crispeed

Very shallow tub.

Hades12

What if a spray build up was done. Like The way housings are being sprayed.

Judge Ito

I have a rotor out of Curtis wright rotary engine company located here in Jersey. Later sold to John Deere.. later sold and named rotary power international. Rotor is about 12.0 to 1 compression ratio. basically no bath tub. 2mm apex seals. I tried getting a tour of the company but they closed it down about 2 years ago. Last time I check rotary power international was making 11.5 liter rotary engines for industrial use. website and company is down. they were looking for investors all over wall street. I guess nothing happend. I still have the rotor. I even had a rotor housing from them with one spark plug. Just the leading no trailing.

Judge Ito

most of their test engine were using deisel fuel

banzaitoyota

arent atkins involve with them now with the surfboard?

Lynn E. Hanover

I agree with the yes answer.



However:



This is usually effective on piston engines ( I used to race and dyno piston engines) because, no matter what compression you can come up with, say 14:1 for example, that is the calculated compression ratio, not the dynamic compression ratio.





(what the hell is Hanover talking about this time?)





Unless the engine design is quite simple with a very small combustion chamber and a long stroke, it is very difficult to come up with a really high compression ratio. Race engines tend to have lots of valve lift, and duration, so, they have flycuts in the pistons to clear the valves. Flame front travel is compromised unless there is a groove between the flycuts to keep the fire going beyond the squish area. And on it goes. So, about 14:1 is about the maximum practical compression you would want to run.



All of the Cosworth engines I worked on had 12:1 ratios, and it is difficult to beat up on a Cosworth.



And now two answers to the question. A degree of crankshaft rotation in a piston engine is indicative of a substantial change in chamber volume.



A degree of rotation in the rotary engine means a small change in chamber volume, at a rate of one third the speed of the piston engine.



In order to help the HP of the engine, the torque lost in the work involved (HP is work) producing the additional compression must be more than recovered in increased HP that results from the compression increase.

So,

if we **** away 10 HP to compressor losses by going from 9:1 to 12:1, we must now produce 10 additional HP just to break even. (Before any value can be recovered from the change) Simple enough.



So to make the change worth the additional expense, it must produce a value in increased HP that is not attainable in some other (less expensive) manor. In piston engines, increased compression is easy to come by, and has been proven to work for years.



Damn the expense, I have a welder and lots of time, I'm going to do it anyway. What would happen?



As in the piston engine, the burning charge would be a bit more energenic, (slightly more energy can be recovered) and if you read about the Mobile Gas Econemy runs of the 50s, you would see near diesel compression ratios being used, so it does work (Pun).



The sad part is that the piston engine has a much lower surface area exposed to the compressed charge than does the rotary. So, more of the added heat of compression just vanishes into the water jacket, before you can light the charge. So, going in, the increased compression in the rotary pays off in a much smaller improvement than a similar increase in a piston engine. There would be an increase in efficiency. So, pounds of fuel per horse power hour would go down. I know you were worried about that.



There would be an increase in HP, as in the piston engine, but not as much for a similar compression increase.



There would be a slight decrease in knock resistance. (detonation).



And the funny shape of the rotary chamber at TDC includes the bump of the Peanut shape imposing into the middle of the chamber. Complete burning of the charge is already difficult with this water cooled dam in the center of the opration. So, two plugs is the minimum number of plugs for anything like complete burning.



The LeMans engine had three plugs.



To help flame front travel there is a dished out shape in the rotor face. The one you plan to make smaller. So, there is a need for that shape to be there, and the increase in compression will remove part of that dish.



So, the new engine with the advertised 10:1 rotors is probably as high as you would want to go.



In the turbo engine, the (dynamic) compression ratio and engine displacement changes all of the time based on the amount of boost.



Yes the effective engine size goes up and down along with the compression ratio.



If the engine displaces 60 cubic inches per revolution, and you force feed it 120 cubic inches of mixture per revolution, is not the effective engine size twice what you started with?



And if the volume at BDC is 600CCs and at full boost, you have jammed in 1200CCs of mixture without changeing the headspace, have you not doubled the compression ratio?



So, turbo engines often detonate, and nonturbo engines seldom detonate.



But wait, there's more. When you rev up a NA engine, piston or rotary, a number of dynamics take place.



In the new engine with the tuned runners, there are RPMs and throttle settings where the engine is processing more than its displacement per revolution. So, its getting bigger than a stock engine? Yes, more than 100% volumetric efficiency. And that means the compression ratio is increasing.



But not everywhere in the RPM range. Piston engines too can do this with a well thought out induction system.

But not everywhere. And that is where the effective compression ratio goes down. So my 14:1 compression ratio becomes very much less as the revs go up. Less time to fill the cylinder, smaller volume to compress,

same head space, LOWER Effective compression ratio.



A few minutes with a die grinder in the ports will get you more power than a year of compression experiments.

Improving the VE increases the effective compression ratio. But don't let me stop you. There is some power to be made. It will just be expensive. So, what isn't?





Lynn E. Hanover

rotaryinspired

I like how your posts are like essays. Keep it coming.







Ito can we get a pic of this rotor.

Lynn E. Hanover

That was supposed to have been one post and one picture.



The web page kept dropping out and leaving a notice that the server could not be found?



Anyway it was a self serving picture of my car. Sorry.





Lynn E. Hanover

rotaryinspired

post pics that car all you want its beautiful.

Lynn E. Hanover

Well,



Thank you for that.



You can weld on rotors. I have repaired rotors that have developed holes during the ligtening process. I use TIG or Tungsten Inert Gas, also called Heliarc. Where a tungsten electrode is used because it does not take part in the metalergy of the weld, and an Argon curtain gas keeps oxygen out of the welded area. Heat is controlled with a foot pedal, similar to a throttle.



The rotors are cast nodular iron, and take to welding (at least TIG) very well.



If I were to attempt to fill in a pocket, I would keep all but the pocket submerged in water. I would TIG just a 1/4" bead, and then let the rotor cool to room temp before going on. I think that any warping would be minimal. These would be clearanced before use anyway, so I just think if you want to do it, it is entirely possible.



I think it would be possible to salvage rotors with apex slots worn beyond 3MM by welding the slots shut and recutting them. But it would be a bitch to jig up, and then pull it off without damage to the corner seal holes.



But it is doable.



Picture is a 13B converted to airplane use. Note the long runners, tuned to 6,000 RPM.



Lynn E. Hanover