Intake Header

[NavySEAL2B at insightbb.com (GTG)]

----- Original Message ----- 
From: "Don Walter" <dswalterwi@gmail.com>
> And you don't think some of that was taken into consideration with the
> design of the 16V intake runners?

Yea, I'm sure it was, but they also consider things like engine noise, 
reliability and the requirements of mass production.  It wouldn't normally 
be necessary to build a new intake manifold just to take advantage of these 
principles, but if you're going to do it for other reasons (i.e. you've 
changed displacement, cams or significant headwork, turbo, ITBs, etc) you 
also have to keep the really geeky physics in mind so as not to lose power 
or anything.  Also, I don't know the exact history of these engines, but I 
know it's pretty common to reuse designs for the sake of economy.  The BMW 
E36, for example, features a single intake manifold design for all M50 
engines, which range in displacement from 2.3 to 2.8 litres.  On the 328's, 
switching to a later manifold designed for the 3.0 litre M3 engine has 
pretty significant power gains.  Swap cams and software and you're making 
something like 50 more hp (at the expense of less than 5 ft/lbs of low end 
torque)...  but I digress...

-Grant-
Annapolis, MD/Louisville, KY
1980 in storage :(





> On Tue, 30 Nov 2004 15:15:35 -0500, GTG <navyseal2b@insightbb.com> wrote:
>> You mean like tuning the length of the intake runners?  Because yes, that
>> does help, similar to scavenging as you've said.  Do you have some sort 
>> of
>> design in mind?  If you're interested in making a really good intake 
>> system
>> without doing any ridiculous physics, look at existing designs.  First
>> things that come to mind for me (I'm a Bimmer guy) are the Euro S50 
>> engine,
>> S14 (esp the Carbon manis for their race cars), and Dinan Z8 intake 
>> systems.
>>
>> Some reading material:
>> http://www.google.com/search?hl=en&lr=&c2coff=1&q=helmholtz+equation+intake+manifold&btnG=Search
>> Vortex also has several threads having to do with the helmholtz principle
>> and intake systems.
>> I skimmed through the first few links there and they look pretty useful.
>> I'm working with wave physics right now in school, and most of the math 
>> is
>> barely beyond the level of a good college level physics 1 course.  Waves 
>> and
>> fluid dynamics are responsible for the "scavenging" effect you're looking
>> for.  The scavenging comes from waves, though, which only produce the 
>> right
>> effect at or very near certain frequencies, which is why it will be most
>> effective in a narrow RPM band.  Some more modern engines have variable
>> length intake runners (along with the variable valves and such) to 
>> optimize
>> for several different RPMs.
>> I've also heard that polishing the inside of intake runners is not a good
>> idea because a rough surface actually creates better flow.  I suppose 
>> that
>> doesn't include the area right up at the valves since polishing is so
>> popular there, but that might be something to look into as well.
>>
>> -Grant-
>> Annapolis, MD/Louisville, KY
>> 1980 in storage :(
>>
>>
>>
>>
>> ----- Original Message -----
>> From: "Kervin Ridgley" <carsandkites@gmail.com>
>> To: <scirocco-l@scirocco.org>
>> Sent: Tuesday, November 30, 2004 12:04 PM
>> Subject: Intake Header
>>
>> >I was thinking about ways to get the the intake side to flow better.
>> > Would something like a intake header help.  By spacing out the intake
>> > sucks (you know, the opposite of exhaust pulses), would it "scavenge"
>> > more air in?  Just a crazy idea I was having.
>> >
>> > Kervin
>> >
>> > _______________________________________________
>> > Scirocco-l mailing list
>> > Scirocco-l@scirocco.org
>> > http://neubayern.net/mailman/listinfo/scirocco-l
>>
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>
>
> -- 
> Don Walter - Waukesha, WI
> 1986 1.8 16V Black Scirocco
> 1986 2L 16V Toronado Red Scirocco (under repair)
> 1988 1.8 16V Toronado Red Scirocco (sold on 3/29/04)
> 1984 1.8 8V Pewter Scirocco (sold years ago)
> 1971 Karman Ghia (sold)
> 1969 Karman Ghia (sold)
> 1969 Beetle (sold)