question about buying new pistons

[little240]

when buying after market pistons and it says "Piston/ Ring Kit, Cast, Dish Top, 89.00mm Bore, 1.2mm/ 1.5mm/ 2.8mm" how can you tell if the motor is going to need to be bored for the new ones cause im looking for high compression with out boreing out the motor just to get a little extra power till i get my sr20 and the money for it its a single over head cam 2.4L ka24e

[ISUJinX]

Well... Dish pistons won't give you higher compression. The stock SOHC pistons are a very slight dish, i think 5cc's or so, in order to raise compression, you will need flat tops or domes. In order to get the right pistons without boring the engine, you will need to take measurements for the full length of the cylinder bore and size your new ones appropriately. So, which pistons you buy will be based on how much clearance you want, and how much your cylinder walls have been worn down. In any case, at least a good honing will help new piston rings seat properly, and is a good idea in any rebuild.

[180fan]

bores won't change that much with wear, with nissans even at 140k+ most blocks I've torn down you could still see the cross hatching.

Look at the top of the piston. You'll usually see a stamp on it, it'll either be a 1, 2 or 3. Those are references to grades. that 89.0mm is a grade 3 kit, and everything past that is oversize. Get a bore gauge to see what your cylinder's diameter is now and buy the appropriate piston for your needs.

[little240]

ok well the website i was lookin at they all say dish top would you happen to know where i could get some pistons that arent dish top

[ISUJinX]

JE makes pistons for everything! But they are also forged, and rather expensive. Wiseco is another brand. or Mahle.

Guess I'm used to bigger v8's - most of those that Ive torn down have needed at least a .030 over to get them back in line and sealing well to new pistons and rings.

[little240]

alright thanks for the help bud