[s-cars] Re: wrt pushing RS2 to the edge...
mik at info.fundp.ac.be
Sat May 10 19:43:23 EDT 2003
Scott et al.,
28 psi *does* gain over 26 or 21 in terms of torque IMHO/IME (I can't but
exist on the Experience part, especially in tuning myself a few RS2 engines
And, I know of several RS2s running 28 psi (i.e. almost 2 Bar boost or PR)
overboost for a massive 530-540 Nm of torque (dyno measured), while stock
RS2 torque is 420 Nm at max. 1.4 Bar. I know 28 psi isn't efficient, but
for torque no one needs 100% efficiency. So what does your statement of 28
psi being almost double the factory boost levels mean? Stock AAN boost?
Maybe, okay but what's the point? What's the point in comparing apples with
So, sorry to insist, boost means torque and if timing is properly
programmed (sorry to insist on that point again), 28 psi will be a lot of
times better than 21, I've personnally BTDT many times.
Then, according to several serious tuners here in Europe (what do you say
of Dupre Motorsport's racing engine management director during the 90's?
He's the guy that helped me with most of what I know about chip tuning),
stock rods (including the crappy AAN units which are the worst Audi ever
used, i.e. the thinnest) are known to break at 600 Nm crank torque, meaning
in excess of 2.5 Bar or PR. This also means that running 30 psi (or 2.0 Bar
or PR) won't break rods, except if the timing/fuel chip is done by an a$$
and if knock sensor function is suppressed or the threshold raised.
Furthermore, maximum boost people are stating doesn't mean anything to me
in terms of HP, what boost levels are you guys seeing at 5500, 6000, 6500
and 7000 RPM? This is more relevant than maximum boost you see for a few
seconds during overboost.
HTH and my 0.02 Euro,
At 12:27 10/05/2003 -0400, QSHIPQ at aol.com wrote:
>Hmmm... I personally think running 28psi on an S-car is silly (I'd say
>stupid, but long nerdy posts about effective compression ratios I don't
>need). IMO, you are "safer" increasing the Density Ratio than the
>Pressure Ratio. I'd also venture to say that 28psi probably isn't gaining
>any performance over 26psi, which means Motronic is probably saving a lot
>of butts here. I'd also venture to say that the difference between 24psi
>and 26 psi is barely measureable. I'd also venture to say that the
>difference beyond 21 psi (RS2 equipped only) comes at a massively
>diminishing rate of return.
>I'd further venture to say that rods are known to pop at 30psi, which
>means the closer you get to it, the higher the danger.
>All anecdotal "evidence" so noted, 28psi is almost double the factory
>boost levels. For street driving, probably not there long enough to worry
>about it. The long straight and intense 30minute track session? I'd be
>worried about it.
>Boost, specifically Pressure Ratio, is only part of the equation in tuning
>for performance gains. Cars *can* run at maximum parameters, but small
>hiccups in any of the ancillary systems can cause catastrophic failures
>because of boost. The good news Joe, is that you can respond in the
>"takes one to know one" concept. Specifically, if it's stupid to run
>28psi, in reality, with no other changes, it's really no "smarter" to run
>it with race gas.
>HTH and my .02
>In a message dated 5/10/2003 8:07:52 AM Central Daylight Time,
>mik at info.fundp.ac.be writes:
>Someone stating 28 psi without race gas on an RS2 motor is stupid simply
>doesn't know what this motor/turbo is. Period.
>Then, you can log timing advance and IAT with VAG-COM, I don't remember
>where exactly but you can.
>At 05:00 10/05/2003 -0400, Robert Myers wrote:
> >[ Picked text/plain from multipart/alternative ]
> >At 08:16 PM 5/9/2003 -0700, Joseph Pizzimenti wrote:
> >>Well, this was sparked by a rather vocal argument I
> >>had with someone about water injection recently. I
> >>was asking his advice and he has experience with B5
> >>S4's and 3000GT VR-4's, etc...he basically said I was
> >>stupid to run 28psi without race gas.
> >>Is there any way I can datalog ignition timing or
> >>intake air temperature with VAG-COM?
> >I dunno, Joe, but I betcha you could get an answer on the VAG-COM list.
> >Mailing-List: list VAG-COM at yahoogroups.com; contact
> >VAG-COM-owner at yahoogroups.com
> >I've been wondering... Who would Jesus bomb?
> > Robert L. Myers 304-574-2372
> > Rt. 4, Box 57, Fayetteville, WV 25840 USA WV tag Q SHIP
> > '95 urS6 Cashmere Grey - der Wunderwagen ICQ 22170244
> > http://www.cob-net.org/church/pvcob.htm
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