----- Original Message -----
Sent: Thursday, April 01, 2004 6:46
AM
Subject: [FlyRotary] Re: 13B Intake
Manifolds
With that clue, I think I know my answer. Atkins
must have supplied you with the 850cc injectors that powered the 85-86 GSL-SE
13B. In that iteration of the car, Mazda used those.
In 1986-87, Mazda switched to using four 460cc
injectors in the naturally-aspirated car and using four 550cc injectors in the
Turbo II. While those had more potential for overall fuel flow, it meant that
they had them staged. I'm not positive of the exact RPM changeover to using
all four but my recollection is that it was 3800 rpm. My Turbo II has a little
hicup in acceleration when it passes through that point and the factory
wrestled with getting that right--something usually chalked up a bad ground.
They worked fine when new but sometimes developed the hicup when they got a
little older and the ground was a tad less reliable.
How many horsepower did you intend to get out of
your turbocharged rig? I think you're fine but might be near the limit at a
little over 200 HP. Any projections?
You've got 1700cc/min. The naturally-aspirated
car ran four times 460cc or 1840cc. The 87 Turbo II ran four times 550cc or
2200cc.
Somewhere around here I've got a book on fuel
injection that figures out the conversion for fuel adequacy (and helps with
the metric/min to pounds/hr conversion). I think you also have to use an 80%
or 85% duty cycle or else the injector is basically open all the time, which
for some reason isn't recommended.
The reason I asked about this is that those 850cc
injectors were some of the biggest in the auto world, at least at the time and
might be still. Other manufacturers used multiple injectors that corresponded
to the number of cylinders, so typically you find hot-rodded Mustangs, etc.,
using eight, which of course could be smaller individually to sum to an even
bigger whole. When I saw your two injectors, the reason I wrote was because I
thought you might have discovered some even bigger ones than the
GSL-SE.
Rumor was that Mazda had a hard time getting the
big ones like you've got to run smoothly at the bottom end, which is why they
switched in the next iteration of the car to four injectors--but remember they
were looking for a smooth 750 RPM idle speed. Aviators need neither that
smoothness nor an idle that low.
Anyhow, I was just surprised to see the two big
MONGO injectors feeding all that airflow. I think the Mazda 850cc injectors
might be on that table that Paul Lamar reprints from time to time, if you're
interested in working out the lbs/hr and then BSFC conversion to re-confirm
the top end of your fuel flow.
Barry Gardner
Wheaton, IL
----- Original Message -----
Sent: Wednesday, March 31, 2004 9:28
PM
Subject: [FlyRotary] Re: 13B Intake
Manifolds
I purchased the throttlebody, ECU and
programmer from Atkins Rotary. The throttlebody came with the injectors
already installed. Not sure what the injector flow, model, etc
are. I have that info somewhere, but it will take some searching
through a lot of e-mails to find it. Paul Conner
----- Original Message -----
Sent: Wednesday, March 31, 2004 4:23
PM
Subject: [FlyRotary] Re: 13B Intake
Manifolds
Paul Conner--
I was looking at that picture of your
manifold you enclosed. It seemed like you only had two injectors.
If true, what kind of fuel flow are they
rated for and what is the brand/model number? Those must be
big--no, MAMMOTH--injectors.
Barry Gardner
Wheaton, IL