GAINS: Cams -vs- Pistons

[del-sol95]

Sol180 have you ever thought about putting a b16A head on your B18B it would give you a lot of juice up high. Sorry I'm off topic just thought I ask

[texan]

What 94tegRS was describing is called flex honing, which is not a true cylinder honing in terms of really taking off any amount of material (nor does it align hone the bore with a torque plate). Honing is the process by which one opens up the bore through precision machine work to either just clean it up or to increase the bore size for more engine displacement. Unfortunately, on most aluminum block motors (which have thin cylinder liners of various materials) there's very little material that can be taken off before you have to replace the sleeve entirely, which is a whole 'nother topic along with more machine work.

[94tegRS]

so what is the thing i described good for? when I rebuilt my bug engine, my dad had me do that to it, and I know they looked alot better inside at least.

[texan]

Oh they work, don't get me wrong. But they only take off about .005" maximum I believe, which is good for a basic cleanup assuming there's no real scoring of the bores. If there is, you can't remove enough material with them and still keep the bores straight. So they work for a simple rebuild when there's nothing wrong with the cylinder bores other than normal wear, but if they are scored or out of round in any way you'll need real honing machine work.

[soul180]

so is there a need to do this if i replace my pistons, or is it just a good idea while it's all torn apart?

[texan]

Yes, you always clean up the bore when you replace pistons. The new rings need a proper surface to seat to. Cylinder sealing is fundamental to engine function and performance, it should be given the highest priority during any engine rebuild.

[Someguy]

Hey Texan, while you're on the subject what do you think is typical for how much over-boring you can do on a Honda motor before you have to re-sleeve it? Just curious.

[texan]

I believe the ballpark is around .020" for most Honda motors, but I could be mistaken. And that damn metric conversion thing always confuses my memory . The gist is that overboring to make meaningful increases in displacement basically isn't possible with stock sleeves, you have to do the expensive machining work to get anywhere with that approach.

[Someguy]

Makes sense. The most you can safely go on the Cobra aluminum block bore is about .030". Enough to be able to play with the valves a bit, but not enough to increase displacement all that significantly. Cool.

[texan]

BTW, what do you think of Ford casting the Cobra block in iron for the upcoming '03 year? Seems like a backwards step to me, evidently Ford doesn't have aluminum blocks quite figured out yet.