how far can i bore

[DeviantClipse]

basically i need to know how far i can bore my 420a engine with out running to thin on the walls.

 

[91 NT Eclipse]

Most guys do .020, do you need to go farther than that? I suppose you could go up to .040 w/o problems.

 

[siueclipse]

.40 is on the edge.

.20 is just fine

 

[MetalJim]

I've heard that .160 over is the hairy limit. Talk to blackdog motorsports - that guy has a 2.1L Neon 420a that I'm pretty sure is NOT stroked. I'm on the virge of finding out for sure. I just bought a block and I've got to call them anyway to see what they can sell me. Anyways, I've heard .140 is ok.

 

[MetalJim]

Ok I called Clay at Blackdog the other day. Turns out that .160" over is just way too much if you want to keep it a daily driver. Evidently when you go to far on these motors - the HG has a hard time sealing betweeen cylinders. He said that he has to replace the HG every week - and he's tried head bolts as well as head studs - it doesn't matter. I just keeps blowing through.

So, I went with some off the shelf oversized CP 10.5:1 CR pistons. .060" is as big as they get off the shelf - puts the bore size to 3.505" and the displacement to 2066cc.

 

[siueclipse]

Honestly. It sounds like that person doesn't knwo what they are doing. Im .20 over without any problems.. Im still a daily driver.

 

[Kirby]

Yeah, unless you need it bigger then go .020. If you have to go to .040. I would not go past 0.60 myself. You're not in danger at .060 but unless you need it then don't bother. If your looking for more displacement then there are better ways of achieving it. I talked to clay about that before too jim, on all motor apps you can go out there pretty far.