almost figured it out! (lonnnnng post!)
Actually, the gas bill WILL go up slightly, as you WILL be burning more gas in idle (as long as it is not reset). Besides, the economy gained from lower revs at speed won't matter as much, since i'm running a 4speed automatic that chews up gas like hell in any event.
The rebore is the supposed maximum, at 0.5 mm. But I've found out that info i've seen elsewhere is also correct, because you can go hardcore and do a 1 mm rebore, and the pistons are commercially available! The bore doesn't sound correct in LexKyB13's message, as it makes it around 79mm, whereas I'm already using 84.5mm pistons, so by formula:
Capacity = ð [pi] r squared h * 4 where pi ~ 3.141592, r = radius [1/2 bore], h = stroke and 4 = number of cylinders.
(thanks, dude!)
Stock:
3.1416 (42sq) 72 * 4 =
1596.03332 cc
(i'm guessing 72 as the stroke in mm, as it makes the calculations fit factory specs exactly!)
0.5 mm Rebore:
3.1416 (42.25sq) 72 * 4 =
1615.09028 cc
1 mm Rebore:
3.1416 (42.5sq) 72 * 4 =
1634.26032 cc
Now, the factory quoted bhp of the ECCS Equipped GA16DE is 116, while the SR20DE is around 145. If you go by HP per liter, the GA gets 72.5 HP (approx- 72.727272 to be exact) per liter, while the SR gets 72.5 HP also. Hoping this applies evenly across the range:
0.5 mm Rebore:
1.615 * 72.7272... =
117.5 hp (my car)
1 mm Rebore:
1.634 * 72.7272... =
118.8 hp (maximum)
But I am also getting an exhaust port polishing as part of the package, so that should ideally give me about 3hp or so more beyond that, maybe 5 or so after I change my headers. I am going to do some exhaust work after we get the car shaken in, maybe get crank HP up to 125 or more, but for the meantime, I will be happy just to get it back!
If this machine shop got my engine right, I'm going to have them do my other Sentra, a 1.3 liter manual. It's a GA13, but the block is exactly the same size and weight as the GA16, and the equipment (dual cam, 16 valve, chain timing) is almost exactly the same, except it's carbuerated. This probably means I can get away with reboring it to 85mm. And it'll cost me 272$, or 13600php. Woohoo! That's a gain of 24hp (from 95 to 118) for less than 300$!