TVR Speed Six Design Spec Upgrade
Melling reveals full tech details of 550bhp Speed Six conversion
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
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
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?
ETA - I was under the impression that TVR changed the design in order to avoid paying Melling rights money...or something like that.
360 brake in the original chassis and set up was quite a handful thank you very much
However in a Cerbera chassis properly set up .... does anyone know ho much it would cost to get a engine shipped out to Australia???
Great if you want a huge power TVR, but a Red Rose Tammy would be plenty for me, and I'd certainly not want to buy one of these cars 2nd hand with a mega engine in it, as it's just more liability if it breaks, more chance of binning it, more for insurance? More strain on gearbox and diff etc!?
Seems like a great exercise in making ballistic S6 Tivvers, but what about most owners who just want assured reliability? Melling are missing that market imho, which it has to be said is going to be much more popular and profitable I'd imagine!?
Dave
Great if you want a huge power TVR, but a Red Rose Tammy would be plenty for me, and I'd certainly not want to buy one of these cars 2nd hand with a mega engine in it, as it's just more liability if it breaks, more chance of binning it, more for insurance? More strain on gearbox and diff etc!?
Seems like a great exercise in making ballistic S6 Tivvers, but what about most owners who just want assured reliability? Melling are missing that market imho, which it has to be said is going to be much more popular and profitable I'd imagine!?
Personally, I find it a bit hard to believe, as I have a 4.3 SP 6 in my Tuscan from TVR power which puts out 415 BHP and 400 torques, it is an immense engine.
Another 101 BHP for a 200 cc increase appears optimistic, unless its revs like hell.
I would love to be proved incorrect though, you can never have enough POWER !!
cheers
Personally, I find it a bit hard to believe, as I have a 4.3 SP 6 in my Tuscan from TVR power which puts out 415 BHP and 400 torques, it is an immense engine.
Another 101 BHP for a 200 cc increase appears optimistic, unless its revs like hell.
I would love to be proved incorrect though, you can never have enough POWER !!
Gassing Station | General Gassing | Top of Page | What's New | My Stuff