Can you actually go 85mm?

[r34 gtr]

Came across this on Yahoo Japan auctions. Its the most screaming deal ever and one of you guys should buy it, I agree, but my question is, is it actually safe to bore out that much material??

http://www.bidjdm.com/auction/f97764611

That bumps you up to 1896cc, which is no joke. If you were to use a SPOOL stroker crank you would have 1973cc, which is REALLY no joke.

Wouldn't your cylinder walls be wafer thin? I was always under the impression that after 84mm you were pretty much going to need a new block. Maybe that's why they are still in NOS condition?

Either way, its like $450 for HKS pistons and Trust rods. Someone (not me) ought to pony up. I suggest TMS do it as he is already in JDM land.

[meminto]

At 85mm you would be getting very close, if you used a grout filling process on the water jackets it would really strengthen up, to a point that i would consider it doable..

You would have to look at a custom bore headgasket though I waould assume...

Well I would do it, not the stroker kit though.... but I am more interested in compounded turbocharging than trying to work capacity into the block.. I reckon that will be the future...

[Amays U G37S]

I don't think you can boost with that high of compression?

Or is it easier?

[float_6969]

As Memento said, you could do it, but you'd have to fill the water jacket and probably run an O-ring'ed block with a copper HG. That's assuming you want to run boost on it. They don't look like they have much of a dome on them so I don't think they're a NA piston, but it's hard to tell for sure from the pics.

If we're talking NA, then I don't see a problem with 85mm. Even with high compression. I still think a 2L CA w/14:1 compression, some good NA cams, and E85 would be a fun car. Might be a little rough to start in the winter though, LOL.

[blownhemi]

That bumps you up to 1896cc, which is no joke. If you were to use a SPOOL stroker crank you would have 1973cc, which is REALLY no joke.

With 1896cc, that's a little less then 5 percent increase in displacement. You won't notice it. As for the SPOOL (or any other) stroker, I think it has already been established, that rod/stroke ratio is bad enough as it is.

Well I would do it, not the stroker kit though.... but I am more interested in compounded turbocharging than trying to work capacity into the block.. I reckon that will be the future...

+1 for more boost, and +1 for sequential bi-turbo.

[float_6969]

The rod ratio is only an issue if you're still trying to rev the motor to 8K. The whole purpose of increased displacement is to increase power across the power band, especially in the bottom end where the CA is the weakest.

Regardless, at best, it's still a stroked out 1.8L, and unless you're running some high boost or compression, it's not gonna make THAT much power.

[themadscientist]

Take one of those wide push brooms. lay it down and pick the handle up a bit and push it straight ahead of you with the head scraping across the ground. How much of the force was translated into forward motion, 95%, 5% lost to friction?
Stick with me Jimbo, stick with me.
Now. tip the handle 30 degrees off the line of intended travel and push forward. It doesn't go straight does it?
Every inch it creeps to the side as it goes forward is wasted force converted into lateral instead of forward motion. That's drag on your cylinder walls too.
Forget stroking the CA, it already has a ridiculously short deck height and you are just making a less than great rod angle worse. Leave the 18 crank in it, bore as much as it take to confirm straight cylinders and BOOST HIGHER!

[r34 gtr]

I was just curious whether or not 85mm was safe. I do not plan on stroking my engine, or even boring it very much. I happen to like it the way it is, completely gutless below 2500rpm. I was simply stating how much displacement increase one could theoretically get by doing those things.

So I take it (and I already suspected) that 85mm is just too much to be boring an engine for normal street use. I actually saw some 87mm N/A pistons on yahoo japan auctions a few years back. They might have been for a CA20, but who knows. I can't read kanji.

I just plan for a .5mm overbore, some new pistons, and thats it. Don't worry about me flying off the handle and doing something crazy with this engine. I don't have the desire.

[float_6969]

The CA20 has the same bore spacing. The blocks are pretty much the same, only the CA20 block is taller. The use of a CA20 block w/a stroker crank would help the rod ratio problem, but the CA20 block lacks a lot of the extra webbing, oil squirters, and the crank girdle that comes standard on the CA18 block. supposedly the oil galley is there for the oil squirters, but I've never heard of anyone having the block machined to find out if that's true. The webbing you can't do anything about, but the crank girdle would swap over.

[themadscientist]

Ryan has a much better block to use. I made a coffee table out of it.

[float_6969]

Ryan needs this crappy azz economy to turn around so ppl start fixing their pools and spa's and I can start making good money again so I can get that block shipped over here!

[r34 gtr]

You could mail it to me instead. I've got the cash for it for once. I not that's cool, I'm gonna go buy some stuff for my existing block. Not 85mm though, I like to have room for error.

Super Ninja Edit:

Or, Mike, you could mail me a charcoal, super black, or white 1989 R32 GTR.

By the way, titanium connecting rods are expensive as hell!

[blownhemi]

Ryan has a much better block to use. I made a coffee table out of it.

CD20?