Hunton/ilmor Build

I believe (do not say I know) that the headers crack at the point where the flange bolts to the head due to this area being stressed from the welding and it is the first area that see's the heat from the exhaust.

Your motors have the CMI headers and they address this issue with a "cool collar" they call it I think. They seem to have got the cracking issue solved for the most part as people complain less and less.

The ignition controlled solenoid will work fine as people have done several versions of this idea over the years. Someone was trying to patent the use of a pressure valve that operated off the engine oil pressure so when the engine was shut off the valve would open and the water would drain. (hopefully to a thru hull so the water would not be in the bilge)

Hi Boatless Again,
They are now heat treated to reduce the stresses caused by bending of the tubes & the welding.

It doesn't need to be that complex.

Cougar used to have a small drain tube from the bottom water feed into the headers (lowest water point) on the Stellings, that ran straight out the transom through a wee skin fitting (X2 per engine) via rubber tube. This had like an 1/8" or 3/16" dia outlet in the skin fitting. during normal running, the losses through this small orifice was insignificant, so didn't affect the cooling performance of the exhaust, but when you switched off, it only took a minute or two to drain the head of water from the exhausts, minimising the risks from ingress via cracked metalwork. And all with no moving parts, or electrics to fail (or buy & rig).

A very Buzzi-esk approach, super simple, but very effective..

Hi Jon,
The small drain hole was my original thoughts but having had 3 charge cooler blockages due to the grass weed that seems to be rife on the south coast in warm weather i decided that a much larger valve would be a more reliable option.

Engine Mountings

Hi All,
Shimmed up the engines to the correct levels & then cut up the carbon fibre angle which will be individually fitted to their respective places. Each piece is numbered as although they all look similar they are all slightly different they will then be bolted to the engine mountings & bonded to the longitudinals.After the bonding has cured i can then remove the engines & drill the mounting holes through the carbon angle & longitudinals,using this method will ensure that there are no tension stresses on any of the mountings.



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Engine Mountings

Hi All,
Finished off shaping the carbon engine mountings & drilled the holes for mounting to the engines.I then ground the surface to be bonded with a fairly course disc to provide a good key,then thoroughly washed the angles & longitudinals with acetone.I used west systems epoxy resin with just enough filler powder added to stop it running away,i also checked the alignment before bonding into position.



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Hi Pete, what is the stringer / longit in the boat made of?

I take it you're bolting in addition to the west bond?

Hi Pete, what is the stringer / longit in the boat made of?

I take it you're bolting in addition to the west bond?


Hi Jon,
The longits in the engine bay only are bonded ply the rest are high density foam.After the engines have been removed i will flow coat the engine bay & then drill through the carbon angles & longits ready for installation of stainless mounting bolts.I will use stainless steel spreader plates on the carbon side to prevent the bolt tension from damaging the carbon.

Hi Jon,
The longits in the engine bay only are bonded ply the rest are high density foam.After the engines have been removed i will flow coat the engine bay & then drill through the carbon angles & longits ready for installation of stainless mounting bolts.I will use stainless steel spreader plates on the carbon side to prevent the bolt tension from damaging the carbon.

Peter me daft but for a second i thought the carbon was just staying glued peter:aaahhh:
Engine Mountings

Hi All,
It's been a busy week finished off bonding in the engine mountings,also started positioning of water strainers & batteries both of which will be easily accessible for service but will also have the minimum length of battery lead/water hoses very important when you are trying to save as much weight as possible.All the water & fuel hoses will be manufactured from stainless steel braided PTFE lined hoses with BSP O-ring fittings.The hose assemblies will be 30% lighter than conventional rubber hose with jubilee clips & are also capable of withstanding much higher pressures.All the stainless steel parts will be polished prior to the assembly to the hoses so the installation should look pretty slick when it is finished :hugegrin:



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great work as usual :up:

That's going to be a spectacular engine bay!:brown:
Hi Peter,

Great thread, and great workmanship going into that set-up.
looking forward to seeing that boat run this year.

What a pleasure seeing it coming together.

Cool Duna:up:
Battery Mountings

Hi All,
Made up some stainless steel angles which i drilled & bolted through the longitudinals so the battery base sits on the angle on one side & the hull on the other side.I will also bond in an upstand on the hull side, the location of the top is taken care of by another pair of angles which trap in the batteries an allowance has been made for a rubber gasket to take care of any movement without stressing the battery cases too much,a very light & strong system.The mounting position chosen gives equal length battery leads to both engines which are also as short as possible & also makes them very close to the trim & tab pumps, also took the opportunity to rethink the mounting positions for the water strainers choosing the new position allows much shorter hose runs but i will have to make some special end fittings for the water pumps & pickup pipes.



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Well as usuall a spectacular & precision piece of Unwin Engineering. Bet you could make the X sick in this. Plans underway yet for Carbon Cheetha 3?
Pete, are the strainers to be below the waterline?
Mn, some like em that way, if you have a stop cock, it can be helpful to clear weed etc from the basket.
I've no doubt Peter has thought about it though.

Pete, are the strainers to be below the waterline?

Hi Jon/JW,
The strainers are mounted slightly below the expected water line at rest,i am also incorporating a flushing connection between the full bore ball valve & the strainer so that i can run fresh water through the heat exchangers & headers if we are away from home for any length of time, can also be used to back pressure the pickup to clear blockages.There will also be a 2 bar pressure relief valve to take out any unwanted pressure spikes.

Water Pickups

Hi All,
Started fabrication of the water pickup pipes, they are made from 1.25" OD stainless tube bent to about 110 degrees this added to the transom angle of 14 degrees gives quite a good scoop effect.When they are fitted the front of the pipe will be level with the bottom, the rear of the pipe is about 1/4" lower which i may need to reduce if i have too much water pressure, also had a mock up of the spark free battery isolator switches.



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Fuel System

Hi All,
Collected a sheet of 3mm thick carbon fibre that E.P.M.Technologies laid up for me.The first requirement is for an access panel between the engine bay & fuel tank.First job was to mask out an area slightly larger than required so i could mark out the shape,mounting holes plus the fuel pipe fittings then i got to work with the slitting saw & the drill bits.The bulkhead between engine bay & fuel tank is totally sealed & is structural which is why i chose carbon & why it has lots of mounting bolts.All the cables & wiring harness that pass through the bulkhead will be totally sealed.The tank compartment as well as the engine compartment will have bilge fans to evacuate any fuel vapours.All fuel lines will be antistatic stainless steel braided fuel hose with swaged ends also had a mockup of the most awkward water hose using a piece of old hydraulic hose & fittings to establish the route & length.



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Pete ... Why don't you just build Hunton boats for Jeff i recon half of Boatmad would love to own one.

On that subject who want's to go thirds.