The Renesis does NOT run rich
05-18-2010, 11:06 PM
#52
I've tuned quite a few JDM and AUDM RX-8s, some with early 2003 build dates and all of the fuel maps are quite functional.
I somehow doubt that there is some sort of "special edition" version for the 2003 New Zealand market that just chooses to ignore 66% of the available fuel maps.
Besides, because of how the PCM actually operates, the scenario you are suggesting isn't possible.
05-18-2010, 11:11 PM
#53
Huh?
I've tuned quite a few JDM and AUDM RX-8s, some with early 2003 build dates and all of the fuel maps are quite functional.
I somehow doubt that there is some sort of "special edition" version for the 2003 New Zealand market that just chooses to ignore 66% of the available fuel maps.
Besides, because of how the PCM actually operates, the scenario you are suggesting isn't possible.
I've tuned quite a few JDM and AUDM RX-8s, some with early 2003 build dates and all of the fuel maps are quite functional.
I somehow doubt that there is some sort of "special edition" version for the 2003 New Zealand market that just chooses to ignore 66% of the available fuel maps.
Besides, because of how the PCM actually operates, the scenario you are suggesting isn't possible.
One possibility is that Protuner somehow dicks with the software so that only one map works
Took me a month of dicking around to realise that only one map had any effect on my car ....
05-18-2010, 11:32 PM
#54
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I was thinking about printing all the pretty charts and wallpapering the closet in my office with them....
Interesting stuff. It would make sense that the fuel mixture would be pretty close to that of a piston engine maybe a tad richer but not a lot. Reason being that when it exits the pipe they all have the same EPA regulations to meet and they all use a spark to ignite. Too lean and it won't ignite (and NOx goes up) Too rich and not enough O2 to satisfy CO and unburned HC requirements. So its really a rather narrow range of fuel/air to keep Uncle Sam happy.
Where the rotary suffers is detonation and Mazda tends to combat that with delayed timing. The problem is Exhaust Gas Temp (EGT) is a good bit higher then a piston engine. Simple conservation of energy would suggest the higher EGT means less energy is extracted from the fuel.
Obviously some people already know that. Others may not.
Thats why the RX8 won't go as far on a gallon of gas as a piston equivalent will. But it sure is a lot more fun to drive.
Interesting stuff. It would make sense that the fuel mixture would be pretty close to that of a piston engine maybe a tad richer but not a lot. Reason being that when it exits the pipe they all have the same EPA regulations to meet and they all use a spark to ignite. Too lean and it won't ignite (and NOx goes up) Too rich and not enough O2 to satisfy CO and unburned HC requirements. So its really a rather narrow range of fuel/air to keep Uncle Sam happy.
Where the rotary suffers is detonation and Mazda tends to combat that with delayed timing. The problem is Exhaust Gas Temp (EGT) is a good bit higher then a piston engine. Simple conservation of energy would suggest the higher EGT means less energy is extracted from the fuel.
Obviously some people already know that. Others may not.
Thats why the RX8 won't go as far on a gallon of gas as a piston equivalent will. But it sure is a lot more fun to drive.
05-18-2010, 11:43 PM
#55
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Based on the data that I've seen, as well as my own car, using the stock map you see bottom 11's in open loop at open throttle loads. In most cases it pegs the O2 sensor bottom limit.
There are of course exceptions as we've seen RX8's all over the board with performance. I have no doubt you could find an RX8 that runs in the low to mid 12's where it counts.
The majority of them run very rich for an NA motor.
05-19-2010, 01:17 AM
#56
Rotary motors are simply less thermally efficient than piston motors because of the movement of the charge as it is expanding.
The BSFC is simply higher.
Ignition timing has nothing to do with it.
In fact, Mazda's ignition timing is very, very aggressive - much more so than many piston motors.
05-19-2010, 01:32 AM
#58
Perhaps! Yes.
I've actually started leaning that way myself. There is more power/drivability to be had with over-fueling and more timing than knife-edge AFR and retarded timing.
EDIT - What just happened to that thread with the guy who hooked up his oil source directly to his piping?
I've actually started leaning that way myself. There is more power/drivability to be had with over-fueling and more timing than knife-edge AFR and retarded timing.
EDIT - What just happened to that thread with the guy who hooked up his oil source directly to his piping?
Last edited by MazdaManiac; 05-19-2010 at 01:39 AM.
05-21-2010, 09:42 AM
#59
The suggestion that the RX8 does not have a realtively rich a/f ratio is incredible to me. Every indication says that is the case and someone like Jeff has more than enough evidence of it. It is more than just my theory (Others agree) that when you don't have a cat to worry about there are many advantages to be had adjusting fuel numbers toward the lean side on an 8. I could be wrong but I am of the belief that MAF calibration is one of the greatest variations on stock RX8s causing some to have better mileage and hp numbers than others (Although still rich).
Rotaries have traditionally been known for not requiring high octane prior to renesis with it's 10/1 compression ratio and aggressive ignition timing. We used to run 87 octane from a local Happy Store gas station in our championship winning race cars (And run a liitle less timing than the other guy
).
Paul.
Rotaries have traditionally been known for not requiring high octane prior to renesis with it's 10/1 compression ratio and aggressive ignition timing. We used to run 87 octane from a local Happy Store gas station in our championship winning race cars (And run a liitle less timing than the other guy
).Paul.
05-21-2010, 03:34 PM
#61
. Nobody would have known if you hadn't revealed it 
.
05-21-2010, 06:51 PM
#67
The suggestion that the RX8 does not have a realtively rich a/f ratio is incredible to me. Every indication says that is the case and someone like Jeff has more than enough evidence of it. It is more than just my theory (Others agree) that when you don't have a cat to worry about there are many advantages to be had adjusting fuel numbers toward the lean side on an 8. I could be wrong but I am of the belief that MAF calibration is one of the greatest variations on stock RX8s causing some to have better mileage and hp numbers than others (Although still rich).
Rotaries have traditionally been known for not requiring high octane prior to renesis with it's 10/1 compression ratio and aggressive ignition timing. We used to run 87 octane from a local Happy Store gas station in our championship winning race cars (And run a liitle less timing than the other guy).
Paul.
Rotaries have traditionally been known for not requiring high octane prior to renesis with it's 10/1 compression ratio and aggressive ignition timing. We used to run 87 octane from a local Happy Store gas station in our championship winning race cars (And run a liitle less timing than the other guy
).Paul.
Exactly, which is why my suggestion at the bottom of the previous page kills two birds with one stone
07-10-2010, 12:41 PM
#71
Boostin'
I am not sure, this engine was shipped in from a forum member. He hasn't owned it long. Carbon chips actually scratched the rotor housings...
P.S. Gimmie that ECU back Jeffe!!
P.S. Gimmie that ECU back Jeffe!!
07-10-2010, 02:18 PM
#72
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I am on the fence of keeping this car. I only got just under 30K since early 2005.
But it definitely seems that if I do the Cobb AP and a schedule of that decarbon procedure are a must.
But it definitely seems that if I do the Cobb AP and a schedule of that decarbon procedure are a must.
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