What does it mean to bore an engine?

[Th3 RiCk]

Hi everybody. I'm still learning a whole lot about engines and how they work. So in general terms, what does it mean to bore an engine? I hear "bored .30", but I never know exactly what they're talking about. My only guess is it changes the displacement? Thanks ahead of time.

Th3 RiCk

[speedy-v6-camaro]

A cylinder's width is its bore. Bored .30 over means to widen the bore by .30".

[3.4 slow to go]

however, comma, I do belive yall meant .030 over. just looking out for the new guy ;)

and from OH I see, hmmm, new victom [img]graemlins/evilgrin.gif[/img]

[Th3 RiCk]

Ahhh... I see now. Thanks

[Th3 RiCk]

Another newbie question. [img]smile.gif[/img] If an engine has been bored will the pistons and rocker arms need to be changed? What kind of performance gains would you expect boring an engine to the max? Since there's more of an area for combustion would it be wise to add some type of forced induction and bigger injectors? Sorry if I sound stupid, because I am for the most part in this subject.
Th3 RiCk

[ June 20, 2003: Message edited by: Th3 RiCk ]</p>

[3.4 slow to go]

any time the cylender is bored, you will need new pistons & rings appropiate to the overbore. rockers can be the same, or upgraded for more lift. However, since the cam will be out of the engine anyway, replace it with a grind more in toch wih what your plans for the engine are. Also have block & heads checked for trueness. A compeent machine shop should aleast suggest this.

[nino]

What does it mean to bore an engine?

that is when you open your hood and tell your engine my girlfriend left me......, my girlfriend thinks........., my girlfriend wants...........
that is why we have the lounge, so you dont have to bore your engine.

[Tireguy]

Nino, I dont think I want to hear what your idea of Strokeing an engine is. :D

[nino]

<blockquote>quote:</font><hr>Originally posted by Tireguy:
Nino, I dont think I want to hear what your idea of Strokeing an engine is. :D <hr></blockquote>

[img]graemlins/rofl.gif[/img] [img]graemlins/rofl.gif[/img]

[Bliggida]

<blockquote>quote:</font><hr>Originally posted by Th3 RiCk:
What kind of performance gains would you expect boring an engine to the max? <hr></blockquote>

First it might help to understand how to calculate bore and stroke into CID numbers...

Example is a 350 Chevy.
4 x 3.48 = 349.67 (350)
Bore and stroke multiply them, multiply sum by Pi (3.14) then multiply that sum by the number of cylinders (eight) equals CID.

4.030 x 3.48 x 3.14 x 8 = 352ci

So, assuming that an engine makes an efficient and minimum of 1HP per cubic inch. That's 2 more horsepower over stock for a .030 overbore. Not all that much in that particular configuration.

Usually it requires bore AND stroke to really make a difference. For a typical hot-rod 383 stroker. You need a .060 over bore and a 3.75" crank. If you had 350 horsepower at 350 cid, you'd now have 383 horsepower as a 383 stroker. A gain of 33 more horsepower in that configuration. But if you make more power than that (easy to do) a 450 horse 350 will make 492 horsepower as a 383ci stroker. 42 more horepower.

But in terms of all out max boring. A Chevy will generally accept a 4.125 bore finished size. An over bore of .125 (very huge, especially for a small block) That alone would account for a 350 becoming a 361ci. Combine that with a crank of a 400ci small block - 4". And you'd have a 415ci small block. Which it it made 350 horsepower as a 350, now makes 415 horsepower as a 415ci. And it it made 450 horses at 350ci, then watch out!!! You'd be making 534 horsepower at 415cid. A gain of 84 horsepower.

If you add on a supercharger or turbocharger that number explicates rapidly.

[nino]

<blockquote>quote:</font><hr>Originally posted by Bliggida:


First it might help to understand how to calculate bore and stroke into CID numbers...

Example is a 350 Chevy.
4 x 3.48 = 349.67 (350)
Bore and stroke multiply them, multiply sum by Pi (3.14) then multiply that sum by the number of cylinders (eight) equals CID.

4.030 x 3.48 x 3.14 x 8 = 352ci

So, assuming that an engine makes an efficient and minimum of 1HP per cubic inch. That's 2 more horsepower over stock for a .030 overbore. Not all that much in that particular configuration.

Usually it requires bore AND stroke to really make a difference. For a typical hot-rod 383 stroker. You need a .060 over bore and a 3.75" crank. If you had 350 horsepower at 350 cid, you'd now have 383 horsepower as a 383 stroker. A gain of 33 more horsepower in that configuration. But if you make more power than that (easy to do) a 450 horse 350 will make 492 horsepower as a 383ci stroker. 42 more horepower.

But in terms of all out max boring. A Chevy will generally accept a 4.125 bore finished size. An over bore of .125 (very huge, especially for a small block) That alone would account for a 350 becoming a 361ci. Combine that with a crank of a 400ci small block - 4". And you'd have a 415ci small block. Which it it made 350 horsepower as a 350, now makes 415 horsepower as a 415ci. And it it made 450 horses at 350ci, then watch out!!! You'd be making 534 horsepower at 415cid. A gain of 84 horsepower.

If you add on a supercharger or turbocharger that number explicates rapidly.<hr></blockquote>

HUH

[Tireguy]

In my '94 3.4, I read something about it being a bored & stroked 2.8. Is that true?

[speedy-v6-camaro]

<blockquote>quote:</font><hr>Originally posted by Bliggida:
If you add on a supercharger or turbocharger that number explicates rapidly.<hr></blockquote>

[img]graemlins/rofl.gif[/img] [img]graemlins/rofl.gif[/img] Explicates....way to use a word that you have no idea what it means.

[nino]

<blockquote>quote:</font><hr>Originally posted by speedy-v6-camaro:


[img]graemlins/rofl.gif[/img] [img]graemlins/rofl.gif[/img] Explicates....way to use a word that you have no idea what it means.<hr></blockquote>

thats just radiculopathy

[img]graemlins/rofl.gif[/img] [img]graemlins/rofl.gif[/img]

unfortunately i know what both those words mean. let me explicate.
explicate: to give a detailed explenation
radiculopathy: any diseased condition of roots of spinal nerves

:D

[Timbo1969]

Umm that's explanation.... [img]graemlins/rofl.gif[/img]