Section : Engine

Vitesse block 2500 head

Posted By : Michael Carpenter, 14-Feb-2005, 10:54pm

• vitesse block 2500 head

  Posted By : Jonathan Binnington, 14-Feb-2005, 11:07pm

  yes, Mike, a 2500 PI head is basically the same as a vitesse mk2 head, although the combustion chamber volume of the 2500 head is greater than the vit head to keep the compression ratio right.
  
  you would need to skim about 1/8" of an inch off the 2500 head to bring the CR back to about 9:1 on a 2000 block
  
  or
  
  you could swap your 2500 head for a 2000 vitesse head that I have, as I have a collection of parts to make a 2500 engine, but have a 2000 head
  
  im in west mids...
  
  bin

• vitesse block 2500 head

  Posted By : John Davies, 14-Feb-2005, 11:16pm

  The Vitesse 2 litre Mk2 and 2.5 heads (and the GT6 MkII-III) are the same casting. The 2 litre engines had a greater thickness skimmed off the face, until late in the life of the GT6, when they were identical and domed pistons were fitted to the GT6 to take up the extra space in the 2.5 combustion chamber. So yes, you can fit it, but will need to skim a LOT off to get a useful CR (memory tells me 100thou!), unless you fit domed pistons.
  John

  • vitesse block 2500 head

    Posted By : Michael Carpenter, 15-Feb-2005, 10:37pm

    Hi thanks for the advice. If i dont skim the head and use it as it is will it make a great diferance to the performance ie will it make it much slower ? thanks Mike.

    • vitesse block 2500 head

      Posted By : John Davies, 16-Feb-2005, 00:15am

      Mike,
      Off the top of my head the CR will be less than 7. Less than the original 948 Herald, but you can be sure of no problem with pinking, even if you run it on old engine oil.
      
      You can work it out for your self:
      CR= (Chamber + Stroke volumes)/chamber volume , ignoring minor volumes.
      CR of 2500 was 8.5-9.5 depending on model and you know the stroke volume, so the chamber volume is just arithmetic, unless you want to measure it. That chamber volume with a 2000 stroke volume will give the CR of your b*st*rd engine. It's too late for me to work it out -you do it.
      
      Or for a fuller discussion, see my article on the TTN:
      http://www.totallytriumph.net/spitfire/skimming_yo...
      
      Hope that helps
      John