zaque

Posted this in the other thread, but I'll put i there too;

I hope this isn't it, because it's really disappointing. It is simply a patent, after all.
It's high, and not going to fit in that low long hood. I figured with the long hood it'd be in front.
It also looks like it'll have crazy cooling problems. Were lessons not learned there?

I was hoping for a split turbo (the compressor many inches away from the turbine so it doesn't absorb the turbines heat and spew out hot air) which would save on plumbing since you put the turbine on the exhaust end that's coming out at 60 degrees, and the compressor far away right at the opening of the intake manifold.
Could have mounted it sideways with the intake at 60 degrees as well with that set up which would improve intake flow just like the 30-60 degree exhaust improves exhaust flow.
Spark plugs on the bottom would have been a pain, but whatever, you get the transmission mounted lower that way and more engine weight down lower.

Or even better, a hybrid-electric turbo that's also split and gives instant boost when you go down on the throttle, increase efficiency, and make good extra use of i-Eloop.

If they're going to keep the car so simple, low tech, invite overheating problems, and not package to the nice looking concepts proportions, I don't know what the selling point is unless it's fairly cheap, like $35k. If they're just basically increasing it from 1.3l to 1.6l, improving the exhaust flow, and making it a single turbo instead of twin, I just don't get it.
But I want a reason to get this car besides "because rotary". I want it to be awesome.

newbbe

Most of the heat gain through the compressor is adiabatic and unavoidable.

j9fd3s

iTrader: (3)

this paper is just showing the layout, and not really any details, although there are a few. for instance it has 2 cats, instead of 1, the spark plugs moved, the intake and porting is very different. it is odd that we're not seeing direct injection, although maybe its just not in the patent? or maybe putting fuel injectors in the oil pan even seemed silly to them?

and it has a turbo. i would bet that the turbo is not only a power adder, but also an efficiency adder. Volvo had something called a low pressure turbo in the 90's, because they noticed that under some conditions the turbo ADDED efficiency (it reduced pumping losses). also when you have the intake pressure greater than exhaust pressure, the rotary works a lot better.

how so? the engine is cooled by the coolant in the radiator, and not by the location of the turbo... if anything, since heat rises, it should be good to put the turbo on top.

if you want the anecdote, i'm playing with a mid engine car, and even though the rear of the car is very well vented and ducted, it still needs a radiator....

i would bet that with the layout changes it lets them have a more optimal suspension, and or tuck the engine lower and further back. it would be cool if it made it so they could put it in a miata, but you know they won't, people would buy that and this is Mazda!

j9fd3s

iTrader: (3)

part II; cars.

Camaro: one of my co-workers has a 2014 1LE Camaro, and we all went to lunch in it a few weeks ago. it basically does exactly what you expect a Camaro to do, it makes v8 noises, and its fast in a straight line. the fit and finish was surprisingly good, as was the interior. its actually a nice car on its own merits. the big problem with it is just size, GM just put a Camaro body right on top of the Holden body, so the result is enormous.

i see a lot of Camaros, and i predict they will be the new FD, it will just become the go to tuner car.

Miata: just to add on to what's already been said, we did a track day where they were auto-xing in the parking lot across the way, and even in the rain the ND is FAST.

Mustang: i don't really know much about these, they do look good, and its fast and its cheap, pretty much that is the mustang formula. wait for the sequel when they bring back the pinto!

t-von

iTrader: (8)

FIY 2016 Camaro is a totally different animal with it's smaller proportions.

t-von

iTrader: (8)

Well direct injection shoud be going on the plug side. Also, since Mazda had met their mark over the entire line-up for fuel economy and emissions, doesn't that mean they can now put out a more poluting vehicle? I bring this up because of the port injection. Besides the 180 rotate, I was really expecting to see some truely advanced re-engineering internally. Guess we'll just have to wait and see a cut-away.

zaque

True, but it's not like there are no gains.

Splitting the turbo creates less plumbing, especially with 30-60 degree offset ports, which makes for less turbo lag as well.

And the intercooler does nothing to lower the heat gained under adiabatic conditions.
You need a smaller intercooler if the heat gained is mostly adiabatic since it doesn't reduce that, which further reduces lag.

No DI is not odd.

1. DI adds another hole where cycles can overlap when the apex seal passes it. Granted, that's a much smaller hole than spark plugs.

2. A rotary creates a stratified charge which improves the air-fuel mixture on its own.

There isn't much point in DI unless it's going to be spraying it during the compression stage moments before the first spark, and if there was laser ignition, where a denser air-fuel mixture could be kept isolated in the combustion chamber, but even then I'm really not sure since that uneven mixture could be more prone to detonation.

It may still be using stronger injectors. The injector is very very very close to the side port.


The compressor puts out hotter air when you have it sitting right by the turbine and atop the engine.

The Mercedes F1 car has a smaller intercooler thanks to its split turbo... that's not anecdote, that's the result of engineering.

https://media.licdn.com/mpr/mpr/AAEA...NjFhNGU5Mw.png

It's like all the benefits of a hot-v turbo without the drawbacks.

zaque

I map out the RX-Visions proportions to get an idea, even though they'll certainly not be exactly like the concepts.
The patent is such weird packaging, though.
The patent puts the engine between the wheels, to sit between the crossmember, and calls for a a fairly high hood.



With the RX-Vision proportions, the entire engine block fits behind the entire wheel wells with room to spare.

And it's 7 inches wider than the FD.

I also made the plumbing a lot less compact than it'd end up being just to illustrate.

But yeah, even while leaving space for the ABS, steering, alternator, and so on, a horizontally mounted 2rotor engine would fit behind the entire crossmember fine with the crazy amount of space the RX-Vision has between the wheel wells and the firewall.


And spacing the compressor from the turbine lets you put the compressor right up to the airbox, helping reduce lag with less air plumbing to fill.

An example of one of those spaced turbos, with an electric motor in between:


Or maybe it could be even more compact with even short plumbing, with the compressor right out on the front of the block, and a water-to-air intercooler right in front of the block as well.

Either way, mounting it side ways means making it shorter and more room to put the turbine overtop like that. I don't get the reason not to do so.

arghx

iTrader: (3)

there's been some concern raised about the heat by having the turbo at the top, but remember there are several V8 engines in production today with turbos inside the valley. So it's not impossible to overcome.

lastphaseofthis

iTrader: (8)

where did you find this? the brushless turbo hybrid thing.

arghx

iTrader: (3)

to clarify, I was alluding to this post

zaque

Right, that's what a "Hot-V" that I mentioned is.
But that's because the problem isn't the turbine being hot. The problem is the heat of what leaves the compressor. Keeping the compressor spaced from the turbine, and even better to keep the compressor not absorbing heat of the engine block either, helps keep temps down a bit.

They tend to use liquid-to-air intercoolers in hot-V engines. That's like how the AMG GTS setup is.

I was thinking that myself, and here is a better design assuming a liquid-to-air intercooler.

Boy that's a lot of space left over..

I was assuming an air intercooler before... but that'd be pretty stupid, really. water-to-air means way less lag and lets it be more compact like this.

But anyway, I think a system like that, with a hybrid electric turbocharger, would make for an amazing car.

Even if not a hybrid electric turbo, I guess a system like that would keep engine temps lower and reduce turbo lag significantly.
But I imagine it's worth it, since a hybrid electric turbo means higher efficiency at lower RPM, so better fuel economy, on top of the huge performance advantage.

Ultimately, I don't understand the whole "put the turbo ontop" thing unless it's a split turbo and the engine is mounted horizontally to get it down lower.

That's a prototype from 2 years ago from an F1 supplier, I believe.

Now basically every team is using something similar. But Mercedes is even more spaced, and some have the motor on the other end.

arghx

iTrader: (3)

The turbo is on top for a few reasons.

1) putting it on the bottom like on an FD makes it hard to mount the engine low, or it means a scavenge pump needed for the turbo oil supply (like on a 2015+ WRX)

2) putting it on the bottom with side exhaust ports, same style as an Rx-8, is not good for exhaust flow.

3) putting it on the top allowed them to make diagonal exhaust ports with a gradual radius that has less restriction than an Rx-8 style side exit, or a completely vertical exit. There's a whole discussion about it in the patent.

4) packaging space is required to fit the cat close to the engine in order to meet emission requirements. They need an air pump too. Air pump is mentioned in the patent.


As for the amount of space needed, any air to water intercooler requires a low temperature cooling system. So that's a separate radiator + hoses and electric pump for it, then probably an air to oil cooler for the oil, plus a normal A/C condensor and . All that stuff takes up space.

The lack of DI thing is mysterious, but it's conceivable that they abandoned it, or at least delayed its introduction until a later time. If they did abandon it or delay it, the main reason is most likely the new California LEV III particulate mass regulation and especially the new Euro 6C particulate number regulation. It may have been impossible to meet particulate emission regulations at this time without a gasoline particulate filter. That's a very risky technology to use on an unproven engine.

the patent implies a conventional single scroll turbo in the section discussing the exhaust manifold.

zaque

With the exhaust on the top, the manifold could still curve to have the turbo to the side.

Regardless, I don't see how mounting it horizontally doesn't give all the same benefits plus more.

Also the same benefits you get from having 30-60 degree exhaust ports, you get from having 30-60 degree intake ports if you mount it horizontally. Increase volume of air, and less turbulent air flow.

newbbe

i'm very confused how a rotary engine can be "upside down". :-)

j9fd3s

iTrader: (3)

well the FD has the layout you propose, they have the turbos mounted low, and as close to the engine as possible. as we know, they had to raise the intake ports to avoid a bend in the lower intake bigger than 90 degrees.

also as we know the FD turbos basically cook everything....

this new layout lets them have an optimal intake, improved exhaust over the Rx8. turbo placement looks pretty ideal too, short runners, etc. look at the bright side, the paint will just get burned off the hood from convection, instead of burning off the hood because the fuel system leaked on the turbo....

it is possible its not in the patent, because the patent has nothing to do with it... although they do show other stuff, like moved spark plugs, and stuff

t-von

iTrader: (8)

Try not to put too much stock in the Visions proportions (the lack of suspension travel on the front wheels should be a obvious). I think Mazda is just showing what's possible with a new RX Vision platform and what "could be possible" over a future rotary line-up. I truely think Mazda will build 2 rotary powered vehicles (Cosmo and Rx7 like in the early 90's) This concept has Cosmo proportions with Rx7 styling cues all over.

Valkyrie

I don't really care about the turbo packaging so long as the car is ready for mid-summer track days, isn't absurdly hard to work on, and has reasonable mileage and emissions during normal driving.

zaque

There is plenty of room for suspension travel in the concept, assuming the wheel well extends right up to the hood and there is no room on top of it.

I assume the damper and cross member would be attached inward a bit. It could even have horizontal linked suspension.
But yeah, I'm sure the dimensions are going to be a bit different. The hood is way longer and wider than what's needed even if the springs and dampers were horizontally linked.

And I care about the packaging because I don't want it to look dumb being high and narrow.

The patent calls for proportions that are more like the RX-8 than the FD.

Then again, it looks like there is no oil pan in the patent, so maybe there is a dry sump and they are getting it down even lower that way, but mounting it horizontally still seems better, especially when talking about a wide and low sports car...

Valkyrie

There's almost no way this isn't going to have a reasonably low-slung hood.

I mean, assuming you moved the ports and manifolds around, there's no reason you couldn't fit a medium-sized turbo between the engine block and the hood (which would need to have some heat protection, of course).

The fact that it will probably have EPS alone saves you a huge amount of engine bay room and complexity.

neit_jnf

iTrader: (17)

there's a lot of space between the top of the engine and the intake manifold in current setups so I don't see any issues with having a turbo on there while the intake manifold is now on the side and provides even better intake length and exhaust flow.

BLUE TII

iTrader: (9)

Valkyrie

There's almost no way this isn't going to have a reasonably low-slung hood.

Exactly. My RX-8 looks like it has a low hood parked next to anything besides and FD or mid-engine car and there is a solid foot and a half of space between the engine and the hood. Could fit a plenty big turbo on top of that engine.

When you tuck the engine into the firewall cowl the vehicle body height above the engine is defined by the belt-line not the hood and side impact crash standards necessitate a high belt-line in modern cars.





If you look at the patent illustration it is showing the back of the engine in the picture above.

Notice the engine is behind the cross-member that laterally connects the front shock towers.




Notice here the position of the engine and firewall. The engine is tucked back even further than the RX-8 engine having the rear side housing behind the plane of the firewall.

The hood line is unaffected by the engine height except if you wanted a concave surface from the windshield cowl to the minimum headlight height- which would be ugly and make the car look like an old Saab 900.

zaque

The turbo comes up significantly higher than the intake manifold does on the RX-7/RX-8.

Even with the removal of an oil pan on the bottom, I don't see how it doesn't come up higher.

Either way, it would have a short hood like the RX-8.

You're right that it's behind the crossmember, but did you measure out the RX-Vision? There is like 20 inches of room between the back of the wheel arches and firewall. So the wheels can be like 8 inches further back and that engine that's tucked into the firewall would still fit.
The proportions on the diagram I made are correct, and there is plenty of room to fit the engine entirely behind the front wheel arches, and crossmember, without tucking it into the firewall.

It would have the same hood length as the RX-8 to package that, but with the front wheels further forward toward the corners. Which makes sense, really, but the RX-8's hood is too high. It might look low compared to other cars, but it's high compared to an FD.

BLUE TII

iTrader: (9)

So you want to figure out a way to lower the area of the body between the front of the door and the wheel where the engine resides.

And how is that going to look?

neit_jnf

iTrader: (17)

looks like it'll fit just fine in there^^