iminhell

I got talked into helping a buddy with his 7 and really don't know enough about them to do too much. The theory is easy for me, it's the mechanical part that is somewhat confusing to me. He wants to make his quicker by way of boost if need be (obviously will be needed ). So I got some questions (cut and paste from another site I asked on, local site and not much in the way of rotary technical knowledge),


1. What effect does compression have, and for that matter how do you figure compression?
2. How do you size a turbo for one, I'd assume by swept volume but what is the true swept volume?
3. What effect does rotating mass have? With a piston engine you will lose TQ by dropping rotating weight, is it the same with a rotary?
4. Can the rotor housing be ceramic coated to retain heat?
a. How about the rotors?



I can figure most of it out, haven't fully searched yet but I will. I did search a bit on #4 though, found nothing. Now I'd assume that you can't coat the rotor housing simply because the apex seals are in constant contact with it, would ware the coating off. But could you polish the housing instead? (Reduced surface area = less area to absorb heat) Or would that create problems with sealing, I can relate it to the crosshatching of a cylinder wall vs a glazed wall.


Oh, how about port dynamics. Do they actually keep the fuel in suspension pretty well? (say with a bridge port) Or is there more that can be done to help with atomization, like a little rougher surface, or just a ripple effect on the port wall to break the surface tension?



I'm sure I'll have more but this is all I can muster at the moment.

farberio

iTrader: (7)

These are some pretty un-newbie questions for the new guy section.

For starters I can't get nearly in depth about any of the questions you asked.

1. My guess is the same way a piston compression is done. There are very few aftermarket rotors, and none of them change compression of the rotors. You can add to the compression by adding material to the pocket of the rotor, but only so much.

2. I have no clue about swept volume, most people I see start with a power output goal and pick a turbo that can support it. You will want to research here because normal sized turbos mean beans on the rotary due to its large compression area.

3. You are going to have to get into some real physics here to really understand what you want, but I can tell you this. Rotaries don't have a lot of torque so I wouldn't worry about it. If you are building a daily driver car then you should ensure daily ability, but if you are building a track car or a weekend car then you car will probably never see below 5250rpm anyway.

4. You can get it treated, its $$$.

5. You can get it treated, its $$$.

Bonus. You can get ceramic apex seals, these will hold gobs of boost. You MUST run brand new housings with them though. ($$$$$$).

Port dynamics I can't tell you much on at all.

It sounds like you want to build a monster car, the best thing will be to get a very good understanding of the rotary engine, then get a good understanding of what other people have done, and then get your game plan together.

iminhell

First post and I wasn't really sure where to put it . Yes I do have a pretty good understanding of traditional piston engines, but rotary I'm lacking a bit in.

I did find a company that says they do ceramic coatings and I'll have to talk with them and the car owner to see if it's something he wants to do (personally I would).

But generally am I on the right track with the heat retention stuff, coatings and polishing?

Turbo II Rotor

iTrader: (2)

You measure compression by the rotors used in the engine. Series 4 turbo rotors are 8.5, series 4 non turbo are 9.4, series 5 turbo are 9.0 and series 5 non turbo are 9.7.

Check the FAQ sticky in the single turbo section. It has a ton of useful information for turbo sizing.

You will lose a small amount of torque due to the loss in momentum but these engines are more about HP numbers than torque.

You cannot coat the inside of the rotor housings because the apex seals need to seal against the chromed stainless steel sleeve inside the rotor housings. Coating the outside will only hold more heat inside the engine and your temps will be hotter than with a uncoated housing.

You can have the face of the rotors coated to keep heat inside the combustion chamber. This will also reduce the amount of heat transferred to the engine oil.

The rotor housing wear surface is to be untouched. It is chromed stainless steel.

All the porting I have seen on this forum has had the port wall as smooth as possible.