Make or break for Mazda ?
10-02-2003, 07:00 AM
#26
Turbo's on light sportscars are a generaly a bad idea anyhow.
Tag and uneven power delivery cause all sorts of problems I'd rather not have.
IMO a turbo goes a long way to ruin what rotaries are good for - liniar power delivery, and a quick throttle responce. Ok , they do up torque too, a big failing of the rotary.
Look at the publics view of the 3rd gen rx-7 (if they have a view, not exactly a well known car).
Unreliable - down to turbo heat.
Uneconomical - drank like a fish.
Leary - turbo + light + RWD = backwards.
Sure Mazda could produce another 3rd gen rx-7 like car , down to its 'problems' but there a mass market company who need to make profit, there not TVR, noble, lotus etc.
Doesnt mean they have to make something usrine, but it does have to fit into the program.
I hope its 300+bhp, 1200kg, and has all the same gadgets as the RX-8 for keeping it on the road (switch-offable) which I'm sure it will be.
Personaly, the RX-8 looks a succsess already, they cant seem to make enough to meet demand, well see in 2 years though.
I also dont see a 4th gen RX-7 production a problem. It'll almost certainly be using the 8's platform (as will a new mx5 I'm sure), and same drivetrain/LSD/gearbox etc. A slightly bigger 2 rotor would fit in nicely too, I cant see it taking that much effort as they have 80% of the work done already.
Tag and uneven power delivery cause all sorts of problems I'd rather not have.
IMO a turbo goes a long way to ruin what rotaries are good for - liniar power delivery, and a quick throttle responce. Ok , they do up torque too, a big failing of the rotary.
Look at the publics view of the 3rd gen rx-7 (if they have a view, not exactly a well known car).
Unreliable - down to turbo heat.
Uneconomical - drank like a fish.
Leary - turbo + light + RWD = backwards.
Sure Mazda could produce another 3rd gen rx-7 like car , down to its 'problems' but there a mass market company who need to make profit, there not TVR, noble, lotus etc.
Doesnt mean they have to make something usrine, but it does have to fit into the program.
I hope its 300+bhp, 1200kg, and has all the same gadgets as the RX-8 for keeping it on the road (switch-offable) which I'm sure it will be.
Personaly, the RX-8 looks a succsess already, they cant seem to make enough to meet demand, well see in 2 years though.
I also dont see a 4th gen RX-7 production a problem. It'll almost certainly be using the 8's platform (as will a new mx5 I'm sure), and same drivetrain/LSD/gearbox etc. A slightly bigger 2 rotor would fit in nicely too, I cant see it taking that much effort as they have 80% of the work done already.
10-02-2003, 07:01 AM
#27
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here is a wee eye opener for your regarding routine maintenance on a car.
This was seen inside the handbook of my Land Rover Discovery TD5...
"check engine oil every 250 miles"
Now this car does easily 450 miles on a tank so it means checking it more often than putting diesel in.
Mazda RX8 unique with its need for frequent oil checking?
I think not..................
This was seen inside the handbook of my Land Rover Discovery TD5...
"check engine oil every 250 miles"
Now this car does easily 450 miles on a tank so it means checking it more often than putting diesel in.
Mazda RX8 unique with its need for frequent oil checking?
I think not..................
10-02-2003, 07:07 AM
#28
lol, thats kinda stupid, having to stop every half tank to check oil, wont burn that much, I hope...
Manufacturers all say that kinda thing to cover themselves, most cars dont need that , but we know rotaries do use oil, like renaults...
Manufacturers all say that kinda thing to cover themselves, most cars dont need that , but we know rotaries do use oil, like renaults...
10-02-2003, 07:16 AM
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well i must admit i have rarely looked under the bonnet to check the oil, maybe because i have it reguarly serviced at a bone fide lexus dealership. I check tyres etc in fact i have a slow puncture at the moment which im loathed to pay for a new tyre when in 4 weeks i will have a new car (tyre has only a few thousand miles on it). just once a week i pump it up to the 34 PSI doesnt really go below 25 anyway.
Clocked up 43000 miles and i think i have looked at the dipstick maybe 3 or 4 times.
However will be changing that habit when the "baby" arrives.
Clocked up 43000 miles and i think i have looked at the dipstick maybe 3 or 4 times.
However will be changing that habit when the "baby" arrives.
10-02-2003, 07:48 AM
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Aw, come on guys: checking the dipstick should be as much a part of your weekly check as tyre pressures and other fluid levels. This is standard procedure.
10-02-2003, 07:49 AM
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Originally posted by RobDickinson
Doesnt mean they have to make something usrine,
Doesnt mean they have to make something usrine,
Originally posted by specman
here is a wee eye opener for your regarding routine maintenance on a car.
This was seen inside the handbook of my Land Rover Discovery TD5...
"check engine oil every 250 miles"
Now this car does easily 450 miles on a tank so it means checking it more often than putting diesel in.
Mazda RX8 unique with its need for frequent oil checking?
I think not..................
here is a wee eye opener for your regarding routine maintenance on a car.
This was seen inside the handbook of my Land Rover Discovery TD5...
"check engine oil every 250 miles"
Now this car does easily 450 miles on a tank so it means checking it more often than putting diesel in.
Mazda RX8 unique with its need for frequent oil checking?
I think not..................
Last edited by AndyPearce; 10-02-2003 at 07:53 AM.
10-02-2003, 07:57 AM
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Originally posted by Lensman
Aw, come on guys: checking the dipstick should be as much a part of your weekly check as tyre pressures and other fluid levels. This is standard procedure.
Aw, come on guys: checking the dipstick should be as much a part of your weekly check as tyre pressures and other fluid levels. This is standard procedure.
10-02-2003, 08:01 AM
#37
Originally posted by AndyPearce
For you maybe, the only thing I have to check on a regular basis is tyre pressure.
For you maybe, the only thing I have to check on a regular basis is tyre pressure.
10-02-2003, 08:55 AM
#38
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Originally posted by AndyPearce
But in reality do you have to check the car every 250, has the engine been damaged because you didn't?
But in reality do you have to check the car every 250, has the engine been damaged because you didn't?
In fact glad I popped the bonnet on the BMW right after a BMW Main dealer service as it was leaking oil from the filter as the seal hadnt been changed. My usual placid self got a bit angry at that one.(see pic below)So observation is everything in this game.
But I do think that due to everybody becoming very litiguous these days there is text appearing in all daft places with daft comments......
10-02-2003, 09:00 AM
#39
Originally posted by specman
But I do think that due to everybody becoming very litiguous these days there is text appearing in all daft places with daft comments......
But I do think that due to everybody becoming very litiguous these days there is text appearing in all daft places with daft comments......
Download and read the US RX-8 owners manual, its at least 50% warnings and DANGER! type message boxes. scary realy.
10-02-2003, 09:58 AM
#40
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OK, first of all, the RX8 uses a rotary engine, which is unique. This means, whoever wants to own one, must abide by the rules, and realize that this unique engine has its own unique "issues" (not "problems" 
), and must be dealt with accordingly.
Second of all, how many sportscars/supercars do you know that DONT need constant care ? I suppose you brits all know about the TVRs and the Elans and the ACs and the Caterhams etc etc, and their constant need for TLC. I assure you, its the same thing with Lamborghinis, Ferraris, Mazeratis etc etc.......The only supercar maker that gives you any kind of assurance when saying "check every 20K km" is Porsche, and they still tell you to make precaution checks for various bits and pieces, fluids, parts etc.......
Now I know that the RX8 is not actually a supercar (which the new RX7 will be
), but it does fall under the same category. I know that Mazda cannot be put on the same level as Ferrari or Mazerati, but still a lot of effort has to be made (even by you and me) to convince people to treat the RX8 as they should.
And again: I dont suppose you buy a DVD, try to put in a VHS tape, expect it to play, and when it doesnt you start blaming Sony or Philips for not making this clear ? :o . Or put a bolt into the socket, get electrocuted, and then blame the PPC or the socket maker for not making them idiot-proof ?
Same deal......
And for morganrogers: at today's level of progress and technology, internal combustion engines when naturally aspirated have around 50-55% efficiency. That means that the conversion of the chemical energy into kinetic energy has an upper ceiling/limit, when considering a given displacement engine. The only way to increase this efficiency is by using other methods, such as F/I. Not only that, but turbos also use part of the energy "spent" on the heat and speed of the exhaust gases. So, to call F/I "easy" and "compromise" is the same like calling the afterburner system on a turbine jet engine "easy" and "compromising"
), and must be dealt with accordingly.Second of all, how many sportscars/supercars do you know that DONT need constant care ? I suppose you brits all know about the TVRs and the Elans and the ACs and the Caterhams etc etc, and their constant need for TLC. I assure you, its the same thing with Lamborghinis, Ferraris, Mazeratis etc etc.......The only supercar maker that gives you any kind of assurance when saying "check every 20K km" is Porsche, and they still tell you to make precaution checks for various bits and pieces, fluids, parts etc.......
Now I know that the RX8 is not actually a supercar (which the new RX7 will be
), but it does fall under the same category. I know that Mazda cannot be put on the same level as Ferrari or Mazerati, but still a lot of effort has to be made (even by you and me) to convince people to treat the RX8 as they should.And again: I dont suppose you buy a DVD, try to put in a VHS tape, expect it to play, and when it doesnt you start blaming Sony or Philips for not making this clear ? :o . Or put a bolt into the socket, get electrocuted, and then blame the PPC or the socket maker for not making them idiot-proof ?
Same deal......
And for morganrogers: at today's level of progress and technology, internal combustion engines when naturally aspirated have around 50-55% efficiency. That means that the conversion of the chemical energy into kinetic energy has an upper ceiling/limit, when considering a given displacement engine. The only way to increase this efficiency is by using other methods, such as F/I. Not only that, but turbos also use part of the energy "spent" on the heat and speed of the exhaust gases. So, to call F/I "easy" and "compromise" is the same like calling the afterburner system on a turbine jet engine "easy" and "compromising"
10-02-2003, 10:07 AM
#41
But the RX-8 in no way compares to lotus, TVR etc, never mind ferrari etc.
Apart from the engine, its 'just' a normal mass produced sports car.
Like the TT, S3/4 , BMW 330ci etc.
Its designed and build by a major manufacturer who gives a 3 year, 60k mile warenty. Try getting that one out of TVR :P
I expect the rest of the RX-8 (not including the engine) to be as reliable as any other mazda, i.e. tops.
The engine, I'm told, as a NA rotary should be far more reliable than a piston anyhow, so long as treated correctly (serviced, and correct oil levels).
If the RX-8 requires anything like the levels of maintanance an elise or TVR requires mazda will be in deep trouble.
As for already at the tops for NA piston engine efficiency , no way. Theres still tons of things they can/will do. Rotaries are 2-30 years behind AT LEAST in terms of development. Pistons have had 1000's of people working on them for 100+years. Rotaries have had as few as 2 people at mazda working on them, and probably never more than 80. They take advantage of current tech and materials, but are still way behind in development, which may go some way to explain poor fuel efficiency and emmisions.
Apart from the engine, its 'just' a normal mass produced sports car.
Like the TT, S3/4 , BMW 330ci etc.
Its designed and build by a major manufacturer who gives a 3 year, 60k mile warenty. Try getting that one out of TVR :P
I expect the rest of the RX-8 (not including the engine) to be as reliable as any other mazda, i.e. tops.
The engine, I'm told, as a NA rotary should be far more reliable than a piston anyhow, so long as treated correctly (serviced, and correct oil levels).
If the RX-8 requires anything like the levels of maintanance an elise or TVR requires mazda will be in deep trouble.
As for already at the tops for NA piston engine efficiency , no way. Theres still tons of things they can/will do. Rotaries are 2-30 years behind AT LEAST in terms of development. Pistons have had 1000's of people working on them for 100+years. Rotaries have had as few as 2 people at mazda working on them, and probably never more than 80. They take advantage of current tech and materials, but are still way behind in development, which may go some way to explain poor fuel efficiency and emmisions.
10-02-2003, 10:16 AM
#42
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And what did I say ? 
And also:
And finally:
The only "problematic" area with the RX8 and the new RX7 is/will be the engine. And thats where the FD got all its bad criticism. So, its the one area that must get a lot of attention by anyone involved.
And as for the comments about the stage of evolution: even if the rotary had the same years of development behind it, it would still be at the same levels of efficiency as the piston engines. Its not a matter of specific engine internal workings, its about the level of evolution of humankind :D
the RX8 uses a rotary engine, which is unique
I know that the RX8 is not actually a supercar
I know that Mazda cannot be put on the same level as Ferrari or Mazerati
And as for the comments about the stage of evolution: even if the rotary had the same years of development behind it, it would still be at the same levels of efficiency as the piston engines. Its not a matter of specific engine internal workings, its about the level of evolution of humankind :D
10-02-2003, 10:21 AM
#43
Originally posted by The Ace
And as for the comments about the stage of evolution: even if the rotary had the same years of development behind it, it would still be at the same levels of efficiency as the piston engines. Its not a matter of specific engine internal workings, its about the level of evolution of humankind :D
And as for the comments about the stage of evolution: even if the rotary had the same years of development behind it, it would still be at the same levels of efficiency as the piston engines. Its not a matter of specific engine internal workings, its about the level of evolution of humankind :D
Pistons are vey inefficient in an up and down kinda way as a lot of energy is lost , but rotaries dont loose all that energy.
In practice there not efficient, but are relativly powerfull (although 238bhp for '2.6l' isnt great, some 4clyinders are getting 200bhp out of 2.0l).
Rotaries also dont have the same drain on them as piston engines from valves/cams etc, and can make use of the same ports for 3 'cylinders' (rotor).
Is energy lost from side wall friction eaqual to pistons verticle momentum change?
10-02-2003, 10:36 AM
#44
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Well, first of all lets state that the F20 engine is right now the most efficient piston engine in the world (240HP out of 2.0lt of displacement). Next are the new E46 M3 engine, and the V10 of the Ferrari.
The rotary engine has a lot of advantages over the piston engine, in theory and in practice.
1) First of all, energy and momentum is not lost in moving parts and an additional conversion from reciprocal to cyclical movement. The rotary has just 3 moving parts, and all of them are moving in the same direction, doing the same generic movement (cyclical, or almost cyclical)
2) Losses due to friction are even less. Rotaries lose energy only due to the apex seals, because the shaft and rotors do not have that much friction between them. Piston engines on the other hand have friction on the pistons, the lobes on the cams, and between gears/cams.
3) The operating limits for the rotary engine are much, much higher than those of a piston engine. This is obvious, so I wont elaborate.
4) The simplicity of the rotary engine allows for much simpler and lighter design, much more durable components, and much more efficient operation. Only taking into consideration the absence of valves, springs, valve covers, cam settings etc etc.....anyone can figure out which design is better
The general problem with the internal combustion engines is their efficiency when regarded as a generic mechanism, not when you start pondering on a specific design's pros and cons. Simply put, burning fossil fuel using these machines at our current state of evolution simply has its limits, and those limits are the ones that impede their output. When comparing these engines to other forms of engines (such as H2 engines, or fuel cell, or simply electrical ones), the differences in their efficiency is staggering. And remember that the other engines are still in their embryo stages
Thats why I say that F/I is a very valuable solution. Not only does it increase the efficiency of an engine, it also uses energy otherwise spent (heat/speed of exhaust gases), so the total entropy of the internal combustion engine is reduced. So, it may not be a quantum leap forward, but its still a pretty decent way to improve the efficiency of these engines.......
The rotary engine has a lot of advantages over the piston engine, in theory and in practice.
1) First of all, energy and momentum is not lost in moving parts and an additional conversion from reciprocal to cyclical movement. The rotary has just 3 moving parts, and all of them are moving in the same direction, doing the same generic movement (cyclical, or almost cyclical)
2) Losses due to friction are even less. Rotaries lose energy only due to the apex seals, because the shaft and rotors do not have that much friction between them. Piston engines on the other hand have friction on the pistons, the lobes on the cams, and between gears/cams.
3) The operating limits for the rotary engine are much, much higher than those of a piston engine. This is obvious, so I wont elaborate.
4) The simplicity of the rotary engine allows for much simpler and lighter design, much more durable components, and much more efficient operation. Only taking into consideration the absence of valves, springs, valve covers, cam settings etc etc.....anyone can figure out which design is better
The general problem with the internal combustion engines is their efficiency when regarded as a generic mechanism, not when you start pondering on a specific design's pros and cons. Simply put, burning fossil fuel using these machines at our current state of evolution simply has its limits, and those limits are the ones that impede their output. When comparing these engines to other forms of engines (such as H2 engines, or fuel cell, or simply electrical ones), the differences in their efficiency is staggering. And remember that the other engines are still in their embryo stages
Thats why I say that F/I is a very valuable solution. Not only does it increase the efficiency of an engine, it also uses energy otherwise spent (heat/speed of exhaust gases), so the total entropy of the internal combustion engine is reduced. So, it may not be a quantum leap forward, but its still a pretty decent way to improve the efficiency of these engines.......
10-02-2003, 12:53 PM
#45
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You have to define what you mean by efficiency. If you mean getting most work done for a given amount of fuel (fuel efficiency) then rotaries are very inefficient (at least currently).
If, as is often the case with sports car engines, you mean getting most power out of a given physical size or weight of engine then rotaries are the most efficient engines. This is because for each rotor all 4 cycles are in progress simultaneously in different parts of the rotor chamber (kind of like pipelining, if you're farmiliar with computer hardware) whereas in a cylinder they happen sequentially. So you need more cylinders (of the same displacement) to get the same power. Plus, of course, there's valves and all the other stuff.
It's almost like there's a law of nature that says you can't have both types of efficiency at the same time. For example, diesels have much better fuel efficiency than petrol engines but their power/weight ratio is terrible because they are so heavy and rev so slowly.
If, as is often the case with sports car engines, you mean getting most power out of a given physical size or weight of engine then rotaries are the most efficient engines. This is because for each rotor all 4 cycles are in progress simultaneously in different parts of the rotor chamber (kind of like pipelining, if you're farmiliar with computer hardware) whereas in a cylinder they happen sequentially. So you need more cylinders (of the same displacement) to get the same power. Plus, of course, there's valves and all the other stuff.
It's almost like there's a law of nature that says you can't have both types of efficiency at the same time. For example, diesels have much better fuel efficiency than petrol engines but their power/weight ratio is terrible because they are so heavy and rev so slowly.
10-02-2003, 01:16 PM
#46
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As you may have understood from my theoretical analysis, I define "efficiency" in the pure mathematical/chemical sense, as the rate of conversion between one form of energy (stored chemical energy in the molecules of the fuel) to another (kinetic energy).
The formula to prove the efficiency (or rather, inefficiency :D) of the internal combustion engine (whether reciprocal, rotary or otherwise) is quite simple actually, and doesnt have too many variables and additions/multiplications/divisions in it, but I just got back from the gym, and I'm just too tired.......
Maybe I'll indulge myself (and you all ) another time......
The formula to prove the efficiency (or rather, inefficiency :D) of the internal combustion engine (whether reciprocal, rotary or otherwise) is quite simple actually, and doesnt have too many variables and additions/multiplications/divisions in it, but I just got back from the gym, and I'm just too tired.......
Maybe I'll indulge myself (and you all
) another time......
10-03-2003, 10:25 AM
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report from the field
Hello from Canada:
Do any of you on this thread actually have your cars yet, or is all this discussion theoretical?
Westie from Toronto
Do any of you on this thread actually have your cars yet, or is all this discussion theoretical?
Westie from Toronto
10-03-2003, 12:48 PM
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No I wasn't trying to but I guess it doesn't take much.
I honestly don't know if any of you have received your cars yet in the UK or Europe. I posted a field report on the "are you concerned about MPG" thread with a list of things to keep an eye on when you receive your 8s. The main problem we had was horrible MPG and extremely short range of the RX8.
Good Luck, Westie
I honestly don't know if any of you have received your cars yet in the UK or Europe. I posted a field report on the "are you concerned about MPG" thread with a list of things to keep an eye on when you receive your 8s. The main problem we had was horrible MPG and extremely short range of the RX8.
Good Luck, Westie
10-03-2003, 07:01 PM
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First, I dont think Mazda will manufacture the any RX car outside Japan, so the price of the RX will depend on the ¥ exchange rate as much as the manufacturing cost.
I dont think it was a coincidence that RX7 was discontinued in
Japan when the RX8 came along, due to the limited number of
people at Mazda with wankel experience and if the RX8 is a huge success, it will take time to educate new engine builders, I sincerely doubt that they would run several different cars with the wankel engine.
But I hope Im wrong, it would be nice if Mazda could make a whole range of wankel cars....
I dont think it was a coincidence that RX7 was discontinued in
Japan when the RX8 came along, due to the limited number of
people at Mazda with wankel experience and if the RX8 is a huge success, it will take time to educate new engine builders, I sincerely doubt that they would run several different cars with the wankel engine.
But I hope Im wrong, it would be nice if Mazda could make a whole range of wankel cars....
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