Forums/Z31P/z31-performance-upgrade-forums engine-mechanical-aa/Anyone measure their Head Chamber Volume?
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spddm0n: (2017-05-23 19:06:39)
I'm going through the process of checking and measuring everything on a couple new VG33E's I'm building and I ran into a discrepancy with the chamber volume on my 0w0 heads. I had actually calculated the chamber volume to be 53.5cc's based on all the other dimensions of the combustion chamber and the published compression ratio. Everything seemed to check out. Then, I decided to actually measure the chambers using a lexan plastic plate bolted to the bottom side of the head. I measured about 49cc's. I measured two sets of heads and repeated my measurements to be sure I wasn't making a mistake measuring. Same repeatable volume of 49cc's (+- 0.5cc).
I have had both sets of head milled by a machine shop, but they don't take off enough to adjust the volume by more than 1.2cc's (based on removing 0.010" of material - which is more than I would have wanted already). The other set I had milled, they removed 0.005". However, there was some confusion on the second set of heads (as to how much they really removed) and I think it may also have been 0.010". Both sets of heads measured 49cc's in each chamber after milling, so it's possible they did remove .010", since both sets measure the same. I measured the area of the chamber opening at the surface of the head too, and removing .010" calculates to about 1.2cc.
Has anyone measured their head chamber volumes? I would love to know the volume of the chamber is before they are ever milled. If they are around 50-51 cc's, that would make sense.
Since I can't find any published info on the chamber volume of these heads, I wonder what it really is. [archived image: smile.png]
NissanEgg: (2017-05-24 22:18:43)
Don't forget about the volume of the headgasket at compressed thickness.
spddm0n: (2017-05-25 17:04:31)
Yeah, I accounted for that. I didn't measure the gasket bore, so it could be a little off, but I did call Victor Reinz and the engineer told me the uncompressed volume was 0.048" with a 6% crush. Compressed should be .0451", OR 1.146mm.
I found an online reference to the VG30E that seems to be fairly specific, so I compared my results to it and made a couple assumptions. The gasket volume is low, relative to other volumes, so I don't think this is the primary source of the discrepancy. http://www.vondrachek.org/automotive…_tech/#StockV6
VG30E vs VG33E VG30E VG33E
- CYLINDERS
6 6 KNOWN
CYLINDER BORE 87.0 91.5 PUBLISHED
STROKE 83.0 83.0 PUBLISHED
GASKET THICKNESS (compressed) (mm) Victor Reinz 1.270 1.146 PUBLISHED
GASKET BORE 87.0 91.5 ASSUMED
DECK CLEARANCE 0.05 0.05 INTERNET REF
VOLUME (cc) (cc)
CYLINDER HEAD CHAMBER VOLUME (each) 52.5 49.0 MEASURED
PISTON HEAD VOLUME 1.0 8.0 MEASURED
GASKET VOLUME 7.55 7.54 CALCULATED
SWEPT VOLUME 493.4 545.8 PUBLISHED
DECK VOLUME 0.30 0.33 CALCULATED
TOTAL COMPRESSED CHAMBER VOLUME 61.35 64.864 CALCULATED
TOTAL UNCOMPRESSED VOLUME 554.8 610.6 CALCULATED
ACTUAL TOTAL ENGINE VOLUME 3329 3275 CALCULATED
TOTAL PUBLISHED ENGINE VOLUME (swept volume X 6 cyl's) 2960 3275 PUBLISHED
COMPRESSION RATIO 9.04 9.41 CALCULATED