questions about a turbo cam for 5kcstq/4kstq

[Robert Deis]

On Tue, 16 Jan 2001, Ken Keith wrote:

> Robert Deis <rdeis at io.com> wrote:
> >
> > This includes a high rpm cam, but from what I've seen on non-audi turbos
> > the cam comes late in the game because intake and exhaust plumbing provide 
> > a much greater benefit with fewer side effects (if any) and at a lower
> > cost in time and $$.
> 
> When you say late in the game, you are refering to the sequence 
> of upgrades, right? 

Right.

This is *not* Audi specific, but a typical boosted car hop-up sequence
would be:

1 instrumentation
2 more boost
3 High-flow filters
4 Exhaust
5 Intake
6 a bit more boost
7 Intercooler
8 fuel system
9 yet more boost
10 turbo
11 fine polishing, cams, and other expensive finishing touches.

Spark often comes in there somewhere as well, but it depends on the car
and boost levels. Also, depending on how much boost you want, you may need
to do engine work-- again, that's very dependent on the car.


> Darn.  I am interested in low end power.

Look for things that will decrease your turbo spool time, then.  Piping on
both ends help this a *lot*, but especially in the exhause close to the
turbo and possibly porting the turbo or manifold.  You could also consider
turbo modification or replacement to move the turbo's "happy zone" lower
in the rpm band, but those are prolly expensive and/or violate various
racing rules.

> What's this I hear about people putting a spark plug in the exhaust, 
> to light off unburnt fuel?  What triggers the spark?  What does it 
> run off of?

Don't know the specifics here, but the theory is that the burning fuel
keeps the turbo spooled up even when you're off throttle (shifting or
whatever..)
 
Again, I'm an Audi newbie- the stuff above applys to turbocharged cars in
general.  Slap me around if it contradicts well-known Audi-specifics

-- 
------------------------------------------------------------------------------
  Rob Deis                  "Let the people know beforehand what the law
  MiB3347                      is and what they are to expect." 
  rdeis at io.com                              -- 18th Congress, Rec. 75