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Darton Sleeves



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The Nissan SR20 DET variable camshaft block
under going the conversion to the DARTON sleeve product.


SR 20 DET block with the DARTON Sleeves installed
and the deck machined

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Sleeves shown with the block as various shots

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A Honda B18C block being prepared for the DARTONsleeve product using conventional machine shop vertical boring equipment.

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This photo shows the torque plate tensioned onto the Honda block to pre-stress and secure the DARTON sleeves for machining the bores.

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The end result in selecting the DARTON sleeve for our purpose: very high compression, successfully built and
tuned to 130kw at the wheels.

(With reliability; thanks to working with owners and skilled dyno technicians who know what they want and understand how to get there.}

This job led us to buy our new state-of-the-art CNC equipment. Very difficult work using conventional equipment.
Those days are gone

This naturally aspirated B18C Honda block went on to develop excellent and reliable street performance, at considerable compression, running on pump fuel.

The DARTON sleeve for this Honda interlocks the walls of the block and has direct contact with the block’s coolant; an excellent product for the top end of engine development.

The demanding machining specifications were achieved without the CNC mill and tooling that we have since installed into our business.


Part of our range of engine block torque plates that we offer with performance engine machining. The method involves pre-stressing the block by assembling this “artificial” head to hold the block in it’s assembled state whilst we finish off the honing of the bores.

The procedure greatly enhances the perfomance of piston rings and represents great value in obtaining cheap horsepower. It achieves this by reducing imperfections caused by head bolt and engine block design problems that distort the machined bores during engine assembly.

Darton Sleeve Work – Ford

Machining for Darton sleeves 003This block is the 5.4 litre XR8 engine. It is set up on our machine ready for the first of many delicate machining stages. Note that there can be no practice runs to  earn how to get it right. First time is when it all has to happen….correctly.

The first stage machining operation machines the original cylinders all the way into the water jacket. Material is carefully left in the upper and lower sections of the block for the next stage.(Refer to 6 Photos Below)

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Machining for Darton sleeves 004After most of the inner block has been turned into chips, the upper and lower sleeve locations are now precision machined to enable an exact fitting of the Darton sleeves.

Machining for Darton sleeves 009With the Darton sleeves now fitted, the final machining stage opens up the semi-finished sleeves to suit the client’s pistons and the block is then decked.

Note that after this major machining you need to expect somemovement in the crankshaft tunnels. We suggest that you allow for a line hone of the tunnels when preparing your budget. Certainly do not line hone before the Darton sleeve work.




Darton Sleeve Work – Subaru EJ25

Machining for Darton sleeves 011These two Subaru cases are from the EJ25 STI enginebeing fitted with Darton sleeves for a road/club car. The photo shows the electronic probe finding the centre of each bore in readiness for the machine’s next step which is to go and get the boring bar from the machine’s tool carousel.

(Below) Two views of the finished machining of the cases ready for the fitting of the Darton sleeves.

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Machining for Darton sleeves 012Darton sleeves are now fitted. Next step is to bore and hone using a torque plate and then bore out the gudgeon pin access hole.

Machining for Darton sleeves 017Bored, honed, decked and the gudgeon pin access hole finished

Machining for Darton sleeves 018EJ25, STI, in the assembly room showing the COMETIC
head gasket that is necessary with the Darton sleeve product.