NissanForums.com :: Nissan Forum - View Single Post

Nismo Skyline · Dec 11th, 2002, 07:19 PM

I for one would not want to bore a VG to 89 mm. There is just not enough cylinder wall left. If you have .180" of wall thickness and now you .040" out with your over bore, you have no margin for error with any detonation, instant cracked cylinder. I am not saying it won't work, cause it's been done. I am just saying I would not due it as the displacement increase isn't worth the cylinder wall thickness in my opinion.

Now on my Z31 I used a VG33 block and overbored it by 1mm to 92.5mm, AFTER I sonic checked the block to make sure I still had enough thickness left and there was no core shift. It made 577 to the wheels and 598 ftlbs at 27 psi.

YMMV

OS giken makes a 3.0 kit in japan. It costs 13k. It's a crank, rods, pistons, sleeves and a deck plate. Not many people use it. Most of the big tuners use a 2.7 stroker crank and only over bore .5 mm. They still split cylinders with just this small an over bore. They like to run LOTS of boost and lots of revs. Like 2.4 bar boost and 10k rpm.

Stock compression is 8.5:1

Dec 11th, 2002, 07:19 PM	#12 (permalink)
Nismo Skyline Nissan Enthusiast Join Date: May 2002 Location: 3rd rock Posts: 205	I for one would not want to bore a VG to 89 mm. There is just not enough cylinder wall left. If you have .180" of wall thickness and now you .040" out with your over bore, you have no margin for error with any detonation, instant cracked cylinder. I am not saying it won't work, cause it's been done. I am just saying I would not due it as the displacement increase isn't worth the cylinder wall thickness in my opinion. Now on my Z31 I used a VG33 block and overbored it by 1mm to 92.5mm, AFTER I sonic checked the block to make sure I still had enough thickness left and there was no core shift. It made 577 to the wheels and 598 ftlbs at 27 psi. YMMV OS giken makes a 3.0 kit in japan. It costs 13k. It's a crank, rods, pistons, sleeves and a deck plate. Not many people use it. Most of the big tuners use a 2.7 stroker crank and only over bore .5 mm. They still split cylinders with just this small an over bore. They like to run LOTS of boost and lots of revs. Like 2.4 bar boost and 10k rpm. Stock compression is 8.5:1 __________________ "It doesn't weigh zero" Dan Barnes "The trouble with the world is the Stupid are cocksure and the Intelligent full of doubt" Bertrand Russell "Racing is life, everthing before or after is just waiting" Steve McQueen Last edited by Nismo Skyline : Dec 11th, 2002 at 07:23 PM.