i'm sure that this has been asked numerous times, but I was wondering what the piston to wall clearance should be when using the oversized 75.5mm vitaras

and by going with the oversized pistons will i notice any power gains or do most people just go with the oversize pistons for reliability and to silence some of the noise associated with the standard 75mm pistons.

 

There are several reasons for running 75.5mm vitara's. I chose to go with the 75mm vitara's because my machine shop said my cylinder walls were in great shape so all I needed was a light hone. I'm running .0065 piston to wall, I'm going to have audible piston slap at start up but that's to expected with a piston to wall clearance of that size. For you I would recomend going with .0035-.004 piston to wall.

 

i'm running the 75mm vitaras right now and the noise is terrible, it may be because of the single digit temps in Pennsylvania. I ran the 75mm vitaras all summer long and all i did was a light hone job in fact some of the original marks from the stock honda pistons could still be seen. i'm amazed they held up this long getting pounded through tuning and on the street/track.

i was just wondering the benefits of using the 75.5mm pistons

 

No real benefit other than being able to control your PTW clearances. I haven't had any issues with my 75s, the engine is really noisey but who cares it makes power.

 

i dont know anything about engine building im tryin to learn right now. So is the 75mm the standard size. Like the cylinder walls wont need to be bored out?

 

yes, but they should still be honed a little to help seat the new rings

 

75mm is the standard bore for a Dseries engine. That is bore out of the factory, not necessarily bore after 100K+ miles. The 75mm Vitara's measure around 74.997 - 74.998. So they would be perfect drop ins for a factory bore, but generally the bores are slightly wider and slightly distorted after 100K+ miles of piston rings scraping the walls so the PTW clearances can be anywhere from .003 to I've seen .009. In other words, you really have no control over what your PTW clearance is going to be, you're just going to have to deal with it. Generally a good clearance for an FI Honda engine would be between .003 - .0035, some tend to build them slightly looser though.

The 75.5mm you need to overbore the cylinders, but you can pick your bore size and get exact PTW clearances. These weren't available when I bought mine.