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RX-8 Dyno numbers...trouble in paradise?

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Old 07-31-03, 08:58 AM
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RX-8 Dyno numbers...trouble in paradise?

Seems like numbers from atleast 3 different dynos suggests the rx-8 is putting out 180 rwhp way short of the advertised 247 bhp. The rx-8 forum has the charts posted. Can anyone here who might work for mazda or a mazda dealer try and find out what the hell is going on??? This could turn into a total disaster for the rotary engine comeback.
Old 07-31-03, 09:03 AM
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OOWIES!!!!
Old 07-31-03, 09:59 AM
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.. oh dear, I hope this is a glitch, Mazda has said that sales of the RX-8 will determine the fate of a north american FE. I know in canada ALL rx-8's have been sold, which is scary considerinng there won't be a single part or enigne available for that car, in Canada, till after Xmas soonest.

Do you have a link to that dyno?
Old 07-31-03, 10:34 AM
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http://rx8forum.com/showthread.php?t...highlight=dyno
Old 07-31-03, 10:35 AM
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For charts, go to www.rx8forum.com tech and performance sections.
Old 07-31-03, 11:46 AM
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When I test drove a prototype RX-8 back in January I thought it had no power. Some people said it was because it was an early car and that something was probably wrong. My streetport GSL-SE felt so much stronger. Looking at those numbers it completely backs up what I said based on my driving impression. My GSL-SE runs mid to high 14's and weighs much less than the RX-8. Based on that chart my horsepower to weight ratio is better. To the people who didn't believe me: Maybe something really is wrong on those cars though or the drivetrain has ridiculous amounts of friction.
Old 07-31-03, 05:51 PM
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Look at the AFR ratio for the Dyno, i think its just the ecu detunning during break in.
Old 07-31-03, 06:41 PM
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manufacturers always quote flywheel hp and you are quoting rwhp. Still seems a bit low though unless there is 30% drivetrain loss. Are you sure it was the higher hp engine? There are 2 different ones.
Old 07-31-03, 06:44 PM
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hmmm....remember when Mazda overstated the hp on the miatas???
Old 07-31-03, 10:05 PM
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umm..read my post again, carefully. I said it made 180 RWHP and mazda has it rated for 247 BHP. You can't have 67HP drivetrain loss unless their clutches are really bad. Anyway, they are the high performance, 6-port cars not the lowly automatics.
Old 07-31-03, 10:07 PM
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If someone really wants to get to the bottom of this... Start a little P.R. problem for Mazda....

Write a letter/email to a major magazine CLEARLY stating the "problem" and provide the links to the proof. Hopefully the magazine will investigate and/or get the scoop from Mazda for you!

Brian
Old 07-31-03, 10:16 PM
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The 255 hp 3rd gens typically dyno around 215 or near this number. It would be hard to believe that a 250 hp engine would dyno only 170-180. That is a huge difference.
Old 07-31-03, 10:29 PM
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Originally posted by rotarygod
When I test drove a prototype RX-8 back in January I thought it had no power. Some people said it was because it was an early car and that something was probably wrong. My streetport GSL-SE felt so much stronger. Looking at those numbers it completely backs up what I said based on my driving impression. My GSL-SE runs mid to high 14's and weighs much less than the RX-8. Based on that chart my horsepower to weight ratio is better. To the people who didn't believe me: Maybe something really is wrong on those cars though or the drivetrain has ridiculous amounts of friction.
My feelings %100 !

I test drove the RX8 and the engine feels "soft" definatley no where near the power they claim ! (In Australia we get the 237bhp version) due to tighter emmissions standards. Either way it sucked ***.

RENISIS is a scam ! give me peripheral exhaust ports any day. Funny how in Japan some tuners are already making mods to bring back the peripheral exhaust obviously to regain the losses in power !
Old 07-31-03, 11:38 PM
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I'm laughing hard now... all these kids were drooling over the thought of 250hp N/As and "imagine how much power they can get with mods!"... not realizing that the nature of side exhaust ports and the way the engine was designed for them means that you can't bolt on 50hp with an exhaust like you could with peripheral exhaust... and now it appears that once again Mazda overstated things. I would like to hope that the problem is break-in tuning, or as someone else mentioned the tertiary ports not opening...

Be interesting to see what Yawpower gets on their dyno, given that all that is being dyno tested is the engine, not the engine + Mazda's tuning.
Old 08-01-03, 03:16 AM
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i think its the ecu break in detuneing
Old 08-01-03, 08:19 AM
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Originally posted by wwilliam54
i think its the ecu break in detuneing
That seems reasonable given the a/f ratio. I doubt mazda would be willing to give up easy gains in fuel economy. However, even if this is true I don't think the mileage switch can account for the entire difference.
Old 08-01-03, 09:31 AM
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Originally posted by rxseven
umm..read my post again, carefully. I said it made 180 RWHP and mazda has it rated for 247 BHP. You can't have 67HP drivetrain loss unless their clutches are really bad. Anyway, they are the high performance, 6-port cars not the lowly automatics.
yeah, um, read MY post again carefully. I guess I should have added a after the 30% drivetrain loss part to clarify for those who might have thought that 30% was "normal".
Old 08-01-03, 10:18 AM
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I hope Mazda can get to the bottom of this soon!
The Miata was one problem they delt with before concerning horsepower numbers also.
Some of the early RX-8's were having problems with the ports not opening when they were tested by the mags.
Let's hope it's the same.
Believe it or not but as of late a lot of the manufacturers are having problems backing up horsepower claims.
The present Viper is showing up with 20 hp missing. The dealers are calling them back to remedy the problem which involves removing both heads and changing all the valves with the only difference than before being that they are putting them back in with a three angle valve job with the hope to gain the missing 20 hp.
When Ford first released the new Cobra they had the same problem also. Their remedy were to replace the intake manifold with a much better desinged one. I remeber one law suit against them where they rented our Dyno for an entire day trying to prove the owner wrong. The owner one that one
Have faith people. Let's hope it's something simple.
Old 08-01-03, 10:49 AM
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I thought most cars ran a running in map until you took the car back for its first oil change.

IIRC Mazda did this with the 3rd gen RX7's
Old 08-01-03, 11:24 AM
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I thought that the out-put was about 250 before all the drive-shaft, and tranny loses.?

which would put it at about 200rwhp?
Old 08-01-03, 01:52 PM
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I heard that there was an RX8 at vishnu tuning with only 1500 miles that only made 157rwhp.

boy the owner must have been pissed. I know I would be
Old 08-01-03, 04:26 PM
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What type of dyno's were those runs recorded on? if they are dyno dynamics then it would be right on que, on a dyno dynamics with 27% reading discrepency between flywheel and RW HP, 180rwhp = 248fwhp. which is what they are claiming
Old 08-01-03, 07:38 PM
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These were dynojet numbers.
Old 08-01-03, 08:58 PM
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i thought dynojet numbers were higher then mustang dyno numbers.
Old 08-02-03, 02:21 PM
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A member of the rx8 forum had their car dynoed at pettit and put down around 170rwhp. What kind of dyno does pettit have?


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