- As we've seen power levels rise with high performance turbo charged
aluminium block engines, the actual strength of the engine block
can become a limiting factor in to how much boost and hence
how much horsepower that engine block can survive with.
It's become a common option with these engines to fit
aftermarket ductile iron sleeves in place of the factory liners
in order to improve strength.
We're here with John from Darton Sleeves to talk about what goes
into that technology.
So John for a start, let's talk about those factory
alloy blocks, what are the weaknesses with those blocks,
and why are the factory alloy blocks a limiting factor
in terms of power and boost?
- The biggest issue with the OEM setups is pretty much all of them,
90% of them come with a stock cast iron sleeve in them.
Issue with that is it's a lower grade material,
they just do it primarily for cost effectiveness.
Their sleeves are only about probably 30, at the max
40000 tensile strength.
Not a lot of strength in that sleeve, and then they're also cast thin
because they're not trying to go bigger bore,
they're pretty much making that block that bore size and that's all
it's gonna do.
So you're limited on how much power that can actually take
because there's also zero ductility with cast iron.
Any type of movement or flex in that cylinder,
since it is only cast iron, it will end up cracking and stuff
and that's gonna be a real big limitation.
Especially when you're trying to take a stock block and increase the power,
add more boost, go much higher compression pistons and stuff,
so adding any more power than what the OEM manufacture intended to,
it will lead to eventual of failure 'cause that cast iron sleeve
it's in the **
- Now another problem with a lot of the alloy blocks that we see are
what's referred to as an open deck design where the sleeves and the cylinders
themselves are really not connected to the outside of the block
so this also presents some other problems even aside from actual
sleeve strength with the sleeves moving around and causing
problems with head gasket failure, is that a sort of a common scenario?
- It is 'cause same issue with the standard aluminium,
they still come with the stock cast iron sleeve,
it's not as much support.
And then added to that, the biggest issue with that,
that goes hand in hand is since there's open deck configuration block,
problem is there's no upper structure or any support.
So what happens under say a high horsepower application,
is you end up getting sleeve walk.
So the cylinders start rocking under a high boost,
the higher horsepower applications.
So as soon as you get any type of movement that cast iron ends up cracking,
and it'll crack all the way out to the aluminium,
ends up blowing head gaskets or cracking the cast iron.
- Even if we're getting to a scenario where we aren't exceeding the strength
of that cast iron sleeve and it's not actually cracking,
with that open deck design, the sleeves will still tend to flex
a little bit at very high boost levels, and ultimately distort slightly,
and that's going to still even affect our ring seal and hence
the power of the engine, even if we aren't cracking the sleeves,
is that correct?
- Correct, there's still your limiting factor of being cast iron.
Having that open deck is just weakening the support.
Like I said any type of movement with that then you're gonna see a failure,
or it's gonna go distort and just completely go out of round anyway,
it's not gonna maintain its figure and stuff throughout the higher
horsepower applications.
- OK so let's talk about Darton's solution to this.
So you've produced a range of ductile iron sleeves.
In particular the product that I want to talk about here is your MID sleeves
that are used to replace the factory cast sleeves on a lot of those
open deck design blocks.
So can you tell us what those ductile iron sleeves are,
and how they work?
- Our MID sleeve, it's made from our proprietary material which is ductile iron
It's based on an ASTM spec for ductile iron but we actually tweaked that
metallurgy to be able to work with a piston ring better
than you know what the standard ductile iron actually is.
So what it is, it's taking say your 30000 tensile strength cast iron
that's in a block and we're replacing it with a much thicker wet sleeve,
and then it's gonna end up 100000 to 130000 tensile strength.
But at the same time still be ductile to where if there say if there is
real high horsepower application, where there may be any distortion
or flex in the bore, it'll flex and not end up cracking,
but it'll still kinda have a memory effect and still go back to its original shape
once the horsepower actually drops back down.
- Now there's two aspects that I wanna talk about there.
So first of all, you've talked about the improved strength of your proprietary
material but on top of the improved strength you're also now,
because you're removing that factory cast iron sleeve plus the alloy
that surrounds it, you've also got a much thicker wall to your
ductile lined sleeve, correct?
- Correct yeah i mean you're looking at say minimum,
you're going from usually stock cast iron, which is only maybe
30000, 40000 thickness in the actual stock and about another 100000
in the ** of the aluminium, we're eliminating all of that and replacing
it with a full wet sleeve design, which will completely take down
the weakest part of that block and replace it with a sleeve
that's gonna be 150000 to 250000 thick.
And a material that's also two to three times stronger,
and then giving you full support at the top so you don't
have a problem with that sleeve walk or the cylinders actually moving
on you under the high horsepower application.
- OK so now just to talk about that ductility because I know you showed
me before, you've got a sleeve out of a top fuel engine
made out of that ductile iron material, and you pressed that almost completely
flat in a press and yet it still hasn't cracked correct?
- Correct yeah I mean I'll show the material.
I'm actually able to take our material, this is a top fuel sleeve,
let's say John Force, Schumacher or ** racing would use,
and we're able to actually take this sleeve and crush it down
probably to roughly about little over an inch
and the sleeve actually its memory effect actually allowed it
to spring back without cracking without any signs of wear
just because of the ductility and strength of the material.
- So obviously if your sleeve crushes to that sort of diameter in operation
you've probably got bigger things to worry about
than your sleeve cracking but it's a good indication or demonstration
of exactly how flexible that material is.
Now the other thing I wanna talk about here is the way those MID sleeves
convert an open deck design block to effectively a closed deck,
so can you tell us how that works?
- Yeah effectively what we're doing is we're eliminating all of that
freestanding wall which is technically the weakest part of the block anyway
so using that kind of limits what you are able to do size wise and power wise.
So we're eliminating that process and then installing our wet sleeve
so then that's allowing you to get full support
at the upper deck of the block so you have zero movement
and then at the same time since the material's so much stronger
than what the stock casting is, and it is thicker,
it also allows you to increase displacement safely and still
be able to push a safe amount of boost through it,
but increase the displacement and adding more rigidity to the block.
- Now I know that a lot of people have trouble with the installation
of sleeves and obviously with your MID sleeves there is a significatnt
amount of machine work required to the block in order
to correctly fit them.
But a common complaint I hear about sleeves in the aftermarket
is that in operation they can drop.
So what causes this dropping and how can that be circumvented
during the installation process?
- Majority of the time it's pure installation error.
The way the sleeves are designed, they have a larger register on them,
it's a solid piece of metal, there's no moving parts,
nothing moves, it maintains its shape, maintains its form once it's
installed properly.
Biggest issue with installation, if the sleeves are gonna move
it's because you're giving it somewhere to go.
A lot of times you have problems where they're decking a block,
and the sleeves aren't completely seated, or they're just not following,
we have specific installation manuals that show you the process
step by step from setting up the block measuring, checking where
your registers gonna be, gives you the tolerances.
If you're not able to hold those tolerances, you're gonna have
problems with installing the sleeve, the sleeve's gonna move
at that point because the tolerances aren't held to spec,
or the machining is just not exact as it could be.
If you're not using like I say a three or four axle CNC,
that would be your minimum basis upon being able to machine
the block properly is it's gonna be a CNC machine.
- So what you're saying there really is this installation,
to do it properly you're getting beyond the capability
of actually doing a good job within your tolerances
using manual equipment?
- Correct, I mean everything's gonna have tolerances to it.
And when you are working with say a half a thou with our stuff,
it's gonna be a half a to a thou tolerances,
a lot of the times without a CNC that's gonna be difficult to maintain,
especially trying to maintain bore centre where that's critical.
Because a lot of blocks have, they're thinner on one side
than the other.
Some of them need an interpolated cut in order to put the sleeves in.
You're not able to do that with a standard boring bar,
or a standard bridge bore without having digitals on it at least,
to be able to maintain that bore centre.
So that three to four axle CNC will give you a lot more accuracy
so that'll eliminate the process of you know taking guess work out,
being able to machine the block properly and get the sleeves in.
'Cause once the sleeves are in, they're seated,
there's a large register on the bottom, heads go onto the top,
everything's held in compression with each other.
So certainly if everything's machined properly,
everything's held in with tolerance, everything's measured exactly
where it should be, there's nowhere for the sleeve to go.
- Now in terms of the installation as well I know there's multiple
schools of thought on whether the sleeves should sit proud
of the deck surface of the block once everything's been machined
ready for assembly,
or whether the sleeves should be flush with the deck.
Is there any recommendations from Darton on that particular aspect?
- It comes down to preference and also application.
Standard street cars where you're just trying to freshen up a block,
you just need to get running again, it's gonna be standard horsepower,
nothing too elaborate, you generally can flat deck the block,
that's gonna be a problem, let the MLS do its job.
A lot of the times when you get to the higher horsepower applications,
some people either prefer to step deck, where they're leaving up
the compression area two to three thou, or running a seal wire in the sleeves.
It comes down to number one, how much power you're planning on running,
is this a street car or is it a drag car, is it a road race a car?
It depends on the power you're making,
how big a bore you're going.
Cause a lot of times when you go to the max bore size on a sleeve,
there's not enough room for a seal wire so you have to step deck instead
to get the better crush on the head gasket.
Or some people with the really high horsepower applications,
they're step decking an running an o ring to get even more
crush on the head gasket.
So it depends on application and certain machinists have
their preferences on which way they're gonna do it.
But a lot of it comes down to, is what the applications gonna be,
street, race, drag race, really high horsepower,
or street strip cars.
- Now the other thing with these MID sleeves or sleeves in general
is if you do have a problem with the engine in operation,
maybe you torch a piston and end up damaging
one particular cylinder, you've got the ability to replace
and individual sleeve?
- Correct, all of our sleeves, our sleeve designs,
they're all replaceable individually or full as a set.
The technology that we based these sleeves upon
was basically the same thing that diesel motors, tractor motors,
ever since they've been in existence that's how they were,
they were generally a ** design.
So what we did is we took that same concept and just
changed the application for it.
So by putting o rings, sealing them along the bottom
of the sleeves, what that essentially does is makes the sleeves completely
replaceable without distorting or bothering the cylinders next to it.
You can take out one cylinder put a new cylinder it,
redeck, rehone and reuse that block over again.
Or if you have a problem, say you go to a max bore size of a kit,
like say on a ** Honda, you go to 90 millimetre,
biggest you can go, you can take all four sleeves out,
put a whole new fresh set it, redeck, rehone,
start it back to 86 or 87 millimetre bore, use that whole block over again.
Since the cylinders are just put in with an o ring,
they don't distort the cylinders next to it because everything's all
individually held in separate from each other.
- Look John it's been really interesting.
Good to get some accurate information behind that sleeving technology,
get some answers to those questions.
If our viewers wanna find out more about Darton Sleeves,
how can they get in touch?
- You can email Darton Sleeves at sales@darton-international.com
Or go to dartonsleeves.com all of our information's right there,
how to contact us, and we have a lot of technical
information on there also that you can look up.
And also download our catalog.
Same thing it has a lot of technical information in our catalog.
- Perfect thanks a lot for your time there John.
- No problem, thank you for coming by.
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