Bore Size
 

I have a simple question: what does merely increasing the bore size on a motor do? I am getting a B18C (early model) and am thinking about boring/sleeving it to a 2.0L, in preparation for a turbo later. I plan on driving the car with the bore/sleeve job and wonder what kind of horsepower, torque, compression, etc I will be looking at?

RE: Bore Size
 

Well, to get really really technical, merely increasing the bore size will make your car stop running. :D Now, if you get some pistons that FIT the new bore size, (depending on the dome displacement) you'll come out with a higher displacement and a lower compression ratio. However, the compression ratio is going to vary depending on which pistons you get, so that's really up to you. If you're driving a boosted, sleeved C1 with low-comp pistons and a fair amount of requisite head work, you could be making 400+ whp and somewhere in the neighborhood of 275+ ft/lbs without too much trouble.

RE: Bore Size
 

Is the engine gonna be less stable or anything due to the increased bore?

RE: Bore Size
 

No not really. I see the myth "B20 cyl walls are to thin to do anything with" all I can say to that is cough*bs*cough. A b20 that is boosted, supercharged, done n/a, or ran with a properly setup cr/vtec are no more problematic than a b18, b16, or d16. What has happened is you have had a few people do stuff like cr/vtec, turbo, supercharger, or n/a setups with the b20 and they do not take into account that the rod/stroke ratio is made for low and mid-range tq not high rpm hp.

RE: Bore Size
 

...smartass :D

RE: Bore Size
 

Well, while they are only a couple mm thinner, I believe they are also taller, which sure doesn't make them any more stable.

RE: Bore Size
 

all engines of the same series have the same bore size right?

RE: Bore Size
 

No. All B-series motors use the 81mm bore, except the B20B/Z, which uses an 84 mm (hence the thinner sleeves). Likewise, the K20 and K24, F20/22 and F23 motors have different bores.

RE: Bore Size
 

also, increasing the bore unshrouds the valves allowing a better flow pattern going into the engine, making some great gains. thats the reason F1 cars have such a big bore and a short stroke. to get the cylinder walls as far away from the valves as possible. and the short stoke helps with the insane redlines as well.