lol... I would have to disagree.
The exhaust ports on the Renesis may be poorly designed, but they can still flow well over 400 HP, and possibly over 500HP if certain RX8 shops are to be believed...

The Renesis in stock 20MPG form has more power than a stock S5 T2, so unless you're talking major engine upgrades that most people can't afford, then the Renesis has it's own advantages over the old 13b's.

 

I completely agree with you that there should be research into larger displacement side port engines, and I can't figure out why this hasn't been done . There are aftermarket eccentric shafts, rotor housings, side plates and rotors for at least the past few years. All the necessary information is available as well. I'm not saying it would be as simple as saying hey lets double the displacement by making the rotor taller and wider, but it's also not as if it would be made from scratch. This could have and should be done. I personally would love to have a 3.0 L two rotor a 4.0L three rotor. With the new materials being used I don't see why this hasn't been done yet. And, I don't want this to seem like I'm just on a soap box. I honestly don't see why the community has allowed itself to remain limited to 1.3L as long as it has. Personally I'm glad to see Mazdatrix producing something new, and I hope they and others like them continue to do so.

 

i agree with that, i was talking about the INTAKE ports though... if you wanna spin it to 10-11-12k rpms then you should skip the side port and go full peripheral.

 

fair enough, but I think that could be compensated by a shallower air flow transition, and maybe a more innovative rotor face... Hard to say. You'd for sure have to go back to the drawing board, and make something a little less orthodox to make it work to optimal levels.

As far as current tech though, I'd agree with you.

 

Are you suggesting a rotor face that is biased to the side instead of it being 100% flat?? That could work if there was a way to adapt the compression face to match the offset.

 

I was just alluding to a theoretical possibility, not that I actually have any plans for such a setup. It was just the first thing that came to mind thinking about the airflow. Straighter / more stabilize direct path.

Just saying that I'm sure there's something that could be done to make side ports more efficient.

 

well my opinion as a mechanical engineer and shop owner is ( and this is just me pulling it off the top of my head so I'm not getting into the specifics plus I'm tired. ) is that p-port style exhaust ports will always be better suited to evacuating the exhaust gases from the engine. Gasses prefer to flow in a straight line ( path of least resistance) Although side ports are preferable for some applications. Now given proper funding funds or a crack research and development team I would design an offset rotor face ( or possibly a variable geometry type ) and housings to support them . with a semi- P-port exhaust . Thus having the best of both worlds. Low exhaust back pressure of the 13BTT while retaining most of the benefits of the Renesis. I suppose that would be possible with out all the fancy rotors if you could somehow hybridize the renesis and the 13B side plates and rotor housing exhaust port....... This is probably a nutty idea, but I think I need to look into the concept. Lets toss this around maybe someone who is more skilled than me can hammer this out.

 

right next to the fancy billet rotors, which are a distraction, was an rx8 motor setup almost exactly as you describe. it was ALMOST the secret sauce japanese rx8 tuner recipe.

they have had more time to play with these, but they are starting to make excellent power, and as usual with almost no trick parts.

 

sometimes. when the moon is Just right and my GF is in a good mood I get a good idea. sadly its usually too late and has already been done by someone else.

 

I personally don't think the semi p-port exhaust would work all that well. There is more to the exhaust ports than which way they point and how well they flow.

 

mazdatrix had an rx8 motor with gsl-se rotor housings, and i thought it was just a bunch of parts thrown together to look cool, until i looked at the 5 into 1 header.

 

you wouldn't happen to have a pic would you?

 

nope, i didn't take any pics.

header might be best described as functional? it looked like some kind of bug with cancer... i recall it going forward too, so there might have been a turbo at the other end.

 

Just because someone built it doesn't mean it's a good way to do things.

 

Not saying they are wrong but we've been spinning engines here to 10.2K here for awhile no issues as of yet. Stock rotors just clearanced and balanced. Though a track car may be different from our drag cars.

~S~

 

I'm just going by info racing beat gave me. I don't remember what RPM, but I know it was for sure above 10k.

meh.. it's been a while.

 

I know guys running over 12k with stock rotors with no issues of the gear moving, so you can nip that one in the butt.

 

yay for mis-information...
thanks for the info.

 

Has anybody ever thought of ceramic rotor bearings? I think this would help in achieving higher RPMs (low friction heat resistant material), maybe even on the e shaft rotor journal?

Any ideas on what kind of compression numbers these rotors have/will have? I think this might just be the perfect thing for what I'm looking for.

 

I've been working on ceramic drawings, and in an all ceramic engine, ceramic bearings would make more since. What makes ceramics expensive is the machining process. You have to use diamond bits and finishing powders. I know of guys that spent over $400 to polish a 3.5sq/in ceramic ring. They would cost more than most people would be willing to pay for (at least with the ceramics that I would use).

I would say that the hardened steal would still be the best idea for now. It's cheep to work with.

 

Can't edit my post for some reason...
The main reason that you don't see any higher displacement two rotors is because of the engineering it requires. You need to make new housings (taller or wider, wider being the more effective route). which I don't think people are up for the challenge. I can see people using the same size stuff for so long because there's still so many different ways to go about doing things, all being cheaper and easier than manufacturing new sized rotors and matching housings (along with side housings as well unless you just made a wider engine). That and because companies realize how much engineering it would require versus the amount of demand in the market. Once one person does it, it won't actually be that bad, in fact, I think mazda is actually working on a larger displacement two rotor for their line of prototypes (at least that's what I read on wikipedia a while ago), I believe it's called the 16X (renesis 2).

 

Actually Mazda found that wider rotors were a mistake. The new 16x has thinner 10a thickness rotors. It's apparently more efficient to make them taller.

The reason people make 13b sized stuff is so it will be Mazda interchangeable. Why manufacture a 1 off eshaft if you can just use theirs. You wouldn't sell enough to make a real profit verses the manufacturing expense. For example, I was pricing manufacturing eshafts, and came to the conclusion that If I couldn't produce and sell the shafts for less than $1500 that sales would be so low, that the investment would take too long to recoup. For stuff like this, if you're not supplying race teams, or don't want to charge so much that it's a nitch, rich market, then you need mass production capabilities, or go home, but to mass produce, you have to invest in temples etc be they forge plates or whatever. Billet / 1 off parts will never effectively make you money in the short run, and are just too expensive to manufacture. I was glad to see that they're going to look into forging. It's equally strong, and highly repeatable with a press and mold. Will greatly reduce cost after the mold cost is recouped.

I don't think it's the engineering that's the issue, or people being "up to the challenge". It's a money issue. If I had the money to do what I'd like, I'd have a prototype already running in my car, and maybe a couple others.

 

Yeah, that's really what I was trying to get at. All the effort isn't really worth it because like you said, the only REAL market for these kinds of products are race teams and people with deep pockets. You wouldn't make your money back at all.

 

It's a sad reality for sure... I'd like more options even if I didn't need or want them. It promotes innovation.

 

we've learned the hard way that it is. its a completely different duty cycle. just to pick something we have data for, thunderhill, is like doing 14 dyno pulls back to back every 2 minutes, and our shortest run time is 15 minutes, and the longest is 25 hours.

drag racing is 100% wot, but your whole season of import drag racing is less than 15 minutes, and the honda crowd expects to rebuild the engine at least once.

not trying to make a judgement, but just pointing out that drag vs road racing IS different.