Melling Sportscars has followed-up news of its 516bhp and 550bhp Speed Six engine conversion launch with a full technical round-up of what the work entails.
As we understand it, those TVR modifications included elimination of oil galleries providing additional lubrication to the valve-train, and also repositioned the cams and finger followers to a location that shifted the stress points on both components. These changes appear to have contributed to the engine's less than perfect reliability record.
The Melling conversion costs £7,500 (plus VAT) for the 4.5-litre/516bhp version, and £8,500 (plus VAT) if you want 4.7-litres and 550bhp. According to Melling Sportscars the figures are not rolling road estimates but actual engine dyno figures, and the conversion comes with a two year parts and labour warranty.
Official details as supplied by Melling Sportscars are reproduced below:
The conversion includes the re-machining of the cylinder head. This re-positions the finger followers and position of the cam shafts. The modifications also include the additional oil galleries to the cylinder head that were removed on the Speed six. These modifications give more power as originally designed. They also give a vast improvement in reliability.
Higher performance cylinder liners which give better heat transfer and less friction.
New design pistons giving better balance and quicker engine response.
Specially designed piston rings to give better sealing and less friction.
The return of solid billet cam shafts with new profiles.
Specially designed valve springs with less load giving quicker engine response.
The return of a solid billet crank shaft with higher performance main bearing.
All Melling rebuilt Speed 6 engines come with the following components replaced as standard and using all original castings,
New Melling Crankshaft
Relinered and rebored cylinder block with deck remachined
New Melling Liners
New Melling forged pistons with Dows D10 dry lubricant to skirts
New high specification piston rings
New forged H beam 4340 steel rods with ARP 2000 rod bolts
New main and big end bearings
New sump baffle panel
Cylinder head completely stripped and rebuilt with new Colsibro valve
guides fitted and seats reground throughout.
New inlet valves
New exhaust valves
New valve stem seals
New Melling finger followers
New Melling camshafts
New oil feed modification to cylinder head (original design)
New high specification timing chains
New half time bearings
New molybdenum disulphide impregnated upper timing chain tensioner
New oil seals
All bhp are genuine Engine Dyno figures and not estimated Rolling Road figures
The AJP/Speed 6 Engine is a result of ongoing development at MCD.
4.5 AJP6 £7,500 plus VAT
4.7 AJP6 £8,500 plus VAT
Engine removal and refit £1,000 plus VAT