Piston and rod size of the D14A3/A4/Z1/Z2

[saxophonias]

Nice! The shorter the better

[baz]

Just curious,

The D14 has a bore of 75mm and a stroke of 79mm, correct me if im wrong. I've heard that if you make the bore 79 you can reach more hp due to more revs?

How does it work?

[BETEK]

yes because the displacement will increase.
but i don't know if the sleeves will afford this

[hondaNickx]

The bore diameter is closer to the stroke ,which gives a more square engine and those are easier to rev.79mm isn't possible without sleeves.And even with sleeves you'll have sealing issues.

[baz]

So close to 79 (almost square) is more feasible?

[mynameisowen]

The bore diameter is closer to be stroke ,which gives a more square engine and those are easier to rev.79mm isn't possible without sleeves.And even with sleeves you'll have sealing issues.

why does it make it easier to rev exactly?? is just because it is better balanced?? so less energy loss making it easier to rev??

[hondaNickx]

Yes indeed , try looking at it like a circle and a oval .They both will turn around but the circle will turn around with less effort and will therefore be easier .The oval promotes torque ,the circle promotes top end.

[baz]

Mm cleary

[Dodo Bizar]

Uh... maybe I am missreading something but:

Just increasing the bore will only get more stresses (hence the sleeves). Having a square displacement compared to an engine with a longer stroke but same displacement... yes, the square is safer to rev. But that's not out case at hand.

We are talking about enlarging our 75mm to 79mm aint we? That wont allow for higher revs since we would be talking about seriously more mass to move around the same track, and much sooner piston/rod failure. And 79mm bore means 1550 cc if I am correct! Actually very close to B16 specs aint it?

Or are we talking gasdynamics? Then I should shut up and listen .

[hondaNickx]

I think it was in theory ... ?In practice you won't be able to run 79mm bore or only for a very short period.Bisimoto made a 80mm D15 a long time ago but that blew up on the dyno because of sealing issues.78mm with sleeves is the max you can go on a engine that runs more then just a couple of drag races a year.The engine does infact breath better and is more square ,and normally in these kind of engines you would use forged pistons and lightweight flywheel.B16a And B16B engines are over square ,some K engine are square and all D-series engines are under square.

The R/s ratio is what helps the D14 a great deal to survive these kind of builds.Luckly the D14's R/s ratio is perfect and right in the middle.I think because of that great R/s ratio it survives those turbo builds that are running 200Nm of torque and 180-200chp on a stock bottem end.