Next Rotary A 16 X
10-25-2007, 11:25 AM
#126
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I doubt compression ratio will go any higher than it is now. It could but I'd be surprised. It would be pointless for them to go down just for the sake of the aftermarket. I'd keep it high if I were them too.
Let's say the engine puts out 270 hp. If we could boost it to a nice 8 lbs we could theoretically get around 400 hp so I'm not too sure why that would be an issue. Imagine a rotary with 400 hp on fairly low boost!!!
Let's say the engine puts out 270 hp. If we could boost it to a nice 8 lbs we could theoretically get around 400 hp so I'm not too sure why that would be an issue. Imagine a rotary with 400 hp on fairly low boost!!!
Now, with a "long stroke" rotary, wouldn't this problem be offset to even higher compression values? And, in this case, wouldn't a comp ratio slightly higher than 10:1 increase the engine overall efficiency by extracting more energy from the combustion? (of course if detonation is not an issue)
Another question: in some photos a huge single port is visible on the middle plate. As I understand it, that location is used on the current Renesis by the primary ports. The question is: couldn't it be that they swapped the locations of the primary and secondary ports? In other words, could it be that those big ports are actually the secondary ports? Or maybe even the auxiliary ports?
EDIT:
Originally Posted by gr8rx
i beleive that I read somewhere that upping the compression on the rx8 further showed no gains, so the mazda engineers stopped at the current comp ratio, if this is the case with the 16x as well, then the ratio should be the same. As far as DI goes its supposed to increase the threshold of where detonation occurs so all other things aside the 16x should be easyer to boost and more reliable to boost, as long as the new dimensions dont somehow screw things up
Last edited by fmzambon; 10-25-2007 at 11:29 AM.
10-25-2007, 11:39 AM
#127
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That's a really good question in regards to compression ratio and the rotor dish. I guess it really depends on how long the dish is vs how deep or wide it is. There will always be the same phenomenon but if it is at the same compression is the real question. That's a good observation that would be interesting to know.
I guarantee the center ports are still the primaries. FWIW the early side port rotaries from the late 60's and early 70's were reversed with the primaries on the outer plates and the secondaries being in the intermediate housing.
I guarantee the center ports are still the primaries. FWIW the early side port rotaries from the late 60's and early 70's were reversed with the primaries on the outer plates and the secondaries being in the intermediate housing.
10-25-2007, 06:03 PM
#128
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Isn't it true that though a higher compression ratio might not result in a power gain in rotaries, it can still be desirable (up to a point) for efficiency reasons? You're looking at meeting emissions regulations and improving fuel economy, two things that rotaries have traditionally struggled at. In this case, even if there are no power gains, as long as there are no power losses it would be extremely tempting to get extra efficiency for that very reason.
10-25-2007, 09:53 PM
#130
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Completely agree with you. This thread has inspired a new savings account for me. When this is released, I'll either buy a whole new car, or just as you said Chetrickerman: "Buy engine and Tranny".
I'm so grateful we have shops out here in British Columbia that specialize in the 20b Rotary engine and the like. Not to mention, our our knowledgeable club mechanics.
I'm dieing to hear the roar of this new Rotary Engine.
I'm so grateful we have shops out here in British Columbia that specialize in the 20b Rotary engine and the like. Not to mention, our our knowledgeable club mechanics.
I'm dieing to hear the roar of this new Rotary Engine.
10-26-2007, 05:07 AM
#134
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Isn't it true that though a higher compression ratio might not result in a power gain in rotaries, it can still be desirable (up to a point) for efficiency reasons? You're looking at meeting emissions regulations and improving fuel economy, two things that rotaries have traditionally struggled at. In this case, even if there are no power gains, as long as there are no power losses it would be extremely tempting to get extra efficiency for that very reason.
I think the possibility of higher compression ratios boils down to another question: Does the minimum surface of the section of the rotor disc needed to effectively transmit the flame front increase with the rotor displacement, or is there an absolute minimum that is valid regardless of rotor size?
In other words, if a passage with, say, 5 square centimeters is needed for a Renesis size rotor, does a 16x size rotor still need 5 square centimeters or does it need more? And if so, how much more?
I have a feeling that this surface needs to get bigger with the larger displacement, but not much bigger. Of course testing and experimenting is the only real way to get an answer, but I think that the flame front only needs a minimum passage area, regardless of chamber size.
This said, I think a mild compression ratio increase (something like 10.2:1 to 10.5:1) would make sense, also because it should help with the flooding issue.
Just my 2.8 cents.
Thoughts?
10-26-2007, 05:11 AM
#135
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Wouldn't those big ports hurt low end torque? I mean, of course it's a bigger engine and it needs larger passages, but there's a limit to everything!EDIT: Now I have found why these ports look so big: the are not ports! What I was looking at was the reflection of the rotor recess on the middle plate!
I've officially won the title for the dumbest of the week
Last edited by fmzambon; 10-26-2007 at 08:14 AM.
10-26-2007, 07:10 AM
#136
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10-26-2007, 08:50 AM
#137
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As someone who's never owned a rotary powered car before (but has wanted to own one for many years), my biggest concerns about buying a current RX-8 are:
1) Fuel economy
2) Oil consumption
3) Engine flooding
4) Lack of torque
5) Maintenance schedule
I think concern #3 was addressed with the new starter and spark plugs for the '06 model years and later, and if the new 16X goes into production, it'll take care of concerns #1, #2 and #4. I can definitely live with concern #5...
If Mazda's claims about this new 16X rotary hold true, it will definitely make the rotary more appealing to a broader segment of the population!
10-26-2007, 09:36 AM
#139
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Actually my wish list for Mazda's next performance car(s): Mazda, can you please style this thing so that it looks really good with 17's? I know the 8 can use them, but it looks sort of goofy. 17" tires and wheels are substantially cheaper, and just the lower moment of inertia and gearing improvement improves all areas of the car's performance.
So yeah, that...plus don't go over 3,000 lbs. It's time to draw a line in the sand. Creeping wheel size and curb weight is like a cancer that is eating away at performance cars.
Thanks! Here's hoping they drop that RENESIS 16X into the restyled RX-8!!!
As someone who's never owned a rotary powered car before (but has wanted to own one for many years), my biggest concerns about buying a current RX-8 are:
1) Fuel economy
2) Oil consumption
3) Engine flooding
4) Lack of torque
5) Maintenance schedule
I think concern #3 was addressed with the new starter and spark plugs for the '06 model years and later, and if the new 16X goes into production, it'll take care of concerns #1, #2 and #4. I can definitely live with concern #5...
If Mazda's claims about this new 16X rotary hold true, it will definitely make the rotary more appealing to a broader segment of the population!
As someone who's never owned a rotary powered car before (but has wanted to own one for many years), my biggest concerns about buying a current RX-8 are:
1) Fuel economy
2) Oil consumption
3) Engine flooding
4) Lack of torque
5) Maintenance schedule
I think concern #3 was addressed with the new starter and spark plugs for the '06 model years and later, and if the new 16X goes into production, it'll take care of concerns #1, #2 and #4. I can definitely live with concern #5...
If Mazda's claims about this new 16X rotary hold true, it will definitely make the rotary more appealing to a broader segment of the population!
Last edited by BaronVonBigmeat; 10-26-2007 at 09:43 AM.
10-26-2007, 09:56 AM
#140
Row faster, I hear banjos
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+1 on #1 and #4 - just a wait and see game with Mazda. With gas being what it is today, buying a 6MT sports car rated at 16city/22highway will turn several buyers away. In the link to the Mazda concept page that chetrickerman posted, Mazda did mention that their direct injection engines will be able to use to their Smart Idle Stop System (SISS) that cuts fuel consumption by ~10%. If the direct injected 16X rotary utilizes that system, city fuel economy could be greatly improved especially when combined with the overall better efficiency of that larger engine. I'm *hoping* for fuel economy numbers in the 20city/25-26 highway range...
10-26-2007, 10:08 AM
#141
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to get the 16x into the rx-8 its a major task for mazda, they would have to change so many things
complete fuel system, engine management,cooling system, maybe even the trans
complete fuel system, engine management,cooling system, maybe even the trans
10-26-2007, 10:31 AM
#143
They already use DI in the MS6/3 and those ECU's are basically the same as ours.
The size not being changed possibly means that the bell housing for the trans is hopefully the same.
It might not be as hard as we think...
I would really like a pic of that siamese port...
I also dont know why they are not simply DI'n a fuel/air/oil slurry...
Maybe there is something intrinsically wrong with the idea...
10-26-2007, 10:35 AM
#144
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When and if the engine does finally make it into production, I'm curious how many people are still going to complain that it's too heavy, doesn't have enough power or torque, and has poor gas mileage? I'm also curious to see how many people complain because it doesn't rev to 18,000 rpms and the car doesn't come with a 5.75:1 rear end. No matter how good Mazda makes this engine, it will NEVER be good enough for some. They could build a 400 hp rotary that gets 30 mpg and some people would still complain that they didn't get more. Then the comparisons would come out as to why a GM LSX V8 engine is a better choice. I can see it happening now.
Keep in mind that if this engine does become a reality, we are really going to see the rotary return as a huge threat in racing. We'll see them dominate again, and again we'll see rules change to handicap them. That is my prediction and I'm sticking to it. I hope I can find this post again in 10 years! If an all peripheral port 13B can be made to hit 350 hp, an engine that is 23% larger could potentially (in a perfect world) hit 430 hp. Let's go racing!
Keep in mind that if this engine does become a reality, we are really going to see the rotary return as a huge threat in racing. We'll see them dominate again, and again we'll see rules change to handicap them. That is my prediction and I'm sticking to it. I hope I can find this post again in 10 years! If an all peripheral port 13B can be made to hit 350 hp, an engine that is 23% larger could potentially (in a perfect world) hit 430 hp. Let's go racing!
10-26-2007, 10:37 AM
#146
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I think it's all about the power/MPG ratio. People will tolerate bad MPG if performance is better. Or mediocre performance if the MPG is better. All the more reason to put this engine in a lighter car, which is really the best way to have your cake and eat it too--better MPG and better performance.
10-26-2007, 10:46 AM
#147
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If the Renesis were installed in an RX-7 chassis (any of them as they are all lighter than the RX-8 by far), with the rear end ratio of the RX-7's being 4.10:1 and the lower weight, the Renesis would already be a 20/30 mpg engine. If they could hit that at a power level around 270 hp or so, that would be awesome. Low weight is definitely the key.
10-26-2007, 10:58 AM
#149
If the Renesis were installed in an RX-7 chassis (any of them as they are all lighter than the RX-8 by far), with the rear end ratio of the RX-7's being 4.10:1 and the lower weight, the Renesis would already be a 20/30 mpg engine. If they could hit that at a power level around 270 hp or so, that would be awesome. Low weight is definitely the key.
All due to weight...stripping it down...
Something that struck me was what the owner said..."We have 7 seat suvs and 4 seat cars that only hold a single person 90% of the time"
The future for efficiency is to reduce weight, and drop the drag, and produce a "targeted" vehicle. The "flow" concepts really demonstrates that Mazda "gets" it...
I need to get rich already so I can get to building my gas powered "teslaesque" roadster...
F1 type suspension...with body lean...and a small gas turbine which only spins up a generator or when the battery bank hits a low enough level...
Step 1 towards electric vehicles...a transition where they use gas for the electricity...