hi compressions: wasDIY_EFI Digest V1 #258
Daniel Ridge
newt at cesdis1.gsfc.nasa.gov
Thu Sep 5 22:09:04 GMT 1996
On Thu, 5 Sep 1996, Todd Knighton wrote:
> John Faubion wrote:
> >
> > Actually the big reason for multivalve chambers is more area is exposed
> > around the valve to flow fuel. Two small valves have much more flow
> > capacity than 1 large valve but is more expensive that manufacture.
>
> That's also what Yamaha though, they went to 5 valves to get even more
> flow. They did pick up flow, but on the F1 motors the 4 valve engines
> made more power still.
> Point is. It's not all flow, but combustion chamber shape and flame
> propogation as well.
Well, I don't think anybody thought that multivalves flow better per unit
area of opening....
Todd's right about chamber shape and flame proopgation. Multivalves are a
hack around the hard limits that geometry places on things -- we're
constrained to have circular valves, it's tough to use real estate well
when you are nesting circles(valves) in circles(cylinder(head)s). The
multivalve people didn't want multivales -- they really wanted rectangular
valves :).
Two small valves have worse flow (per unit area) than one large valve, but
you can get better aggregate flow with multivalves with a larger total
area than would be possible with univalve configurations.
-Dan
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\___/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Daniel Ridge | USRA CESDIS
Research Minion, Beowulf Project | Code 930.5
email: newt at cesdis.gsfc.nasa.gov | Nimbus Rd., Bldg. 28, Rm. W274
tel: 301-286-3062 | Goddard Space Flight Center
fax: 301-286-1777 | Greenbelt, MD. 20771
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~\_|_/~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
http://cesdis.gsfc.nasa.gov/people/newt
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