does this explain the dyno problem
01-28-2005, 03:13 PM
#51
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First I must say that what Mazda is claiming seems to be correct to me. All anyone needs to do to prove these claim is to hook up a scan tool to an RX-8 while it is on the dyno during a pull and then to the same car during a run through that gear on the road. Just compare the throttle position, timing, and injector pulse width readings. If there are obvious differences in even one of the numbers, then there will be a major difference in HP.
01-28-2005, 04:05 PM
#53
Bummed, but bring on OU!
Most of the relatively stock 6 port dynos that I've seen look similar to this
https://www.rx8club.com/attachment.p...chmentid=30989
now ignoring the max power number, and looking at the general slope of the horsepower curve. If the curve didn't freak out after 7500rpm, and followed the same slope, it looks to me like the car would put down about 210hp to the wheels. Almost every stock 6 port dyno has this erratic behavior at the top of the curve. What's the deal? Not enough air? Timing? Something else?
https://www.rx8club.com/attachment.p...chmentid=30989
now ignoring the max power number, and looking at the general slope of the horsepower curve. If the curve didn't freak out after 7500rpm, and followed the same slope, it looks to me like the car would put down about 210hp to the wheels. Almost every stock 6 port dyno has this erratic behavior at the top of the curve. What's the deal? Not enough air? Timing? Something else?
01-28-2005, 04:29 PM
#55
RX8 and a Truk....
Originally Posted by therm8
Most of the relatively stock 6 port dynos that I've seen look similar to this
https://www.rx8club.com/attachment.p...chmentid=30989
now ignoring the max power number, and looking at the general slope of the horsepower curve. If the curve didn't freak out after 7500rpm, and followed the same slope, it looks to me like the car would put down about 210hp to the wheels. Almost every stock 6 port dyno has this erratic behavior at the top of the curve. What's the deal? Not enough air? Timing? Something else?
https://www.rx8club.com/attachment.p...chmentid=30989
now ignoring the max power number, and looking at the general slope of the horsepower curve. If the curve didn't freak out after 7500rpm, and followed the same slope, it looks to me like the car would put down about 210hp to the wheels. Almost every stock 6 port dyno has this erratic behavior at the top of the curve. What's the deal? Not enough air? Timing? Something else?
Judging from my CanScans, I'd bet that's the result of the ECU dumping ALL KINDS of fuel into the mix. We're talking 11.x: 1 A/F ratios.
01-28-2005, 04:52 PM
#56
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I think someone needs to try converting the throttle to being mechanically controlled, and use a stand-alone ECU (or, can you get a standalone to work with and electronically controlled throttle?). Then the engine will be forced to do whatever the tuner tells it to do. 
01-28-2005, 05:09 PM
#57
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Originally Posted by dmp
Judging from my CanScans, I'd bet that's the result of the ECU dumping ALL KINDS of fuel into the mix. We're talking 11.x: 1 A/F ratios.
01-28-2005, 05:11 PM
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Originally Posted by shaolin
I really hate how people say they don't feel or do feel that the car has 238 HP....fact of the matter is, 240-ish HP feels very differently from car to car, mainly due to the difference in weights and more importantly, the TORQUE CURVE.
IMHO the car feels like it has 238 HP for sure, but it also feels like it only has 155-ish torque...in other words, without a good torque curve, 238 HP means nothing. Not that the RX-8 has a terrible curve, just not as good as other cars, and that's the nature of the rotary. That's why you have a 9K RPM redline. Get used to it, and row that gear box.
What alot of people don't realize is that cars that usually have 240-ish HP, by nature of design, usually have a larger amount of torque making them FEEL powerful. So in short, when someone says they can "feel that the HP is there, or isn't there" they are actually talking out of their ***. LITERALLY.
IMHO the car feels like it has 238 HP for sure, but it also feels like it only has 155-ish torque...in other words, without a good torque curve, 238 HP means nothing. Not that the RX-8 has a terrible curve, just not as good as other cars, and that's the nature of the rotary. That's why you have a 9K RPM redline. Get used to it, and row that gear box.
What alot of people don't realize is that cars that usually have 240-ish HP, by nature of design, usually have a larger amount of torque making them FEEL powerful. So in short, when someone says they can "feel that the HP is there, or isn't there" they are actually talking out of their ***. LITERALLY.
The way a car steers, corners, handles, rides and accelerates is all about the "feeling" your senses get when you drive a car. And for me, that's where the pleasure and excitement comes from. Not some dyno run that may or may not be a good data point.
But anyway, I do have a gtech as well. I rarely use it and mainly just to benchmark how my personal cars fair vs. what the magazines get for 0-60 runs. I haven't used it on my RX-8 until last weekend, because I've always felt the power in my RX-8 was strong. Well for grins, I tried a few 0-60 runs: 7.4, 7.3, 6.8, and then 6.4 secs (with a 5k rpm clutch drop). I'm satisified. I feel if I did a 7K drop with a good launch, I'd come close to the 5.9 secs that the mags got.
Anyone can say what they want, but I love the way this car "feels" when I drive it! The car the mags have all validated its performance and my little gtech has validated my own car for me. I'm happy, all is right with the world.
01-29-2005, 03:57 PM
#59
Originally Posted by RX-Hachi
Sure this is true, but how the car "feels" to me is the only thing I care about.
The way a car steers, corners, handles, rides and accelerates is all about the "feeling" your senses get when you drive a car. And for me, that's where the pleasure and excitement comes from. Not some dyno run that may or may not be a good data point.
But anyway, I do have a gtech as well. I rarely use it and mainly just to benchmark how my personal cars fair vs. what the magazines get for 0-60 runs. I haven't used it on my RX-8 until last weekend, because I've always felt the power in my RX-8 was strong. Well for grins, I tried a few 0-60 runs: 7.4, 7.3, 6.8, and then 6.4 secs (with a 5k rpm clutch drop). I'm satisified. I feel if I did a 7K drop with a good launch, I'd come close to the 5.9 secs that the mags got.
Anyone can say what they want, but I love the way this car "feels" when I drive it! The car the mags have all validated its performance and my little gtech has validated my own car for me. I'm happy, all is right with the world.
The way a car steers, corners, handles, rides and accelerates is all about the "feeling" your senses get when you drive a car. And for me, that's where the pleasure and excitement comes from. Not some dyno run that may or may not be a good data point.
But anyway, I do have a gtech as well. I rarely use it and mainly just to benchmark how my personal cars fair vs. what the magazines get for 0-60 runs. I haven't used it on my RX-8 until last weekend, because I've always felt the power in my RX-8 was strong. Well for grins, I tried a few 0-60 runs: 7.4, 7.3, 6.8, and then 6.4 secs (with a 5k rpm clutch drop). I'm satisified. I feel if I did a 7K drop with a good launch, I'd come close to the 5.9 secs that the mags got.
Anyone can say what they want, but I love the way this car "feels" when I drive it! The car the mags have all validated its performance and my little gtech has validated my own car for me. I'm happy, all is right with the world.
The magazines actually say their best times were done with a 7000 rpm drop - I've done a few before on a nice, warm day and the car just hooks up and flies.
As for the torque curve, its a pretty flat line - much better than the S2000s - you can still get some pull in almost any gear, even if its not a high amount of torque.
01-31-2005, 10:23 AM
#60
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Re:
Way back when this was being discussed, Canzoomer noted, through schematics and testing, that the only sensors that monitor front wheel speeds are disabled when the DSC was fully disabled, thus there is no way for the computer to know if the wheels are turning or not. So in my opinion, this cannot be the reason, and having driven a fair amount of cars in my day, I do not believe the RX8 is making much over 210hp.
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