I got a stroked ls3 bolted up in a 2009 g8gt, but....

the aftermarket 160 deg thermostat is different than the stock one. Diameter of the stock is 54.1 mm and the aftermarket one is 55.8, both without gasket.. it don't fit the housing. The gaskets are the same, but the aftermarket one dont fit.

I'm using the stock L76 water pump and thermostat housing. my understanding of the progression of these Gen III-Gen IV thermostats is ls1 used housing integral, then Ls2 used 53 mm, and LS3 is using a larger 60 mm.

also, the aftermarket one is much longer from the "flange" to the backside.

can a small block thermostat be used?

any info or experience would be appreciated!

 

found a solution through Maryland Speed. The 09 North American vehicles and above have a thermostat that is 56 mm diameter and a touch longer in length. 09 l76 G8GTs have the older style 53 mm shorter thermostat. the 09.5 G8GTs have the newer version. all LS3 G8s have the newer version as well.

my G8GT with a self swap LS3 stroker is the oddball.

 

Hmm..Interesting...So they won't interchange with one another???

 

nope. small incremental change. the new version worked in the 2009 P/U

 

That's odd....So that means they changed the actual pump inlet housing correct??