any tips for boosting 2.5TD performance?

Sorry to but in one somebody elses argument, but when TMHM said the unswept VOLUME has not changed i can't see how that is true, because if you increase the diameter of the cylinder, and clearly the volume of the unswept part of the cylinder (excluding the recess in the piston) is pi x (d/2)x (d/2) x height (pi x r x r x height)

I follows that increasing the diameter of the cylinder does increase the volume of the unswept area.

However the spwept areas volume is increased even more, so therefore if the incomming air supply is infinate, and the airflow unobstructed, and the pressure of the air outside the cylinder in both cases is identical, the like TMHM said the pressure in the cylinder at TDC at the top of the compression cycle will be higher in the large diameter cylinder.

Therefore both wrong and both right

James - the piston going up and down the bore SWEEPS the bore. The swept volume is the volume that the piston moves up and down in.
the UNSWEPT volume is and space left after the piston has completed its compression stroke.

therefore increasing the bore increases the SWEPT area, not the unswept area.

further to ^^^^, if the piston has a depression in it of volume X, and the head is flat, increasing the bore will not increase the UNSWEPT volume. If the depression is in the head, the same applies.

Yes but what i was trying to say was that the unswept space increases slightly as well, becuause by boring it out you increase the diameter of the cylinder.

If you leave the head intact, then thats fine, that space stays the same, and hence that part of the unswept area remains the same, however you need to have a bigger head gasket as well - therefore this volume of the space in this part of the unswept stroke area(althought it will be around 1mm of the unswept area I admit) DOES increase (only slightly)

I was just trying to be exact and to say the unswept space increase as well, but only slightly due to the bigger gasket, +/- and changes to the cylinder head bore sixe if that has been altered to allow it to fit the head gasket as well.

if the 2.5TD has the same block as the 200TDi, how about fitting a 200TDi head on it?

The Mad Hat Man said:

yes - that is what i said


if by CC you mean Cubic Centimetres then yes it must.


Wouldn't it effectively become a 28:? - only in my example.
you can also increase the compression by reducing the combustion volume - it used to be the case of skimming the head and thereby reducing combustion volume, but that doesnt work if the combustion volume is in the piston and the head is flat.

yet?

Click to expand...

I understand