[s-cars] Re: wrt pushing RS2 to the edge...

[Mihnea Cotet]

Scott, please, once again, you didn't read my posts from the first to the
last word. I have only mentioned 2.8 PR as being reasonable IN OVERBOOST,
nothing more nothing less. No car that I have done has seen 2.8PR yet for
more than 15-20 seconds of overboost, period.

I know what heat soak is, I know how intake temps rise but I also know some
IA chips people are using in the US detonate in summer heat and that's no
wonder, they could detonate even with 1.2 PR simply because of the crappy
programming, but that's not the topic of the whole thread, it's simply that
it doesn't surprise me a few people blew engines on the track with 30 psi.

So, no I'm not tuning every RS2 equipped car for 2.8 PR, some of them stop
at 2.7 overboost (again, OVERBOOST) and then continuous pressure is about
2.5 until 5000-5500. And I can assure you none of them blew yet, including
when being used HARD on the track or on the street (some of us here think
the street is a track).
Then, please, go ask Mr Thomas Schmalz in Germany who's more reputable than
me and who certainly has more experience, what PRs he is programming in his
RS-2 type chips that put out according to him ~370 crank HP, you'll see for
yourself. The point is that, if I was the only stupid guy who has played
with such boost levels on RS2 turbos, I won't have ever claimed that 2.8 PR
in overboost makes sense, sorry but I haven't reinvented the wheel nor have
I ever claimed so. If you read Audijim's 5zylindertechnik list on Yahoo,
you'll see an email in the Carillo vs. Pauter rod thread from a certain
"Ed." stating 1.8 Bar (or PR for us at sea level) overboost and 1.2 Bar at
7000 RPM being the maximum safe limit on an RS2 turbo. Well, guess what?
This guy is a good friend of mine and is also a "hobby tuner", and he has
done about 3 times as many RS2 equipped cars in Germany as myself (I only
did 4 as of yet, of which 2 were real RS2s) with the above mentioned PRs.
Guess what again? He tunes just like I do (or maybe I tune like he does?
whatever), i.e. he does every car in real time, thus each car is tuned
individually (with a very expensive software and eprom emulator that traces
accesses in real time) while EGTs and O2 (with a WB Oxs) are being
monitored. Guess what again? Not a single car he did broke anything yet and
several of them are used weekly for 1/4 mile runs and so on.

So, with this last email I'm out of this "pushing RS2 to the edge" thread,
I've said enough times where's the edge and I think I know how to get there
without breaking anything on the track or on the street so you can continue
to argue about whatever you want, but that's without me, I have enough work
to do so I can't follow this indefinitely.

Mihnea

At 20:23 10/05/2003 -0400, QSHIPQ at aol.com wrote:
>Whew, didn't know which to pick, till I saw this one.  I'm with Calvin and
>MLP here.  Minhea, first off, a dyno is a great tool for a single
>run.  IME, with many comical hours with imported 3phase fans on high and
>plant sprayers (even CO2, and a variety of fridgedly 'Icey cocktails") in
>hand, Calvin is on the money.  If you want to see what's happening in the
>"continuous world" of boost, try logging pre and post IC temps and
>pressures.  For simplicity of argument I just chose the RS2 full metal
>jacketted regalia 90% of the S car boys do as "upgrades".
>
>Remember too, with any turbo there is a maximum boost/hp level, and a
>continuous boost/hp level.  As we further any discussion, we should
>differentiate the two.  In maximum boost levels, Frank ran over 30 (before
>some batboy whacked him), and another lister ran over 30 too, whom I also
>whacked in a public fashion years ago.  He wasn't as lucky as
>Frank.  Personally, for momentary boost levels, I've been witness to
>numbers that defy belief on many audi turbo quattros (even 1.8t).  I've
>also seen several cars grenade themselves at their very first track event
>with those exact same levels they ran for years on the street.  IMO, I
>would point you to Calvins formula for the exact reasons why.  And I would
>take exception somewhat to 20Nm being huge (if anything at all, I've seen
>that difference in two runs with the same plant sprayer), in fact, in a 5
>minute drive, or <2minutes on track, that could become nothing, or less, btmt
>
>You can dial a lot of things thru "chip" tuning, but heat soak is tough,
>even for the "good/proper ones".  IME2, finding a turbo that will blow
>2.8>PR at good efficiency really isn't applicable to an I5 2.3L motor
>(save specifically only the RS2 turbo, but read more below).  Given the
>formula below Calvin shared, something has to change, specifically one of
>the variables has to change.  What are you doing in the programming to
>decrease T in the boost equation?  But specific to your argument Minhea,
>if you look strictly at the RS2 Map itself, your "peak" hp/torque levels
>at 2.8PR (turbo spinning at 135,00+rpm) vs 2.4PR at 120,000rpm, which will
>heat soak first?  If you look at it harder, you will see that the output
>(volume) can be the same 400cfm for both PR at the same compressor
>efficiency of 72%.  Why more pressure?  Isn't this really an indication of
>a Density Ratio problem?
>
>I'm also with MLP...  At Steamboat's expensive Bagel-fest parking lot get
>together earlier this year, lot's of discussion with MLP regarding that
>intake manifold you guys are using, specifically, can it really ram all
>that air down the throat of that motor?  I think it will to a point (which
>I'm putting forth at about 400RWHP), then more pressure is, well, more
>pressure.  In fact, it can become so unstable (since it doesn't really
>have anywhere else to go) that surging, on both sides of the combustion
>chamber and both sides of the turbo, can get really ugly.
>
>I'm a fan of education AND btdt.  I look at the btdt guys for some
>background too.  If what you are doing is taking the "I ran/run/program
>this with no problems" routine, I'm investing in 20vt motors now....  If
>what you are doing is advocating a more complete understanding the
>principles of turbocharging and heating charge air, then I argue you
>aren't running 28psi...  Either.
>
>In absolute full race regalia audisport liked 2.6PR, and when they were
>really close to a competitor and wanted to win,  2.8PR with the expressed
>permission of AS management based on the exact conditions at the time of
>the request.  Messing with 2.8PR in a street car?  Ok, I guess my library
>and btdt makes me a bit more conservative than youze guize.
>
>I'd also suggest Minhea, that if we want to "nerd" on pressure, that we
>speak strictly in terms of Pressure Ratio, not "psi".  Since PR applies to
>turbcharging anyhow, and we must keep our boys in the CO mafia from false
>pretenses.
>
>Scott "T not P" Justusson
>QSHIPQ Performance Tuning