ka24de overbore questions

[PuNcHdRuNk]

just curious if anyone has any info about the saftey of overboring a ka, i found a set of pistons that allows for a .060 overbore and was thinking about going that route but not if it would risk damage to the block, i.e. sleeve failure or such........

[r3v_v3ng3]

the block is iron and closed deck so no sleeve. very strong but heavy. i would be more worried about finding a matching bore headgasket and the combustion chamber the same bore

[CTS13]

Why would you wanna do .60 overbore. If your walls are really that messed up, get a new block. Ka's are so cheap, you can buy 3 shortblocks for less than 100 bucks.

[WDRacing]

Is the motor going to be boosted or NA? I dunno how much power I'd wanna throw at a block after it's been .060 over.

WD

[PuNcHdRuNk]

the motor is going to be boosted, and my build block is in good shape. i was looking at it from the perspective that its basically free displacement since im replacing pistons anyway. if the block has enough meat to it to remove that much safely anyway.

[WDRacing]

I'd rather run 1 more psi of boost then trim .060 from the block. I've heard that some blocks aren't drilled perfectly on-center from the factory. Have the machine shop that's performing the work measure everthing and go with what they say.

WD

[tctomasc]

Also the blocks are sand casted, so apparently more prone to imperfections.

"Sand is not a very precise material, so sand-cast parts have to be made extra thick to allow for shifting of the blanks. Sand casting's big advantage is it can be trapped in place and then washed out, allowing tremendous flexibility for making strange shapes" -http://www.modified.com/tech/0104scc_tu ... index.html

[PuNcHdRuNk]

im going to be running a gt35r and from what i hear its a bit laggy so i was hoping the extra displacement would help spool the turbo a bit faster and give me better throttle response. that was my main thought in going .060 over. thanks for the input everyone.

[C-Kwik]

im going to be running a gt35r and from what i hear its a bit laggy so i was hoping the extra displacement would help spool the turbo a bit faster and give me better throttle response. that was my main thought in going .060 over. thanks for the input everyone.

If you are thinking about attempting it, have your block sonically tested to determine the wall thicknesses. As mentioned before, sand cast blocks are subject to a large tolerance range. This is fine for the bore intended as engineers will have accounted for it and any that fail to meet specs will likely have not made it into a vehicle, but overboring a motor may produce a thin wall if one of the walls is already very close to the limits of a tolerance. This could lead to something as simple as flex under load which will increase blow-by and slight loss in power or in a worst case scenario, lead to a failure.

[CTS13]

.060 is so little on displacement. I calculated the displacement on my 350 vq after a .020 over and it came out to 353. lol. thats so little, wont even matter. If you want more displacement, go for a stroker kit.