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NO, it does not. Every piston engine has overlap,
with far worse consequences as the valves are very close together.
For the record, I speak mostly of 13B engines, not
the Renesis. The 13B has always had overlap, a street port has
more, bridge port more still. This is no different than increasing the
overlap with cam profiles on those funny up and down engines.
Typically, the PP is on par, or above the Bridge port when it comes to size and
overlap, because it's the only possible way to get more size and overlap than a
bridge port has. To my understanding, that's the only reason a PP is
worth having, to get what you can't with a side port.
Now you can make a custom PP, and reduce the size and overlap,
which knocks it right down the scale. Once you do that, it won't be making
any more power than a side port can make at our rpm's. I just don't
think Powersports is doing anything a well built 13B side port engine
couldn't do just as well.
The reason the renesis makes good power is the
size of the side ports. Look at the complexity of the manifold on the
RX-8.
I totally agree, but the complex manifold it there
to make the engine behave in a car. They have to make the engine
capable of continuing to run when someone floors the gas, in 5th gear, at 20
mph. This has nothing to do with side ports vs PP.
My personal guess is that if Tracy applied his
knowledge of the induction system and EFI to a PP engine He would blow away the
renesis. This might not be a result he could sell to all of his customers
though.
I don't understand that
last sentence. You're saying he could make a superior engine, but
it's not what his customers would want? I must not be a typical customer
:-) I figure you mean that he could make more power, but with
limitations that some customers wouldn't be willing to accept, which has been my
point all along.
Run
your renesis Rusty, I'm sure you will be happy with it.
I
don't have a Renesis, and don't have any immediate plans to have one. I'm
not sure they provide a tremendous power advantage over a good 13B, unless
you're willing to turn them up to 8500 rpm, but they do have other advantages
like cooler, quieter exhaust.
I am just saying that I believe your
desire for a high power single rotor could be met easier with the
PP.
I haven't been pursuing a high power single
rotor. In fact, anything over 100 HP in the Kolb will require serious
restraint (note to Al W- BIG risk factor with me on the throttle <g>),
because the plane was only made for 80 HP originally. Since I just bought
a small turbo to use as a muffler, it's going to be tough to avoid producing too
much power.
BTW, I hope you're enjoying this in the spirit of good
clean discussion like I am. If not, we need to call it off, because I
don't really mean to piss anyone off.
Cheers,
Rusty (must have something better to do)
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