5k Pistons In 4k-c

[toyota_ae71]

I'm wanting to put 5k pistons in my 4k-c but will they fit onto the 4k's con rods and how much thou will have to be machined out??

[dfunkt]

taken from here

 

the 4k has 75mm bore, and the 5k has 80.5mm bore, i don't think they'll fit very well :P

 

BUT, 1ggte pistons will fit into a 4k

[toyota_ae71]

yeah i no what the bore sizes are, but can i get the 7mm bored out from the block so they do fit or is it 2 much??

[Xany]

7mm out of a 4k bore.....i've heard of some 4k's going out to 160 thou over......but i'm pretty sure they were a jap commerical engine.

 

taking 3.5mm off each side of the bore is going to greatly hamper the running of said engine i would think.

[toyota_ae71]

how much would 3.5mm be in thou but? and would it make the block unreliable or not much difference??

[aidaniel[RL]]

dude ... no chance taking the block out that far ... get a 5k

[camerondownunder88]

Xany you hit it on the DOT :P

 

The commercial 4K motor got thicker bores and can be bored out more. Mate of mine proved this. The average 4K out of your KE70 etc can't be bored as far.

 

I think some fork lifts did get 4K motors I know these have thicker bores.

 

But probably easier to get a 5K than track down a commercial 4K.

 

Cam

[toyota_ae71]

well thanks for all the info, so what pistons will fit into 4k that are a bit oversize but arent custom made, and arent 1ggte pistons, or do people think i should go bigger pistons for motorkhana/khanacross or just get some aftermarket standard bore size??