The Test Drive and Review - (long post!)
09-01-2003, 03:57 AM
#26
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Ace, I hear what you say, and I know you are not trying to shoot the messenger. It does sound challengign but lets wait for the dealer to let slip more info.
AnilS.
AnilS.
09-01-2003, 04:18 AM
#27
Personaly, looking at the dyno graphs, more revs with the induction on the car wont help anyhow.
At 7250 rpm when the extra induction valve/port thing opens it seems to cause problems right through to at least 8000rpm - after that its sometimes peaks @ a higher bhp than 7250 , but not by much.
Torque trails off a lot then too.
I'm half convinced the engine would perform better without that 7250 induction valve opening at all.
Seems like it causes such an air intake problem (leading to the over rich fuel mix?) that the cars biggest fault has to be there somewhere.
I cant see it being helped with an exhaust as that should affect the air intake at that point(?).
At 7250 rpm when the extra induction valve/port thing opens it seems to cause problems right through to at least 8000rpm - after that its sometimes peaks @ a higher bhp than 7250 , but not by much.
Torque trails off a lot then too.
I'm half convinced the engine would perform better without that 7250 induction valve opening at all.
Seems like it causes such an air intake problem (leading to the over rich fuel mix?) that the cars biggest fault has to be there somewhere.
I cant see it being helped with an exhaust as that should affect the air intake at that point(?).
09-01-2003, 04:33 AM
#28
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Dont forget that the rotors and the eccentric have been balanced to about 10K (or was it 11K) rpms, so the Renesis shouldnt have troubles going upwards until 10K-10,5K rpms. However, as Robdickinson pointed out, even the HIGH-Pow's dyno line seems to drop at about 8K. So, even if you extended the RPM range, it wouldnt do much good 
However, I'm more than sure that a free(er) flowing exhaust would help immensely. Rotaries are notorious for their restricted intakes and exhausts (in order to pass emissions), so freeing those two up should add a good chunk of HP/torque to their figures. However, it would still be a long way before hitting that +80HP mark
Just a thought: since lots of guys are posting very bad WHP figures, I was thinking maybe this has something to do with the ECU running the Renesis very rich. If someone was able to alter the fuel maps of the Renesis' ECU, and run the engine a bit leaner, then that would be a very nice start to "discover" those elusive ponies
However, I'm more than sure that a free(er) flowing exhaust would help immensely. Rotaries are notorious for their restricted intakes and exhausts (in order to pass emissions), so freeing those two up should add a good chunk of HP/torque to their figures. However, it would still be a long way before hitting that +80HP mark
Just a thought: since lots of guys are posting very bad WHP figures, I was thinking maybe this has something to do with the ECU running the Renesis very rich. If someone was able to alter the fuel maps of the Renesis' ECU, and run the engine a bit leaner, then that would be a very nice start to "discover" those elusive ponies
09-01-2003, 05:05 AM
#29
Thi sis hte best dyno I've seen so far :
What happens when :
RPM___SYSTEM_______WHAT
3750__Fuel Injectors__#2 primary and secondary injector start
___________________controlled by ECU fuel maps
___________________(All in use during WOT!?!)
3750__SDAIS________#2 primary intake ports open
5500__SDAIS________VFAD may open (Yamaguchi p 115)
6250__SDAIS________Auxilary intake ports open
7250__SDAIS________Primary intake ports interconnnect
___________________adds a second shorter path
7250__SDAIS________VFAD opens on WOT
-------------------------------------------------
Now it seems to me that at 7250 rpm this happens :
7250__SDAIS________Primary intake ports interconnnect
___________________adds a second shorter path
7250__SDAIS________VFAD opens on WOT
And theres a drop in power thats not recovered from until sometime after 8000rpm. Then torque takes a dive.
And the car runs rich over 6000rpm. Looks to me like whatever happens at 7250 affects airflow so much(on a dyno) that it causes to low an air pressure? resulting in not enough oxygen for good burn(I'm no mechanic/engineer).
Even when the Airflow seems to sort itself out some, it still doesnt get that much more power than whats at 7250. This prolly gives a 'flat' feel to the top end power.
Theres something wrong up there, I point my finger at SDAIS, I dont see that being an exauhst problem.
What happens when :
RPM___SYSTEM_______WHAT
3750__Fuel Injectors__#2 primary and secondary injector start
___________________controlled by ECU fuel maps
___________________(All in use during WOT!?!)
3750__SDAIS________#2 primary intake ports open
5500__SDAIS________VFAD may open (Yamaguchi p 115)
6250__SDAIS________Auxilary intake ports open
7250__SDAIS________Primary intake ports interconnnect
___________________adds a second shorter path
7250__SDAIS________VFAD opens on WOT
-------------------------------------------------
Now it seems to me that at 7250 rpm this happens :
7250__SDAIS________Primary intake ports interconnnect
___________________adds a second shorter path
7250__SDAIS________VFAD opens on WOT
And theres a drop in power thats not recovered from until sometime after 8000rpm. Then torque takes a dive.
And the car runs rich over 6000rpm. Looks to me like whatever happens at 7250 affects airflow so much(on a dyno) that it causes to low an air pressure? resulting in not enough oxygen for good burn(I'm no mechanic/engineer).
Even when the Airflow seems to sort itself out some, it still doesnt get that much more power than whats at 7250. This prolly gives a 'flat' feel to the top end power.
Theres something wrong up there, I point my finger at SDAIS, I dont see that being an exauhst problem.
Last edited by RobDickinson; 09-01-2003 at 05:12 AM.
09-01-2003, 05:58 AM
#31
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RobDickinson, you have some valid points, but also a couple of mistakes too.
Freeing up the exhaust has nothing to do with the intake or the way the intake paths change according to RPMs. Freeing up the exhaust means less backpressure, which means less strain for the rotors/shaft, which means easier spinning and more power. That is 100% guaranteed on ALL rotary engines, so you can take that as a given
As for the dyno sheet: I would guess about 187WHP, so this means either 20%
losses due to transmission, or NOT 230HP at the shaft. However, it could mean that the engine is running rich all the time. You say that the engine runs rich above 6K. Did you see the results of the O2 ? Is it possible to post these as well ? Only then can I make a educated guess about the fuel maps of the ECU. These sudden drops could be attributed to the intake paths changes, but also to additional percentage of the injector duty cycles (say from 70% to 75%). Which means that the engine starts to run a bit richer at those RPM points
Anyway, without the wide-band reading, its hard to decide what's to blame here. But since you said it yourself, its pretty obvious that some ECU tuning (to lean out the mixture) could lead in some very nice results
Freeing up the exhaust has nothing to do with the intake or the way the intake paths change according to RPMs. Freeing up the exhaust means less backpressure, which means less strain for the rotors/shaft, which means easier spinning and more power. That is 100% guaranteed on ALL rotary engines, so you can take that as a given
As for the dyno sheet: I would guess about 187WHP, so this means either 20%
losses due to transmission, or NOT 230HP at the shaft. However, it could mean that the engine is running rich all the time. You say that the engine runs rich above 6K. Did you see the results of the O2 ? Is it possible to post these as well ? Only then can I make a educated guess about the fuel maps of the ECU. These sudden drops could be attributed to the intake paths changes, but also to additional percentage of the injector duty cycles (say from 70% to 75%). Which means that the engine starts to run a bit richer at those RPM points Anyway, without the wide-band reading, its hard to decide what's to blame here. But since you said it yourself, its pretty obvious that some ECU tuning (to lean out the mixture) could lead in some very nice results
09-01-2003, 06:18 AM
#32
The rich/O2 stuff was posted on other dyno results, may go find them later.
I'd like to see the car dyno'd without that induction crossover valve thing opening at 7250, see what it does, as bhp seems to be climbing rather rapidly before it opens, and les sso when it does.
It may hurt high rpm bhp but the overall curve may be better of for it.
And yes, a better exaust will free up some HP, but I dont see that as the Renasis's problem at the moment, it seems to have a high RPM power problem, and that looks like its to do with whats going on at 7250 rpm.
I'd like to see the car dyno'd without that induction crossover valve thing opening at 7250, see what it does, as bhp seems to be climbing rather rapidly before it opens, and les sso when it does.
It may hurt high rpm bhp but the overall curve may be better of for it.
And yes, a better exaust will free up some HP, but I dont see that as the Renasis's problem at the moment, it seems to have a high RPM power problem, and that looks like its to do with whats going on at 7250 rpm.
09-01-2003, 10:39 AM
#33
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Is anybody else lost with all this technical stuff? I certainly am
£2k and 300+ bhp does sound too good to be true, but if it is then I would be much happier with my RX8.
£2k and 300+ bhp does sound too good to be true, but if it is then I would be much happier with my RX8.
09-01-2003, 11:09 AM
#34
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[sceptical hat on]
It does seem a bit odd that a UK Mazda dealer seems able to get over 300+bhp from a motor that they've not even really had any time to get their hands on, when the Japs have had this car 4-6months+ and haven't managed it?
[sceptical hat off]
But then us Brits can come up with some good engineering if we want to!
-andy-
It does seem a bit odd that a UK Mazda dealer seems able to get over 300+bhp from a motor that they've not even really had any time to get their hands on, when the Japs have had this car 4-6months+ and haven't managed it?
[sceptical hat off]
But then us Brits can come up with some good engineering if we want to!
-andy-
09-01-2003, 02:07 PM
#35
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Originally posted by sixspeed
[sceptical hat on]
It does seem a bit odd that a UK Mazda dealer seems able to get over 300+bhp from a motor that they've not even really had any time to get their hands on, when the Japs have had this car 4-6months+ and haven't managed it?
[sceptical hat off]
But then us Brits can come up with some good engineering if we want to!
-andy-
[sceptical hat on]
It does seem a bit odd that a UK Mazda dealer seems able to get over 300+bhp from a motor that they've not even really had any time to get their hands on, when the Japs have had this car 4-6months+ and haven't managed it?
[sceptical hat off]
But then us Brits can come up with some good engineering if we want to!
-andy-
For example, the Mugen S2K was announced and presented to the public weeks before the actual Honda S2K even made it to the dealers
09-01-2003, 02:39 PM
#36
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Let me see ... a torque curve that ranges from 115 to 135 over a rev range of 3000 to 8700 ...
That is one hell of a flat torque curve isn't it?
Sounds pretty OK to me.
BTW: I'd give £2k for 300bhp before you could blink hehehe
That is one hell of a flat torque curve isn't it?
Sounds pretty OK to me.
BTW: I'd give £2k for 300bhp before you could blink hehehe
09-02-2003, 06:38 AM
#37
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Sorry chaps - dont think it is gonna happen....
No dis' to AnilS or others , but you are not going to get that sort of power hike with a NA engine.
I am not even convinced that aftermarket headers will be available for the Renesis for a while at least - My understanding is that the 'bulge' in the floor of the drivers side is where the exhast manifold (or cat ) is.
)Did I read somewhere that Renesis does not have the 'Thermal Reactor' of previous gen rotaries ? )
Anyway - point is becasue of where this engine is (i.e. next to your knees) I dont thing there is the room for any fancy headers etc.
The fuel mappings is our best bet , IMHO.
That said , like the rest of you , I would jump at it.
Dont get your hopes up though, that's all.
M.
No dis' to AnilS or others , but you are not going to get that sort of power hike with a NA engine.
I am not even convinced that aftermarket headers will be available for the Renesis for a while at least - My understanding is that the 'bulge' in the floor of the drivers side is where the exhast manifold (or cat ) is.
)Did I read somewhere that Renesis does not have the 'Thermal Reactor' of previous gen rotaries ? )
Anyway - point is becasue of where this engine is (i.e. next to your knees) I dont thing there is the room for any fancy headers etc.
The fuel mappings is our best bet , IMHO.
That said , like the rest of you , I would jump at it.
Dont get your hopes up though, that's all.
M.
09-02-2003, 07:13 AM
#38
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Someone has produced a header, there were photos of it on the main forum. Lovingly curved stainless steel pipes that met up in expensive looking welded joints all meeting up just before the cat.
Not sure if that was just a prototype though, but there have been photos.
I'll do a search, think it was the Tech forum.
Not sure if that was just a prototype though, but there have been photos.
I'll do a search, think it was the Tech forum.
09-02-2003, 07:17 AM
#39
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Headers ? Why even bother ? It has been proven that rotaries dont have THAT much trouble with their headers.......Its almost always the last mod anyone does to its FC or FD......
Believe me guys, first thing to go will be the exhaust and the filter (I think that intake is a bit more complicated to just ditch it and get a cone filter). Then, if you really want to increase the HP output, the pre-cat (downpipe) and the main cat (racing cat or even mid-pipe :D ) will the next two things.
After that, a proper tuning of the ECU to take into account the above mods, and maybe lean out the A/F ratio a bit will be the best bet. All the above should be good for about 40-50HP.....
Believe me guys, first thing to go will be the exhaust and the filter (I think that intake is a bit more complicated to just ditch it and get a cone filter). Then, if you really want to increase the HP output, the pre-cat (downpipe) and the main cat (racing cat or even mid-pipe :D ) will the next two things.
After that, a proper tuning of the ECU to take into account the above mods, and maybe lean out the A/F ratio a bit will be the best bet. All the above should be good for about 40-50HP.....
09-02-2003, 07:19 AM
#40
Originally posted by Titanium Grey
Someone has produced a header, there were photos of it on the main forum. Lovingly curved stainless steel pipes that met up in expensive looking welded joints all meeting up just before the cat.
Not sure if that was just a prototype though, but there have been photos.
I'll do a search, think it was the Tech forum.
Someone has produced a header, there were photos of it on the main forum. Lovingly curved stainless steel pipes that met up in expensive looking welded joints all meeting up just before the cat.
Not sure if that was just a prototype though, but there have been photos.
I'll do a search, think it was the Tech forum.
But it was also a header for a 20b turbo conversion, not for the standard for renasis. (Have a close look, it has ports for 3 rotors).
They put in a huge custom intercooler too. Looks like a complete (800bhp) monster.
Heres the thread.
09-02-2003, 07:24 AM
#41
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Sorry didn't mean header :o I ment Pre cat.
I think I have seen a cone filter fitted but it looked crap!
And I cant believe it provided much of an improvement.
I think I have seen a cone filter fitted but it looked crap!
And I cant believe it provided much of an improvement.
09-02-2003, 07:24 AM
#42
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09-02-2003, 08:00 AM
#44
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Well, as you can see from those threads, our friends in Japan have managed to get a 12HP increase from the exhaust, and another 10HP from the downpipe. So the exhaust should give you about +20HP (I told you the rotaries are restricted )
So, dont expect much more than 4-5HP increase from a drop-in or cone filter, so the "usual" mods should give the RX8 a +25HP increase. Thats about it.......Its still legal, but you cannt pass visual or cold emissions.......
)So, dont expect much more than 4-5HP increase from a drop-in or cone filter, so the "usual" mods should give the RX8 a +25HP increase. Thats about it.......Its still legal, but you cannt pass visual or cold emissions.......
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