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should i bore my D15b?

  • leave it stock

    Votes: 18 35.3%
  • go to 75.5

    Votes: 33 64.7%

  • Total voters
    51
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Discussion Starter #1
im gonna start work on D15b and i cant decide if im gonna bore it to 75.5 or leave it stock. what do you think?
 

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Discussion Starter #3
no scaring perfect shape
 

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Discussion Starter #4
the options are there
 

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well whats the piston/wall looking like? if its not past .008 id stay 75mm if you are doing a vitara turbo setup..if just stock parts id go 75.5 for the perfect piston/wall. and if using vitaras make sure to install the arrow facing tranny side they are saying now.
 

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umm thats something for you to decide.. if you can get a good PTW clearances the way it sits with just honeing it then go that route. if you cant get a pretty tight PTW clearances then it looks like youll have to go 75.5
 

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first u need to check for and washboarding, u can check for washboarding with a stone hone and see if it only touches the high parts of the sleeve (it will be shiny new lookin metal where the high spots are). washboard is from the piston slaping the wall after combustion. if i has washboarding it will need ot be bored.

u need to check for taper (\ /)
and for out of round (0) at the top and bottom of each sleeve

and if the sleeves are straight and perfectly circular, and no signs or washboarding, check ur piston to wall clearance...then u'll know if u gotta bore or not

to check for piston to wall clearance u just put the rings on the piston and use a piston ring compressor to get it all into the cylinder and then use a feeler gauge to check the clearance.(forgive me if u knew that)

goodluck!
-jack
 

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Discussion Starter #8
the motor only has about 50000 miles on it and i was thinkin about just boreing it over for the bigger vitaras just for the extra power.
 

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Discussion Starter #12
but is it worth it?
 

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you wont feel any more power, if you want a little more power, go with fjt's rods to bump the comp up a little. 8.5- 9.1 would be sweet turbo comp.
 

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Discussion Starter #15
with the vitaras ima be at 7.85 comp
 

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your ether within spec or not...... If your out of spec. you have to bore it. your in the turbo section. the extra displacement isn't going to make that much of a difference on a turbo setup where you can just turn up the boost to make more power.


I see rebuilds 2 ways. within spec. and restoring to new. boring will technically give you a better seal and less blowby. though, just putting in new rings and bearing helps substainally, because all the clearances are going to be way tighter.
 

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my advice, for what it's worth, take the block to a machine shop and have them check the bore out. If you can use stock bore, you might as well...and if you have to go bigger later on down the line, the block will still be good.
 
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