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
--
Homepage: http://www.flyrotary.com/
Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html