Certainly not, and not with circa 90's technology like most cars. I didn't mean to suggest that they could still be selling them, only that it wasn't "the concept" or "the price" or "the rotary" that kept them from being more successful when it did sell.

That all being the case, I think that should inform the decision on what to make next... vs. falling into the whole "revive the FB, it sold well in 1980" mentality.

 

Or, if it's just mechanically not possible for a rotary to pass emissions, just say so and forget it... don't tease everybody with new drawings or 16X motors, or release some choked off 1.2 liter pea-shooter. Get real or pack it in.

 

Or, if it's just mechanically not possible for a rotary to pass emissions, just say so and forget it... don't tease everybody with new drawings or 16X motors, or release some choked off 1.2 liter pea-shooter. Get real or pack it in.

One major problem with the rotary was that you lose a lot of intake/fuel out the exhaust in the overlap phase.

For the RX-8 Mazda worked to decrease overlap to none to pass contemporary emissions and still magically managed to make some upper rpm power though intake tuning trickery and large port area.

What you can see on the new rotary with peripheral intake port and side exhaust port is Mazda has been able to add overlap back in (and better then before as its intake biased overlap) through the use of direct injection.

Now it will just be intake air lost out the exhaust port as the fuel is injected in the combustion chamber.

Its like having a giant air pump on the motor, helping completely burn hydrocarbons that do make it into the exhaust due to the poor combustion dynamics of the long rotary combustion chamber.

If it can't pass current/future gas emissions (which I am betting it does since they have put so much work into it) it should be able to pass diesel emissions (it is multi-fuel after all).

Because the rotor moves 1/3 the eccentric shaft rpm and the compression ratio is low rotary diesels can rev.

This new motor in 1.2l would have much more top end than the old renesis 13B. Bottom end power? Just a little more through the improved VE of peripheral ports and a bit lost through displacement.

Bottom end power will have to be addressed by putting it in the 2,400lb Miata, gearing it high (like S2 RX-8) and the increased response of direct injection giving the perception of torque.

Stock it will be faster than a stock S2000 or FD, but won't be able to touch a 300-400rwhp modded FD or supercharged S2000.

Luckily, the new rotary will take to forced induction very well compared to the RX-8 since they were able to move the sideseals back into the rotor for better cooling as well as not torturing the sideseals over the mess of the intake port they made trying to get a sideport to open as early as possible on the renesis.

 

Great. But why is it a 1.2? What happened to the 1.6?

 

You just described the Rx8 to perfection.

 

You just lost me about the side seals location?

 

I agree, the S2K does not handle as well at high speeds. When I had my AP1 I raped that car for 3 or 4 months (went 5k miles) and have a very good idea of how they handle.

Last weekend my FD was wandering around at high speeds (no worries) dial in some positive caster. Probably do the same on the S2K etc... but the FD susp is very easy to work with and reacts well to changes.

It's really crazy just how similar these cars are but the edge goes to the FD. I've driven both and in my opinion the FD is the better handling, better balanced car that's easier and more fun to drive. Both cars give you a cart like feel but I think the FD feels even more cart like (sitting low near the rear axle vibe). It's truly one of the greatest driver cars ever made and yes the S2K is as well but there has to be a winner and I vote FD.

S2K

Weight 1,250 kg (2,756 lb) 1,299 kg (2,864 lb) 1,254 kg (2,765 lb) w/o AC
1,295 kg (2,855 lb) w/ AC
Height 1,270 mm (50.0 in) 1,288 mm (51 in)
Width 1,750 mm (68.9 in) 1,750 mm (68.9 in)
Length 4,135 mm (162.8 in) 4,117 mm (162 in)
Wheelbase 2,400 mm (94.5 in)

FD

Dimensions
Wheelbase 2,425 mm (95 in)
Length 4,285 mm (169 in)
Width 1,760 mm (69 in)
Height 1,230 mm (48 in)

PS If Kyle had his FD setup anywhere near the same way he has that S2Ksetup the RX7 would quite simply destroy it and the driving experience would also be vastly different. My daily driver is setup better than kyle's old car from the susp standpoint and my track car is way beyond that. What I'm trying to say is if you spend just little money setting up the FD the driving exp and speeds are incredible, the car reacts to mods better than any other car I know.

PSS The full cage alone in the S2k is good for 2 seconds.

 

No doubt. My old car was under damped for the performance I needed. That was the first thing getting changed after I was going to sort out the engine (I was looking to do a NA 20B swap). I do think the RX7 is easier to drive than the S2000 overall (regardless of suspension upgrades). You can see even Honda struggled to make it more "safe" for normal folk with all of the variation across the years with springs and ARBs. Just about every year they tried something different it seems to tame it down some. I do like that little bit of edginess with the chassis. I'm not sure I'd like it as a street car.

However, I'm not really comparing my S2K as it's not a street car at all. Stripped, caged, custom dampers, etc.. Just more of a comparison of the handling with a street based FD and a street based S2000. NSX's are in another world... If they weren't so tiny in the cockpit area, I'd love to build a race car out of one of those.

 

Great. But why is it a 1.2? What happened to the 1.6?

I can only assume that Mazda met their power goals for the chassis with 1.2l and since one major complaint with the rotary since the 1973 oil crisis has been its gas mileage they went with the lower displacement.

The rotary engine is quite sensitive to displacement in regards to efficiency due to the long combustion chamber and set rate of flame front propagation of pump gas.

Curtis Wright did a whole lot of research on this building test engines of various displacements.

I can't tell you what % the change in efficiency is between an optimized 1.2l versus optimized 1.6l, but there is a chance it was a factor excluding the obvious decrease from added displacement.

Because the frictional forces are low in a rotary, it would actually be more efficient to build a 3 or 4 rotor of the same displacement as the 2 rotor, but production costs go up.

Unless you can factor in the efficiencies of scale in mass production.

Sadly, .33l x4 is equal to 1.3l still so either Mazda is misleading us or will not be building a 4 rotor based off the generator parts.

You just lost me about the side seals location?

On the renesis 13B engine Mazda moved the side seal location further out on the rotor flank and used a larger corner seal button so that they could move the opening edge of the port out more for earlier opening.

This combined with the beveled rotor (for the same purpose of earlier intake port opening) meant that the side seals were not cooled as well by the oil circulated in the rotor and when combined with their exposure to hot exhaust gasses from the side exhaust port the results were poor reliability and emissions from the renesis. They had to have more end gap for the high rate of thermal expansion they would see at peak temperature and the high temperatures decreased the affects of lubrication and the side seal spring integrity.

This was especially apparent in turbo charged renesis engines where the increased exhaust manifold pressure increased the side seals exposure to exhaust heat.

Furthermore, in their attempt at opening the intake port as soon as possible they employed the racers trick of letting the leading sideseal edge drop into the intake port unsupported, but did not include the beveled edge or scissored action, so side seal wear was again magnified. They went even further and shaped the port to vault the trailing side seal leading edge over the lower part of the intake port while it is mainly supported on the housing below the port. Again, without regard to side seal wear.

Perhaps you know all this already.

On the new engine they no longer had to worry about opening a side intake port early so they moved the side seal in toward the center of the rotor more (you can see where it intersects the corner seal below the median). This allows more cooling from the oil in the rotor and along with the non beveled rotor edge reduces the exposure to exhaust gasses from the exhaust port.

The side intake port indentation (there to relieve sideseal groove sealing gasses) has very side seal friendly timing where both side seals maintain contact on the housing for reduced wear as in post Cosmo Sport engines up to the renesis.

Not only that, they have now revised the sideseal oiling to include its own oil injector on the side housing for increased lubrication without intake charge oil contamination.

If Mazda opens the side intake ports up as primary ports in the production car motive engine the side seals will still receive the intake charge cooling.

If they do not and leave it peripheral port only as in the static generator engine, they may have a problem with thermal management of the side seals/springs again as in the renesis- unless there are other factors I am missing.

 

When I raced my friends AP1 S2000 in auto-x I literally made over 3 corrections with each throttle and steering before the apex on the very first turn. I had driven the car before on remote country roads.

I found his AP1 S2000 was almost telepathic in its translations of inputs to changes in vehicle attitude, but not hard to drive at all. Very easy to place compared to my FD.

For me the FD is more relaxed to drive, except I do have to drive it with the rear end unsettled before apex to get it to make rotational corrections quickly. I found higher rear spring rates and low profile tires help quite a bit.

The S2000 driver found my FD disconcerting because of this as he said he couldn't clearly feel the transition into slip angle.

It should be noted that when I hear the Japanese mention the S2000 as one of the best handling Japanese cars it has always been "AP2 S2000". Perhaps the AP1 is considered a bit "twitchy".

 

I suppose that all of the above comes from observations of the RE generator, unless I missed some big announcement in the last few weeks . While most of this analysis could be true, I'm not so sure on some points, such as the peripheral intake ports.
They may work well on a generator (running at constant speed and nearly full load) and with a much smaller rotor breadth (reducing the problem of apex seal support), but for a road engine with significantly thicker rotors the all side port configuration may be preferable. Or, at least, a mixed configuration with side and peripheral intakes. Particularly for idle combustion stability and for the better apex seal support that the all side port configuration provides. This is especially important if the apex seals are made even thinner in an attempt to further lighten them.

But this is just a thought, after all the Suzuki RE5 did with a single rotor, all peripheral port configuration. And that was before an ECU could be used to stage the 3 peripheral intake ports of that engine.

As for the smaller rotors, what about a marketing choice to allow for the creation of both a 2 and a 3 rotor engine in the desired power class (as in "adding a third rotor to the 16x would give too much power and it would not sell")?

You know, this smaller rotors rumor came out bundled with a 3 rotors rumor, so...

Andrea.

 

Nah, you can't sell a $75k track-focused car through a mainstream brand:

2015 Chevrolet Camaro Z-28 - First Drives - Road & Track

 

 

$75k Camaros and $100k Corvettes. Who'd have thunk it?

It'll be really interesting to see if Chevy prices themselves out of sales volume. I know they are selling fewer C6's and Camaros than they used to... is that good, bad, ok?

 

They can't keep the c7s on the shelf

The new Z06 will sell like hot cakes even if it's as high as 90k

I'm just waiting for all the c6s to pop up for sale on forums when the owners look to move up into the c7

 

Yeah, there are going to be some great deals on C6's to look out for. You ought to pick up a C5 Z06 track car as your backup track car. Much simpler than a 6, and probably dirt cheap now, and bulletproof.

 

Agree. C5Zs with LS6 don't have the oiling issue you will run into with r compounds and the speeds you drive.

BTW, saw a TT1 mildly modified c6z ran a 1:54 at VIR this weekend. ST2 mustang ran 2 flat.

 

see mazda look , potential customers , going psht screw that 200 hp rx7 ..

 

There *is* a lot of subjectiveness in "good handling". But you've got the roles reversed. It's the FD that feels more stable and "easy to drive".

^^^
True. Particularly for the AP1.

Definitely sit lower in the FD, but you're much closer to the rear axle in the S2000. Driver is situated a lot more like in my 240Z relative to the wheelbase, whereas you're a bit further forward in the FD (which of course was a 2+2 in Japan). Definitely affects the feel a bit. Not in a "good" or "bad" way, necessarily, but in a way that people can certainly have different preferences.

I love them both.
Stock vs. stock, performance is very similar. Modded vs. modded, of course it's super-easy to make big power gains with the turboed FD.

For feel, I think I like the S2000 better on the street. It just feels more responsive to input at the helm. This is not necessarily a benefit at the track! The FD is more forgiving and less twitchy. I don't think I'd consider dropping a 500+hp V8 into an AP1 S2000 without some changes to the rear suspension geometry!

 

So, the mechanical base of the upcoming ND Miata has just been shown at the New York auto show (link).

Since it's fairly safe to assume that any new Rx-7 will be based off the Miata chassis, I'd say it's possible that (part of) what appears in that article may find its way in the new 7, if it eventually gets done.

I'm specifically thinking about the suspension layout (front double whishbone and rear 5 link multilink), and the power plant frame. Does anyone spot anything else that may carry over?

Andrea.

 

The RX-8 used the Miata transmission so I suppose it can carryover also

 

I guess that really depends on the relative power levels: if the miata is around 170hp and the new 7 is around 250hp, then the transmission may be shared. If a three rotor or turbo engine is used, however, a new transmission would be needed. I seriously doubt they'd use a transmission rated for 350+ hp in a miata...

In case there are two engine options for the 7, then the smaller engine may use the miata transmission, while the top of the line model would surely need a dedicated trans.
Or, for economies of scale, they may develop a transmission for the bigger engine and use it for both the small and the large engine in the 7, while the Miata has its own transmission.

Who knows...

Andrea.

 

^ or, this whole thing could be a complete fantasy and I will just have to buy an Alfa 4C instead.

Sorry, guess my glass is half empty today.

 

Interesting how they did the power steering rack.

 

I'm specifically thinking about the suspension layout (front double whishbone and rear 5 link multilink), and the power plant frame. Does anyone spot anything else that may carry over?


Engine position is pretty far back for a Miata. A 2 rotor would be tucked way back!

I say throw some rotors in that b*@tch as it is!