be honest i dont think that i can explain in laymans terms why its beneficial to lower the compression ratio but as engine tuners have been doing this since the dawn of time i think you might just have to accept that its the right thing to do! If you want to argue about it maybe you should just get some higher compression pistons or have your head skimmed and try it?
 

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More compression creates more torque (which we really don't need), but it also creates a heap of cylinder heat which we definitely don't need.

Hotter engine = softer metal, plus you get hot spots that can pre-ignite the air fuel mix. Detonation.

Does this sound like liner splitting conditions?

That's a really simple way to put it.

Also, if you do have a strong engine with a great cooling system, lower static compression gives a larger physical space to squeeze in more air and fuel to ignite, so a higher combustion volume for the same swept compression level for the same cylinder capacity, with no extra heat other than maybe exhaust gas temps. Bigger bang, more power.

The lower compression on an ST with RS rods, crank and pistons but still using a KO4 turbo is more about safety against heat/liner issues as the turbo is too small anyway. Cylinder temps will be lower and it will be less stressed to make the power.

On the RS, it's to make it work for the bigger turbo, to get more power. Big turbo and high compression doesn't go together.
 

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Discussion Starter · #14 ·
More compression creates more torque (which we really don't need), but it also creates a heap of cylinder heat which we definitely don't need.

Hotter engine = softer metal, plus you get hot spots that can pre-ignite the air fuel mix. Detonation.

Does this sound like liner splitting conditions?

That's a really simple way to put it.

Also, if you do have a strong engine with a great cooling system, lower static compression gives a larger physical space to squeeze in more air and fuel to ignite, so a higher combustion volume for the same swept compression level for the same cylinder capacity, with no extra heat other than maybe exhaust gas temps. Bigger bang, more power.

The lower compression on an ST with RS rods, crank and pistons but still using a KO4 turbo is more about safety against heat/liner issues as the turbo is too small anyway. Cylinder temps will be lower and it will be less stressed to make the power.

On the RS, it's to make it work for the bigger turbo, to get more power. Big turbo and high compression doesn't go together.
Thing is though, from what I've read the reverse is true. Bigger the compression ratio the cooler the exhaust gases. I can link to the sites which state this.
 

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I've never heard anyone want to increase CR when tuning an engine? higher compression ratio means more heat in the cylinders, which we all know the ST really doesn't like let alone any other engine, especially ones with alloy blocks/heads.
 

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Discussion Starter · #16 ·
If you fully read the artical and open up the related documents you will see that the Nissan technical feature is dated Fen 2010

http://jalopnik.com/5467038/the-ford-engine-technology-good-enough-for-the-nissan-gt+r
I know what your saying, but that's Nissan. Ford state it debuts in their car in the 2011 Shelby Mustang.

When I read what Don has put up it leads me to believe that a simpler method MAY have been used. Something along the lines of putting the liner in a mould and simply pouring molten alloy around it perhaps?
 

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I've never heard anyone want to increase CR when tuning an engine? higher compression ratio means more heat in the cylinders, which we all know the ST really doesn't like let alone any other engine, especially ones with alloy blocks/heads.
From one of a number of sources:

http://en.m.wikipedia.org/wiki/Compression_ratio

A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass ofair-fuel mixture due to its higher thermal efficiency. This occurs because internal combustion engines are heat engines, and higher efficiency is created because higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer expansion cycle, creating more mechanical power output and lowering the exhaust temperature

On top of that there's static and dynamic values, with dynamic always being lower anyway.
 

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From one of a number of sources:

http://en.m.wikipedi...mpression_ratio

A high compression ratio is desirable because it allows an engine to extract more mechanical energy from a given mass ofair-fuel mixture due to its higher thermal efficiency. This occurs because internal combustion engines are heat engines, and higher efficiency is created because higher compression ratios permit the same combustion temperature to be reached with less fuel, while giving a longer expansion cycle, creating more mechanical power output and lowering the exhaust temperature
And as it states at the bottom and Robbo has already mentioned:-

Higher compression ratios will however make gasoline engines subject to engine knocking if lower octane-rated fuel is used, also known as detonation. This can reduce efficiency or damage the engine if knock sensors are not present to retard the timing.

See here what that does:- http://en.m.wikipedia.org/wiki/Engine_knocking
 

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On a normally aspirated engine increasing the compression is desirable to increase the torque and widely used to do so. The limiting factor being pinking/pre-ignition or detonation call it what you will. Us old school mechanics call it pinking. Ignition timing has to be set accurately to cope with higher CR's. On a turbocharged engine increasing the compression ratio is not really a desirable option. Two different engines - two different approaches.
 

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On a normally aspirated engine increasing the compression is desirable to increase the torque and widely used to do so. The limiting factor being pinking/pre-ignition or detonation call it what you will. Us old school mechanics call it pinking. Ignition timing has to be set accurately to cope with higher CR's. On a turbocharged engine increasing the compression ratio is not really a desirable option. Two different engines - two different approaches.
So in other words, on a turbo charged engine it is far simpler and safer to lower the compression ratio and turn up the boost than to increase compression ratio and try and deal with 'pinking'?
 
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