Stoops417

Was trolling on SF like usual, and saw this...



http://www.supraforums.com/forum/sho...hreadid=239877


was pretty sure the idea was bs, but hey... ive learned not to underestimate the rotary engine and its possibilites.


Sooo.... CF rotors?

Stoops417

oops wrong forum... sorry mods.

ghettostamps

No I doubt it, I'm not a mechanical engineer but I dont think the molecular structure is the same. After readin that though, cermaics engine parts with no heat expansion sounded cool... again not sure if its possible. But if they can make 411 totally automated who knows?

RETed

Maybe "carbon apex seals"?

There is no way in hell CF engine rotors would work.
You can't even lighten stock iron rotors to much.
If they get too light, they kill bearings like crazy.


-Ted

bigmack000

BAHAHAHAHAHAHAHAHAHAHA

RETed

Yeah, you should really stay away from those idiots...


-Ted

Carl Byck

Check my post on there, I think we put an end to that thread, problem is a seven owner was the one talking ****. BTW,check the dyno section, they have three or four cars over 1000rwhp in the last 30 days. these guys are not all dyno queens either. I was at Supras Invade LV this year, try a street driven car, drives from Chicago to LV, Dynos 1170 RWHP, goes to the track, runs low 9s at 150XX, and drive home. He later dyno'd 1248 no spray. These guys SHARE their secrets, that is why they are so far ahead in terms of large numbers of very high HP cars IMHO. I frequent both forums, the info flows very freely there, you want to make 900-1000rwhp, just post, and they will tell you exactly how to do it, no secrets, just lots, and lots of 10 sec cars. And there are plenty of road racers as well, although not near the number on here. Carl

Kenku

All righty, time for me to play the engineer with a tenuous grasp of practicality...

No, carbon fiber rotors are a silly idea for something to put in an engine. Carbon/carbon composites work well for brake rotors (well, they have advantages and disadvantages) but the material has relatively poor thermal conductivity, so the faces would get a lot hotter than the core and it would quite possibly crack. In addition, at high temperatures, it oxidizes. It undergoes a chemical reaction and basicially burns. Is *THAT* something that sounds ideal for an engine part?

There are some alloys that might be well suited for rotor materials... but AFAIK, noone's ponied up the godawful-big amounts of money.


RETed: What's that about lightened rotors killing bearings? Could you elaborate, I've never heard anything like that before (trying to learn, not trying to call BS)

rotarygod

iTrader: (1)

I hate secrets. I personally think that if you have a secret, it's because you don't want anyone to see how stupid it was or how bad your skills are. We have a few people on this forum that do this and you never see any numbers to back them up, just claims.

When you share your knowledge, you help everyone. I like groups that help their own rather than competing against them. This isn't Formula 1. Unfortunately half of the info that does get shared here is wrong so oh well. For the newbie this can be hard to sift through.

Some of those Supras are damn impressive. I really hate it when some RX-7 guy goes over there and talks crap. They make the rest of us look bad.

Kenku

I rather agree... uh, like my "secret" slide valve throttle body, peripheral port configuration, homebrew dry sump, dog/sequential conversion for the Mazda tranny, ubermodified Nikki carb, or the monocoque ubercar. Those are all secret and will remain so until I get them working to the point where they all work properly! Or I realize how bad it was and quietly pretend it never existed...

... note that I'm making fun of myself. My skills are developing and my ideas are largely untried so the projects will be secret for a while. I'll talk about any of my ideas though to anyone who wants to know... and when I turn out something impressive that works like I want it to, I'll try to answer any question given. Hell, anyone want to know some of my ideas? PM if you want, or I'll listen to yours...

Heh heh... I shoudl't type this stuff at 3:30am

RETed

Hmmm...like how they are all running stock bottom ends even over 600hp at the wheels?


-Ted

RETed

I think it was even posted on here somewhere...

When the rotors get too light, it ends up banging up the rotor bearings too much.
Think of it like heavy flywheels versus light flywheels.
The heavier the rotor, the more the rotor absorbs all the bumps and harmonics from the weird rotation.
The lighter the rotor, the more these harmonics gets transmitted into the bearings.
At a certain point, the premature wear on the bearings gets too much.

Ever wonder why there's no really ultra-light rotors?
Or even aluminum rotors?
There's a problem with ultra-lightened rotors killing their bearings.


-Ted

peejay

Iron is close enough to no expansion, in the temp ranges we're talking about.

Run a piston engine out of coolant - aluminum pistons expand faster than the iron cylinders - engine eventually siezes, or breaks pistons.

Run a rotary out of coolant - aluminum rotor housings expand faster than the iron rotors - engine keeps running. Till you shut it off, but hey, at least you don't sieze the engine.

Jeff20B

iTrader: (13)

I was able to start and drive an overheated engine. It fired up and ran even a day or two after the event (my friend didn't treat his radiator with dignity). Either it wasn't overheated as much as it could have been, or maybe most/some rotaries can still run after overheating. Water would go into the combustion area, exhaust gasses would go into the water jacket, water, as steam, would go into the oil pan, the radiator blew some solder joints; it was all good. Actually, the really good thing is that I was able to rebuild the engine with nothing but a gasket set and two rotor housings. Even the oil O rings survived (Atkins Viton).

Kenku

Hmm. From playing around with a milling machine and spare rotors, I had figured that the weights RB listed for their ultra-light sets were about all the material you could get out of the stock castings without putting holes in them; there may be more metal to come out than I figured out, but not easily. And new ones, I'd always just figured it was because they're too internally complicated to machine and most people don't want to go to the trouble of casting new pieces.

Cheesy

carbon carbon pistons are already being used
http://www.replikamaschinen.com/porsche912_gallery.htm

RETed

I believe lightest they went was about 7lbs.?
If you wanted to get really extreme, you can cut the rotor in half, mill the insides, and weld it back.
If the rotor was dynamically balanced and stayed that way, then extreme lightening would not be a problem.
It's all the fricken oil sloshing inside the rotor that creates all the headaches.

I believe the 7lbs. limit was the magic number of lightening.


-Ted

peejay

I've kissed the H line on the 12A in my '85 three or four times. (Damn heater hose keeps blowing, and one time the radiator split when the mostly water in it froze) It's calmly sucking coolant right now, after about 15-18k since the last overheat.

You musta not overheated it. The overheating I mean is when you run out of coolant, and keep right on going, and going, and going. Picture flying an aircraft and losing all of your coolant, and continuing on to the nearest airport instead of pulling off to the side at 8,000ft and topping up

I did that to a Subaru and a Ford once, the Ford demolished a piston (kept running though!), the Subaru had high miles on it and the pistons just self-clearanced. Destroyed the cylinder heads too, of course.

Speedworks

just refering to the heat issue regarding CF rotors. high tech carbon creations wil desintigrate at +- 6500°C

I have no knowledge how the weight aspect might influence othe engine parts.


Looking at the rotors structure, I dont think that carbon fiber can be put in this form and be vacumed to come to the necessary technical specifications.

Carl Byck

I am assuming you are indicating that that is no big deal to do, which is true. There are literally hundreds of cars making over 600rwhp, and the vast majority have never even been opened. The stock bottom end is good up to ~800 ft lbs of torque(repeatedly by several dozen owners. That typically means high 700s to~1000rwhp. Most times those are ~70K-100K mile motors. Blowing out main seals is the biggest problem, but they seem to have found a solution to that. I haven't researched it, since i am using a little turbo, and will only be making ~650rwhp. That is with ~5000 worth of bolt ons, and an E manage. You can just use a VPC, ad a Boost controller to get there, but I like the fine tuning afforded by the E Manage as compared to AFCs etc. That is just for you Teddy, not looking for a Supra VS 7 debate here. I love my FC, Carl

Bluem

renault runs carbon graphite valves in the rs24 f-1 engine

bill Shurvinton

Don't buy that theory. Look at the extreme G that a piston pulls in a boinger at 6000RPM at TDC. They also use oil film bearings, and a lot smaller than a rotary. Oil films make incredibly good bearings if you have all the pressures and tolerances right. Even with the oil 'slosh' I cannot see a workable mechanism for causing bearing damage by lightening rotors.

BLUE TII

iTrader: (9)

I think Mazda was pretty sure the ceramic coated aluminum rotors of the MX-03 prototype were going to work.

Mazda has a lot of cost issues and I think that has largely governed the rotaries development rather than engineering issues...

RETed

Actually, it is the opposite.


-Ted

enzo250

it's actually very easy to do ted. i have done two cars already one making 700 and the other 808 both stock blocks.