[s-cars] RS2 MAF deliberations

[Mihnea Cotet]

Hi Scott, thanks for your thoughts, I'll try to do my best to send you
complete answers :-)

At 08:23 19/04/2003 -0400, you wrote:
>Hi Minhea,
>First, let's make it clear that a "couple hundred dollars" on a dyno
>doesn't exist in the states.  For dyno tuning, one would need to have that
>nice bosch programmer.  Expensive toy.  We're a bit behind you guys across
>the pond, we just started getting local awd dynos a couple years ago max.

There's no need for expensive toys like Bosch programmers! I'm using a 15
or 20 year old Eprom programmer but the software before it is pretty
expensive, though totally useless without proper Motronic programming
knowledge... and just as a FWIW, there's no AWD dyno anywhere closer than
200 km away from me in Belgium.. :-(


> >I know of no one among the "real"
> >tuners (I mean not the vendors that are in the US and I really mean
> >**vendors**), especially in Germany who'd recommend to install the RS2 MAF
> >in order to have "proper" HP and operation.
>
>I don't see why not - recommended.  That AAN screen appears to be rather
>restrictive to airflow, even if you gander at the claims in the
>archives.  Proper?  I'm not sure I know what that means...  Just about any
>Bosch MAF will work, and with dyno "tuning" that bongo SQ MAF is the cats
>meow.  I guess I'd defer to departed Rod Haney for "proper" HP
>definitions.  I know our 400+ S2 rally car has run the AAN MAF with proper
>tuning.  So, I guess I don't disagree with the statement, only accept the
>obvious with what I get in my shop.

Agreed, the screen is restrictive but the MAF itself (electronically
speaking) is useless IMHO...


>Given 2 MAF, one with a fine mesh, one with an open mesh:  ALL else being
>equal Minhea, which one would you recommend?  Why did the RS2 with only 80
>more ponies than the AAN, use a different MAF?  Your claim is that ***
>with proper tuning***  the RS2 didn't need to change MAF application.  I
>won't argue the point, only raise a question.

Totall agreed the RS2 is preferable from an "open mesh" point of view but
from a programming point of view, I prefer the stock unit. And I think
several people over there have found out the RS2's screen only gives a few
more horses (with the right programming of course, there's no point in
comparing 2 MAFs with the same SW when the SW doesn't take the MAF values
into account the same way), nothing really relevant actually... I can't
explain why the RS2 used that MAF as at that time I was still playing and
repairing/upgrading guitars and amps, not cars, though...


>Those asterisks are what keep me smiling Minhea.  I'll go back to a point
>I made long ago.  That MAF - ANY MAF - in the I5 20vt is not necessary at
>all.  ***  With proper tuning ***  it can be eliminated alltogether, in
>which case:  up goes HP, torque, throttle response, preturbo inlet
>pressures and temps lower.  Why not "properly tune" that pipe right out of
>the fuel equation?

Well, at least me and the German engineer whom I've learnt Motronic systems
with don't think it's good to remove the MAF from the circuit *** in a
Motronic I5 20vt ***, not even for 500 HP...

I don't want to enumerate the pro's and con's of alpha-n vs. MAF vs. speed
density systems but my point is that Bosch know their stuff better than
anyone else and if they did and still do the Motronic with a MAF (as in the
S4tt's, 1.8T's, VR6's and so on), there is a reason to it. The new systems
are very complicated right now, i.e. they monitor EGT, use wide-band O2
sensors, check for the feasibility of an actual particular injector opening
time and so on, but so far, they do still use MAFs, even on the RS6.... and
this is because the MAF Mo(t)ronic system has proved that for everyday
driving it is the best system around. Alpha-n and speed-density require
reprogramming every time one changes a part that alters VE and can't
compensate by themselves for an engine wearing out and loosing compression...

Then, if one removes the MAF and reprograms the chips accordingly, the
system would only be an alpha-n system, and I think an SDS or similar
system is cheaper than an alpha-n reprogrammed Motronic, right? The
Motronic can't run as a speed-density system as the MAP or PT is only used
by the "boost control" part of the ECU, i.e. the bottom board. Then, the
pressure drop across the MAF is only 0.05 Bar (measured by a friend of
mine), which is minimal and I can't see why the intake temps will be lower
without a MAF rather than with a MAF... of course the argument can go on
for days and months but I simply can't see why the MAF is such a big
problem in here...


> >This is just my 0.02 Euro from my "tuner" point of view, but I'm open to
> >discussions and different opinions anyway,
>
>I'm open for ***proper tuning***.  The problem I have Minhea, is I'm a
>tweekster and an installer, I sold my chip programmer long ago (I take too
>long and it doesn't excite me - building race blocks does tho).
>So mostly I'm given the tools with which to work, and it's my job to make
>them work.  I do.  I am NOT a tuner, I prefer "tweeker"....   With the
>"hoppen" stuff here being the most prolific, I'll let you comment on his
>ties with MTM programs...

Well, Scott, this is where and what my respect goes to you for! I've tuned
quite a few different 20vt engines, some of them with weird parts bolted on
(Garrett hybrids, unusual injectors and so on) but I haven't built an
engine myself yet!!!! So, you're a tweeker but better than I am (though I
did my 20vt swap on my own from scratch and only with my wife's help). So
this is why I respect you and I don't want to argue with you on this
subject for months.. :-)
WRT Hoppen and MTM programs, I can't really commit as I dunno what they
really sell... I've received a supposedly Lehmann SW for RS2ed AANs which
is almost identical to a SW I got from MTM so I really dunno who or what to
believe except what I program myself and check for "proper" EGTs myself...


>With regard to accepting/needing any MAF at all, I'll freely argue our
>definition of ***properly tuned*** will always differ.  I know it can be
>deleted, I saw it done on a S4tt.

Of course it can be deleted, I just simply still think it's not so
necessary to delete it, but maybe when I blow 2 or 3 per month (with 450+
crank HP) I'll see the need to delete them :-)


Anyway, thanks for your thoughts again Scott!

Mihnea



>Scott "improperly tuned" Justusson

Come on now ;-), no one said you're improperly tuned, Scott !