When do we get the 3.25 or 3.5:1 ratio PSRU?  ;-)

Bob

1600CC. Kind of ends the talk about direct injection. Still looks like a 6 port but the primary ports (the small ones in the center iron) are much bigger. With a combined end port as on Paul Yaws site, and maybe a mild bridge port, I think 340 HP at 9,000 is an accurate estimate.

 

Maybe 250 HP at 6,500. Going to need three blades and 74 inches of prop.

 

Where do I sign up?

That displacement is difficult to imagine, in light of the power estimates, and similar estimates by racing and sanctioning organizations has been a struggle from day one. So if you have guessed the HP of your 13B installation based on pacing a 180 HP RV whatever, you can start there.

 

The 12A side port with bridge ports, engine has 1147CC and 175 HP at 7,000 RPM and peak power at 9,400 RPM is 244 HP.

 

A similar Pport engine has similar power down low but peak power is higher because the Pport just keeps going and going, so 320 HP at 10,700 RPM. There will be no more 12A parts manufactured and housings are now in very short supply. The irons still work with early 13B stuff but nothing else.

 

A bridge ported 13B has about 1303 CC and 180 HP at 6,500 RPM and about 255HP at 9,000 RPM. Much lightening work must be done to go higher because of crank flex. So 265 HP is available, but not for airplanes. A big Pport 13B can do 335HP at 10,000 RPM.

 

There is a 6 port 13B with the end irons having a slow port and a high speed port with a ghastly system of rotating valves to open and close the 6th port at high speed. Racers use the 4 port versions of the end irons.

 

However, if you have some die grinders with carbide bits, you can join the two ports and runners in the 6 port irons to make one whopping big port that flows like the wind. How well this works at airplane RPM I don't know, but Paul Yaw is claiming 240 HP well below 9,000 RPM. See www.yawpower.com

 

The new 16X engine is 1600CC. And appears to be a 6 port. The late injection into the closing chamber will place the fuel in line with the plugs, so there should be some improvement in starting and burn efficiency. Airflow without fuel involved will be higher. It is shorter and lighter than any current 13B so that is good. The crank is drilled for lightness like early 12As. Shorter means a stiffer crank that has been a problem with the 13B. The stock (emissions) version may not be a barn burner out of the box. Europe and Australia will (as always) get higher HP versions. But the porting looks very modest, and a few minutes with a die grinder to bring it a bit beyond the street porting will but some real punch into this engine.

 

The race organizations make us double the actual displacement as punishment for the rotary getting all of its work done in one revolution, while the poor piston engines have to turn over twice to get in their full displacement.

 

So my logbook says my 12A has 2292CC. A 13B has 2606 CC and the new engine will have 3200CC.

 

The longer stroke will be a big advantage for aircraft use.

 

It makes the piston people feel better when an engine the same size as theirs beats them. Loosing to a big lawn mower engine just makes them feel bad. 

 

I wish I had not sold my Stuska.

 

Lynn E. Hanover