[200q20v] RE: Lifting Stains... and Gains

[Rob Andrews]

Good conversation fellows...But I have been wondering this now....
I run a 2.8 30 v V6.  It is aftermarket supercharged....
SOOO....would I gain anything by adding a cam, or would I be blowing too
much boost out through valve overlap?

> -----Original Message-----
> From: quattro-admin at audifans.com [mailto:quattro-admin at audifans.com]On
> Behalf Of QSHIPQ at aol.com
> Sent: Monday, January 28, 2002 9:24 AM
> To: mlped at qwest.net; quattro at audifans.com; 200q20v at audifans.com;
> s-car-list at yahoogroups.com
> Subject: RE: Lifting Stains... and Gains
>
>
> --
> [ Picked text/plain from multipart/alternative ]
> Michael:
> Comments inserted below:
>
> >"Early AAN Head Stock Bench Flow Baseline"
> >INTAKE - measured in Inches (") of lift / cfm
> >Lift      Cyl1    Cyl2    Cyl3      Cyl4    Cyl5
> >.050       39.9    39.9    41.5       40.7    37.6
> >.100       74.0    72.2    75.5       74.5    72.2
> >.150      100.2   102.4    103.3      100.3    99.2
> >.200      132.6   128.9    130.9      131.6    132.0
> >.250      159        155.1    161      158.4    157.5
> >.300      177.2   175.5    178.8      178.4    175.3
> >.350      185.8   185.7    188.8      190        184
> >.400      188.2   190.3    193.6      194.4    188.2
> >Total 1,056.9 1,050.0 1,073.4 1,068.3   1,046.0
>
> Mike:  you are adding the wrong way.  Totals are not lift cfm
> vs duration,
> it's total cfm AT a given lift.  So your total for .400lift
> is 954.7....
>
> >EXHAUST - measured in Inches (") of lift / cfm
> >Lift      Cyl1    Cyl2    Cyl3      Cyl4    Cyl5
> >050       31.8    32.9    33.1       31.8    31.7
> >.100       61.2    61.2    62.5       61.4    60.4
> >.150       85.5    84.8    85.9       84.1    84.8
> >.200      109.1   111.3    110.6      108.9    108
> >.250      120.3   123    123.5      120.9    119.8
> >.300      126.5   128.4    129.5      127.3    125.2
> >.350      129.5   132    132.7      129.7    128.2
> >.400      131.4   133.7    134.8      131.4    129.5
> >Total   795.3   807.3   812.6   795.5     787.6
>
> See above: at .400 lift you have a total flow out of 5
> exhaust valves of
> 660.8.   IMO, it would be interesting to compare these
> numbers with the RS2
> exhaust cam.  Looking at the above (as I'm sure porsche did),
> I'd want better
> exhaust numbers.  This would also reflect the pretty
> impressive gains in
> torque just adding a RS2 cam to the AAN delivers.
>
> Current theory on the turbo heads is almost opposite the N/A
> heads.  Since
> you have boost pressure as a variable, that really is
> "effective" valve area.
>  IOW, you can change the size or lift of the intake valve, OR
> add boost, both
> do the same thing.  In N/A cars you can ONLY add valve size
> or lift for
> effective valve area.
>
> >Last, I offer for free beer conversation the following
> hypothesis regarding
> >heads, valves & "pressurized" operations thrown at me by one
> porting maven
> >confronted by the question, "Well, if all that polishing and
> grinding you
> >are doing isn't generating a number better than anything
> above, what the
> >hell are you doing?"
>
> Well here's where the magic starts...  Javad is right that
> these numbers all
> give you the theoretical amount of flow, and that reducing
> the restrictions
> TO a valve is key.  This includes a bunch of variables to
> make it optimal:
> temp, pressure and flow.  The smoother the flow TO a valve,
> the closer you
> are to the ideal flow the valve generated.  These numbers
> also don't include
> engine volumetric effieciency, which then includes cam
> overlap, exhaust pulse
> theory etc....
>
> >Bleary eyed hypothesis/theory/defense (??), "Well, A**H**,
> it don' make no
> >difference in a pressurized car.  Pressurized {editorial
> clarification here,
> >i.e. super & turbocharged applications) cars don't need to
> worry about all
> >that flow bench B*S* (s/he'd had more than a few beers, and I believe
> >his/her SO had recently tossed them out of the house, or
> something like
> >that.)  If'n its pressurized, all you want to be go'n fur is
> SIZE!  S/he
> >told me "SIZE matters.""
>
> Vixen; it does, but the caveat is it's EFFECTIVE size that
> matters (insert
> all inuendos here).  In a pressurized car, size is created by
> boost pressure
> or a bigger valve or more lift, in a N/A car, size can only
> be created by a
> bigger valve, or more lift.  That's why many of us turbo
> tweeksters (me
> included, 2.5mm larger EV) leave the intake valves stock, go
> (physically) big
> on the exhaust valve.   The side benefit, is more exhaust
> energy to spin the
> turbine.
>
> I'm hoping you can buy me those Fat Tire Ales after I
> terrorize Steamboat
> this weekend.  Monday?
>
> HTH
>
> Scott Justusson
>
>
>