Over Bore

[Smokey Eddy]

What would the displacement be on a 1.6 that has a 1mm over bore?
I know its simple geometry but what are the dimensions to begin with?
I know it would be a barely noticable increase but I did an over bore on a v8 racing engine and it raised the displacement by a LOT. I know that makes sense because it had way more than 1.6L to begin with and many more cyls to take steel off of , i know with you lot i don't have to explain the math but i was just curious what the numbers would be with a 1mm over 1.6.

[James8485]

well i have a 1.9AAZ and its bored 1mm over and i dont notice any difference at all on these small engines .0393 isnt much IMO

more boost + fuel i think is where your power come from and tweeked pump and big exhaust

[subsonic]

more boost + fuel i think is where your power come from and tweeked pump and big exhaust

Which in a small way you will be able to run more of as you have lowered compression a small bit.

[theman53]

I think a stock bore for the 1.6L is 77.48mm or something like that, so 1mm over would be 78.48...I have not bored and driven a diesel yet so I don't know what the result will be. But if the saying holds true there is no replacement for displacement it should run better. How much??? don't know.

[jtanguay]

no repacement for displacement is somewhat true, but just look a the 1.4L turbo motors over in europe.  those things are putting out more hp than a stock 2.2L engine.  :lol:

i highly doubt that little extra will give you much.. you will most likely feel a difference just by having a nice tight motor.  so you need to compare apples to apples by driving a fresh engine.

[Smokey Eddy]

Yeah i was thinkign the same as all of the above.
Just wondering what you guys thought.

That sucks about the lower compression thought bu you can't really reasonably compensate that and i dont THINK it will be too much to care about. maybe i'll step down from a 3 notch to a 2 notch if my clearance allows.

[dillenger1]

why would the compression lower if you have the same piston to head clearance?Your just compressing a little more air/space.Same stroke,just more to compress. :?

[Smokey Eddy]

... Hmmm
That's a very good point but is the relation directly preportionate and linear like that?
more volume compressing to a larger area than the less volume would.
It would make sense that the compression would stay exactly the same but it could also not. If the stoke was very long for instance the comp would go up but if it was a HUGGEEE over bore like just exagerate the numbers and a really short stroke i don't think you'd have the volume advantage. You could use calculus to figure out the "best" bore for the stroke. If anyone has taken any calculus courses its like the "make the biggest box with x amount of area" question. You could make several boxes of different shapes and sizes using the same amount of area but one configuration would hold the most volume.

Just assuming here, i think when they engineered the block they probably did exactly that to determine the stoke and bore.

This is just a google answers page but it uses the exact principle im talking about in the context to a cube. You could do exactly the same thing with a cylinder, just change the formula
http://answers.google.com/answers/threadview/id/603399.html

[Smokey Eddy]

Mhmm so over bore actually increases comp.

[MJF]

Yep, it does. Stock bore for 1,6 is 76,5mm

[Smokey Eddy]

AWESOME

[vegfuel]

well i have a 1.9AAZ and its bored 1mm over and i dont notice any difference at all on these small engines .0393 isnt much IMO

more boost + fuel i think is where your power come from and tweeked pump and big exhaust

I'm looking for ways to up the power of my 86' n/a without making it turbocharged. How much extra horsepower could I get if I sent my pump away to be tweaked and did some exhaust work.

[jtanguay]

well i have a 1.9AAZ and its bored 1mm over and i dont notice any difference at all on these small engines .0393 isnt much IMO

more boost + fuel i think is where your power come from and tweeked pump and big exhaust

I'm looking for ways to up the power of my 86' n/a without making it turbocharged. How much extra horsepower could I get if I sent my pump away to be tweaked and did some exhaust work.

http://www.vwdiesel.net/phpBB/viewtopic.php?t=14734