83mm pistons for 4AG

[Ben Wilson]

I've heard that both Nissan CA18 and Mazda BP pistons fit. Has anyone actually tried it?

Is either piston any good stock?

[takai]

Is the block capable of supporting that?

[Ben Wilson]

Apparently 83mm is the upper limit.

Once again, I'd like to find someone who has done it before I start shopping....

[Billzilla]

I was very seriously looking at going to 83mm for the new engine, but I got nervous as to how thin the bore walls were going to end up so I wussed out and went for 82mm.
That's the 7A block though, it may well be a little different.

[takai]

Hm, i wonder what the extra displacement would be for 83mm over 81mm...
Edit: For a 7AGE it would come up to near the 1900cc mark, which interestingly is what Dave Loftus is running according to the entry regs. I wonder if they have just bored it out to 83mm?

[RONA]

1682cc with stock stroke for a 4age

[takai]

1682cc with stock stroke

Aye, see my reply above for as to why my mind was ticking over that way.

As for pistons, the CA ones are pretty poor im sure, but the BP ones could be interesting. All depends on how much one could pick up a set for.

[RONA]

Aye, see my reply above for as to why my mind was ticking over that way.

As for pistons, the CA ones are pretty poor im sure, but the BP ones could be interesting. All depends on how much one could pick up a set for.

I'd already replied before you edited it, thanks for the explanation

[Billzilla]

1682cc with stock stroke for a 4age

Close, it's 1666cc.

[RONA]

Close, it's 1666cc.

The website I used to calculate it lied then .

[Billzilla]

The website I used to calculate it lied then .

Yep, looks like it.

83mm x 77mm = 1666cc.

[RONA]

Argh not the websites fault the knobhead that comes up on google lists a 4age stroke as 77.7mm

[Ben Wilson]

Edit: For a 7AGE it would come up to near the 1900cc mark, which interestingly is what Dave Loftus is running according to the entry regs. I wonder if they have just bored it out to 83mm?

1851cc by my numbers....

[jezza323]

i believe Dave Loftus is running an offset ground crank of some sort to get his 1.9L 7age

[takai]

1851cc by my numbers....

Yeah, but a lot of the NSW guys run to the closest 100cc to add some intentional vagueness as to their engine setup. Its concievable that an 1850cc engine would be listed as 1900cc.

Interesting about the offset crank though, cheers