In a message dated 6/25/99 12:26:54 PM Central Daylight Time,
dg50@daimlerchrysler.com writes:
> I have a big problem with this. On my first gen Talon (TDO5-14B) the waste
> gate solonoid would close and drop boost to 8 psi or so any time it went
over
> 12 psi.
< Then you had a knock problem. The DSM ECU has NO concept of manifold
< pressure at all, only airflow. The ECU does not attempt to manipulate the
BCS
< unless there is a problem. If you get a tank of bad gas and lots of knock,
it flips
< the solinoid and reduces the boost to wastegate spring pressure only.
Well, I sold the car just a few days ago. I always used either Shell or Amaco
premium, rated at about 93 or 93 octane and we are close to sea level, so it
should be good stuff. The ECU does calculate boost to do ignition timing and
the stupid lousy boost gauge. When I put a good gauge on the car it was
almost dead on 12 psi, the solonoid switched. I never heard ping even when I
pushed it to 24 psi. I didn't even have octane boost in it then.
< Contact Todd Day (today@tmo.com) for confirmation. He reprograms Talon
< ECUs for a living.
Now that I no longer own the car, I can't test what you are saying. I have no
reason not to believe you, but mine sure did not seem to act that way. I
would test it again if I still had it. Maybe the later ones were different,
mine was a very early 90 AWD.
> If you are making it creep higher with a downpipe
> blocking the waste gate outlet, you are using a very creative CHEAT. The
> stock gate has no trouble keep up UNTIL you do something else to make it
get
> over 15 psi in the first place, I run turbos, I know how they work.
< Ahem.
< 1) My downpipe does not block the wastegate opening. In fact, I'm using the
< stock O2 sensor housing. The exhaust stream at the downpipe is the same as
< stock.
< 2) The 14b, without a cat and with a decent exhaust, creeps at high loads in
< high gears, no matter which DSM you have. Ask any of the 3000-odd drag
< racers out there. If yours was not, you had a problem with your car. Many
of the
< drag racers who run 16Gs (same turbine housing with a different compressor)
< wind up hogging out the wategate passages and installing a bigger flapper
(or
< just running an external wastegate) to prevent creep from happening. Check
the
< archives at www.dsm.org for confirmation.
I find this very strange, I ran VERY open exhausts on my talon a few times.
If I left the stock boost controls all hooked up, it never crept more then 2
psi to about 14 max, and then it would dip at max revs. Put any tiny leak in
the wastegate line though, and it would climb. A big leak (vacuum T in plase
of solonoid) and I could run 24 psi til the fuel cut hit around 4000-4500
rpm. Connect the gate back stock, 14 PSI, always.
< 3) ALL of the boost control devices on my car are in stock configuration
and are
< fully operational. I have done NOTHING to alter the way they function. With
all
< the scrutiny I get? Are you kidding? How could I do anything else?
I would like to see it, and take a ride. I asume you have a good boost gauge
in the car. My Celica beast runs very close to how my Talon did. With the
gate spring set to lift off the seat at 10 psi, it runs 11 to 12 under load,
all the way to redline. My gauge reads a tiny bit high, I go by the MAP
sensor that I datalog through the TEC II ECU, and I tested it with a hand
pump and Snap On gauge. Even with my Huge TO4E "60" compressor and small
stage 2 .48 A/R exhaust housing, it does not creep with just the stock Garret
waste gate from a Renault Fuego, yes you read that right, it is small, and
the actuator is fairly large so the pressure on the flapper has almost no
effect. I run upwards of 12 psi of exhaust pressure at 6000+ rpm. With the
previous T-3 I was running a Grand National exhaust wheel, but in a bored out
.36 A/R/ housing from the Fuego, and it still did not creep, with exhaust
pressures of 22 psi at only 5000 rpm. This was with the same actuator and
flapper. The gate hole is only 5/8 inch. If this does not creep, why would
yours. I also have 2.4 litres. Only a single cam 8 valve, but the valves are
huge and the cam is probably more agressive. The motor made almost 170 hp
without a turbo. 2nd gear acceleration calculates back to close to 350 hp at
14 psi, but my injectors were over 90% duty, so I dropped it to just 11 to 12
psi now.
> The downpipe withthe restriction
> in front of the waste gate was a BLATANT disregaurd for the spirit of the
> rules, and I believe was the whole reason for this to come up.
< IF one were to make a pipe that pinched off or blocked the wategate outlet,
I
< would agree with you. I do not have, nor have I ever had, nor have I ever
SEEN
< or HEARD OF such a thing actually existing.
It was talked about on team net a short while back, and a couple weeks later
the proposal to require stock exhaust rules on turbo cars followed shortly. I
don't have all the facts, but someone tried it, and I would venture to guess,
caused this whole thing to be brought to light in the SP rules.
< I really do not like being accused of cheating, nor do I like people
assuming I
< have done something actively nasty like attempt to somehow block off the
< wategate outlet. Ordinarily, I'd be very upset over accusations of this
nature.
< However, it appears in this case that you mistook a failure mode of
operation
< for a normal condition, and so you are working from bad information. That's
< forgivable.
Like I said before, I would really like to see your car in action. I didn't
accuse directly, but after re-reading my post, yes it did sound a bit harsh,
sorry. But from my 9 years driving my Talon, it sure sounds a bif fishy. I
also read turbo magazine and read alot of their articles, on Talon projects.
They also seem to have no creep problems, UNTIL the boost is raised. When
they add a boost controller, they then have trouble with the boost spiking up
and hitting the fuel cut. This is how mine acted too, But in all fairness, I
did not have it built to SP rules limit, I only raced the car in stock class
one year, and I was in B-Stock and gave it up because I knew it was futile.
When it was moved to G I almost broughbt it back, but was having too much fun
in the Celica by then.
With the stock 90 air meter in front of the turbo, maybe it is enbough to
keep creep in check, but my Celica has nothing in front of the turbo, and a
smaller gate, so I still have to see it to believe it.
< I have indeed seen the "BCS pops at 12-ish PSI" behaviour you describe at
the
< dragstrip once. It turned out to be bad gas - a can of octane boost tossed
into
< the tank fixed it. You may well have had a loose or faulty knock sensor on
your
< car. Again, check the archives at www.dsm.org for confirmation.
The BCS on my car was very active. Once I took off the muffler, it seemed to
be THE boost control. Is there a difference in the 90 and later ECU's? Even
wiring the solonoid to stay open though only gave 10.5 to 1 psi of boost.
Removing the solonoid and running the vacuum hose to the port in the air
meter directly did crank up the boost to 18 psi and some creep. But as you
know, this would not be SP legal now would it? Changin the hose sizes and
adding a needle valve is how I got it to run as high as 24 psi from about
2900 rpm til fuel cut. WOW the first time it cut at high boost it felt like I
threw a rod. From 1G pushing in the seat to slowing with a pop from the
exhaust, DAMN. After I did that, I stoped messing with it that high. If it
was detecting some ping, It never showed any sign of it, the plugs were
always perfect, too. I pinged my Celica and it fried the plugs in seconds.
Sorry for overstating, my point of view, but either my car was real picky,
running a different program, or the air meter on it is a huge cork compared
to even other 1st gen cars.
Gary M.
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