Speedpro experiences

[Jörgen Karlsson]

The car I have worked with is a GMC Syclone, before we installed the
speedpro we used a DFI on the car. As soon as we installed the SP we gained
half a second on the quarter mile! Before we did any tuning! Harry at
Dynamic turbo sent along the program from his truck to get us started
quickly...

After an hour of tuning we didn't have more then 7% o2 correction at any
point on the table. Harry said that we didn't need to get closer to the
target.

Before I start listing the problems I might mention that this car is quick,
unfortunally we haven't gotten any official times for it to prove that it is
the world's fastest Syclone with stock crank, block, still running awd and
using street tires. 11.33 is the best figure we got but we run on ordinary
street asphalt here in Sweden...

Most of the problems we have with the speedpro are probably related to the
fast repeated shifts and traction problems. If we hold back enough to run
0-60 in 4s we don't see any oscillation tendencies. Under all circumstanses
that this computer would see in a normal fast car it works great.


Problems:

The manual isn't worth sh*t, there are probalby a dealer manual that is far
better but I haven't seen it.

One problem is that when you coast towards a speedbump or something the
mixture is trimmed down a lot, I don't understand why... This makes the car
bog when you push the throttle after the bump, it takes a second for the car
to run fine again. There should be a setting that limits the closed loop
under these circumstances. A workaround for this car is to raise the closed
loop treshold to 900rpm. This way the car is not running closed loop while
coasting to a stop. Even if I remove almost all fuel at the load sites that
the car passes under these circumstances the same problem will occur.

Detonation: will cause the computer to over compensate for the rich mixture
and then the mixture will go too lean resulting in more detonation... Not
good.

Shifts: If the engine are to rich at high rpms, the controller will not
start over with a fresh o2 correction setting at the next gear. It will
continue to remove fuel from the base VE table at the lower rpm too, not
good if the engine is properly tuned there or if it is already lean at that
load site. Instant mixture oscillation then.

We tried using a launch control(MSD two stage moduel), didn't work at all,
the controller didn't behave properly during the entire pass. I estimate
that the mean power during the run was 200hp lower then without the launch
control. This is a good reason to go open loop on the strip. We can't use
_any_ boost of the line with the traction problems we have, but with the
launch control we could _easily_ build 20+psi of boost of the line at
3000rpm. Could be very interesting on a good track.

One problem that we have is launching, we have to tweak the mixture at the
launch rpm to prevent oscillation. The launch mixture can be far from the
ideal mixture for runnning the car on the street at that load site, but
since you in reality only use that load site when launching that is not a
problem.

The coputer gets confused when the water/methanol injection kicks in, not
much but it adds to the mayhem that the computer has to work with.

Last week we limited the o2 correction to 5% and suddenly the car started
running better, the mixture is a lot more even thruout the pass and we can
run a leaner mixture without detonation. We are running a 12.5:1 AFR at full
power now, with exhaust temperatures in the 1750F range. When we had some
oscillation we needed a 11.5:1 AFR to run without detonation.

I have heard of one missfeature with the Speedpro the battery voltage
compensation does not consider injector size, it is set for 24lbs injectors,
if the voltage drops below 11.5v if you have large injectors you have a
problem, I heard that the mixture would get 20% to rich at 11v with our
setup.

Jörgen Karlsson
Gothenburg, Sweden

Check the site: http://syclone.cjb.net (English) The only thing I do on this
car is the tuning, exept for the web page the rest of it is Roberts work. An
article in a swedish magasine is available here:
http://www.syclone.freeserve.co.uk/ (ISTA UK) Search for Robert with the
search engine on the first page. English readers has reported that swedish
can be understood without problems, hmm, strange...

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