HiWire

The stuff I am thinking of is kind of sci-fi, but we seem to be living in a sci-fi world already. I noticed that the Le Mans 787B had a variable intake, for example, and I know that other car manufacturers have been producing variable intake engine designs for a few years.

For example, what about a variable-profile intake and exhaust port (e.g., some kind of liquid metal "thingy" that can change shape at high speed, or barring that, a similar computer-controlled assembly from solid metal) or a rotor face with a better optimized (or reconfigurable) shape?

I've already mentioned laser ignition, but I think somebody mentioned in a thread a few months ago something about new research on the shape and behavior of the flame front propagation (if that's what it's called) inside the engine.

j9fd3s

iTrader: (3)

Porsche had a system, called varioram, that is just like the 787B system, so it has been done in a production car.

variable profile intake ports have also been done, Mazda has had that since 1983, the 6 port system. the Rx8 has a developed version, where it runs from the 2 primary ports, which are sized to go from idle to ~3200rpm (or what ever it is), then it opens the secondary ports, which are sized for 2500-6200rpm, and then the 3rd set of ports open, these are timed to make power up to redline. each pair of runners is its own tuned length too, so its fairly optimal. with the Rx8 the trouble is the exhaust ports, the timing is ok, and the area looks great, but being 4 small ports instead of 1 big one, they don't flow enough.

the 16x helps, as it should support larger ports

HiWire

Sounds good. The next rotary engine, if it ever comes, will almost certainly have variable intake ports, then. Is there any benefit to a variable exhaust port or would a turbo system make this irrelevant?

Two-stroke power valve system - Wikipedia, the free encyclopedia

j9fd3s

iTrader: (3)

Mazda always has taken the variable ports off on the turbo cars, so they either seem to think its too complex, or too expensive the gains? if we get a new one it probably would be more staged than the FD was though.

Fritz Flynn

iTrader: (263)

Yep, still hope to do it one of these days (bucket list item for sure)

They probably haven't met Leh Keen and his GTR LOL. The car ran a 1.56 at vir on street tires. That's who you have to beat for the OLOA title.

fmzambon

For one thing, the switch to the new proportions in the engine (narrower rotors for any given displacement) will increase the available port area for the same port timing, both for the intake and for the exhaust.
This means that Mazda could keep the primary and secondary ports at the same area as they are today and possibly make them with milder timings to help make more down low torque. And then the aux ports could be made quite a bit larger to help with top end power.
This would be even more useful should Mazda decide to go with aluminium rotors and consequently raise the redline.

Also in patents from 2009 it was clearly shown that the center exhaust port was split in two independent ports. That would help with exhaust tuning as well.

But then there was also the RE range extender which showed a peripheral intake with side exhaust. While a side intake ports would be useful for idling and very low load operation, a combination side+peripheral intake with side exhaust was certainly considered ad Mazda. That intake configuration was already used for the 8A engine back in the '60s, but then it was rejected due to the excessive leakage due to the peripheral intakes, and the combination port 8A was replaced with the side intake 10A. I feel that a carefully designed valve in these ports could solve the problem though.

As far as continuously variable intake goes, BMW had such a system in one of their engines (N62 V8). Given that the rotary is a fair bit smaller than a V8, it seems to me that such a device would easily fit together with a rotary.

Andrea.

j9fd3s

iTrader: (3)

if the cc per chamber is larger, then it will need to have larger ports to keep the same power curve, but yeah it will give them a little more flexibility.

i wonder if they really need to, isn't 8500rpm too much?


its been my experience what the peripheral intake is just far far better than the flabby side ports. although the overlap is a problem. it does seem like a peripheral intake, and side exhaust is a good combo, but i guess we'll see

fmzambon

I did the calculations a while ago. The switch to 800cc rotors partially offsets the gains given by the thinner rotors, but nevertheless there is a gain in the port area to chamber volume ratio.


The ability to rev very high is one of the strong points of the rotary, so why not emphasize it? At the very least it would be a very good marketing item. How does "the only 10000rpm automotive engine" sound?

Andrea.

j9fd3s

iTrader: (3)

i think they will do just that, however they need to make sure the engine stays together at that rpm this time

t-von

iTrader: (8)

Even with side exhaust, you will still have huge overlap. That overlap will destroy the emissions. The only way to make a PP work is to utilize the side ports for the low range were emissions come into play and open the pp in the upper rpms. Even then, the pp would have to be 100% closed.

j9fd3s

iTrader: (3)

agreed, except the PP needs to open with load and not rpm. i've driven my 12A P port back to back with a stock 12A with the bolt ons, and the P port makes more power under 4k than the stock engine does anywhere. the P port is like a truck, in fact it feels stronger around 2k than my turbo FC does! its certainly more immediate.

what the PP does not like, is part throttle. driving to work @12mph behind a prius is where the PP wouldn't be happy, this is where you want the side ports.

the scoot 4 rotor passed the japanese shaken, which has an emissions test, although its not very strict

t-von

iTrader: (8)

Gordon, did Logan put the butterflys upstream from the secondary injectors? They only need to be closed enough to allow most of the flow to enter through the primary runners. I hand fabricated my primary and secondary butterfly system and will be driving my car the 700 miles round trip to Elpaso next weekend for my emissions test. I was suppose to be going this weekend but, due to the nature of my job being in the oil field, we just layed off 50% of staff across the board. I survived but my weekends off have changed. Hopefully I will have some positive results.

ptrhahn

iTrader: (9)

Here's your BRZ competitor... could've been done years ago with or without a rotary. No need to wait for a downgraded 2017 "RX7"

t-von

iTrader: (8)

Is that a photoshoped Miata? Looks nice!

rx7 SE

iTrader: (5)

Agreed, that looks awesome

ptrhahn

iTrader: (9)

Note: I didn't do anything but find it on Facebook, but it does look pretty cool. Not as an "RX7" though.

Mazderati

iTrader: (3)

Looks Chrysler Crossfire-esque.

j9fd3s

iTrader: (3)

i don't know why they don't do that?!!

RCCAZ 1

iTrader: (10)

Rear of a cross-fire looks like a dog hunching over taking a ****, so I hope not!!

ptrhahn

iTrader: (9)

Truth, LOL. The Miata rendering sorta looks like a little baby MKIV Supra.

Montego

iTrader: (1)

aah an old Jeremy Clarkson reference to the crossfire I see

j9fd3s

iTrader: (3)

if we were having this discussion in a bar over a beer (or several, long thread!), i'd do my impression of the model S.

BLUE TII

iTrader: (9)

Even with side exhaust, you will still have huge overlap. That overlap will destroy the emissions. The only way to make a PP work is to utilize the side ports for the low range were emissions come into play and open the pp in the upper rpms. Even then, the pp would have to be 100% closed.

You have some overlap with p-port intake and side exhaust, but it is good intake duration bias overlap.

Emissions won't be a problem (obviously, they made it work for the Mazda2) as with the new real direct injection you are just losing intake air into the exhaust during overlap and not air/fuel.

The only issue is if you have idle instability from a big p-port you would still dump air/fuel into the exhaust from misfires. But I don't believe Mazda would let a production engine go out that had a real race p-port idle.


Edit- I guess there is the option of no idle as well.

BLUE TII

iTrader: (9)

Quote:
Originally Posted by gmonsen View Post
Trey... We were never able to control the primary and secondary intakes you and I discussed. The tolerances on the port throttle butterflies when closed allowed too much air/fuel to go through, so there was like $2,500+ wasted. I know you have something that might be up and running. Could and should Mazda be looking at this?

G

Gordon, did Logan put the butterflys upstream from the secondary injectors? They only need to be closed enough to allow most of the flow to enter through the primary runners. I hand fabricated my primary and secondary butterfly system and will be driving my car the 700 miles round trip to Elpaso next weekend for my emissions test. I was suppose to be going this weekend but, due to the nature of my job being in the oil field, we just layed off 50% of staff across the board. I survived but my weekends off have changed. Hopefully I will have some positive results.

I really think for a small p-port, semi p-port system the p-port should be used as the primary port.

P-ports make more power across the board, so it will have more low rpm torque.

Flowing air through the P-port at idle will provide some intake velocity to fight the reversion from compression stroke that the p-port will allow even with a closed throttle body (across the apex seal as it spans the p-port).

Additionally, late closing sideports CAN and have been closed off at low rpm (by Mazda) as the 2 un-compromised sideseals still form a sealing grid at the rotor flank to stop the compression reversion.

So, to recap.
Primary P-peripheral port with injector
Secondary (stock primary) side port
Tertiary (stock secondary) side port
Quaternary (stock aux) side ports *2 rotor option*

t-von

iTrader: (8)

I completely over looked that! The constant overlap air could put oxygen into the exhaust just like an air pump does. DI was something I was gonna do on my spare Renesis.