(HPI) Engine ID

[Suburban_Hooligan]

pretty sure i know what they are (well at least the one with purple head) I'm just looking for confirmation. but the different motor mounts, different webbing on the block under the carb and one being labeled "Made in Japan" is making me question what the second one is.
the purple headed one got pulled out of an HPI Nitro RS4 2 and I'm 99% sure is a Nitro Star .15FE. the other came out of a Tower Hobbies ST-15 (truck bought used) i know it's an HPI cause it's cast into the block.

 

[Chubaka]

.15fe

The left one looks like a nitro star 12r ss. But those are black and this is silver. Maybe another 12 they had or a different style .15 block?

 

[Suburban_Hooligan]

i could pop the head off and measure it. is the cylinder bore size different between the .12 and .15? or is a .15 a stroked out .12?

 

[Chubaka]

i could pop the head off and measure it. is the cylinder bore size different between the .12 and .15? or is a .15 a stroked out .12?

I just recently got a .12 but I'm sure you'll see it in the piston diameter. @Littlemotor might know.