"Weinstock, Rob" wrote:

One of the things I'd like to understand better is how/why the

13B

is
superior to the Renesis, breathes better, but makes ~66% of the

peak

power.

Otherwise, very informative!

Regards,

Rob

They raised the RPM where peak power is generated by adding 30%

to

the intake
and 17% to the exhaust port areas.

HP = (Torque x RPM) /5252

Assume for the moment torque is constant.

So 8500/6500 x 185 HP is 240 HP.

I also think they made some sort of improvements in the oil

pressure

system.
I am pretty sure the rotors are not significantly lighter in

weight.

A peripheral port version of the RX8 motor should generate well

over

325 HP with a Lemans type fixed intake system at 8500 RPM. Even

with

side exhaust ports.

I don't agree the RX8 engine is a step backwards. Perhaps a

little

more
heat is rejected to the cooling system but the later timing of

the

side
exhausts ports does indeed result in more energy being extracted
from the
fuel.

Until we have an RX8 engine on a dyno I don't think we will find

out

what
the best BSFC is. I am sure the BSFC at low RPM/power levels is

far

better than the older engines. That was Mazda's main focus on
developing
the side exhaust ports.

When the electric assisted turbo charged version of the RX8

engine

appears
you will see much better acceleration performance out of the

RX8.

Probably exceeding the acceleration performance of the stock

1995

third
gen 260 HP sequential turbo charged RX7 despite the extra weight

of

the RX8.

Paul Lamar

Rob, and Paul

 All engineers are a wee bit biased towards what they know

works:)

Mazda
people are no exception. Remember one of guys, Mr. Kagawa,

designed

the
LeMans 4 rotor intake system. The context in which they were

speaking

was
that the  P port exhaust engines breath easier and....

Mr. Nakane said for turbo applications the exhaust P-port is
superior to

the the high drag and heat absorbing side port RENESIS.

 I sure if I asked them what is good about the RENESIS they would
could have
mentioned a lot of things, such as a bigger water pump, and, and?

No seriously if the engine has enough ummph to power a

turbo-charger

the
configuration should get better BSFC. and I'll still want to use

it.

If not
then I'll be more than happy to make up a 20B from parts. For
potential
power and all around use in majority of aircraft I think the 13B

has

a

fantastic cost/performance ratio and this dog still has a few

tricks

to show
us.

Speaking of P ports.  Jerry do you need to know the exact ID
dimension of
the P-port used in the LeMans?  A little late perhaps since I see

you

already have it bonded in.

Doug in Japan

Doug,  sorry I misread the paragraph above.  I thought you were

asking

for the Leman P port numbers.  Yes I would like to have them.

However,

the Leman p Port and the  Racing Beat P port which are  similar to

each

other are intended for much higher rpm operation.  Jim Mederer told

me

they would not work well at our rpm.  He advised going to a much
smaller port. Based on the calculations of Rolf Pfieffer our port

did

in fact end up  smaller.   Our port is aimed at the 6000 to 7500 rpm
range.  It will run well up to about 8500 rpm but after that a

bigger

hole is needed.   Jerry

Jerry,
What diameter butterfly did you end up using?  I have an old drawing
that shows 1.5" which also happens to be what Paul Yaw recommended
(maybe 3 years ago?). I couldn't read the drawing that Paul L. just
sent.
Ken Powell

 
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