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Author Topic: Lister-Petters TR2 or Changfa clone?  (Read 13020 times)

btrcj

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #15 on: June 10, 2009, 06:19:53 PM »


Makes sense to me.

Thanks for everyone’s help.

C.J.

compig

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #16 on: June 10, 2009, 07:59:33 PM »
The TR2 is a modern engine design and being twin cylinder the bores are smaller so burn more efficiently  , this means that it will run at part load without any issues.
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TimSR2

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #17 on: June 11, 2009, 06:10:28 AM »
The Lister engines  and the the ST heads are both rated for continuous 24 hour  power and good for 10% overload for long periods of time. My SR2 is rated at 18.8 hp max 15.5 hp 24hrs @2500, 9hp 24hrs continuous at 1400 rpm, has absolutely no problem with a 5 kw resistive  load, and still can start 1 hp compressors on top of that.  There is no need to oversize your head; there is plenty of overload capacity built into them already.

Considering that you have such  a large engine in excess of your generation needs..... this is  what I have done.   Pick a head that suits your needs.   I suggest 5 to 7.5 kw  for residential backup, unless you need to run a monster air conditioner you may want a 10. The fuel consumption will go up commensurate with the available power so it is best to slightly undersize a bit IMHO.   From the power curve chart of your engine, reduce the rpm to provide the power that you need, 1.75 to 2 hp/kw. Pulley drive  it down to the desired rpm. The fuel consumption ,noise and wear will all go down to match. The fixed speed governor weights and springs are much tighter than the variable speed setup and worth the investment ( USD 50 or so)

  Vee belts are cheap and long lasting, you can run a single b series vee belt up to about 10 hp if you use  large pulleys. Buy the largest cast iron pulleys you can get. And make sure you have a Murphy switch on it in case something goes wrong! Even just an oil pressure controlled fuel supply switch  can save you a major catastrophe....

TimSR2

TimSR2

btrcj

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #18 on: June 15, 2009, 02:33:09 AM »
Well the seller had two.
They both had twin disk clutches.
They both fired up and ran just fine. 
They both had about the same amount of hours on them.

So I bought them both. ;D

Pics and tons more questions to follow.


Thanks to everyone for their help.

C.J.

oliver90owner

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #19 on: June 15, 2009, 07:34:20 AM »
the bores are smaller so burn more efficiently 

So how do you explain the 'over 50%' efficiency of those huge bores in those large marine engines?
RAB

compig

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #20 on: June 15, 2009, 11:50:55 AM »
Actually , I should have said more efficiently than a CS at part load.  Aren't most large modern marine diesels pressure scavenged 2 stroke cross head  types with heat recovery systems etc ?  Hence the efficiency.
DON'T STEAL , THE GOVERNMENT DOESN'T LIKE COMPETITION !!!
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Villiers C45 industrial
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ANOTHER Lister 6/1 CS SOM , temporarily !!!

GuyFawkes

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #21 on: June 15, 2009, 03:02:55 PM »
The TR2 is a modern engine design and being twin cylinder the bores are smaller so burn more efficiently  , this means that it will run at part load without any issues.

smaller bores more efficient?

Load of tosh.

The relationship between swept and head volume and swept and head surface area is not linear.

Volume of a cylinder is piR2H
Area of the sides of a cylinder is 2piRH
Area of the flat piston top is piR2
Area of hemi head is 2piR2

Let's take a 10 cm bore and 12 cm stroke

Swept volume is 3.14 x 5 x 5 x 12 = 942
Swept area is 2 x 3.14 x 5 x 12 = 376.8

942 / 376.8 = 2.5:1 volume to area ratio

Lets take a 5 cm bore and 6 cm stroke

Swept volume is 3.14 x 2.5 x 2.5 x 6 = 117.75
Swept area is 2 x 3.14 x 2.5 x 6 = 94.2

117.75 / 94.2 = 1.25:1 volume to area ratio

Plus, the smaller bore with a smaller swept volume will require 942 / 117.75 = 8 cylinders to develop the same swept volume.

So you can have your smaller bore with far lower swept volume to swept area ratio, far higher piston ring / liner friction length, far more journal friction, and you think this is somehow going to be more efficient than the larger bore.

Never, not as long as you have a hole in your ass.

The ONE advantage of the smaller bore as in this example is your 8 cylinder engine COULD be made, not WILL, but COULD be made with lower total piston and con rod weight than the big single of the same swept capacity.

The ONE advantage this gives you is you can rev the tits off it, pump more air in any given unit of time, thus burn more fuel, this achieve higher specific BHP, this WILL NOT equate to greater efficiency.

Even at partial load, a worst case scenario, the big single will hammer the 8 cylinder engine working at peak efficiency, when it comes to efficiency alone.

Small bore engines NEVER beat big bore engines of the same capacity and similar design for efficiency, to claim otherwise is to simply ignore Physics and invoke greater than unity efficiency or zero point energy of some other bollocks.


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forgot to do this sum.

big single 10cm bore x 12 cm stroke = 8 cyl 5cm bore x 6cm stroke in swept volume.

quite apart from area losses.

PiD = length of a circle, eg piston ring.

Single has one 3.14 x 10 = 31.4 cm length of top scraper ring

8 cyl has 8 x 3.14 x 5 = 125.6 cm length of all 8 top scraper rings

repeat and rinse for all rings, then add 10% frction due to extra losses in a small bore vs big bore engine, small bores start to burn oil at low hours...
« Last Edit: June 15, 2009, 03:08:45 PM by GuyFawkes »
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Original Lister CS 6/1 Start-o-matic 2.5 Kw (radiator conversion)
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Original Lister D, megasquirt multifuel project, compressor and truck alternator.
Current status - project / standby, Fuel, good old pump diesel.

compig

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Re: Lister-Petters TR2 or Changfa clone?
« Reply #22 on: June 15, 2009, 03:20:06 PM »
Thanks for that , always wondered why race car engines weren't big singles !!! LOL !!!  Will have to get onto John Force and tell him to forget that V8 and install a 500 CI single , he'll waste everyone based the above !!
DON'T STEAL , THE GOVERNMENT DOESN'T LIKE COMPETITION !!!
Lister A
Onan W3S Genny
Petter A1
Villiers C45 industrial
Continental flat six powerpacket
ANOTHER Lister 6/1 CS SOM , temporarily !!!