# Engine bored 0.40 over?



## bosshogglac (Oct 25, 2003)

I just had my 307 engine bored 0.40 over, how much extra HP should I expect?


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## T BONE (Feb 2, 2002)

you won't even notice it

just get an olds 350, if you are interested I know where you can get a nice one cheap!!


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## bosshogglac (Oct 25, 2003)

I just spent 1800 on my 307,lol if you want!

tell me about your 350 rocket..


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## T BONE (Feb 2, 2002)

> _Originally posted by northcoastrida_@Dec 9 2003, 02:31 AM
> *I just spent 1800 on my 307,lol if you want!
> 
> tell me about your 350 rocket..*


 Nevermind, I thought you meant you had a 307 and wanted this done,


but if its already done, keep it... will be a reliable motor, and run forever


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## bosshogglac (Oct 25, 2003)

yea... but napa wanted 1800 just for the complete performance rebuild kit, alone! ''I told them that Ide rather eat cat shit with a nit & needle, than pay 1800 on a 307''.. so they reduced the price.. Its hard as hell to find parts for my engine, and the emissions clutter is a b*tch! 

do you know anything about enging bores?


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## Bonez305 (May 25, 2003)

1800 ? wtf ?
just buy a 350 bored it 0.030 (355ci)
and you'll be good


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## bosshogglac (Oct 25, 2003)

wtf, is what I said! and Im getting free labor, $1800 just for the kit with rebuilt heads, roller cam, and a lot of other shit! But anyways how much extra HP should I expect.. My car was 140hp stock.. what do you guys think?


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## Foompla (Jul 15, 2003)

5 mpg 6 on the highway.


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## Joe6pt0 (Jan 24, 2002)

> _Originally posted by northcoastrida_@Dec 9 2003, 01:41 AM
> *I just had my 307 engine bored 0.40 over, how much extra HP should I expect?*


 If it was 0.40 over it would be something like a 450 cubic inch :biggrin: 

So that said, being 0.040 over increases displacement slightly. Maybe to 310-312 cu in and SLIGHTLY increases compresson ratio from about 8.5:1 to around 8.55:1. I'd say you'll gain about 10HP. And thats not noticable.


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## bosshogglac (Oct 25, 2003)

> _Originally posted by Joe5pt0+Dec 9 2003, 08:29 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (Joe5pt0 @ Dec 9 2003, 08:29 AM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin--northcoastrida_@Dec 9 2003, 01:41 AM
> *I just had my 307 engine bored 0.40 over, how much extra HP should I expect?*


If it was 0.40 over it would be something like a 450 cubic inch :biggrin: 

So that said, being 0.040 over increases displacement slightly. Maybe to 310-312 cu in and SLIGHTLY increases compresson ratio from about 8.5:1 to around 8.55:1. I'd say you'll gain about 10HP. And thats not noticable.[/b][/quote]
So, whats the point of boreing an engine.... 10hp thats it?


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## ..LaZt oNe LeFt.. (Oct 15, 2002)

> _Originally posted by northcoastrida+Dec 9 2003, 12:17 PM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (northcoastrida @ Dec 9 2003, 12:17 PM)</td></tr><tr><td id='QUOTE'>
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So, whats the point of boreing an engine.... 10hp thats it?[/b][/quote]
:roflmao: :twak:


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## BigLinc (Mar 6, 2002)

> _Originally posted by northcoastrida_@Dec 9 2003, 03:38 AM
> *yea... but napa wanted 1800 just for the complete performance rebuild kit, alone! ''I told them that Ide rather eat cat shit with a nit & needle, than pay 1800 on a 307''.. so they reduced the price.. Its hard as hell to find parts for my engine, and the emissions clutter is a b*tch!
> 
> do you know anything about enging bores?*


 who uses the emissions "clutter" anyways? :dunno:


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## Joe6pt0 (Jan 24, 2002)

> _Originally posted by northcoastrida+Dec 9 2003, 01:17 PM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (northcoastrida @ Dec 9 2003, 01:17 PM)</td></tr><tr><td id='QUOTE'>
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So, whats the point of boreing an engine.... 10hp thats it?[/b][/quote]
EXACTLY. Anyone who claims they're engine is hot shit soley because it is bored out don't know shit about engines. 

(MY personal favorite is when I hear "yup, this engine is bored out as much as it can go".....ooh congradulations lol)

The ACTUAL reason for boring and engine is when u take it apart and the cylinder walls have wear that cannot be removed by simple honing. Then, you would need to bore it. 

I mean, sure the increased compresson ratio and cubic inch displacement does a little bit, but not enough to notice. Now, if you are building a racing motor, that 10HP might end up being 20 or more and that's a big deal in 1/4 mile times. For 307 though, it don't mean shit.


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## 64 CRAWLING (Nov 26, 2001)

i heard it was better just to bore 60 over they say 40 dont to to much, shit i dont know


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## Foompla (Jul 15, 2003)

ill learn all this shit next semester :dunno: :biggrin:


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## Jeff (Jan 12, 2003)

> _Originally posted by lowcadi_@Dec 9 2003, 03:51 PM
> *i heard it was better just to bore 60 over they say 40 dont to to much, shit i dont know*


 .60 over os OVERkill, most do .15 or .30.


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## schmidt64 (Oct 31, 2002)

> _Originally posted by Joe5pt0+Dec 9 2003, 07:29 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (Joe5pt0 @ Dec 9 2003, 07:29 AM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin--northcoastrida_@Dec 9 2003, 01:41 AM
> *I just had my 307 engine bored 0.40 over, how much extra HP should I expect?*


If it was 0.40 over it would be something like a 450 cubic inch :biggrin: 

So that said, being 0.040 over increases displacement slightly. Maybe to 310-312 cu in and SLIGHTLY increases compresson ratio from about 8.5:1 to around 8.55:1. I'd say you'll gain about 10HP. And thats not noticable.[/b][/quote]
it actually decreases the compression ratio....think about it, bigger cylinder, more room for the mixture = less compression.


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## Chris (Oct 25, 2001)

> _Originally posted by Joe5pt0+Dec 9 2003, 07:22 PM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (Joe5pt0 @ Dec 9 2003, 07:22 PM)</td></tr><tr><td id='QUOTE'>
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EXACTLY. Anyone who claims they're engine is hot shit soley because it is bored out don't know shit about engines. 

(MY personal favorite is when I hear "yup, this engine is bored out as much as it can go".....ooh congradulations lol)

The ACTUAL reason for boring and engine is when u take it apart and the cylinder walls have wear that cannot be removed by simple honing. Then, you would need to bore it. 

I mean, sure the increased compresson ratio and cubic inch displacement does a little bit, but not enough to notice. Now, if you are building a racing motor, that 10HP might end up being 20 or more and that's a big deal in 1/4 mile times. For 307 though, it don't mean shit.[/b][/quote]
:thumbsup:


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## Joe6pt0 (Jan 24, 2002)

> _Originally posted by schmidt64+Dec 9 2003, 08:40 PM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (schmidt64 @ Dec 9 2003, 08:40 PM)</td></tr><tr><td id='QUOTE'>
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it actually decreases the compression ratio....think about it, bigger cylinder, more room for the mixture = less compression.[/b][/quote]
Actually, I beg to differ :biggrin: 

The logic you are using isn't how compression ratio is determined, but rather volume of the piston cylinder. See, compression ratio is determined by the volume of the piston cylinders ratio to that of the cylinder head's volume. So, an increase in piston cylinder volume (boring an engine out) would also increase the compression ratio if the cylinder head size was the same. Look at it like this:

if the volume of the cylinder head is 64cc and the cylinder volume was 640cc then your compression ratio would be 10:1. If you increase your cylinder volume to lets say 650cc then it would be 10.16:1 

Here's a calculator to help you out and is a nice tool to figure these things out:

http://www.csgnetwork.com/compcalc.html


To test what I am saying, look at the compression ratio of a 4" bore engine. Then change that bore to 4.030 (0.030 over bore) and you will see it will increase the compression ratio :biggrin: 

class dissmissed


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## concrete (Mar 11, 2002)

> _Originally posted by Joe5pt0+Dec 10 2003, 07:23 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (Joe5pt0 @ Dec 10 2003, 07:23 AM)</td></tr><tr><td id='QUOTE'>
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Actually, I beg to differ :biggrin: 

The logic you are using isn't how compression ratio is determined, but rather volume of the piston cylinder. See, compression ratio is determined by the volume of the piston cylinders ratio to that of the cylinder head's volume. So, an increase in piston cylinder volume (boring an engine out) would also increase the compression ratio if the cylinder head size was the same. Look at it like this:

if the volume of the cylinder head is 64cc and the cylinder volume was 640cc then your compression ratio would be 10:1. If you increase your cylinder volume to lets say 650cc then it would be 10.16:1 

Here's a calculator to help you out and is a nice tool to figure these things out:

http://www.csgnetwork.com/compcalc.html


To test what I am saying, look at the compression ratio of a 4" bore engine. Then change that bore to 4.030 (0.030 over bore) and you will see it will increase the compression ratio :biggrin: 

class dissmissed [/b][/quote]
smart ass...lol


what's up Joe, what you been up to?


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## Joe6pt0 (Jan 24, 2002)

> _Originally posted by concrete_@Dec 10 2003, 11:39 AM
> *
> smart ass...lol
> 
> ...


  I wasn't tryin to be a smart ass  


Schimdt is cool, I see him up in M&R giving help all the time, was just tryin to help out.


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## BigLinc (Mar 6, 2002)

Joe cant help it, its just his nature

lol


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## schmidt64 (Oct 31, 2002)

> _Originally posted by Joe5pt0+Dec 10 2003, 06:23 AM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (Joe5pt0 @ Dec 10 2003, 06:23 AM)</td></tr><tr><td id='QUOTE'>
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Actually, I beg to differ :biggrin: 

The logic you are using isn't how compression ratio is determined, but rather volume of the piston cylinder. See, compression ratio is determined by the volume of the piston cylinders ratio to that of the cylinder head's volume. So, an increase in piston cylinder volume (boring an engine out) would also increase the compression ratio if the cylinder head size was the same. Look at it like this:

if the volume of the cylinder head is 64cc and the cylinder volume was 640cc then your compression ratio would be 10:1. If you increase your cylinder volume to lets say 650cc then it would be 10.16:1 

Here's a calculator to help you out and is a nice tool to figure these things out:

http://www.csgnetwork.com/compcalc.html


To test what I am saying, look at the compression ratio of a 4" bore engine. Then change that bore to 4.030 (0.030 over bore) and you will see it will increase the compression ratio :biggrin: 

class dissmissed [/b][/quote]
i think you may be on to something, thanks for filling me in on that
:biggrin:


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## bosshogglac (Oct 25, 2003)

> _Originally posted by schmidt64+Dec 10 2003, 04:28 PM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (schmidt64 @ Dec 10 2003, 04:28 PM)</td></tr><tr><td id='QUOTE'>
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i think you may be on to something, thanks for filling me in on that
:biggrin:[/b][/quote]
So if my 307 was bored 0.40 over, what is the size of the engine now? How will this improve hp?


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## concrete (Mar 11, 2002)

> _Originally posted by Joe5pt0+Dec 10 2003, 01:11 PM--></span><table border='0' align='center' width='95%' cellpadding='3' cellspacing='1'><tr><td>*QUOTE* (Joe5pt0 @ Dec 10 2003, 01:11 PM)</td></tr><tr><td id='QUOTE'><!--QuoteBegin--concrete_@Dec 10 2003, 11:39 AM
> *
> smart ass...lol
> 
> ...


 I wasn't tryin to be a smart ass  


Schimdt is cool, I see him up in M&R giving help all the time, was just tryin to help out. [/b][/quote]
not like that... you just know too much about this shit...


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## schmidt64 (Oct 31, 2002)

with a .040 overbore you now have a 313 cubic inch Olds small block, horsepower improvement will be minimal
:biggrin:


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