Quote: thank guys next time I will buy am R3 block, I will leave the bore at 3.900 to have thicker wall.
No need to be sarcastic Carlos. Besides your 360 has a bore of 4.00" you would need to sleeve it to go down to 3,90. Heck even the 318 is just 3,91" std bore.
In the end, the extra 0,040" overbore you are thinking of will yield just an extra 8 inches on a 4" stroke crank motor.
That should amount to an extra 10hp - 15hp on your w2 motor at the most. Thats if your cylinder walls are nice and thick at the thrust side.
If you think that will give you the extra edge that you need to go win races, then go for it.
