80tq drag racing- Intercooler reevaluation [long]

[Jorgen Karlsson]

Hi,

Hmm, 15.8 and 96mph is an very strange combination. As you say 96mph is more
like a low 14', the funny thing is that you had an acceptable 60ft time. One
run like that is very hard to explain and a whole bunch of them is a
nightmare.

Since the 60ft say that your starts are good and the trap speed say that you
make good power (around 200hp) I wonder what happened, the ET try to tell us
150hp. Somehow you lost at least one second between 60ft and 1320ft. That is
very hard to explain but I have a theory.

The high ambient temperature and the intercooler sitting like it does
probably give you an intercooler temp in excess of 120oF when you roll into
stage. I remember that you use a Spearco core, these are very heavy and
store a lot of energy. Very good on the street, less soo on the track and a
disaster on the strip.

You can manage to make a good 60ft time without a good intercooler, or more
like a interwarmer in this case. Then you probably spend half of the way to
finnish with very retarded ignition (excessive air temp and minor
detonation). The car is probably very slow now, you are hanging in your
harness... The car then picks up its pace but since you are in a higher gear
now you don't feel a lot of acceleration, anyway the car make a lot of power
the last 200meters or soo. Probably around 250hp.

In any case you make a lot of power somewhere at the end of the strip, you
can't loose time at the end of the strip. Time can only be lost at the
begining of the strip.

I agree that an IC mister would have given you different results, I guess
that you would have been sent back to the pits for inspection ;) All excess
fluids must be collected and must not drip on the track... Freely translated
from the swedish dragracing rule book. While not on the strip a mister is a
very good idea. A fan would be a betterinvestment on the strip.

Water injection would on the other hand probably have suppressed detonation
and lowered the intake temperature a lot. I guess that most of the
performance would have been regained with water injection right after the
intercooler.

A core with equal size but less mass would probably have helped a lot too,
the HKS cores I have compared with spearco are about half the weight for a
the same size. The cores I have seen from charged air systems are about half
the weight compared with the HKS cores...

A water/air intercooler is also a good idea for dragracing, you don't even
have to have a radiator for it. Use a separate water tank packed with ice in
the trunk, then start the pump when it is your turn. At the end of the strip
you kill the pump again. On the street the water will give the same benefit
as the heavy spearco core give over the lightweight cores while on the
street.

Other things that can make a big difference is an other turbo, a lower
temperature termostat, a fan switch that makes it possible to run the fan
regardless of temperature. An intercooler fan is hard to install on our cars
but it would help a lot. A thermally isolated intake or one made of
stainless steel is also a good idea. Aluminum is probably the worst material
an intake for an efi car can be made of. Plastic is the best but stainless
steel is a good compromise on our cars.

I really appreciate the report on this experiment, this way I know that I
have to use a combination of a water/air intercooler and the big front
mounted air/air intercooler.

I recived this link today from an other list, to my suprise the standard
numbers are for a five cylinder engine with 86.4mm stroke.Unfortunally it
seem to assume that all the water is evaporated before it reaches the
cylinder.

http://members.home.net/pfahlgren/cars/turbo/glossary/turbo_calc.html

Jorgen Karlsson
Gothenburg, Sweden.