overbore miata pistons

tnord

New member
our latest peoplesoft conversion update at work isn't really working at all, which means i'm sitting here killing time thinking about racing. in my constant debate on whether to go full-on IT racing and build a car to the IT ruleset, or to get some toyos and go back to SM, i started pricing out a motor build for each.

in my travels i've found lots of neat stuff over at ISC, baffled oil pans, oil coolers, crank scrapers, headers, etc, but have only seen overbore pistons on mazda motorsports' website. it looks to me those puppies will run about $500 plus the cost of boring/sleeving the block. i'm guessing about $1k by the time it's all done. this one item alone basically doubles my build costs.

i thought previously that mazda didn't offer .40 overs, but only .20 overs, and i thought i'd remembered people saying they weren't worth much over the stock pistons. i'm wondering if .40's provide more/worthwhile gains. coming from SM i know how valuable each 1/2hp is, but i don't think twice as high of a price tag for 1hp/1ftlb is worth it.
 
Yes they are worth it in the overall scheme. But for you don't do it. You will wax my butt with that type engine. :unsure: You have an email coming.
 
Trav,

I bought my .020's for $40 each from MC. Crazy good deal IMHO. The .040's are $125 each?

My thought process was to go .020 now and leave 'room' for the .040 slugs when it needs to get freshened.
 
yeah, i was looking on Mazda Motorsports website, and they list some .040 overs for the 1.6 for $500, didn't see anything for .020. maybe they're listed in the stock replacement parts section instead of the competition parts secion? maybe the 1.8s have some different options? the site is down right now so i can't check.

i was thinking i would have the block sleeved, as that's legal for SM, didn't even think to look to see if it's legal for IT.

another issue is that i'm tearing down 3 or 4 motors to do my own version of a balance job, so buying 4 new pistons likely won't be matched as well as i'll get handpicking from 16 others.

who knows, it's a debate i have just about every day. i really hate to start going down the road of converting my SM to a real IT car, as i know it's way better to just sell this one and buy an IT miata, though there aren't really any out there.
 
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