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-   -   The Renesis does NOT run rich (https://www.rx8club.com/series-i-tech-garage-22/renesis-does-not-run-rich-195091/)

Brettus 05-18-2010 11:02 PM


Originally Posted by MazdaManiac (Post 3564854)
You are correct.

The 2006 and up have them grouped 1/2/3 & 4/5/6.

early models here have only 1 map (that does anything ) although there are 3 available .

MazdaManiac 05-18-2010 11:06 PM


Originally Posted by Brettus (Post 3564966)
early models here have only 1 map (that does anything ) although there are 3 available .

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.

Brettus 05-18-2010 11:11 PM


Originally Posted by MazdaManiac (Post 3564972)
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.

well - i've tuned 3 different cars here with protuner and on all 3 , 2 of the maps did nothing . Believe it !
One possibility is that Protuner somehow dicks with the software so that only one map works :dunno:

Took me a month of dicking around to realise that only one map had any effect on my car ....

kartweb 05-18-2010 11:32 PM

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.

Flashwing 05-18-2010 11:43 PM


Originally Posted by kartweb (Post 3565000)
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.

The problem is it isn't close to that of a piston motor, at least not the examples that have been given.

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.

MazdaManiac 05-19-2010 01:17 AM


Originally Posted by kartweb (Post 3565000)
Thats why the RX8 won't go as far on a gallon of gas as a piston equivalent will.

Uh, not exactly.
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.

Brettus 05-19-2010 01:26 AM


Originally Posted by MazdaManiac (Post 3565125)
In fact, Mazda's ignition timing is very, very aggressive - much more so than many piston motors.

aggressive because it runs so rich perhaps ?

MazdaManiac 05-19-2010 01:32 AM


Originally Posted by Brettus (Post 3565134)
aggressive because it runs so rich perhaps ?

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?

Mazmart 05-21-2010 09:42 AM

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.

Razz1 05-21-2010 09:57 AM

ahh... so now you reveal your secrect.
Watered down gas :)

Mazmart 05-21-2010 03:34 PM


Originally Posted by Razz1 (Post 3568551)
ahh... so now you reveal your secrect.
Watered down gas :)

Shhhhh! I was speaking in code :eyetwitch. Nobody would have known if you hadn't revealed it :spank:.

Paul :)

dannobre 05-21-2010 04:59 PM


Originally Posted by MazdaManiac (Post 3565137)
EDIT - What just happened to that thread with the guy who hooked up his oil source directly to his piping?


I think he got so much teasing that he deleted the thread ;)

I was going back to chuckle when it was deleted :)

Brettus 05-21-2010 05:05 PM


Originally Posted by dannobre (Post 3569219)
I think he got so much teasing that he deleted the thread ;)

I was going back to chuckle when it was deleted :)

Yeah - I suggested to him that might be a good idea once he had downloaded the instructions ...

dannobre 05-21-2010 05:07 PM

DAmn you Brett...You ruined all of our fun ;)

Brettus 05-21-2010 05:11 PM

heh . He was a least smart enough to take that advice

dannobre 05-21-2010 05:22 PM

:) :lol:

TeamRX8 05-21-2010 06:51 PM


Originally Posted by Mazmart (Post 3568525)
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.


Exactly, which is why my suggestion at the bottom of the previous page kills two birds with one stone

MazdaManiac 05-21-2010 07:35 PM


Originally Posted by TeamRX8 (Post 3569331)
Exactly, which is why my suggestion at the bottom of the previous page kills two birds with one stone

You were serious about that suggestion?

So you think running super lean below 4000 RPM is the solution for getting appropriate AFRs at higher RPM?

Turblown 07-10-2010 01:00 AM

1 Attachment(s)
I think a Cobb ecu should be everyone's first mod. Carbon buildup kills these engines..

MazdaManiac 07-10-2010 01:57 AM


Originally Posted by Turblown (Post 3629670)
I think a Cobb ecu should be everyone's first mod. Carbon buildup kills these engines..

Wow. Holy crap, that's a lot of carbon chips.
What were that engines symptoms before you tore it down, E?

Turblown 07-10-2010 12:41 PM

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!!

RX8PDX 07-10-2010 02:18 PM

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.

MazdaManiac 07-10-2010 04:09 PM


Originally Posted by Turblown (Post 3629965)
P.S. Gimmie that ECU back Jeffe!!

Give it back? It's still at the hacker's place (Yoshi). He's only had it a month. I told your uncle that it will take a few months.


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