I doubt that a larger TB will do any better Buly. That's about the
same size I have on my Renesis engine and it is very well matched. Several
other builders have installed monster sized TBs on Paul's advice and found no
improvement and in some cases less power. Contrary to his usual
philosophy, bigger is not necessarily better.
Here's a simple test you can do to remove the 'opinion factor'
out of this discussion. If your manifold pressure at WOT is the same as
ambient barometric pressure (at low altitude), there is nothing a larger TB will
do to improve it. If MP is less than ambient, start looking at your
intake path factors like inlet, SCAT tubing (if used), air filter, and anything
else in the air path. If none of these are the limiting factor, then and
only then should you think about going to a larger TB.
I'm using a 70mm TB on my 20B which I think is about the minimum size for
the 300 HP I expect. It should give good linear throttle response without
the "dead travel" of an overly large TB. I'm betting it will pass the MP
test mentioned above although I haven't had a chance to test it in flight
yet.
On another topic, Paul has been spreading the story that the EC2 will not
work with a CS or variable pitch prop. After hearing this, one
builder immediately put his EC2 up for sale without even asking me if this were
true. That's incredible to me but a testament to the blind faith that
some people put in Paul's opinion. Simply put, Paul's claim is pure
nonsense.
The same applies to his warning to never use anything but Mazda
factory apex seals, a thinly veiled negative reference to the "RA Seals" that
Bruce Turrentine and I collaborated on. (Full disclosure: Bruce did the
major part in their development, I merely offered advice from time to
time).
After years of listening to Paul's claim that my cooling system is not
suitable, marginal at best, will not work out west where there are mountains,
etc, etc, I declined his offer to market his new book "How to Cool
Your Wankel". Much of it is valid data from a number of sources but I
simply do not agree with his conclusions on how to apply it. I
expect an up-tic in his vitriol : )
Tracy Crook
----- Original Message -----
Sent: Sunday, April 29, 2007 6:05
PM
Subject: [FlyRotary] Throttle body
size
I originally planned and tried TA set up on my Cosmo 13B. Soon
after
the first few flights removed the turbo and vent NA. At the
time did
not pay much attention on the throttle body size, counting
on the
turbo to make up for any losses. Today I measured the inside
opening
of the TB and was surprised to find it was only 60mm. This
is rather
small. Paul Lamar on his visit also said I should get a
bigger one. I
wander what size TB other people are using, or any
comments and
suggestions on the matter will be
helpful.
Buly
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