Working out engine capacity

[Emanresu]

I have recently rebuilt my Pajero engine due to a bore problem. It was originally a 3.5. I am now running +.050 pistons.

Is there any simple formula to work out capacity?

[Crafty_]

http://performancetrends.com/Calculators/Engine-Di...

Assuming its a 6G74 engine I reckon you've added ~96cc.

Edited by Crafty_ on Thursday 18th May 18:45

[Mignon]

Words fail me. For both posts so far.

[Krikkit]

Mignon said:

Words fail me. For both posts so far.

Quite.

Using the nifty calculator above, 94.27mm for the new bore gives swept capacity of 3593cc

[Mignon]

Oh jeez. Clearly "0.050" is not meant be 50 thou (1.27mm) on a metric engine. It's undoubtedly 0.5mm. Stock bore 93mm. new bore 93.5mm, stroke 85.8mm. Original capacity 3497cc. New capacity 3535cc. Increase 38cc. I despair.

[E-bmw]

Mignon said:

Oh jeez. Clearly "0.050" is not meant be 50 thou (1.27mm) on a metric engine. It's undoubtedly 0.5mm. Stock bore 93mm. new bore 93.5mm, stroke 85.8mm. Original capacity 3497cc. New capacity 3535cc. Increase 38cc. I despair.

No, 0.050 isn't 0.5mm! It is 0.05! Which would be 5/100ths, not 5/10ths! I despair!

Edited by E-bmw on Thursday 18th May 13:00

[Mignon]

Pistons don't come in 0.050" increments. They come on 0.5mm increments. That seems to be a no-brainer to me.

[Krikkit]

Too easy Mignon

[Camaro]

Pistons can come in whatever increments you want them in if you pay for it. .050" would be a perfectly normal over bore size, so there is no reason that it could entirely be marked up as .050" - just because it's a Japanese and thus metric engine, doesn't mean that it'll be a metric overbore. The machine shop can bore it out to whatever size is required as long as the cylinder wall isn't compromised.

[99hjhm]

Never seen replacement pistons, custom, OEM or forged etc come in imperial sizes for Jap engines. .25mm or .50mm is far more common.

[tristancliffe]

And if you're in the market for having custom made pistons to an inch size, then working out swept capacity would be as easy as 1 + 1, so that thread existing means that it almost certainly isn't 50 thou.

[tapkaJohnD]

Do they no longer teach that the area of a circle is Pi x Rsquared?
And that the volume of a cylinder is Pi x R squared x H?
Where R is the radius and H the height?

Either the workshop manual or a vernier gauge measurement and the back of a crisp packet (who smokes fags these days?) will give you the answer in moments, Emanresu.

John

[Mr2Mike]

Camaro said:

Pistons can come in whatever increments you want them in if you pay for it. .050" would be a perfectly normal over bore size

Not for a metric engine. 0.5mm is a very common oversize on modern engines, 50 thou isn't.

[stevieturbo]

FFS you're all thick.

Just get a litre bottle of water and fill it.

Ensure piston is at BDC, then pour all the water into the cylinder via either injector hole or glow plug hole...and then measure what is left.

Then you know how big that cylinder is !

Either multiply this by number of cylinders, or repeat for all of them