Re: 89.5 10vt [200]

[QSHIPQ@aol.com]

In a message dated 97-03-09 15:44:39 EST, you write:

<< 	Scott, sometimes I have a hard time understanding your posts.  
 Usually, I find some of the most important information, in anything, is 
 the stuff that gets dropped due to our penchant for using .... I will try 
 to avoid ... and tell what I know [which ain't much] using full sentences.
>>>>>>>>>  my use of "..." is for saving a tangent baseline explanation,
making my nerdy posts longer and nerdier...  The ... indicates a knowledge of
the summary as correct.  If I need to back up on any of it, please advise.
>>>>>>>>>
 
 	On the cam portion of your post.  Yes, I have it.  Yes, I know 
 the difference.  *One* difference is the profile related to timing of the 
 exhaust valve closure, relative to intake valve opening.  In the drag 
 racing days we spoke in terms of "overlap", that being the amount of 
 "time" the exhaust valves were open--while the intake valves were open.  
 Depending on your purpose in building the motor, ie., what you were using 
 the motor for, your desire for overlap increased or decreased.  The cam 
 on the dual knock sensor motors was designed by Audi to go hand-in-glove 
 with the acual purpose of the dual knock sensor motor itself, to-wit:  
 Increase low-end response [some would say throttle response] with a 
 reduction in turbo lag.  Lighter pistons, lighter flywheel, higher 
 compression, slightly bigger compressor, reduction [to near zero] of 
 overlap, on and on.  Bottom line to this motor [the dual knock sensor 
 motor] was make it feel like something it was not---a small block V8.  
 The cam in the dual knock sensor motor is ground so that an *improvement* 
 is [was] made in overlap.  Specifically, the exhaust valves close at the 
 same instant the intake valves open.  On vehicles [like yours, Scott] the 
 exhaust valves are open for some period of time while the intake valves 
 are also open.  Thus, on your car, some measure of performance is lost by 
 the goodies coming in through the intake valve  being released through 
 the exhaust valves--before the goodies have a chance to burn--thereby 
 creating power.  If I am not mistaken, the overlap was "solved" so as to 
 meet the intent of the design, that is, better low end response, better 
 throttle response.  
>>>>>>  Good explanation of overlap.  However, a turbo motor has two demands
on the cam profile, lift and duration.  Given the reduction in overlap of the
"newer" cam, this can be overcome, in fact improved on, by addressing lift
instead of duration.  Yes the valves are open at the same time for a time
(increasing HC output), the opposing factor to that is that increasing lift
at the same time creates a valve float problem.  So the trade off is a
slightly revised exhaust ramp for increased lift, or decreased lift for a
decrease in overlap.  My homework indicates that for mamimizing turbo
efficiency, lift is more important than a slight reduction in overlap.  As
you change the sizing of the valves this theory moves some, but lift still
prevails.
 
 >	Do I get an "A" on the cam portion of the test?:)
Yup, though some thoughts on overlap vs lift could be expounded, A-  :).  
 
 >	The second portion of your post was a bit more nebulous.  That 
 >is, the increased *risk* of computer box changes, turbo changes, etc.
 
 >	First, I very much understand that I am assuming the risk of 
 >anything done to my car.  Secondly, risk, and especially *increased risk* 
 >is so relative a term, or phrase, as to almost be meaningless.  You speak 
 >in terms of increasing the "kaboom" factor.  I assume you are talking 
 >about the risk of burning holes in the pistons, etc.  Correct?  If so, I 
> will be the first to stand by this statement:  You technically increase 
 >the risk of some failures when you increase boost in a turbo motor.  Now, 
 >we probably aren't talking much of an increased risk if we are talking 
 >about a .00005% increase in boost--but I think you understand my point.  
> That is why *many* hp seekers in expensive vehicles like Porsche---run 
> stock levels of boost, but increase hp dramatically.  Extrude hone, valve 
 >work, head work, exhaust manifold [read header] changes, intercooler 
> changes, stroking, boring, etc., are but some of the ways you can 
 >maintain relatively stock levels of boost while increasing hp, often 
 >times dramatically.  Frankly, unless we are going to talk a specific hp 
 >increase at a specific rpm range--increase hp means nothing to me.  
 >Torque is what I like [and yes, you do [can] increase torque by 
> increasing boost].  But when we talk hp mods., let's talk specific rpm 
 >range hp changes, ok?  *If*, a person is looking for low-end performance 
 >gains [hp gains, torque gains, throttle response, etc.] then the RS2 that 
 >everyone is talking about is best kept on the shelf.  The lag it carries 
 >stock will have you putting my "little" turbo back on.  Simply bolting on 
 >some "new" turbo is not the answer for 99% of the people on this list who 
 >want more usable power for city driving, 1-2-3 gear driving, etc.  
>>>>>  Won't bungee jump with you on the conclusions drawn.  Are we talking
about a 24 or a 26 based turbo?  A drive in a properly executed RS2 turbo
doesn't exibit the characteristics you describe.  Maybe PDQSHIP's buyer can
help out with a torque tesimonial.  There is a k26 that is smaller than the
stock k26 in the audis.  IN FACT, the RS2 hot side IS smaller than the k26,
so I might suggest, you need more information.  A given exhaust velocity can
do so much transmitting of "power" on a turbine, given it's design.  A k24
and a k26 have a similar "given" design.  The RS2 however, smaller than the
k26 transmits more power than either the k24 or the k26, so one could deduce
a "different" design.  To run the k24 is OK for what it was designed to do,
however, if you take that motor and put a different turbo on it, you will
find that most of the "torquey" feel is still there. WHY?  Cuz it ain't the
turbo with the main effect.  It is the lighter reciprocating assblies...
 ("..."=per your post).  There are, and I've done them, k26 turbos available
with the k24 "characteristics" you are describing.  The biggest problem with
the k24 turbo is that it is a specific purpose built turbo, that is to say,
you try to increase it's output characteristics by adding a larger cold side,
you snap it's (reduced reciprocating assbly) small shaft, btdt.  
 
 >	In short, I do understand the risk of increased boost, but I also 
 >understand that people are misled into thinking that an RS2 turbo tweek 
 >is going to make them see naked mermaids on their next trip to the 
 >7Eleven.  Won't happen.  Ever.  IMHO, you must address how you drive and 
> where you drive.  If you want to put a car on the track at Daytona and 
 >run for 3 days, get a huge turbo, huge intercooler, etc., because it will 
 >increase power.  If you want to drive a quicker car to work, maybe play 
 >with a Mustang or 3 at the corner light----seek out the budda named 
 >"low-end power".  BTW, detonation is what we should fear, and it is 
 >called many things like "kaboom".  Scott, my fingers are tired, and my 
> test is nearly written.  Why don't you explain to the good folks the 3 
 >best ways to avoid detonation.  Intake air density is where we begin....
 >>
Well naked mermaids I've never seen them with or without RS2's, so not sure
the point.  The question to you is torque.  There the 24 turbo is it by
design, at the expense of high end power.  What if you could have both bruce?
 You can, but no one is there yet, not in computers.  In RS2's, I assure you,
I target the k24 for low end on all my tweeks, I had one in my car to get
baseline numbers.  And it works.  What I do is overlay the plots from k24
output (and the matrix is constant, cuz you can't tweek one) to various k26
outputs.  The peak turbo output on an I5 is at 2000rpm on a k24, however, if
one did their homework on an RS2 for example, output (turbo efficiency, boost
and temp) is equal to a k24 @ 2200, then increases everywhere else, wouldn't
you have a better application?  For your detonation example, another post as
to "best," however, in addition to air density, I would want included items
that effect compression ratio (static and/or effective) and spark firing...
 One hits you directly, the other should hit anyone with a computer mod.
 Remember the computer you have Bruce, is not an EPROM mod, which by
definition, means the timing and boost maps remain UNCHANGED.  By definition,
for TWICE the boost values the Maps were written.  Sound scarey?  I think it
is, especially considering the accuracy of the PT in the audi boxes.  

I appreciate your thinking on this, and I remain firm with the caution on any
commercially available mod for the 89.5 and later cars.  How is the boost
attained?  FACT:  The nerds on this list have Ned et.al. hustling to make
improvements, why?  Cuz some members of this list is waaaay ahead of the rest
in execution.   Don't sell this list short.  Some are finding ways to improve
on an old idea, to make it better.  


BTW, the listing I have for the "new" cam profile is audi PN
034 109 021 AK

Exiting times this year coming up....  A toast to all to remain boosted and
together

:0)

Scott