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Old 05-14-2012, 10:18 PM   #1
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Default Are all 1.8 Short blocks the same?

If anyone has any hot leads on a shortblock please email me [email protected]Well I am back in the miata world! I picked up a 99 with a hole in the block, head appears to be good (im sure metal is stuffed in the oil galleys in the head but that will all be taken care of)

Question is all 1.8 short blocks the same. I will be rebuilding it so realistically is the block and crank the same, and with my 99' head what are the variances in compression ratio (I will probably shave .0020 off to give a little bump)



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Old 05-14-2012, 10:21 PM   #2
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I wanna say the 94/95's have a oil feed plug for a turbo but I think besides that they are all the same up to 05. There is a sticky somewhere?
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Old 05-14-2012, 10:25 PM   #3
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94s and early 95s have 8.8 comp, 96-97 have 9.0 comp, some NBs had 9.5 comp, some had 10.0 comp, etc.

As Flounder mentioned, 94s and 95s have an oil and water feed for the turbo located in the block. There's a few other minor/major differences, such as a MBSP (01+) and whatnot, but you should visit the search button for yourself.
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Old 05-15-2012, 11:45 AM   #4
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A general rule of thumb, for every .007 milled off a head it closes the combustion chamber up by 1cc

Just going in and milling a head for a bump in compression is a haphazzard way of doing things, on a push rod engine it is simple, but with a DOHC things start changing that you may not be aware of. the big one is changing the cam center line to crank centerline relationship. This can have an affect on the mechanical timing of the engine.
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Old 05-15-2012, 08:19 PM   #5
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Quote:
Originally Posted by blaen99 View Post
94s and early 95s have 8.8 comp, 96-97 have 9.0 comp, some NBs had 9.5 comp, some had 10.0 comp, etc.
99-00 are 9.5:1, 01+ are 10.0:1, MSM are (I think) back to 9.5:1

I'm confused about why you want to shave the head though. You say you're going to rebuild the bottom end -- I'd think it would make more sense to buy the pistons that have the compression ratio you want, rather than try to band-aid it by shaving the head?

--Ian
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Old 05-17-2012, 02:18 PM   #6
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+1 to Ian, the only reason to shave the head is to get more compression than you can otherwise get with the OTS piston you want to use.
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Old 05-21-2012, 02:15 AM   #7
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Head had some marks from a broken piston flying around cylinder 2. oh.....and ***** cracked. wtb longblock
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Old 06-02-2012, 11:31 AM   #8
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I thought the 01 block had a improved/larger thrust bearing
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Old 06-05-2012, 09:53 PM   #9
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would a 94-95 1.8 block be the same casting as a MSM block?
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Old 06-05-2012, 09:58 PM   #10
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Quote:
Originally Posted by NeedDirection View Post
would a 94-95 1.8 block be the same casting as a MSM block?
It's a 99-00 motor. BP4W
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Old 06-06-2012, 12:33 AM   #11
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In addition to the higher compression, 01-05 motors also have a main bearing support plate.
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