For the UK view on today's debacle which I imagine sums up a lot of folks
feelings, take a look at www.pitpass.com.
Gary
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: "'Michael Porter'" <portermd@zianet.com>
Cc: "'Jack W. Drews'" <vinttr4@geneseo.net>; <fot@autox.team.net>
Sent: Tuesday, June 14, 2005 10:44 AM
Subject: RE: 225hp
> Actually, as I'm sure you know, that's not the usual reason offered for
> why
> multiple valves work better than single valves. While the theoretical area
> for a single valve is larger, in fact you can pack more valve area into
> the
> available space with multiple valves. And the flow is not a function of
> the
> total valve area, but rather the opening of the valve, which imitates at
> the
> perimeter and starts off as almost a linear function, transitioning to an
> area function as the valve opens (look at some of the new three
> dimensional
> flow diagrams--there was a very cool discussion of this in an issue of
> race
> car engineering last summer). Extremely complex flow--none of it works
> like
> we visualize it. Initial intake flow at higher RPMs is explosive--almost
> as
> much so as exhaust. Small valves also have very small stems and narrow
> guides, which block the flow less even in proportion to the head size.
> Finally two valves are individually much lighter than one, so they can be
> controlled by their spring much more easily at high RPM
>
> -----Original Message-----
> From: Michael Porter [mailto:portermd@zianet.com]
> Sent: Tuesday, June 14, 2005 9:51 AM
> To: Bill Babcock
> Cc: 'Jack W. Drews'; fot@autox.team.net
> Subject: Re: 225hp
>
>
>
> Bill Babcock wrote:
>
>>But one lesson that YOU learned is that bigger ports aren't necessarily
>>better. Possibly if you can change the other tuning factors to take
>>advantage of the increased velocity, you might have a gain.
>>
>>
> And, this might be one of the reasons why two (or more) small intake
> valves
> generally produce more power than a single intake/single exhaust bathtub
> style chamber. High velocity combined with equivalent volume to a single
> larger port (although port angle--particularly with a pent-roof
> chamber--has
> something to do with the flow). I've always had the feeling that
> additional
> velocity is good for mixture turbulence, but there're compromises to be
> made
> when one only has one intake valve per cylinder to work with. That may be
> why there were so many experiments with long ram intakes in `60s engines.
>
> Cheers.
>
> --
> Michael D. Porter
> Roswell, NM
>
> Never let anyone drive you crazy when you know it's within walking
> distance....
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