Let's Do some math, shall we? :banned: Area of a circle = pi x radius squared. Volume of a cylinder = pi x radius squared X height of cylinder Bore (diameter) of a standard Z32 cylinder is 87mm, therefore radius = 43.5mm Area of the piston top is 5944.68mm squared Stroke of cylinder is 83mm 5944.68x83= 493408.33mm squared, OR 493.4 Cubic Centimeters. Blah blah blah blah blah... more math If you were to keep the 83mm stroke of the engine (ie not change the crank or rods) to get 3.3L, each cylinder (6 of) would need to be 550 cc's. (3300cc's / 6 ) This equates to a RADIUS increase of 1.8668mm (or 0.0735 inch / just over 7 hundredths of an inch.) From memory, 40 thousandths of an inch is a pretty significant re-bore. ie MUCH LESS than that. Suggest you DO NOT rebore to that level. You would most likely breach the water jackets around each cylinder.
It was done to at least one VG30DETT over here and it was not successful, the bores were left so thin they were flexing under boost and ..... well lets just say it was rubish. That engine ended up being sleeved and donated to a jet boat project (that could take years to get going and will only ever be a toy). Don't do it would be my advice. 89mm piston max.
Severe modification required. Not worth the hassle. I looked into it during my mental NA plans, too hard.
I looked into this before when i was interested in getting a VG33 block over from the states, i was also interested in a VG33R The only thing that dissapointed me was that the stroke is no different, its all in the bore. My understanding is that the blocks are identical. A vg30dett crank and rods will go into a VG33 block and a vg30 oil pump can be used. So this brings us to the bore 91.5 in the 33 and 87 in the 30. Its a significant increase in the bore, but since the blocks are the same it would lead me to belive that the 30 block could be taken out that far, or perhaps it needs to be lined. I havent seen a 33 block in person. Lining is not that expensive. Pistons, this is a stumbling point, VG33 pistons would obviously be useless, Vg33R may be useable for a turbo'd motor since they are designed for a blown motor, but i dont know how good they are. Aftermarket support for VG33's is non-existant so finding a set of upgraded aftermarket pistons would be a mission. Even getting oem replacement pistons would be hard. Of course you could get some pistons made specifically for it but id say they would be between 150 and 200 US each , plus shipping plus machine work on your block can make it quite an expensive proposition. I had been keeping this to myself a bit since its something i have been thinking of doing, but its out there now. lol
What's the effect of the Bore to stroke ratio of an engine? I remember reading it was ideal to have them as close to 1:1 as possible? Can anyone elaborate quickly as an aside?
It effects N/a engines more than turbos. A undersquare motor (long stroke) will make alot of torque down low but will restrict the power at high rpms . An oversquare motor (big bore short stroke) will be lacking in low down torque but will deliver more power higher inteh rev range . A vg30 is already oversquare, a Vg33 would be heavily oversquare so it wouldnt be a torque monster but that suits turbod application more i think
if your serious about getting some big capacity. you could always buy a vq 35, swap in a forged stroker crank pistons rods and decompress the engine add turbos. all off the shelf items prepare 2 open your wallet !.... or do a ls1 conversion, or a rb2/30 dett conversion. or 2jz. or ...........
