# Correct sizing for SR20 Headgasket
**URL:** https://forums.speedlife.net/t/correct-sizing-for-sr20-headgasket/231604
**Category:** SON240sx Automotive
**Created:** [July 6, 2013, 8:40am UTC](https://forums.speedlife.net/t/correct-sizing-for-sr20-headgasket/231604 "2013-07-06T08:40:09Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@240pimp](https://forums.speedlife.net/u/240pimp)
#### Post date: [July 6, 2013, 8:40am UTC](https://forums.speedlife.net/t/correct-sizing-for-sr20-headgasket/231604/1 "2013-07-06T08:40:09Z")
Hey,
Picking up a new Apexi headgasket for my SR engine. From what I have read, the thickness to buy is 1.1mm and 87mm diameter. Can anyone confirm? I have done alot of reading on this but am still confused as some of the info doesn’t agree with what I read.
I plan on running 300-350hp.
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### Author:  [@Bk-87](https://forums.speedlife.net/u/Bk-87)
#### Post date: [July 6, 2013, 9:42pm UTC](https://forums.speedlife.net/t/correct-sizing-for-sr20-headgasket/231604/2 "2013-07-06T21:42:16Z")
For proper head gasket fitment you should use a 1mm to 2mm larger gasket then the bore. for example the stock bore is 86mm so a 87mm gasket would be used. when choosing a apexi head gasket you will need to pick a 86mm gasket for a 86mm bore because apexi gaskets are actually 1mm larger then the package says it is, the gasket package will say 86 but the tru size of the gasket is 87mm.