o No: Where did the link to the inclined bore axis article go??? If anyone still has it, can you post (or email) the link for me? Thanks! Jay Spinella
I haven't found the article, but I think it is located in the moparts.com site (thanks Adam and Scott). I did a search for it, but came up empty handed. When I find it, I'll post the link.
Hi Guys, Here's the link I saved for it... http://board.moparts.org/ubbthreads...9&page=0&view=collapsed&sb=5&o=7&fpart=1&vc=1 ...But...I went there just now and it's evidently been deleted from that site also!o No:
Hmmm something fishy going on around these here bulletin boards.... If you find anything that is factual about it, let me know. I haven't figured out how it's real different than offset pins....maybe I'm thick-headed on this one. I'd like to see a good explanation.
I'm not EXACTLY sure of the science behind this. It has to do with reducing friction on the thrust side by moving and/or changing the angle of the bore. Here is what I DO know. NHRA changed the rulebook this year under Pro Stock. It used to say 90* V-8. Now it says "90* V-8, each cylinder bank must 45* from a line drawn vertically between the crank centerline and the camshaft centerline" or something to that effect. The Pro Stock guys called this the "Greg Anderson Rule". Apparently Greg was messing with this type of thing. I heard that Jason Line, who came to Greg's team from Joe Gibbs Racing (NASCAR) may have brought the idea with him. Either way, I also heard that Greg found very little, if any horsepower with it. Poker face? Probably. I don't think it is worth the time and effort for a typical bracket or street-strip motor in the 500-1000 HP range. Some machine shops have a problem boring a block STRAIGHT, let alone at some weird angle. If a 1350 HP Pro Stock motor only shows a 3 or 4 HP gain, it's not worth it for the rest of us. Have fun.
Adam I think one of the main differance's is with the inclined bore your valve to bore angle changes , sort of like offset grinding the head .
AHA! now that makes more sense! Nobody had mentioned that before, it was always tied to mechanical friction (maybe just what was stuck in my head anyway, and it didn't make sense). Thanks Dave!
With all due respect, I really don't think valve angle is the major reason they are doing this. Let's think about this. First, most of the classes we are talking about have fairly liberal head rules. They can use about whatever valve angle they want to optimize the set-up. Second, if they were trying to achieve a better valve angle, they would have angled BOTH cylinder banks closer to vertical to get a "line-of-sight" port on both cylinder banks and heads. However, looking at the way the NHRA rulebook is stated, and based on what I have read, this trick was to move both cylinder banks the same direction. In other words, the driver's side bank was angled up (closer to center) and the passenger's side bank was angled down (away from center). This would move the thrust side on both banks. I think they were creating more of a tangential force direction. Rather than push straight down on the piston, this makes the piston push at a slight tanget to the stroke circle, thus creating more of a mechanical advantage. But the TOP of the bore is in the same location, so the tech guys won't see it. Make sense? Confusion? Oh well, I tried. I'm sure I'm missing some details. Have Fun.
Makes sense, but then we are back to the same principle as the offset piston pin. Is there a rule against that, or some strength issue about offsetting the pin I don't know about? Not too many pro-stockers in central Idaho.
Jeffrey Diamond (panic) has a web site:www.victorylibrary.com-Has a tremendous amount of info,definitely worth a look although I didn't see the" inclined bore axis" article there.
Mr Diamond is the person who was named "Panic" on this site prior to threatening to sue the BB because he got picked on by somebody else. Anybody that unstable probably can't be relied upon for solid information. But thanks for the suggestion.
When you think about it, inclining the bore axis also increases the number of degrees of crank travel during the power stroke. Drawing an imaginary line from the piston pin, rod journal, and crank centerline while at piston TDC and doing the same when the piston is at BDC. One gets over 180 degrees of travel, but not sure if this would actually result in more power...
I'm trying to visualize that, and can't see how the crank rotation during power stroke could ever exceed 180*, or in real terms, the number of crankshaft degrees controlled by cam timing. What I do see is that rod angles would change in relation to the cam timing, piston location, and crankshaft angle. But then you may have to re-time the cam for the new piston height, and the end result we be...?? (no idea)
Hey guys, been doing some thinking and reading on this and here's how I see it in my mind. This inclined axis bore process leaves the top of the bore centered over the crank radial centerline and perpendicular to the deck, but the bottom of the bore ends up shifted (in the direction of rotation) some (x) # of degrees. What I see would be something similar to a variable off-set pin? The effect would be negligible during the intake and exhaust strokes but would add some thrust friction on the compression stroke but would reduce thrust friction on the power stroke much more leaving a net reduction in piston frictional losses, all else remaining the same. Any more thoughts?
