[s-cars] Re: RS2 TURBOCHARGER

[QSHIPQ at aol.com]

In a message dated 10/18/2004 10:04:46 AM Central Daylight Time, 
jbufkin at austin.rr.com writes:
>The RS2 seems 
>limited at the upper RPMs at high boost.  Limited in its ability to supply 
>air without overheating and its ability to flow the air out of the exhaust 
>without a rise in EGTs.   Hence the reason why Audi ran K27s on All their 
>I5 race machines. 

Not really a true statement James.  Ned's 3472 K26 is a perfect example.  
Interesting to note that the well documented complaints from the drivers on the 
k27 were so high (no torque) that the Antilag system you own was installed on 
the engine, even with it's limited half life.  

>That is huge evidence.   Audisport could have made any 
>K26 they wanted in the 1980s.  They had custom runs of only 15 turbos made 
>and chose to use exclusively K27s.   Surely if those guys felt the K26 was 
>the way to go they would have used one in their race cars. 

They did, see above.  There were plenty of others, including some wild RS2 
variants.  I know cuz out '95 S2 Rally car had one.  From Lehmnann in fact.

>   Lehmann is 
>quite adamant about it for high HP cars and anything that will race or see 
>extensive track use.    I've gone against his advice a bit and opted to use 

>the #7 K27 instead of the #9 K27 hotside.  Now perhaps his decisions are 
>based more on controlling EGTs and DRs for prolonged high HP production and 
>not drivability.  But if we're talking about making HP to get speed then 
>drivability takes a backseat.

Displacement can solve that problem.  I claim if you really want to have both 
driveability and HP, increase the displacement.  2.226Liters and k27 aren't a 
good match.  A quick read of urq featured in June issue of european car?

>I would however recommend an RS2 for any street car that is designed to 
>make 350 Crank HP or so.  Like the original RS2.   Going beyond that is 
>wishful and/or time limited for short durations of high HP in optimum 
>environments.

No problem with that statement actually.  I claim it can make 400 for that 
short duration (with a big torque hit), and you can certainly "live" with the 
350cHP after that.  In fact, as several are learning, big turbos can find that 
real world performance data might adjust their thinking.  I can think of a lot 
of track events where Big turbos would turn a slower lap time.  

Look guys, if you aren't doing ANY gear matching with these big turbos, money 
at big turbos is just a dyno number without much attached to it.  Most are 
already finding that on the quarter mile run, the numbers are much less than 
expected.  James, read Stig or Walter's "off cam/off boost" comments.  That 
antilag system in your car was the 'fix'.  Is that the ultimate turbo system if a 
new motor is required after 1hour?

SJ