j9fd3s

i've seen a few different ways to do a P port, and if its done right it won't leak any water.

the Japanese go in straight from the side, and thread a sleeve in. its fairly neat as the placement of the sleeve means that the sleeve is straight at the end, and there is enough housing casting to make the rest of the port. fill the rest of the area with something appropriate and you're in business. they make two cuts, one for the port opening in the trochoid, and one for the sleeve

you will want something to support the weight of the throttle/carb/intake.

on a regular full P port, i'd think 200hp @6k would be a breeze.

at full load it will get better MPG than a side port too.

MolsonB

The airplane is a composite, 2 seater, low wing.
Tango XR, | Team Tango


Here are some pics of the irons after Chips Motorsports did his Re-Nitriding magic.
Plate Lapping and Re-Nitriding - chipsmotorsports

TeamRX8

iTrader: (25)

https://www.rx8club.com/series-i-maj...3/#post4656570

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MolsonB

I'm not looking for HP numbers, the oem engine is enough for this plane. The p-port is merely for simpler intake setup with a slide throttle. If it gives me a few extra HP, then great.

Does anyone sell just an alternator pulley to reduce ratio drive? I can only find the main pulley for an RX7, which reduces the water pump aswell.

j9fd3s

well based on that, why bother with the P port...

WTF does he do to get 50hp?

TeamRX8

iTrader: (25)

You don't need a potentially less reliable and certainly more expensive PP conversion to have a slide throttle. Further, for 6k - 7k rpm operation a 4-port Renesis makes significantly more sense.

It's your dough to blow though ...

When the 6-port Renesis debuted it was rated 250 fwhp ..


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j9fd3s

i'm finishing PP #2 (#3 is a 3 rotor), and it is the most simple way to do a rotary. except for the rotor housings and intake, the engine is just stock. its anti climatic to build even.

i did the back of the envelope calcs, and if the 13B PP does its rated 300hp@9000, it should be ~194hp @6000rpm.

#1 is my 12A and its tame even with giant ports, #2 is a 13B with some moderate sized ports, its going to be like stock...

TeamRX8

iTrader: (25)

A 13B is a different than a Renesis in many regards. I don't think that needs to be rehashed here.

There's no should be. It either is or it isn't. The issue with the PP is unless you have a sophisticated variable intake design the powerband is a very narrow rpm range. Exact placement and sizing is very critical.




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Legot

iTrader: (1)

Well, the Renesis is a 13B so maybe you meant to say the REW is different from the MSP

TeamRX8

iTrader: (25)

Pre-Renesis incorporates more than REW for 13B too, so the next touche is now back in your court ..,

Legot

iTrader: (1)

Presumably we're talking about engines with the largest ports that you wouldn't have to trade children to source parts for, leaving us with the REW.

Check.

TeamRX8

iTrader: (25)

The biggest ports are irrelevant if the target rpm is 6000 - 7000 rpm.

j9fd3s

an aircraft engine is almost a stationary engine. my friend has a piper cherokee, and takeoff rpm is 2500. cruise rpm is 2400. any speed changes are done with prop pitch and whatever the other lever does.

you'd need to do the maths with the gear reduction, as the propellor can't break the speed of sound, and is limited to ~2700rpm, so the rotary would be more like 6k takeoff and 5700rpm cruise....

logalinipoo

That varies with the plane type, with a homebuilt plane he probably wont have a variable pitch prop.

That other lever is probably the mixture. You lean it out to reduce power and save fuel.

CRO8TIA

In a typical small plane, the propeller turns at the same rpm as the engine, which is usually limited to 2500 rpm. The limiting factor of any propeller is that the tip speed cannot exceed the speed of sound, or it basically quits working.
In planes with more horsepower, the prop is normally geared down from the engine, since the prop is larger in diameter to absorb the extra horsepower. Even though the engine may still only peak at 2500 rpm, the larger diameter prop would break the speed of sound, thus necessitating a reduction in propeller rpm.

TeamRX8

iTrader: (25)

Guys, they use a PSRU 2.85:1 adapter/gearbox between the prop and engine to reduce the prop rpms and compound the prop torque

j9fd3s

2500 prop rpm = 7125 engine rpm.

given ~200hp, and about 7k rpm, i think either, the MSP or a full PP engine work fine.

my preference is the PP, as its simpler

MolsonB

Correct, it's a 2.85:1 gearbox reduction unit.

Here's a link where they suggest welding SS to the chrome of the rotor housing.
Weld P-Port to Chrome

What do you guys think of the process? A sleeve is added to the outside to help coolant seepage. Dyno showing 264hp at 7200rmp

j9fd3s

too much work, too much risk. welding on the sleeve risks warping it.

the JDM housings drill two holes, but then it uses a straight sleeve that screws in. the JDM way uses part of the casting instead of having to make the insert a fun shape at the end.

the area around the sleeve is filled with something.

||| Revolution :: Catalogue - ???????????

MolsonB

Finally I can get back onto this project. Been working on the fiberglassing of the plane for too long, be nice to work on engine and avionics this summer.

Iron plates have been lapped and re-nitrided by Chips Motorsports
New rotor housings with p-ports welded in by Cimarron
Overhaul kit with seals and o-rings by Rotary Aviation
Devcon side intake ports
New bearings
E-shaft weber jets
rx7 rear oil psi regulator


This weekend I'll put the block together. All the measurements have been recorded and logged. The only 'gotcha' was which rotor is front. I assumed the S1 & S2 markings at first, but after cleaning the rotors I saw the FB and RB markings on the faces. After a little quick research, the S1 & S2 are assembly line markings and not which one is front and back.

I attached a picture compared to an equivalent airplane engine, without the turbo the HP would be close. So tiny and light, but powerful.

Legot

iTrader: (1)

Neat!

Matt_P

Pretty cool. Had a friend that was doing one of these. Seemed like a good powerplant for a small plane.

WaitingforFI

iTrader: (1)

Nice work. Is that a Lycoming or Continental engine?

MolsonB

The airplane engine is a Lycoming TIO-540. Twin turbo 350hp. About 30k used. They are using it in the bigger 4 seater plane.

Since I'm the smaller 2 seater, a 200-250hp is more then plently.

MolsonB

RX8 side seal clearances.

The maximum clearance (sum of both ends) is 0.4mm (0.016 in). Since I'm grinding to length, what is the recommended clearance? I see a lot of info for RX7's, but with RX8 and the side exhaust ports, it sounds like you don't want it too tight either with the heat expanding the seals a lot more?

The engine only had 108k (km) and the old oem side seals clearance are huge. Well over .016in