DISCO 4.0 THOR REBUILD TO 5 LITERS
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DISCO 4.0 THOR REBUILD TO 5 LITERS
I need to re-build my Disco 2 engine as its dropped a liner,I'm thinking of getting the block tophat lined to 96mm,using some chevy 305+40"pistons and rods(not sure of length)and a stroked 4.6 crank 85mm? need a high comp ratio as it runs on LPG,any input would be greatly appreciated
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CastleMGBV8
- Top Dog
- Posts: 2334
- Joined: Sat Aug 18, 2007 5:09 pm
- Location: Sidcup, Kent, UK
Name?
Real Steel & V8 Tuner amongst others do stroker kits, and can work out cheaper as a matching set of parts as you may not need to rebalance.. you may be able use your crank in part exchange.
There are now other standard performance pistons than chevy 305 available for large bore conversions.
Various comp ratios are possibly available.
Thor manifold/plenum will be quite restrictive for large capacity engine.
Kevin
Real Steel & V8 Tuner amongst others do stroker kits, and can work out cheaper as a matching set of parts as you may not need to rebalance.. you may be able use your crank in part exchange.
There are now other standard performance pistons than chevy 305 available for large bore conversions.
Various comp ratios are possibly available.
Thor manifold/plenum will be quite restrictive for large capacity engine.
Kevin
There are now other standard performance pistons than chevy 305 available for large bore conversions.
Various comp ratios are possibly available.
What are they and how much do they cost?,I found an old thread on here about using Chevy 305 pistons,my 5.5 I had in my Griff used custom Diamond pistons and Chevy rods.
The stroker kits in this country are too much money,I can buy a set of pistons in the Statrs for £150 and the rods about the same.
Various comp ratios are possibly available.
What are they and how much do they cost?,I found an old thread on here about using Chevy 305 pistons,my 5.5 I had in my Griff used custom Diamond pistons and Chevy rods.
The stroker kits in this country are too much money,I can buy a set of pistons in the Statrs for £150 and the rods about the same.
Hi
The 305 pistons are available in several pin heights, to get the final compression height you want you need to find a combination of rod length and pin height that works with your stroke, you want as low a piston height as you can as they tend, with everything else being equal, to be the lightest. Don't dismiss hyperutetic pistons as they are generally strong enough for anything you are likley to get out of the rover and are lighter and more stable than forged, and considerably cheeper. Unless you are using wildcat heads then with ported rover heads you won't be reving a 5+ litre engine much above 5500 revs.
Personally I wouldnt go the big displacment route as you will get far more pover for your money by going for more moderate displacment and spend the money on better heads. Kevin's route of a 4.2 base engine with 305 pistons and good heads will produce a better mannered engine that is less stressed and has better performance for the money.
For the budget of a 4.0/4.6 base 5+ litre engine you could have a 4.2 base engine taken to 4.35 with the hyperutetic pistons, chevy I beam rods, merlin or buick 300 heads and a roller cam setup that will give you a much wider powerband and more peak power and just be more fun with less maintanence.
Best regards
Mike
The 305 pistons are available in several pin heights, to get the final compression height you want you need to find a combination of rod length and pin height that works with your stroke, you want as low a piston height as you can as they tend, with everything else being equal, to be the lightest. Don't dismiss hyperutetic pistons as they are generally strong enough for anything you are likley to get out of the rover and are lighter and more stable than forged, and considerably cheeper. Unless you are using wildcat heads then with ported rover heads you won't be reving a 5+ litre engine much above 5500 revs.
Personally I wouldnt go the big displacment route as you will get far more pover for your money by going for more moderate displacment and spend the money on better heads. Kevin's route of a 4.2 base engine with 305 pistons and good heads will produce a better mannered engine that is less stressed and has better performance for the money.
For the budget of a 4.0/4.6 base 5+ litre engine you could have a 4.2 base engine taken to 4.35 with the hyperutetic pistons, chevy I beam rods, merlin or buick 300 heads and a roller cam setup that will give you a much wider powerband and more peak power and just be more fun with less maintanence.
Best regards
Mike
poppet valves rule!
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richardpope50
- Gold Member
- Posts: 616
- Joined: Thu Jan 28, 2010 12:25 pm
- Location: Horsham, West Sussex
Yes but when you add tax and carriage you may find it much, much, more. I almost imported a clutch m/cylinder until it was all 60% more.topsparks wrote:I can buy a set of pistons in the Statrs for £150 and the rods about the same.
Richard.
Dax Rush 5.0l TVR V8, EFI with Megasquirt ECU and wasted spark, Racelogic Traction Control and Quaife LSD ....... Now nut and bolt restoring a TR6
Dax Rush 5.0l TVR V8, EFI with Megasquirt ECU and wasted spark, Racelogic Traction Control and Quaife LSD ....... Now nut and bolt restoring a TR6
Yes its me did the 5.5 give it away!,Rob wants £1800 for a short tophat lined 4.6 short engine s/h crank and rods,Elles wants £1880+vat for a short 4.6,standard new block and parts .
Thought it would be cheaper getting Chessmen to do my block and as US bits are so cheap,use bigger pistons and rods and off set grind a 4.6 crank I have.I have a good friend who is the main aeroquip importer so getting stuff over is no problem it will get stuck onto one of his pallets.
Thought it would be cheaper getting Chessmen to do my block and as US bits are so cheap,use bigger pistons and rods and off set grind a 4.6 crank I have.I have a good friend who is the main aeroquip importer so getting stuff over is no problem it will get stuck onto one of his pallets.
