Sensitive subject, the true HP rating of a stock RX-8
09-23-2009, 03:18 PM
#26
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tmak, here you go.
This is a 2004 RX-8 BONE STOCK on 87 octane fuel
only 23% drivetrain loss.
This is a 2004 RX-8 BONE STOCK on 87 octane fuel
only 23% drivetrain loss.
09-23-2009, 03:28 PM
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09-23-2009, 03:52 PM
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23% sounds too steep (unless you have some weird mounted VW with AWD). Most cars should be around 15-20%. I think this sort of proves my theory, the engine probably isn't at 232HP
09-23-2009, 03:54 PM
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09-23-2009, 04:20 PM
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Well we live in a world where nothing is 100% provable beyond doubt, so as far as that goes the real crank power of the rx-8 is forever unknowable
But if you gather up all the stuff you can measure, and look at it together, you can sorta take a guess about what's probably going on:
1. Chassis dynos that tend to produce about 180whp, 130wtq for healthy cars
2. Hub dynos that tend to be around 210-220bhp: hymee's and racing beat's
3. Strip times
So whatever, the car doesn't make it's rated power in stock trim, it's still fine the way it is. Even if it's only 215bhp mazda has made some great progress refining the little 1.3L NA rotary, especially considering mazda is relatively small and they're the only manufacturer still working on this
But if you gather up all the stuff you can measure, and look at it together, you can sorta take a guess about what's probably going on:
1. Chassis dynos that tend to produce about 180whp, 130wtq for healthy cars
2. Hub dynos that tend to be around 210-220bhp: hymee's and racing beat's
3. Strip times
So whatever, the car doesn't make it's rated power in stock trim, it's still fine the way it is. Even if it's only 215bhp mazda has made some great progress refining the little 1.3L NA rotary, especially considering mazda is relatively small and they're the only manufacturer still working on this
09-23-2009, 04:36 PM
#33
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I know the car is rated for 232HP and 159FT-LB torque. Who on here thinks the number might be on the high side? I personally think the number is overflated slightly, I think the number is probably around 210-220HP stock.
This is not about if the car is good or not, it is simply an opinion on the car's reported figures. Think of it like Tom Cruise saying he is 5'11.
This is not about if the car is good or not, it is simply an opinion on the car's reported figures. Think of it like Tom Cruise saying he is 5'11.
09-23-2009, 04:37 PM
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I have to scan the charts, but I have dynoed the following cars on the dynojet (give or take 5hp as I am going off by memory here.
238RWHP on 2004 350Z (287HP) 17%
101RWHP on a 1993 Miata (116HP) 13%
337RWHP on a 2005 C6 (400HP) 16%
140RWHP on a 90 S5 NA RX-7 (160HP) 13% (I have a chart here that shows 141, but I think it was with a catback and exhaust. Stock was a few HP lower, might have been as low as 127)
238RWHP on 2004 350Z (287HP) 17%
101RWHP on a 1993 Miata (116HP) 13%
337RWHP on a 2005 C6 (400HP) 16%
140RWHP on a 90 S5 NA RX-7 (160HP) 13% (I have a chart here that shows 141, but I think it was with a catback and exhaust. Stock was a few HP lower, might have been as low as 127)
09-23-2009, 06:08 PM
#35
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well hey at least it's not as bad as old cars overrating power. Ferrari claimed like 260-300 bhp for their 3.0- 3.3l V12's from the 60's, yet when dyno'd the engines only make a little over 200 at the crank. Still probly sound amazing though.
09-23-2009, 06:15 PM
#36
HP measured at the flywheel is just pointless marketing BS anyway. The number that matters is the power at the wheels, and that's really what car manufacturers should advertise.
But measuring at the wheels results in lower numbers, and customers can also easily confirm those numbers, so no car manufacturer wants to advertise that. Instead they advertise a higher somewhat theoretical number that customers can't easily call BS on. That's true of all car manufacturers, not just Mazda.
But measuring at the wheels results in lower numbers, and customers can also easily confirm those numbers, so no car manufacturer wants to advertise that. Instead they advertise a higher somewhat theoretical number that customers can't easily call BS on. That's true of all car manufacturers, not just Mazda.
09-23-2009, 06:51 PM
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Mazda has a history of overrating their cars, see RX-8 & Miata.....
HP measured at the flywheel is just pointless marketing BS anyway. The number that matters is the power at the wheels, and that's really what car manufacturers should advertise.
But measuring at the wheels results in lower numbers, and customers can also easily confirm those numbers, so no car manufacturer wants to advertise that. Instead they advertise a higher somewhat theoretical number that customers can't easily call BS on. That's true of all car manufacturers, not just Mazda.
But measuring at the wheels results in lower numbers, and customers can also easily confirm those numbers, so no car manufacturer wants to advertise that. Instead they advertise a higher somewhat theoretical number that customers can't easily call BS on. That's true of all car manufacturers, not just Mazda.
09-23-2009, 06:56 PM
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and yes the sound was amazing!
09-23-2009, 07:04 PM
#39
Yes I know, hence the buyback offer when the 8 was introduced, and in that case Mazda was obviously telling a fairy tale. But Mazda isn't the only car company guilty of this. I do hope they are a bit more realistic when the 16X is introduced, I won't believe their claims until I see dynos.
09-23-2009, 07:04 PM
#40
HP measured at the flywheel is just pointless marketing BS anyway. The number that matters is the power at the wheels, and that's really what car manufacturers should advertise.
But measuring at the wheels results in lower numbers, and customers can also easily confirm those numbers, so no car manufacturer wants to advertise that. Instead they advertise a higher somewhat theoretical number that customers can't easily call BS on. That's true of all car manufacturers, not just Mazda.
But measuring at the wheels results in lower numbers, and customers can also easily confirm those numbers, so no car manufacturer wants to advertise that. Instead they advertise a higher somewhat theoretical number that customers can't easily call BS on. That's true of all car manufacturers, not just Mazda.
09-23-2009, 07:09 PM
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Well well well. I opened up the engine today, and a small person was stuck inside, and had been working continuously to power my vehicle using a bike-peddling mechanism. Actual horsepower was 0.25 when I had the person attempt to lift piles of coal by the neck, averaged and calculated over 10 minutes.
Last edited by User24; 09-23-2009 at 07:17 PM.
09-23-2009, 07:11 PM
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I honestly think most people aren't, this is why I said I believe the car might have been overstated in terms of power. I think most cars are at around 180rwhp, that makes it 210-220bhp roughly.
09-23-2009, 10:36 PM
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I don't think the motor is dropping 10-30HP, there is just no way. My old RX-7 didn't even lose that much at 76K and then at 167K miles.
09-24-2009, 09:21 AM
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Think about transmission fluid degrading at our higher-than-normal heat ranges. Think about or diff fluid degrading. Thing about or coil packs degrading, or plugs degrading, our wires degrading. THIS is where most RX-8s have power loss on the dyno, because it isn't firing as good as it should, and it wastes more power turning old fluid.
Seriously, keep them in top condition, and the only loss you will experience is general engine wear, causing a loss in compression, and with proper premixing, you can avoid a chunk of this as well.
You can't claim one engine is weaker than another seemingly identical engine without taking these variables into account. Most owners don't do a good enough job at feeding their engine correctly, and keeping drivetrain loss down.
Hymee did this on a heavily used engine, with a stock, brand new RX-8 ignition.
http://www.performancedesign.com.au/...EngineDyno.pdf
09-24-2009, 12:32 PM
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Is the motor dropping 10-30hp? No. But the car is. Right off the lot, the 232 is accurate, and it will be accurate for the motor if you make sure it is being fed correctly. The problem is, most RX-8s drop from this, but not from the motor. They certainly do drop 10-30hp over time.
Think about transmission fluid degrading at our higher-than-normal heat ranges. Think about or diff fluid degrading. Thing about or coil packs degrading, or plugs degrading, our wires degrading. THIS is where most RX-8s have power loss on the dyno, because it isn't firing as good as it should, and it wastes more power turning old fluid.
Seriously, keep them in top condition, and the only loss you will experience is general engine wear, causing a loss in compression, and with proper premixing, you can avoid a chunk of this as well.
You can't claim one engine is weaker than another seemingly identical engine without taking these variables into account. Most owners don't do a good enough job at feeding their engine correctly, and keeping drivetrain loss down.
Hymee did this on a heavily used engine, with a stock, brand new RX-8 ignition.
http://www.performancedesign.com.au/...EngineDyno.pdf
Think about transmission fluid degrading at our higher-than-normal heat ranges. Think about or diff fluid degrading. Thing about or coil packs degrading, or plugs degrading, our wires degrading. THIS is where most RX-8s have power loss on the dyno, because it isn't firing as good as it should, and it wastes more power turning old fluid.
Seriously, keep them in top condition, and the only loss you will experience is general engine wear, causing a loss in compression, and with proper premixing, you can avoid a chunk of this as well.
You can't claim one engine is weaker than another seemingly identical engine without taking these variables into account. Most owners don't do a good enough job at feeding their engine correctly, and keeping drivetrain loss down.
Hymee did this on a heavily used engine, with a stock, brand new RX-8 ignition.
http://www.performancedesign.com.au/...EngineDyno.pdf
Ya I agree with that actually. I mean, with perfect conditions (altitude, air temp, etc), with a nicely broken in motor with pretty low miles, with perfect coils, plugs, air filter etc, the Renesis probly does make 230 ish BHP. There have been completely stock 8's that make about 190 wheel hp, so that only be an 18% drivetrain loss to get up to 232 crank. seems very plausible. Factor in less than ideal climate conditions, less than ideal coils and plugs, old tranny and diff fluids, and you can easily dyno at 175 or so. Makes sense.
I mean, if i were a professional engine maker, such as mazda, I would claim a power figure that IS achievable in perfect conditions. Why would you advertise a motor as making less power than what it is technically capable, albeit unlikely in most real world scenarios, of producing? 232 makes sense to advertise in my opinion.
Although it is odd to learn that some makers are actually doing the opposite, such as BMW. Everyone knows the 335i makes about 330 bhp or so, considering it dynos at 275+ at the wheels.
