Honda B16/B18C Darton Liners
Here is an example of our machine shop capabilities. In this example, we will show you how we can achieve over 250bhp on an 85mm bore B16B block. A bore size that would be impossible without this process.
First of all, the donor block is measured on our Renishaw Cyclone Series 2 digitising/scanning machine. The reason for this, is that the bore size is so large for the block that absolute alignment is a must.
(This machine is capable of measuring the centre position of each liner to a tolerance of +/- 10 microns. )
The block is then clamped on the table of our Deckel Maho DMU 70 Evo machine. This machine is a 5-axis high speed machining centre capable of machining all parts of the block within 1 clamping operation.
(This machine has an operational accuracy of +/- 1 micron.)
The block is then ‘datumed’ , this is where the machine uses a Renishaw MP700 probe to measure the exact position of the block in all 4 axes that are being used in this job. Here you can see the probe measuring the overall height of the block (i.e. the Z axis).
Here, the probe is finding the centre of the datum dowel hole. (The X and Y reference).
Here, the probe is finding the centre position of the second dowel hole. (This establishes any rotational offset from clamping)
Here, the boring tool is being measured by the Renishaw NC1 laser tool setting device. This measures both tool length and cutting diameter.
In this picture, we can see how the liners look as standard, albeit a little rusty from non-use. This is 81mm.
The boring tool then proceeds to bore out the cast iron liners from the Aluminium. This is done at a cut-rate of 1mm per pass.
This is how the block looks with only 2mm removed from standard bore sixe of 81mm. At 83mm, there is virtually no cast iron left.
At 84mm, you can see the cast iron breaking through into the aluminium backing, proving that big bore Honda engines have very little cast iron strength.
At 86mm, there is only aluminium.
Now, the bores are finished at exactly 89.0mm for the O-ring sealing part of the Darton liner.
You can see a Darton sleeve being test fitted for O-ring seal.
Now, the remaining aluminium liners are removed down to the specified bottom step height.
Next, the top of the block is surfaced to allow for exact height finishing of the liner-steps.
The top liner step is then machined.
Here, a liner is now test fitted.
The bottom step is now finish-machined.
Liners are now test fitted for overall diameter fit.
The liners are now clamped in place as they’re supplied in the standard bore size of 81mm.
The liners are now bored out to 84.7mm allowing for finish-honing.
Before finish-honing, the liner protrusion is checked. This is essential as slip-fit liners need extra ’squish’ on the gasket, as they eventually settle. This stops any head gasket failures many years down the road.
The protrusion height is set at 45 microns.
This illustrates how the block looks when fully machined for Darton slip-fit liners.
The block with the liners clamped is then finish-honed on our in-house Sunnen CK10 Cylinder Hone.
(The bores are now honed to give the correct piston to bore clearance and maintain the correct surface finish for oil distribution. Each bore is honed to a tolerance of +/- 5 microns for both roundness and taper.)
The block is the cleaned and reassembled, ready for building.
Pricing starts at €400 + VAT for supply of Darton liners and €600 + VAT for fitting and honing.