[s-cars] An interesting FMIC "fact" (?)

[Lewis, Gary M]

Scott,
To my knowledge I am running the most advanced KKK K26 in the world that is outside of a full race program, i.e., commonly available to Joe-Schmuck-Off-The-Street(that would be me).  The compressor wheel and housing are currently being used in some Porsche racing programs (and NOT the RS2).  Cody has the same turbo.  I have been told that the next step for me is either a bigger turbo (like a hybrid e,g, Garrett, or bigger KKK with custom spec compressor wheel), or, for example, have a titanium turbine wheel, shaft, and compressor made to fit what I currently have, which is SERIOUS money.  In other words, the argument that Cody and I need a better turbo is specious given what we have (well, Hap does make fun of it, but, He's Hap, He can.  MLP could, but he doesn't).  Bigger maybe, but not better. 

I do agree that the 4 sensor approach is correct, awesome data, but it isn't necessarily the most practical given all the data that exist WRT URS4/6 IC.  Eventually needs to be done, Hap probably should if he hasn't.  Some positives, with just 2 sensors aft of the turbo compressor, you can tell the approx turbo efficiency by boost psi, turbo-out air-temp, ambient and altitude.  I'm not going to do the final two (well one really) aft of the IC right now until I install the IC since I already have the IC, happy with the idea of 25 hp, and I want to spend the additional money on other stuff instead of 2 more sensors.  Also easier to install the temp probe into aluminum pipe...

In terms of currently published data, the stock IC efficiency is easily reverse-engineered:
1. A comparable Spearco IC Flow-Chart for - The Stock IC, and the IC I have, which is more efficient than the one Amoroso used.
2. The increase in flow that nets 25hp and 400rpm reduction in max boost achieved.

Doing the above nets me:

a comparable IC to ours has ~ 4psi pressure loss at 24 psi, efficiency is less than 50%.  What 50% means is that if ambient is 70F, RS2 turbo exit temps at 28 psi and 60% efficiency, the exit temps are 381F.  (381F-70F) * (1-.5) + 70f = 225.5F

Contrast that with a properly sized FMIC.  Pressure drop is less than 1/2 psi.  Efficiency is over .8 (80%!!!!) at 20 mph.  So an RS2 turbo at say 25 psi (1 psi over requested of 24 psi) is at 72% efficiency, exit temps are 309F.  (309F-70F)* (1-.8) + 70F = 132.8F.  It is almost HALF as cool as stock.  Also, making 25 psi happens A LOT earlier than 28 psi, so pressure drops also create more power thru lower rpm torque.

You stated that the stock IC is very efficient.  I agree, at 15 psi on a 2.2liter motor it is wonderfully efficient.  I hate the placement, but that is another discussion.  At 24 psi, it is a whole completely different ball game.  No IC in the world I know of can be perfectly sized at one boost level, and still be perfectly sized when increasing the boost 63%( yikes !!!!!!!!!!!).  Spearco states that the efficiency ON ALL IC's drops at least 30% from 10 psi to 20 psi. That's a large drop.  The last 4 psi, now really HOT, probably add another 20%.  In other words, the 50% efficiency I used above was generous.

Gary Lewis

1995.5 S6 Avant, Green/Ecru, RS2 MAF, RS2 Exhaust Manifold, RS2 Injectors, Custom Turbo (K26 Turbine, Factory K26 Cold side (Audi Works '999' P/N) with 50mm intake and custom Innovative Turbo compressor wheel), TurboXS Type 25 Bypass Valve, Bilsteins, Eibachs, Big Reds, Spec II Clutch.




> -----Original Message-----
> From: QSHIPQ at aol.com [mailto:QSHIPQ at aol.com] 
> Sent: Friday, February 27, 2004 9:07 AM
> To: cpayne at bconnected.com; s-car-list at audifans.com
> Subject: Re: [s-cars] An interesting FMIC "fact" (?)
> 
> 
> You guys are guessing on the turbos to date.  I'd focus 
> there, create the 
> demand for a better IC.  That's much easier to justify than 
> 'want' in terms of 
> dollars spent.  Who has 4 probes installed?  Right now 
> without question *that* 
> is the first step for most of y'all feeling less than Hapersized.
> 
> SJ
> In a message dated 2/27/2004 11:04:46 AM Central Standard Time, 
> cpayne at bconnected.com writes:
> Oh I wouldn't say that it is the cheapest HP...but heck once 
> you are fully RS2'ed or beyond..it is the next step IMHO.  
> This assumes that you have done all the other goodies like 
> suspension, brakes, etc.
> 
>   IF you want 400+ HP I don't think you are going to be able 
> to do it w/o some larger/better flowing IC.
> 
> cp
> _______________________________________________
> S-CAR-List mailing list
> S-CAR-List at audifans.com 
> http://www.audifans.com/mailman/listinfo/s-> car-list
>