TVR Speed Six Design Spec Upgrade

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.

New lease of life for Speed Six TVRs
New lease of life for Speed Six TVRs
The conversion returns the Speed Six engine to its original design spec (as conceived by Al Melling on behalf of TVR), and which was subsequently modified prior to production by the Blackpool firm.

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 headgasket
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

Comments (158) Join the discussion on the forum

  • PhantomPH 12 May 2009

    Whilst that sounds great, nearly £11k for the full business is a LOT of money.

    For those chasing reliability, £11k can go a long way towards alternatives or a few cheaper rebuilds.

    P~

  • JonRB 12 May 2009

    Given it's Melling, are new parts made from unobtainium, vapourwareum and grandpromiseum?

  • Fume troll 12 May 2009

    Good to get some more facts at least. Keep them coming.

    Cheers,

    FT.

  • Podie 12 May 2009

    PhantomPH said:
    Whilst that sounds great, nearly £11k for the full business is a LOT of money.
    Agreed. Makes me wonder if TVR would have been better adding circa £8-10k per vehicle to give better reliability...

  • PTOTY 12 May 2009

    This questions has probably been answered a few times, BUT.....

    Why did TVR change the original design of the engine? Was it a manufacturing cost issue?

    I would have liked to have been in the design meetings where the decision was made to re-position the finger followers and to remove the oil wells...surely somebody would have asked what affect those changes would make to the engine.

    Or were there other constraints that we don't know about??...were the design changes justified by more than just cost?

    I would like to see how much money TVR lost through having to repair the engines due to these design flaws Vs. the amount they made in repairing cars out of warranty.

    If the orginal engine design had been used would that have reduced the price of the warranty costs on TVR and end users?

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