question on 200tq tuning
brett at cloud9.net
Thu Jun 24 00:46:13 EDT 2004
At 3:07 PM +0100 6/23/04, pronn at rock.com wrote:
>Fellow 200 drivers, I am looking into a possible stage 2 tune for
>my '91 200tq20valve.
"stage 2"? Ie, you have a chip and you want to do more? If so,
that's big bucks. Injectors, MAF, turbo, exhaust manifold, and ECU
programming to match all that- and yes,they must be done together.
> There is also a K&N filter installed.
These are lousy and do even less on a turbo car than they do on a
normally aspirated car. Filters for the 200q20v cost well under $10
from the local auto parts store, and yes, just about any brand will
do fine (I stay away from Fram just on pure principle, however).
They're pretty easy to change, as well. By the time you get through
with the K&N filter, the cleaning stuff, the oil, etc...you'd
probably have to buy dozens of paper filters before the K&N was more
Especially if over-oiled they can cause contamination on the MAF
sensor, which costs over $300 to replace. K&N's claims of increased
filtering via their "it's wet, so it traps more!" has never, to my
knowledge, been actually proven.
Cone filters are even worse- they often fail to provide smooth enough
airflow, which is very important for the MAF sensor to work properly.
Look at the top side of your stock airbox. See the Venturi horn?
That's there for a reason. See the really wide opening in the front,
with the curved lip? Ditto! Audi/Bosch have lots of smart guys
working for 'em to figure out exactly how to make that airbox flow as
best it can. Lastly, cone air filters usually have dramatically less
surface area, and thus must have very large pores with low filtration.
K&N's do flow a little better than a paper element since they're
more open. This makes them better, purely from a power perspective,
on highly modified or very well designed normally aspirated engines
where the intake plumbing itself is less of a restriction than the
filter, and the airbox size can't be increased because of rules (ie
racing) or space limitations. Many race cars run so low # of hours
and rarely under very dusty conditions, so the lack of filtering
isn't a huge concern for them...and really serious racers may not run
a filter other than a really open foam unit, since they may tear down
the engine on a regular basis.
There's an old rule about aftermarket performance do-dads. Ask
yourself, "if _______ is so good, why didn't the original equipment
manufacturer use it?" This is very valid, because manufacturers will
KILL to get some extra "free" horsepower. So why is it that not a
single car company on the face of the earth- uses K&Ns from the
-they cost more; more expensive materials, more complex
manufacturing, lower volumes, less market competition.
-they are extremely labor intensive to service. Clean, rinse, dry,
oil. As mentioned the filter can be overoiled, causing expensive
component failure. it is virtually impossible to mess up a paper
filter element change.
-they do not filter as well, which means increased failure rates for
-they do not, for most cars, provide any performance increase because
the rest of the intake system(such as the MAF sensor) are more of a
Further research shows I'm not quite right- apparently Ford installs
K&Ns on the "Cobra R" model (which I believe is extremely limited
production #'s, maybe even at least partially hand-assembled).
>Are there any simple mods I can do at home with standard tools for
>increased performance? Do H.P. injectors make a big difference
Upsizing injectors without reprogrammed fuel maps will result in
extreme rich running as the ECU will be using grossly inappropriate
injector timing values for the airflow it senses. Larger injectors
are not necessary unless you plan on doing more than "just a chip".
Injectors that are too large reduce the metering precision of the
system because the ECU can only use a subset of the injector's duty
>, and how do I change out my waste gate spring?
You don't change the wastegate spring; it works fine and is good for
significant levels of horsepower as-is. The engine controller is
very sophisticated with knock detection, charge air temperature, etc-
this isn't just a purely mechanical, pressure actuated wastegate
setup; the ECU plays an active role in boost control.
Prost's "Bosch Fuel Injection" is a excellent introduction and
discussion of everything from early Jetronic CIS systems to the early
Motronic systems; it covers Motronic theory of operation quite
nicely. A local library -might- have it, since it's been out for
quite some time. Look for a blue soft-cover book with a photo of a
MAF sensor with a glowing wire.
"They that give up essential liberty to obtain temporary
safety deserve neither liberty nor safety." - Ben Franklin
More information about the 200q20v