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Message
Keep in mind that Tracy has tuned intake and exhaust.
How far
away from the exhaust ports do you join the headers into one?
I've been told
that you can gain as much as 20 HP with the tuned exhaust.
Racing Beat
says 22-25 inches, and I believe mine came out closer to 30". I
believe Tracy has had a few different lengths over the years, and said it
didn't make any noticeable difference. Hopefully, he'll correct me if
that's not a true statement.
On the intake, it
doesn't have to wrap over the engine. It could stay on the intake side.
From the ports all the way out to the cowl cheek and back. Or you could make a
"snail" as PL suggested - basically bending the tubes into a circle. In the last
case it will probably be better to have butterfly valves near the ports. I'm
thinking a 3/8" to 1/2" thick manifold flange should be thick enough to hold 4
or 6 butterfly valves and their shafts.
I've been
planning to make a short intake, with a two throat TWM TB, and figured that
I can extend the tubes on the air intake side to attempt some tuning.
The convenient way to do this is with flexible tubing, which can conform to
any reasonable shape to clear obstacles.
Now that you
mention it, an almost universal intake "system" could be made about like
you suggested. We would need an
intake flange that was thick enough to include 4 butterflies, and 4 injectors
(at least two if you prefer to use the stock injectors in the block). It
would have hose flanges on the inlet side to accept flexible hose. On
the other end, would be a resonant chamber, with 4 hose flanges as well.
These two parts could be positioned as space allows, and the hoses connecting
the two parts could be different lengths as
needed.
I'm going to
keep thinking about this, but I fear that making the intake flange portion is
beyond my machining capabilities. Also, the primary ports are so
close together, that it would be tricky to getting two butterflies to fit close
to the block. Once you start moving them out away from the block, it
becomes a short intake, rather than a plate. Very interesting thoughts
though. Thanks.
I now have a
new excuse for holding off on changing to tuned intake and EFI: waiting to see
what Tracy comes up with next.
Is Tracy's new intake for his current engine, or
the Renesis, or maybe the 20B? With all the projects he has
going, I can't imagine him spending time making an intake for the 13B, when he's
more interested in getting the Renesis installed. So go ahead and order a
new Renesis Finn, and you'll be ready when Tracy gets the intake done
:-)
BTW, what do
you get for static rpm Finn? Best I can tell, you have 3 more inches of
pitch than Tracy's old prop, but with the same diameter.
Rusty
(scaring myself and the airport neighbors
later)
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