Jedi54

iTrader: (7)

while I agree with most of that, unfortunately for Mazda most potential owners will only see the 250hp figure and look the other direction.
Die Hard rotorheads will still buy it, but that alone will not take the RX where it needs to be in terms of sales.

This is a tough one for Mazda....

rotarygod

Why would 250hp be a negative when 225hp (238) isn't? The only thing that matters is performance and fortunately that isn't directly related to horsepower on it's own but rather a bunch of other factors. Design a car that has less power and equal or better performance than the others in it's class and you don't look bad at all. The other guys do.

Jedi54

iTrader: (7)

Most car buyers are easily swayed by numbers they read in a brochure or things sales people tell them. It's sad, but it is unfortunately the truth.

If the new RX has 250 hp and all these customers are seeing is that the G37 is putting down 350 hp (I made that up, but you get the idea) then I can tell you right way what's going to happen.
On paper, the RX is an inferior machine (in the eyes of your typical buyer)

- Less HP
- Less torque
- worse gas mileage.


I don't for one second believe that the RX is inferior to it's compeitors but many will see it that way.

rx8frank

I agree with you but I really think that stretching vertically the e-shaft would be a great idea for the torque issue.....no!

rx8frank

And what the hel* I am thinking about this for a long time now......what if.....you take a 20B and throw out those 9:1 compression rotors and put the renesis 10:1 into that 20B and keep it N/A (as you all know the renesis rotors are lighter than previous 13B) and just do a street port and I think we could go to that 400+whp we are looking for..... and....if it is not enough just slightly turbo it and we may hit the 450 whp mark...I personally think THIS could be the best idea for our 8.

Cheers, Frank.

zoom44

anybody?

rotary crazy

you really think putting a 12a turbo in a 3000lbs car would give better fuel economy?

In my opinion a 12a engine would have to work harder to make the same acceleration than a 13b, not to mention that when you hit boost economy goes out the window, I think a 1.5l 3 rotor would be better, more torque, less agresive gearing, 4.10 or 3.90 rear diff, same red line, and the MOST COOL SOUNDING ENGINE

I know it will be heavier than a 1.5l 2 rotor engine but I think the avantages out weight the disavantages

rotarygod

What do you mean when you hit boost economy goes out the window? If I have engines, lets exaggerate this and say a 3 liter nonturbo and a 1.5 liter turbo, and they both make the exact same horsepower, the 1.5 turbo will get better economy. It has less area for heat loss, less friction, and the extra air from boost aids in fuel atomization. A smaller engine with a turbo is the easiest way to keep power up, fuel mileage down, and emissions in check.

A 1.5L 3 rotor would have worse mileage due to larger friction area, and larger area for heat loss. If we had a 12A turbo and a 15A nonturbo making the same peak horsepower, the 12A turbo would have more average power, better emissions, and better mileage. Not to mention the fact that it is a physically smaller package. Bigger is not always better. Yes the 3 rotor would sound cool though.

rotary crazy

your theory is right, to some degree, if the engine its on a test bench than you are right but if you have to move 3000lbs and produce 300hp a 1.5l turbo engine its not goin to be more economical then a 3.0l NA, I can give you a lot of examples of larger displacement engines producin the same amount of hp than smaller engines and the larger engine give better mpg, in a relative equal weight car

brillo

I can see how the above could be possible with piston engines, but the biggest single "flaw" with the rotary design is the odd combusion chamber shape which gives rise to all the thermal inefficiency issues and subsequent economy and emissions problems. The smaller that odd combustion chamber shape, the better.

This is why I want a 1.1L turbo motor.

rotary crazy

well im not an engineer, but Im sure the reason for going from 1.2l to 1.3l was a good one, or did mazda make a mistake?

As i undurstand it the reason you dont see a FI rx-8 today is because it was too dificult to make it pass emisions and reliability problems

the renesis replacement will be a larger displacement engine, 1.4l or 1.5l, dont get me wron I love turbo rotarys, but given a choise with the same hp Ill go NA

rotarygod

Don't start just comparing different engine sizes and mileage and claim there's a correleation. That alone won't work. Gear ratios have alot to do with it. If I have a small engine that has a 4.44:1 rear end and a large one that has much less agressive rear end ratio, the large engine is turning slower which means per unit time, it's displacement of air and consequently fuel is closer to that of the smaller engine. Then we need to take the efficiency of each engine into account as they won't be the same either.

If you have a small engine producing the same power as a larger one, you can keep the gear ratios the same. You really need to show me 2 cars that weigh the same and have the exact same gear ratios. One needs to have a small forced inducted engine and the other one a naturally aspirated larger engine making the same power. The size and weight of the vehicle are irrelevant so long as they weigh the same as each other. That's a relevant comparison. Comparing 2 random engines of different sizes isn't.

The forced inducted smaller engine will be more efficient than the larger naturally aspirated one. It's completely true unless you really mess up the small engine's design.

rotarygod

When Mazda switched from a 10A to a 12A and then later a 13B (and even had an old 13B in the 70's that they discontuinued in favor of the 12A), they also weren't using turbos yet. The exception to this is in 1984. The 13B appeared in the U.S. GSL-SE edition first gen for 84 and 85. The rest of the world got a turbo 12A instead. The 13B remained naturally aspirated until the Turbo II model 2nd gen in 1987 but even then a naturally aspirated one was still available through 1992. The 3rd gens all had turbos. Mazda claimed that they couldn't get anymore power through turbocharging than they did at the time. Of course we know you can but they had different production goals to contend with. Then of course we had the 20B which was short lived. They are back to a nonturbo now for obvious reasons. They've got power up in the engine and their past turbo attempts were less than reliable. That's was the reason.

rotary crazy

you are correct, I was not thinking clearly, the smaller FI engine has a lot of avantages, a DI 12a with a variable geometry turbo so that not a lot of boost lack is present would be a great idea

Now the real question is would mazda make a new force induction engine? will the general public accept a samller engine when we know that public perception is that bigger is better

rotarygod

I think a Renesis based 12A would be great. Think about it. You have more port area per engine volume yet the same timing. Since all ports are side ports and this dimension doesn't change, the port size wouldn't either. It would be like a large ported 12A. The total exhaust port area of the Renesis ports would also be much greater than those of the 12A peripheral exhaust ports which are tiny. Also consider that since a 12A is narrower, that also means that the apex seals are narrower. That means that they are stronger as you have less seal length that can flex. Blowing up a 12A is much larder than blowing up even a 3mm seal 13B for this reason. They are durable. Remember also that narrower rotors would be lighter rotors. Another plus. Now bolt a turbo to it. Add direct injection in there and make the whole thing out of aluminum and now we've got a nice little package.

It's the equivalent of going from a 2.6 to a 2.2 liter engine. Now look at how many small engines out there are getting turbocharged and getting good power numbers. The STi, Evo, SRT-4 and even the MZR engine in the MS3 and MS6 are a few that come to mind. We are also seeing this trend in certain V6's which through the help of turbos advertise the power of a V8 with the economy of a V6. Just apply this trend to rotaries. It would be a hit. It works in other markets. If you advertise it as a plus, it'll sell. The narrower rotor is actually a benefit to strength. I think it's a great idea. I'd buy it.

FWIW: The max power I've seen someone hit out of a 12A is almost 700 rwhp! Not a street engine but still impressive.

rotary crazy

I agree completly,we had a firts gen 12a Pport and that sucker made 217+ rwhp, the ports on the renensis are huge they must be almost as big as a Pport 12a, and with a turbo it could hit 280 hp with out much problems, and those 12a love to rev hi 10,000+ rpm, and they are really hard to brake!


I LIKE IT!!!

Floyd

still, a 3 rotor NA rx-7 would become legendary. and, by basing it off the 12A your would still gain all the benifits of reliability RG mentioned. I can't even imagine what kind of after market gains could be made on that platform w/o the expense of the current 20B swap for 3 rotor power!

cornrowdpantha

I feel the need to repeat my opinion that Mazda should leave the RX-7 in the grave, and make the next gen RX-8 a serious competitor. That way, they can continue to attract people that want a versitile 2+2 sports car, while simultaneously satisfying peoples craving for increased performance...

Floyd

With 2 kids of my own I would be thrilled if this were the route they took. Still the thought of a 3 rotor production car in the US gives me goose bumps.

RG, would there be even more reliability benifits if they based a 3 rotor off of the 10A rotors? Or is there a deminishing returns on the down scaling of the rotor sizing?

kiyoshi

I welcome bigger 2 rotor rotary and I thought it was coming but I now doubt it. Because other cars are getting so much hp numbers these days, I don't think mazda will comes with 1.6L NA (I assume it produces around 300hp) as a heart for next rx7. I also doubt they will come with turbo rotary. I believe they can make it run quick in corners, but I don't think it's attractive for sales point of view. I am sure you will chose rx7 even if it is 300hp, but I don't think others who don't care about rotary chose that number - that means mazda cannot expect good sales on rx7 again.

IMHO, mazda needs to make rx7 pure light weight sports car (say, like Lotus) with 1.3L NA rotary, which is primary targeted for track driving and should be designed to swap engine easily to 3 rotor 2.0L rotary for ultimate performance.

Red Devil

Sounds perfect to me...just as long as my 6'2" frame can fit in it...

mac11

iTrader: (1)

how does someone with a name like kiyoshi end up in indiana?

cavemancan

You certainly know more than I regarding rotaries but I have a question...

Is it true when dealing with a Piston engine going up in displacement will normally mean a larger mid range torque curve? Keep in mind I am basically talking about Chevy LS series motors as these are the ones I know the most about. It just seems that when comparing lets say a Turbo echoteck to a LS2 motor you can modify the turbo 4 to the power of the LS2 easily but the LS motor will provide a better torque curve. (Sorry I am bringing up the torque questions...Don't kill me)

With that thought in mind building a smaller turbo rotary engine...Wouldn't a larger turbo rotary give a better torque curve? Also, how would the torque curve compare from a 12A Turbo to a 3-rotor NA based off of 10A or 12A rotors?

Truthfully I am not that worried about fuel economy...If it gets better then great...If it stays the same and we get more power...Awsome! Ultimately, I want an engine with good power out the box that has potential to be modded to good power numbers (like 400 wHp) relatively reliably.

dillsrotary

Zoom it says 16C

77mjd

Does anyone know exactly what Mazda's target hp is with this new rotary? Everyone seems to say the magic number is 300. I dont even think it has to be that high. I think giving it 275 would be plenty. Remember the prototype 8 in Speed magazine? (the pearl white with the supercharger) Is that setup just not doable or what? Would there be emissions issues?