.40 bore?
Apr 20, 2009, 10:01 AM
#1
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.40 bore?
ok so i dnt know if there is another thread that discusses this topic. i blew my motor and now sending a core to buschur to do 2.0 build, the block tho has to be honed out to .40. are there any problems with running this big of a bore? also who is running a shortblock with .40 bore and why did you choose to do this? i am just curious because i would just like to learn as much as possible about different bore options and what they will change.
Apr 20, 2009, 12:11 PM
#5
The only issue is whether your block's cylinder walls have enough metal to support a .040 bore/hone. Most do. If you're cautious, you'd do a sonic test on the block to measure the thickness of the cylinder walls. Sounds like from your prior damage it's your only option. On the other hand, you'll get more displacement since the bore is bigger 
.040 is the second oversize (.020 is the first). That just means that it will be less likely that you can overbore it again when it needs a rebuild.
.040 is the second oversize (.020 is the first). That just means that it will be less likely that you can overbore it again when it needs a rebuild.
Apr 20, 2009, 12:17 PM
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I have been running my motor with 86mm bore (.040 over) since last september with lots of boost and a little spray here and there too. I just cracked a wrist pin so the motor had to come apart, but my block is perfectly fine.
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Apr 20, 2009, 01:30 PM
#8
There is no less reliability with +.20 or +.40 with a 4g63 iron block.
The designations represent the next size up pistons you have to use since you destroyed the ability to go +.20
If the damage is too deep into the cylinder walls it requires machining further to the next size piston.
The designations represent the next size up pistons you have to use since you destroyed the ability to go +.20
If the damage is too deep into the cylinder walls it requires machining further to the next size piston.
Apr 20, 2009, 04:29 PM
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oh ok...does having .40 increase any type of performance,spool time? i know these questions prolly sound dumb but i am just curious because this is my first build with a .40 overbore
Apr 21, 2009, 09:03 AM
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ok that is what i had heard and i was just seeing if this was true... i tend to run either a 3582r with meth or a 3782 with meth... i want a solid 600-700 i know both turbos can accomplish that but one is laggier then the other soo i am debating..just wondering about the bore and if have a .40 over bore would significantly make a difference
Apr 21, 2009, 09:10 AM
#12
Its not going to have a noticeable impact on anything. The ONLY downfall to running that bore is if you ever have a problem you cannot safely go any larger.
Its also 40 thousandths not 40 hundredths. ( .040 NOT 0.40 )
Its also 40 thousandths not 40 hundredths. ( .040 NOT 0.40 )
Last edited by Bggstin; Apr 21, 2009 at 09:14 AM.
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