Paul wrote:
Hi, Paul. I noticed on the Racing Beat website that they claim the
peripheral ported 13b with a Weber 51IDA is good for 300 hp. Any idea
what rpm they need to turn to get that kind of hp?
Also, I have noted that some of the Weber carbs are mounted
vertically, and some horizontally. Does "side draft" Weber indicate
that
it can be installed horizontally?
I see that they also have a "down draft" Weber, and that is the
one
that is pictured mounted vertically. I assume that the internal
workings
must be different, as the float inside a carburetor
is typically orientated horizontally.
Last question....have you ever seen a successful modification to
add
a mixture lever to a Weber? Sorry for the barrage of questions, but I
was hoping you might be able answer some of these
questions. Thanks in advance for your reply. Paul Conner
My guess the HP peak on that engine is right around 9500 RPM.
You will need slightly longer pipes for 7500 RPM max.
providing you have a 2.85:1 gear box. My guess would be 250 to 260 HP
at 7500 RPM.
Wow a 51 mm dual Weber! That is just about exactly 2 inches in
diameter.
Does that
sound familiar or what? :) Side draft and down draft never the twain
shall
meet.
Back in the 60's Weber made a dual 58 mm side draft carb.
When I was working for Chaparral we wanted to run four Weber carbs on
our
big block V8. We wanted to run something like them in down draft mode.
So
the
Rochester Carburetor Division of GM copied the 58 mm side draft Weber
but
converted it to a down draft version for our use only. You should have
heard our Group 7 competitors complain.
It is a float bowl orientation problem Paul.
Paul Lamar
Thanks for that information, Paul. Only one question missed....ever hear
of
a successful mixture lever mod to a Weber? Thanks again. Paul Conner
I know it has been done with a Holley but I never heard it done
with a Weber. I guess it is possible. I think the guys running Ford V6
are using some sort of mixture control on their carbs as I recall.
BTW I can understand why you are interested in carbs. What are your
thoughts on this subject? Just for the record.
Paul Lamar
Hi, Paul....the primary reason is simplicity. I realize that the EFI has
distinct advantages, such as being able to control the exact amount of fuel
injected at various rpm's, and carburetor icing is not a concern (with the
exception of the long intake runners that Mistral experienced icing in). My
problem is with it's complexity....It requires two high pressure fuel pumps,
expensive injectors that can clog, programming maps, and a fuel return line
for unused fuel. The system also places considerably more current demand on
the electrical system. (Important if you should have an electrical failure,
as it shortens the distance you can continue flying to an airport). The
complexities of setting up proper maps for an ECU can also be time consuming
and at times frustrating. I have found it difficult to find anyone who could
assist in programming maps into my ECU. (Every A&P mechanic at our airport
could help out with a carb).From what I am reading, there seems to be a lot
of people using Webers on rotary powered cars, with many sites revealing
proper tuning techniques/jetting, etc.
There are advantages and disadvantages to both systems, obviously. I am
personally drawn toward the simple nature of the beast, and I have had a lot
more experience with carburetors on aircraft (all 7 of my previous aircraft
had carbs). I was pleased with their performance and reliability. Just
needed a throttle and a mixture control. If I could get the same kind of
performance and reliability with a carb on a rotary, I would be just as
pleased as I was with my previous Lycoming powered aircraft...No, make that
MORE pleased, as I would have a carb equipped rotary instead of a carb
equipped hand grenade. Just my opinion, and I could be wrong. (Again).
Take care. Paul Conner
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