[s-cars] Re: wrt pushing RS2 to the edge...
pizzoman at yahoo.com
Sat May 10 14:33:42 EDT 2003
WRT timing advance, upon datalogging group 3, I
believe with VAG-COM, I only saw negative numbers,
will post a graph this week.
Time for water injection, I suppose, as a FMIC is a
bit more of an undertaking for me right now.
--- Mihnea Cotet <mik at info.fundp.ac.be> wrote:
> At 11:24 10/05/2003 -0600, mlp qwest wrote:
> >Mihnea -
> > >From my limited experience, and I readily admit
> it is both limited and
> >probably suspect at best, but on a "BTDT" basis I
> do feel comfortable saying
> >that 28 psi @ 350F+ isn't the same as 28 psi at
> 225F +/- a degree or two. I
> >further suspect, but again admit that I also don't
> really know, 28 psi at
> >350F+ wouldn't be quite the same, or necessarily
> better than 26 or 25 psi,
> >or maybe even 24 psi at 225F or less.
> >I think a KKK RS2 K26 pushing 28 psi at anything
> over, oh say 5,000 rpm or
> >so is going to be more likely to be in the former,
> i.e. 350F + camp, than
> >the latter.
> Of course I've never said 28 psi should happen at
> over 5000 RPM, nor should
> it happen otherwise than in overboost. More than
> 1.5 Bar or about 21 psi
> at 5500 RPM is the maximum an RS2 turbo can take,
> and hopefully I've never
> Been There Broke That yet because I've always
> limited boost correctly in my
> programming. Please, what's 350F???? Is that
> chinese? ;-)
> This is why I mentioned about "maximum boost
> pressure" or overboost figures
> and "continuous" or after overboost pressures. 2.0
> Bar for a short period
> of time in overboost isn't bad for the turbo, if
> boost is lowered enough
> past 5500 RPM.
> >Before going off on maximum psi figures, I wish
> someone had the
> >instrumentation at hand to correlate those with an
> actual charge air intake
> >temperature and power perceived",
> I have. with 1.8 Bar overboost on an RS2 turbo and
> 25°C ambient air temps,
> the intake air temps in the IM go to around 70
> degrees C, and timing is
> being pulled off a few degrees (professional secret,
> I won't say how many).
> This is still good for 520 Nm of torque (~380 lb/ft)
> even though with 15
> degrees ambient temps and 55-60 degrees intake temps
> torque bumps to 540,
> and IMHO 20 Nm is something that one's 'buttdyno'
> can feel. Thus, yes, too
> hot isn't really good but it's still better than 1.6
> Bar with less timing
> retard (because of lower intake temps).
> >.... like, as I understand, the ECUs are
> >already measuring & doing and report on via "the
> VAG display group 03, Field
> >4 (Bentley Table J 01-76) off the air temp sensor
> located, I think, in the
> >intake manifold after the intake charge passes the
> throttle plate. That
> >particular sensor is there, and in that specific
> place for a reason, right?
> Yes, it is there in order to correct the following
> -timing advance at WOT and part throttle
> -fuel enrichments
> -boost control.
> >~-----Original Message-----
> >~From: On Behalf Of Mihnea Cotet
> >~Sent: Saturday, May 10, 2003 10:43 AM
> >~To: QSHIPQ at aol.com; robert at s-cars.org;
> pizzoman at yahoo.com;
> >~s-car-list at audifans.com
> >~Subject: Re: [s-cars] Re: wrt pushing RS2 to the
> >~Scott et al.,
> >~28 psi *does* gain over 26 or 21 ....
> >~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
> >~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
> >~>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
> >~>Scott Justusson
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