KKK RS2 race turbo charger

[Ken]

On somewhat of a tangent, I'd like to get some feedback on some plans I have for an eventual 20vt with efi, using a bunch of different parts.

So, I hear the RS2 exhaust cam is the same as a 7A exhaust cam, or at least it's considered an upgrade from 3B exhaust cams (according to Tommy from the http://groups.yahoo.com/group/Audi20V_Kruemmer/ list.  That's good for me or someone else trying to use a 7A head to construct a homebrew 20vt.

What of the intake cam tho'?  Is the 7A intake cam profile a bad one for a turbo application?  Do I need to get an RS2 intake cam, or would a 3B cam be good enough?  Or, would the 7A intake cam be okay?  Perhaps some adjustable cam sprockets to reduce overlap or something.

Also, I had thought that with some of the comments I've read about the RS2 turbo being "old technology" compared to the more recent offerings or designs from Garrett, leading people to use hybrid turbos intended to perform better than an RS2.  Sounds great, especially because they are like half the cost of the genuine article.

I have read some of what Javad has written about his hybrid turbos, and I know other sources of hybrid turbos are out there as well.

I would like to hear some comparisons of these hybrid turbos and the a real RS2.  Perhaps there not a lot of firsthand knowledge from the same person and both turbos, but even a discussion would be nice.

After finding out about the hybrid option, I pretty much thought the RS2 turbo was just for people that wanted to have "factory parts" rather than it actually being better than a hybrid.  But I still read comments and see people offering RS2's, so it must still be a contender.

For the amount of money the RS2 costs, I sure want it to be the right choice.  Perhaps it's so expensive because it's brand new, while most of the hybrids are rebuilt?

Also, it seems like the main drawback to a ball bearing option on a hybrid turbo is the cost.  If it makes it more responsive and spool up faster, it seems like you couldn't throw that same amount of money ($600?) at any other part of the system to get the same result (if other systems are already optimized, manifolds and exhaust).  Now, if it were true that ball bearing designs hadn't been perfected yet and they blow up all the time, that's something different.  I still aspire to have one.  Whether I will end up with one is a different story.

Thanks,

Ken

QSHIPQ at aol.com QSHIPQ at aol.com wrote (snipped):
>
> WRT the RS2 turbo in the 20vt application.  The RS2 exhaust
> cam helps low end greatly.  So does the 3in turbo back exhaust
> system.  The 91 200 with the RS2 stuff on it just smokes the
> k24, btinstalledthat.  I think the reasoning is that the 91
> 200/urq is the only 20vt application without the dual mass
> flywheel.  That dual mass really dogs off the line.
>
> The RS2 turbo power output exceeds the k24 by 2250rpm (from
> your own comparo chart Dave).  Although you 'own' both, a
> direct comparo to your two applications isn't fair.  The RS2
> has a serious weight disadvantage to the urq, and the urq has
> a much lighter reciprocating mass.  Since you run both cars in
> stock trim, I too might conclude the k24 is a better driver.
> Tweeking either car, the RS2 turbo give the 24 a hard punt.