[s-cars] Re: RS2 definitive answers

[QSHIPQ at aol.com]

In a message dated 10/19/2004 4:26:37 PM Central Daylight Time, 
jbufkin at austin.rr.com writes:
>Scott,
>Getting off the RS2 stuff for this post.  I don't think  you or I are in 
>disagreement about the RS2's potential and limitations.  Its fine for 
>street cars.

Ok.

>I personally think you are reading way too much into the few instances of 
>Audi's attempt to implement the Anti-Lag system on their I5s.  They did try 
>it.  Yes.  And they subsequently dropped it.  yes.  They then continued to 
>use K27 turbos for their cars.   

And k26 based turbos as well.

>Now RS2 variants, etc from the mid 90s are 
>interesting and I'm sure they tried the smaller turbo but, I suspect it was 
>due to intake restrictions by the rules.  My machine had an RS2 7200 comp 
>turbo but was also fitted with a 40mm restrictor according to SCCA 
>rules.  Interesting choice.  Lehmann mentioned that the more appropriate 
>turbo for my car without the restrictor would have been a K27, and that is 
>what he would have used if it weren't for the restrictor.   

Interesting.  I haven't seen a inlet restrictor ck in SCCA ProRally in 25 
years.  I'm sure they had it, but we never ran it in the '95 S2, in fact we 
didn't even take it to the rallies most of the time.  Lehmann sent the 26 based 
turbo for the S2, and that cold side was awesome.

> You cite two 
>examples of K26 turbo use in I5 competition, but both of those are much 
>later and possibly non-works examples.  

Are you sure of that?  I'm not.

>I still contend that the K26 family 
>was just as commercially available to Audisport and they could have put 
>together whatever K26 they wanted, but they didn't.  What that tells me is 
>that with the right driver who can take advantage of the power and handle 
>the lag, the K27 is the better turbo for racing on the I5.    

Depends on venue.  "Racing" is all inclusive.  There is a big difference 
between WRC efforts (1000 turns usually blind) vs Tarmac racing (10 turns, LFB on 
turbo/cam).  There is factory works driver complaints regarding the off 
cam/off turbo lag of the WRC cars dating back to the A1>S1

>The IMSA 
>example that Mihnea cited isn't fitted with the 2nd wastegate 
>anti-lag.  

I understand that.  They didn't need it for Tarmac racing.  They did need it 
for Hillclimbs, and it was tried in rally.  They needed it because Audisports 
problems with FIA Group B 1.4 equivelency Rules.  

>That system was tried in the 1985 Season on the S1 and at the 
>1985 Pikes Peak which is where my setup is from.  I see the anti-lag setup 
>as an attempt to make a good setup even better.  Not to make an unworkable 
>system tolerable as you seem to see it.

The S1 Evo II (all SQ's were technically S1's James) was indeed to make an 
tolerable system.  The problem Audisport had was twofold in '85.  First, the 
success of the S1 chassis was plagued with reliability problems, and had works 
driver complaints of off turbo/cam lag just as the A1 and A2 before it.  
Audisport didn't want to give up HP to give the drivers more torque.  Why?  Cuz the 
awd competition (namely Puegeot) had a better awd car with a better winning 
record.  Audisports days of buying the best drivers (Mikkola, Blomqvist, Mouton, 
Rohrl) was falling to better equipment.  Rohrl had to be begged to come back 
for '85, and Audisport was pulling all the stops to get wins in '85.  So, IMHO, 
not only was this system for "tolerance" it was just plain desparate attempts 
to keep HP at the highest level, and still give the drivers "torque".  For 
the Pikes Peak win, the "whackies of the whacky" setup ever was needed, since 
you have a small motor with a huge turbo and a 9000ft elevation change.  A 
really tough opinion you carry there James, since this desparate attempt by A.S. 
gave it's race motors a half life of 1 hour.  I'll suffice it to say I disagree.

>   The IMSA car ran a large frame 
>K27 and they just Left Foot Braked it to keep it spooled.  The results 
>speak for themselves.

Yeeha.  Light chassis, massive HP, massive turbo, legendary drivers.  Well, I 
see 1 of the 3 comparing the scar list.

>So respectfully, I think the K27 choice speaks for itself in the racecars 
>and I hope your not implying that the IMSA would have been faster with a 
>K26 hotside

Massive jump there James!  Never implied, and I might argue the "speaks for 
itself" with a healthy dose of Audisport '85 WRC history and works driver 
quotes.  720HP IMSA motors need k27 (or bigger), 900HP IMSA motors probably bigger 
than that.  500HP Trans Am motors didn't exclusively use k27's.  I'd also 
argue that Audisport used even larger turbos too James, don't limit yourself to 
k27's, 

To bring it back to the S-car list....  I'm not sure I understand this quest 
for monster turbos on small displacement I5's.  Audisport was restricted to 
2.1 liters in FIA for years, and it made for some laggy monster race cars (at 
half the weight of miss piggy too).  We on these lists, on the other hand, 
aren't at all restricted to 2.1 or 2.2 liters.  Want to run a k27 with lots of HP 
and torque?  Add the couple hundred cc's to the I5, and do it right.  This 
quest for HP confuses me some, especially on these lists.  Miss Piggy *needs* it's 
own equivelency formula, and I'm just not convinced a k27 is the answer.

My own prediction?  Cold side technology is going to really shake down to 
street turbos.  I've seen some pretty radical cold side wheels and housings over 
the last few years.   After bolting one of these radical cold sides up to the 
'95 S2 group A car then driving it, I'm certainly convinced.

Scott Justusson
QSHIPQ Performance Tuning