Joined
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177 Posts
this was brought up not too long ago..
and i emailed the guy that seemed pretty knowledgable on the subject...
and this is what he said in return...
"CAt,
The only information I really have is from my highschool auto shop
class.
That was back in 80-81, and we took a 6.6 Trans Am and reverse-flowed
it in
conjunction with many other HP mods. We were putting 660HP to the rear
wheels, getting 20mpg if you were REALLY careful, and had the engine
cooled
by a modified waterpumo and a Radiator out of a 73 Toyota Corolla! The
big
thing was (in theory) that the cylinders stayed round, and you had
cooler
head temps allowing more compression and advance on pump gas than you
ever
wcould do otherwise. It worked, we were running 46-50 degrees advance
during
trials (for mpg...) and were suing jets and power valves two sizes
smaller
than what everyone at the local speed shops told us would give the best
power. Believe it or not, this was an ECONOMY project, and we entered
it in
a competition at a local community college (since two of us were in
both
Physics, Pre-Calc, AND AutoII, this worked across the greaser-nerd
line...)
It all worked out pretty well, and have been interested in doing this
on a
Datsun for a while. The idea has merit from GM's point of view, as I
understand the new Small-Block utilizes reverse-flow cooling from the
factory.
The pump is from one of the GM V-6's, I've got the stuff all written
down
somewhere, I don't recall which specific model it was from but it's
current
production. Basically, I have to mount the pump externally, just like
on the
GM application, make a pump blockoff/thermostat housing, and remove the
thermostat from it's normal place. The Temp sensor has to be relocated
to
where the waterpump is now, in the same blockoff plate. The big
advantage is
that you still run 190 degree thermostats, but now the head temperature
is
more like 160 under full-load dyno testing on a 100 degree day, instead
of
above 220!
So from there you realize more heat is taken from the head, and
transferred
to the lower part of the cylinder, allowing a non-tapered bore,
promoting
better ring-sealing, allowing less leakdown etc etc etc...
On the SBC, reverseflowing is fairly easy given the design of the pump,
as
it is for Pontiac, and ot6her GM products. Them going to an external
water
pump makes doing it to ANYTHING easier as you just must mount the pump."
and i emailed the guy that seemed pretty knowledgable on the subject...
and this is what he said in return...
"CAt,
The only information I really have is from my highschool auto shop
class.
That was back in 80-81, and we took a 6.6 Trans Am and reverse-flowed
it in
conjunction with many other HP mods. We were putting 660HP to the rear
wheels, getting 20mpg if you were REALLY careful, and had the engine
cooled
by a modified waterpumo and a Radiator out of a 73 Toyota Corolla! The
big
thing was (in theory) that the cylinders stayed round, and you had
cooler
head temps allowing more compression and advance on pump gas than you
ever
wcould do otherwise. It worked, we were running 46-50 degrees advance
during
trials (for mpg...) and were suing jets and power valves two sizes
smaller
than what everyone at the local speed shops told us would give the best
power. Believe it or not, this was an ECONOMY project, and we entered
it in
a competition at a local community college (since two of us were in
both
Physics, Pre-Calc, AND AutoII, this worked across the greaser-nerd
line...)
It all worked out pretty well, and have been interested in doing this
on a
Datsun for a while. The idea has merit from GM's point of view, as I
understand the new Small-Block utilizes reverse-flow cooling from the
factory.
The pump is from one of the GM V-6's, I've got the stuff all written
down
somewhere, I don't recall which specific model it was from but it's
current
production. Basically, I have to mount the pump externally, just like
on the
GM application, make a pump blockoff/thermostat housing, and remove the
thermostat from it's normal place. The Temp sensor has to be relocated
to
where the waterpump is now, in the same blockoff plate. The big
advantage is
that you still run 190 degree thermostats, but now the head temperature
is
more like 160 under full-load dyno testing on a 100 degree day, instead
of
above 220!
So from there you realize more heat is taken from the head, and
transferred
to the lower part of the cylinder, allowing a non-tapered bore,
promoting
better ring-sealing, allowing less leakdown etc etc etc...
On the SBC, reverseflowing is fairly easy given the design of the pump,
as
it is for Pontiac, and ot6her GM products. Them going to an external
water
pump makes doing it to ANYTHING easier as you just must mount the pump."
