New Mazda 'WIDE' (15B) Rotary 2007
#151
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fred has been known to say that from time to time. so the formula for figuring out volume is
Excentricity X Radius X Width X 5.196. then multiply by the number of rotors. found it here http://66.102.7.104/search?q=cache:h...ient=firefox-a and here http://www.rotaryaviation.com/rotaryhistory.htm
E x R x W x 5.196 = 750cc . so lets plucg in some numbers and see what we can find out. lets keep the W the same as current and solve for E and R. what is the current W?
Excentricity X Radius X Width X 5.196. then multiply by the number of rotors. found it here http://66.102.7.104/search?q=cache:h...ient=firefox-a and here http://www.rotaryaviation.com/rotaryhistory.htm
E x R x W x 5.196 = 750cc . so lets plucg in some numbers and see what we can find out. lets keep the W the same as current and solve for E and R. what is the current W?
#152
Originally Posted by RG
It still makes no sense. A larger 2 rotor will develop no more power than the current engine. It will just develop the same power at lower rpms. It's airflow limited to only what the current engine has. There is no room for more port area. No engineer can change that. The real truth is that we aren't going to see a larger rotary. It makes no sense. Direct injection can't change that. What's more likely is that we will see added power with a power adder on the current engine. I'm not sure who started the rumor of a 1.5L and why anyone would believe it but I don't believe they are developing one at all. It's not practical. If we are going to get into the "not yet" game, Chevy just hasn't released the supercharged 3 rotor C6 yet. It's not "never" and just as likely as a 1.5L rotary in an RX-8.
But even if you can't increase the port area you can still increase the power of the engine. If you increase the stroke on a piston engine you increase power over the whole rpm range even though the valves didn't increase in size either. Admittably, the power gain is higher in the lower than in the upper rpm range.
#153
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the thin is that mazda prefers NA (as do I) and the logic for going bigger is the same that was used to go from 12a to 13b and remember that the 12a turbo made the same power that the 13b NA.
If mazda wants to keep up with the competition they must find a way to increase power and TORQUE in NA form and if you look at the competitors they all increase power by increasing displacement.
what way is mazda going to use? we'll see and have fum guessing
but there are 2 ways of doing it 1 increase the rotor wid( more easy and faster) 2 increase the entire engine wid and height, entire new engine, more heavy but a lot more power
If mazda wants to keep up with the competition they must find a way to increase power and TORQUE in NA form and if you look at the competitors they all increase power by increasing displacement.
what way is mazda going to use? we'll see and have fum guessing
but there are 2 ways of doing it 1 increase the rotor wid( more easy and faster) 2 increase the entire engine wid and height, entire new engine, more heavy but a lot more power
Last edited by rotary crazy; 10-26-2005 at 12:59 PM.
#156
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Originally Posted by rotary crazy
Another thyn I was thynking about , can the engine injest air faster thru the same port size, I read some where that the speed of the air going in is what is important not the port size?
maybe some sort of ram air?
maybe some sort of ram air?
We can't really compare the old 10A, 12A, 13B ,15A, engines to the Renesis and it's scale. Remember that all of those old engines, including the 15A, had smaller intake ports than the current engine. They could very easily vary their size to make some larger than others back then as they had room to grow. There is no more room to grow. Also remember that with a peripheral exhaust port a wider rotor housing also allowed a larger exhaust port while being able to keep the same port timing. With the side ports, we can not add exhaust port area. We are out of room.
It has been said that there won't be a 3 rotor (even though we've had one before) due to added costs and complexity. Dont' foprget the complex nightmare that twin turbos were also that they also used instead of cheaper simpler singles. It is also unlikely there will be a larger 2 rotor due to lack of airflow capability and the fact that mileage will suffer. Don't bring DI into this as a justification. It's not a solution to making an engine larger although it does have it's benefits. What is most likely is that we will see the current size stay right where it is but using forced induction. We will probably also see it progress into the realm of DI to improve other areas. I just don't see a larger engine that makes no more power that uses DI to just bring it back to the current engine emissions and mileage numbers being a practical thing to do. It would make more sense to improve what we have and then to boost it. That would be the cheapest alternative.
It is interesting to note that Mazda has progressed from an 8A and smaller (testing only) to a 10A to a 12A to a 13B and then tried the 15A and 21A configurations but still settled on the 13B size. Use the gas crisis as an excuse all you want but it is this size that had the fewest compromises. It was also this size that was used to add a rotor for the 20B rather than just making a larger 2 rotor. The Renesis castings are all new from the 13B and share nothing. It wouldn't have been any more difficult to make a 15A sized engine if it was so advantageous. All the castings changed anyways. As I've said, I'd be more than happy to see a 1.5L 2 rotor appear. I won't complain. It just doesn't make much sense and the appearance of one would hint of potential improvements that should be made to the current engine.
#157
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Originally Posted by rotarygod
I'm not sure who started the rumor of a 1.5L and why anyone would believe it but I don't believe they are developing one at all.
the original rumour was started by mazda engineers. follow the link in the 2nd post by buger in this thread from 2002
https://www.rx8club.com/showthread.p...t=widen+rotors
edit- oops the link doesnt take you to the article anymore, s'okay as buger quotes the important part.
#158
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Originally Posted by rotarygod
This is true. If there was more power from a 1.5, this gives us some different possibilities. If in fact a larger 1.5L Renesis with the same port size does in fact make more power due to added intake velocity, this would also imply that the current Renesis has ports that are too large and it is not making the power that it could be. In which case you could get more power yet out of this engine and therefore have no need to go larger. You also need to remember that the current engine brings more intake ports and area online as rpm's rise because they are maxing them out. This doesn't imply there is much room left in area to get much more power.
We can't really compare the old 10A, 12A, 13B ,15A, engines to the Renesis and it's scale. Remember that all of those old engines, including the 15A, had smaller intake ports than the current engine. They could very easily vary their size to make some larger than others back then as they had room to grow. There is no more room to grow. Also remember that with a peripheral exhaust port a wider rotor housing also allowed a larger exhaust port while being able to keep the same port timing. With the side ports, we can not add exhaust port area. We are out of room.
It has been said that there won't be a 3 rotor (even though we've had one before) due to added costs and complexity. Dont' foprget the complex nightmare that twin turbos were also that they also used instead of cheaper simpler singles. It is also unlikely there will be a larger 2 rotor due to lack of airflow capability and the fact that mileage will suffer. Don't bring DI into this as a justification. It's not a solution to making an engine larger although it does have it's benefits. What is most likely is that we will see the current size stay right where it is but using forced induction. We will probably also see it progress into the realm of DI to improve other areas. I just don't see a larger engine that makes no more power that uses DI to just bring it back to the current engine emissions and mileage numbers being a practical thing to do. It would make more sense to improve what we have and then to boost it. That would be the cheapest alternative.
It is interesting to note that Mazda has progressed from an 8A and smaller (testing only) to a 10A to a 12A to a 13B and then tried the 15A and 21A configurations but still settled on the 13B size. Use the gas crisis as an excuse all you want but it is this size that had the fewest compromises. It was also this size that was used to add a rotor for the 20B rather than just making a larger 2 rotor. The Renesis castings are all new from the 13B and share nothing. It wouldn't have been any more difficult to make a 15A sized engine if it was so advantageous. All the castings changed anyways. As I've said, I'd be more than happy to see a 1.5L 2 rotor appear. I won't complain. It just doesn't make much sense and the appearance of one would hint of potential improvements that should be made to the current engine.
We can't really compare the old 10A, 12A, 13B ,15A, engines to the Renesis and it's scale. Remember that all of those old engines, including the 15A, had smaller intake ports than the current engine. They could very easily vary their size to make some larger than others back then as they had room to grow. There is no more room to grow. Also remember that with a peripheral exhaust port a wider rotor housing also allowed a larger exhaust port while being able to keep the same port timing. With the side ports, we can not add exhaust port area. We are out of room.
It has been said that there won't be a 3 rotor (even though we've had one before) due to added costs and complexity. Dont' foprget the complex nightmare that twin turbos were also that they also used instead of cheaper simpler singles. It is also unlikely there will be a larger 2 rotor due to lack of airflow capability and the fact that mileage will suffer. Don't bring DI into this as a justification. It's not a solution to making an engine larger although it does have it's benefits. What is most likely is that we will see the current size stay right where it is but using forced induction. We will probably also see it progress into the realm of DI to improve other areas. I just don't see a larger engine that makes no more power that uses DI to just bring it back to the current engine emissions and mileage numbers being a practical thing to do. It would make more sense to improve what we have and then to boost it. That would be the cheapest alternative.
It is interesting to note that Mazda has progressed from an 8A and smaller (testing only) to a 10A to a 12A to a 13B and then tried the 15A and 21A configurations but still settled on the 13B size. Use the gas crisis as an excuse all you want but it is this size that had the fewest compromises. It was also this size that was used to add a rotor for the 20B rather than just making a larger 2 rotor. The Renesis castings are all new from the 13B and share nothing. It wouldn't have been any more difficult to make a 15A sized engine if it was so advantageous. All the castings changed anyways. As I've said, I'd be more than happy to see a 1.5L 2 rotor appear. I won't complain. It just doesn't make much sense and the appearance of one would hint of potential improvements that should be made to the current engine.
Interesting write-up, thanks for the info
Something that I didn't know and think I know now; the 20b was actually ~1950ccs? I never really thought about it, but it should be just around the 1950-1960 range if it's just another rotor from the 13b, correct?
#159
Actually there would be a way to increase the port area on a 15B. Granted that this would increase complexity, but they could add peripheral ports in addition to the side ports.
Of course the peripheral ports should then only open above a certain rpm (e.g. 6500rpm), to keep the benefits of the side ports.
Also, a widened 15B could still reach the rpm of a 13B.
Of course the peripheral ports should then only open above a certain rpm (e.g. 6500rpm), to keep the benefits of the side ports.
Also, a widened 15B could still reach the rpm of a 13B.
#160
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We are never going to see a peripheral port added in due to emissions reasons so that isn't a viable option. There is no way to get more port area. Even that porting style was tried back in the 70's.
Last edited by rotarygod; 10-26-2005 at 04:58 PM.
#161
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Originally Posted by Aoshi Shinomori
Interesting write-up, thanks for the info
Something that I didn't know and think I know now; the 20b was actually ~1950ccs? I never really thought about it, but it should be just around the 1950-1960 range if it's just another rotor from the 13b, correct?
Something that I didn't know and think I know now; the 20b was actually ~1950ccs? I never really thought about it, but it should be just around the 1950-1960 range if it's just another rotor from the 13b, correct?
#162
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Originally Posted by rotarygod
The 20B is just another rotor of the same size added on.
#163
Originally Posted by RG
We are never going to see a peripheral port added in due to emissions reasons so that isn't a viable option. There is no way to get more port area. Even that porting style was tried back in the 70's.
Besides if the peripherals only open at a very high rpm, it won't cause emission problems because the drive cycle doesn't require the engine to go up to 8000 rpm or something.
#164
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RG... what do you think of the use of hybrid over FI? You can loose some weight as you no longer need several conventional drivetrain parts. The electric motor would give the car the needed low-end boost it needs while also improving fuel economy. We can see they are at least studying it with the Premacy/Mazda5 RE Hybrid.
Speaking of which... what do you think of Mazda "re-engineering" the RE to fit transverse mounted in the Premacy/Mazda5 RE Hybrid? Mazda planning other applications?
Speaking of which... what do you think of Mazda "re-engineering" the RE to fit transverse mounted in the Premacy/Mazda5 RE Hybrid? Mazda planning other applications?
#165
This is all speculation but for following reasons I believe it would make more sense to 'widen' the 13B to a 15B than to make a 3 rotor 10A:
* The 2 rotor is already perfectly balanced (so what's the point?).
* The 3 rotor is obviously more complex and therefore more costly (33% more intakes, 33% more headers, 33% more injectors, 33% more valves, 33% more rotors, 33% more seales etc.).
* The 3 rotor will be heavier.
* The 3 rotor would have 33% more sealing surface (= more frictional losses and more pressure loss since no seal is perfect).
* The 3 rotor has a higher overall surface to volume ration (= more heatloss = less efficient and less power.)
* If the 3 rotor has 2 spark plugs per chamber the 2 rotor can have 3 spark plugs per chamber.
* The 3 rotor in this configuration (10A) wouldn't allow higher rpms without overstressing the crankshaft. If the rotors were wider and smaller in diameter then there might be a point in making 3 rotors (higher rpm = more power). But would general customers want to buy a car that needs to be run at 11000 rpm to get somewhere?
Why did Mazda built a 20B? Maybe because it wouldn't have gained enough power by widening the 13B or maybe for the same reason it built a 1.8l V6?
* The 2 rotor is already perfectly balanced (so what's the point?).
* The 3 rotor is obviously more complex and therefore more costly (33% more intakes, 33% more headers, 33% more injectors, 33% more valves, 33% more rotors, 33% more seales etc.).
* The 3 rotor will be heavier.
* The 3 rotor would have 33% more sealing surface (= more frictional losses and more pressure loss since no seal is perfect).
* The 3 rotor has a higher overall surface to volume ration (= more heatloss = less efficient and less power.)
* If the 3 rotor has 2 spark plugs per chamber the 2 rotor can have 3 spark plugs per chamber.
* The 3 rotor in this configuration (10A) wouldn't allow higher rpms without overstressing the crankshaft. If the rotors were wider and smaller in diameter then there might be a point in making 3 rotors (higher rpm = more power). But would general customers want to buy a car that needs to be run at 11000 rpm to get somewhere?
Why did Mazda built a 20B? Maybe because it wouldn't have gained enough power by widening the 13B or maybe for the same reason it built a 1.8l V6?
#166
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Originally Posted by zoom44
this one was started by wheels magazine.
the original rumour was started by mazda engineers. follow the link in the 2nd post by buger in this thread from 2002
https://www.rx8club.com/showthread.p...t=widen+rotors
edit- oops the link doesnt take you to the article anymore, s'okay as buger quotes the important part.
the original rumour was started by mazda engineers. follow the link in the 2nd post by buger in this thread from 2002
https://www.rx8club.com/showthread.p...t=widen+rotors
edit- oops the link doesnt take you to the article anymore, s'okay as buger quotes the important part.
#167
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Originally Posted by globi
This is all speculation but for following reasons I believe it would make more sense to 'widen' the 13B to a 15B than to make a 3 rotor 10A:
* The 2 rotor is already perfectly balanced (so what's the point?).
* The 2 rotor is already perfectly balanced (so what's the point?).
Originally Posted by globi
* The 3 rotor is obviously more complex and therefore more costly (33% more intakes, 33% more headers, 33% more injectors, 33% more valves, 33% more rotors, 33% more seales etc.).
Originally Posted by globi
* The 3 rotor will be heavier.
Originally Posted by globi
* The 3 rotor would have 33% more sealing surface (= more frictional losses and more pressure loss since no seal is perfect).
Originally Posted by globi
* The 3 rotor has a higher overall surface to volume ratio (= more heatloss = less efficient and less power.)
Originally Posted by globi
* If the 3 rotor has 2 spark plugs per chamber the 2 rotor can have 3 spark plugs per chamber.
Originally Posted by globi
* The 3 rotor in this configuration (10A) wouldn't allow higher rpms without overstressing the crankshaft. If the rotors were wider and smaller in diameter then there might be a point in making 3 rotors (higher rpm = more power). But would general customers want to buy a car that needs to be run at 11000 rpm to get somewhere?
Originally Posted by globi
Why did Mazda built a 20B? Maybe because it wouldn't have gained enough power by widening the 13B or maybe for the same reason it built a 1.8l V6?
Last edited by rotarygod; 10-27-2005 at 03:04 AM.
#168
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Originally Posted by zoom44
this one was started by wheels magazine.
the original rumour was started by mazda engineers. follow the link in the 2nd post by buger in this thread from 2002
https://www.rx8club.com/showthread.p...t=widen+rotors
edit- oops the link doesnt take you to the article anymore, s'okay as buger quotes the important part.
the original rumour was started by mazda engineers. follow the link in the 2nd post by buger in this thread from 2002
https://www.rx8club.com/showthread.p...t=widen+rotors
edit- oops the link doesnt take you to the article anymore, s'okay as buger quotes the important part.
Originally Posted by Buger
"Mazda powertrain managers have ruled out the chance of turbocharging the RX-8 RENESIS rotary engine but admit they are looking at ways of increasing capacity of the 1300cc two-rotor engine, bringing more naturally aspirated power to the lightweight unit."
I was confused by the "looking at ways of increasing capacity" part because it would have been simpler to just say that they were looking at using a 3 rotor. In thinking about other ways Mazda could increase displacement, I found that they have widened the rotors in the past to increase displacement.
I was confused by the "looking at ways of increasing capacity" part because it would have been simpler to just say that they were looking at using a 3 rotor. In thinking about other ways Mazda could increase displacement, I found that they have widened the rotors in the past to increase displacement.
I do have to point out that if they have ruled out the chance of turbocharging the Renesis, how come Mazda keeps playing with forced induction on the Renesis? I'm not sure I put any trust in a magazine article that has never been substantiated especially one that is 3 years old and came out before the RX-8 even did. I've seen alot of magazines post pictures of the "new RX-7" too and they've all looked different. Not sure I trust them either.
Last edited by rotarygod; 10-27-2005 at 03:16 AM.
#169
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RG, in your opinion can mazda make a 3 rotor power rx-8 for less than $30,000? a performance version mazdaspeed, lihtter, better handling, 300 NA hp, no accesorys like the evos used to be .
I read some where that mazda was making 20b crate motors for racing teams is this true?
I heard from a very relible source that mazda was testing a lot of diferent comfigurations of rotary engines, 3 rotors, wider rotors, turbo and super charge, hybrids, etc. And the teams that where wining where the 3 rotor the wider rotors and the hybrids, turbo and super charge had relaiblity concerns but this is just a RUMOR .
I read some where that mazda was making 20b crate motors for racing teams is this true?
I heard from a very relible source that mazda was testing a lot of diferent comfigurations of rotary engines, 3 rotors, wider rotors, turbo and super charge, hybrids, etc. And the teams that where wining where the 3 rotor the wider rotors and the hybrids, turbo and super charge had relaiblity concerns but this is just a RUMOR .
Last edited by rotary crazy; 10-27-2005 at 07:49 AM.
#170
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Yeah, RG...it seems your a 3-rotor guy (like myself while I know little about rotary engines).
So, the E-Shaft has to be bigger but from the looks of one rotor housing it seems that the difference wont be that much.
So what's keeping the 3-rotor from becoming the norm? Maybe Mazda should make it slightly smaller (1L) add a rotor to make it a 3-rotor engine and then use direct injection to help with the fuel economy. Also, since it would have more power and torque they then could re-do our tranny to have a higher top end so in reality fuel economy might actually get better and not worse.
But, I don't know much about this stuff. From what I hear from the members here going with a Turbo or SC might just make things worse and I think it's time that the rotary engine starts producing more HP as a NA engine if it wants to gain more acceptance in the car world.
Listen up Mazda...give us a 3-rotor 1L rotary engine making about 325HP along with direct injection and a higher 6th gear and we might just have solved all our complaints in one engine design.
I'm such a dreamer...I know...lol
So, the E-Shaft has to be bigger but from the looks of one rotor housing it seems that the difference wont be that much.
So what's keeping the 3-rotor from becoming the norm? Maybe Mazda should make it slightly smaller (1L) add a rotor to make it a 3-rotor engine and then use direct injection to help with the fuel economy. Also, since it would have more power and torque they then could re-do our tranny to have a higher top end so in reality fuel economy might actually get better and not worse.
But, I don't know much about this stuff. From what I hear from the members here going with a Turbo or SC might just make things worse and I think it's time that the rotary engine starts producing more HP as a NA engine if it wants to gain more acceptance in the car world.
Listen up Mazda...give us a 3-rotor 1L rotary engine making about 325HP along with direct injection and a higher 6th gear and we might just have solved all our complaints in one engine design.
I'm such a dreamer...I know...lol
#171
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And sell the renesis 3 rotor as a crate motor, mazda could sell 10,000 engines.
A lot of RX-7 and RX-8 will fit this engine to they'r cars
A lot of RX-7 and RX-8 will fit this engine to they'r cars
Last edited by rotary crazy; 10-27-2005 at 08:04 AM.
#172
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Originally Posted by rotarygod
If you notice,
of course i noticed i knew exactly what he wrote when i posted it i like argueing in circles it keeps people on their toes.
to sum up for those that dont read the link- it was Buger that started the wider rotors rumour 3 years ago but even he was against the idea and pointed out the reasons why a 3 rotor would be more advantageous. later in the thread its wakeech who champions the 1.5 or .6 2rotor. its amazing to me how the conversations repeat themselves with new players
#173
Originally Posted by RG
Actually it's 50% more which is still less than any piston engine in terms of total number of needed parts. Valves??? They've obviously done it before and put it into production which is more than can be said for a larger 2 rotor.
Originally Posted by RG
And? Not much if done right as the rotors and housings would each be smaller. A wider 2 rotor would also be heavier than the current engine. Not much advantage either way.
Originally Posted by RG
Again it's actually 50%. It would also have the potential for more breathing ability over the current engine which a 2 rotor wouldn't have. A 3 rotor Renesis of any size can always have 50% more breathing ability than a 2 rotor Renesis of any size in terms of port area. A larger 2 rotor would also have more stress per seal as each seal is responsible for a larger area. A seal that has less stress on it also needs less spring pressure against it (this is assuming a 1.5L 2 rotor vs a 1.5L 3 rotor) which would actually result in a seal that would last longer and housings that wouldn't wear out as fast.
As I mentioned before you could always add peripheral ports in addition to the side ports if side port area was indeed a problem. However is port area really an issue and is it not port timing? The S2000 has smaller sized valves than the Renesis has side ports relative to its engine size and can still spin as high and generate even more power (breath).
Originally Posted by RG
The internal surface to volume ratio is an advantage to a smaller chamber based 3 rotor in terms of combustion and fuel distribution.
With a smaller volume you can achieve better fuel distribution, but if fuel distribution was indeed and still that bad it would have a hard time with emissions in the first place.
Also, frictional losses are almost 50% higher in a 3 rotor 10A vs. a 2 rotor 15A.
Originally Posted by RG
What makes you think that there is any reason why a 2 rotor can use 3 plugs per chamber and a 3 rotor can't. How does the amount of rotors affect this?
Originally Posted by RG
First off, why would you need to rev a 3 rotor higher?
This has been known with piston engines and I don't see why this would not be applyable to rotary engines at all.
Last edited by globi; 10-27-2005 at 10:57 AM.
#174
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I still don't buy any of that.
A rotary engine HAS NO VALVES!!!!! None. How else do the intake ports open? It's called the movement of the rotor itself past the port. There are no valves. No poppet valves or anything.
A rotary engine HAS NO VALVES!!!!! None. How else do the intake ports open? It's called the movement of the rotor itself past the port. There are no valves. No poppet valves or anything.
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all of the losses in a 3 rotor are ofset by the increase power, a 3 rotor renesis will produce more power than a 15l or 16l, MPG is another cuestion but theres a lot of people runing aroun with stock port 20b in NA form getting 250+ rwhp and about the same 12 to 15 mpg the renesis gets, theres even a couple of members in this forum with street ports 20b NA getting 320 + rwhp and this all its done on older tecnology.
the thing is that a renesis 20B does not need the gearing to be so agresive so maybe 3.90 instead of the 4.44 the rx-8 has now, or keep the 4.44 but put taller 5ht and 6ht gears.
the sheap solution in the short run are FI systems but if mazda wants to invest in the rotary future the 3 rotor or wider engine and the hybred's must be adopted.
the thing is that a renesis 20B does not need the gearing to be so agresive so maybe 3.90 instead of the 4.44 the rx-8 has now, or keep the 4.44 but put taller 5ht and 6ht gears.
the sheap solution in the short run are FI systems but if mazda wants to invest in the rotary future the 3 rotor or wider engine and the hybred's must be adopted.