RX-8 Dyno numbers...trouble in paradise?
08-07-03, 10:07 PM
#76
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Originally posted by KiyoKix
Do we have anyone here who did testing on a RENESIS engine with the Mazda engineers? Proly...no wait...HELL NO. So we really have no right at all to say they lied (or even imply). I would think they the people who are dumb enough to dyno a car THAT NEW are out of their minds.
On another note...if you were Mazda and you were re-releasing an important product into the line wouldn't you put a safeguard on it to make sure it's broken in right. They WON'T I repeat...WON'T give the chance for people to break the car quickly like the FD and risk dumbass people giving the rotary a bad name again. It's pretty much common sense the car is gonna limit what you can do until the engine is fully broken in. A car that weighs 1300kg and only puts 185rwhp is NOT gonna give you 0-60 in 5.9 and a quarter time to match. Think about that next time you say they lied. How is it that factory demo car that everyone reviews has the power but the others don't...hmmmmm I wonder.
Think before you speak (lash out at someone else who obviously knows more than you about the product) out harshly on something. We should all just be happy the rotary has returned to the states again, go to the dyno later on when it's time. Be patient
Do we have anyone here who did testing on a RENESIS engine with the Mazda engineers? Proly...no wait...HELL NO. So we really have no right at all to say they lied (or even imply). I would think they the people who are dumb enough to dyno a car THAT NEW are out of their minds.
On another note...if you were Mazda and you were re-releasing an important product into the line wouldn't you put a safeguard on it to make sure it's broken in right. They WON'T I repeat...WON'T give the chance for people to break the car quickly like the FD and risk dumbass people giving the rotary a bad name again. It's pretty much common sense the car is gonna limit what you can do until the engine is fully broken in. A car that weighs 1300kg and only puts 185rwhp is NOT gonna give you 0-60 in 5.9 and a quarter time to match. Think about that next time you say they lied. How is it that factory demo car that everyone reviews has the power but the others don't...hmmmmm I wonder.
Think before you speak (lash out at someone else who obviously knows more than you about the product) out harshly on something. We should all just be happy the rotary has returned to the states again, go to the dyno later on when it's time. Be patient
When I started this thread, I was not trying to bash mazda just stating that the initial numbers were dissapointing and people who paid over 30K for the car were disgusted. If it was detuned on purpose then how come no mazda dealer could confirm that? They had a special training program for the dealer service techs according to my local dealer and there was no mention of such a thing. Btw, pre-production models also had HP problems and it was attributed to 5 & 6 ports not opening up. These dyno charts do show the ports opening up though.
Man, I really want the renesis to be a commercial success because I love rotaries. But I would not swap it into an rx-7 just yet. I have heard some 3rd gen guys were trying to buy some crate motors for better reliability, that is why I brought it up on this forum.
08-08-03, 01:29 AM
#77
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Originally posted by wakeech
sorry to take you apart peejay, but any design with less port area will not happen. also, having a greater displacement with a smaller e-shaft stroke is really REALLY counter productive. longer block is not really conducive to better performace (with high revs). there are lots of problems with this, like volumetric efficiency (not just the ports)... it's certainly not ideal.
sorry to take you apart peejay, but any design with less port area will not happen. also, having a greater displacement with a smaller e-shaft stroke is really REALLY counter productive. longer block is not really conducive to better performace (with high revs). there are lots of problems with this, like volumetric efficiency (not just the ports)... it's certainly not ideal.
Also note that between the 10A to the 12A to the 13B in the 70's, torque was rising out of proportion to displacement. I wonder why that is.....
08-08-03, 01:36 AM
#78
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Originally posted by dragula53
"Lee Bender of C&L Performance and Paul Svinicki of Paul's High Performance are both well versed in evaluating Mustangs on the dyno, and they both agreed that extrapolating drivertrain horsepower loss via percentages is flawed._ Lee believes that the stick Mustangs experience roughly a 35hp loss through the drivetrain, whether they make 200 hp or 400 hp._ He did explain that ultra-high-powered vehicles - typically race cars - can be and exception to this rule, but that's a topic for another time."
(courtesy of http://www.superstang.com/horsepower.htm)
I've also seen this same thing stated related to miatas on miata forums, etc.
Anyhow.
Just didn't wanna come out of left field for no reason.
moo
"Lee Bender of C&L Performance and Paul Svinicki of Paul's High Performance are both well versed in evaluating Mustangs on the dyno, and they both agreed that extrapolating drivertrain horsepower loss via percentages is flawed._ Lee believes that the stick Mustangs experience roughly a 35hp loss through the drivetrain, whether they make 200 hp or 400 hp._ He did explain that ultra-high-powered vehicles - typically race cars - can be and exception to this rule, but that's a topic for another time."
(courtesy of http://www.superstang.com/horsepower.htm)
I've also seen this same thing stated related to miatas on miata forums, etc.
Anyhow.
Just didn't wanna come out of left field for no reason.
moo
Drivetrain losses are due to friction. This friction converts power into heat. The more power you send through the drivetrain, the more friction there is from forcing the gears against each other harder and forcing the bearings harder, so the more heat you generate and the more power you lose.
About 10 years ago my stepdad (engineer) have me a big gear on a precision bearing, a souvenir from his days with Timken. If you stuck it on your finger and spun it it would spin for MINUTES. I noted this when he gave it to me and I'll never forget what he said... "Yeah, but what about when it is *under load*?"
08-08-03, 10:06 AM
#79
People shouldn't be dynoing their cars with so few miles on them anyways. Got to get them broken in first.
I drove an RX-8 2 days ago. I also drove a prototype car back in January. My initial impressions back in January were that the car had almost no power. It felt like my Civic. I am proud to say that the production car is much faster everywhere in the powerband. It still isn't a rocket by any means but it feels very nice. Anyone used to the turbos on the 3rd gen will be dissappointed but it will still outrun any stock T-II.
I drove an RX-8 2 days ago. I also drove a prototype car back in January. My initial impressions back in January were that the car had almost no power. It felt like my Civic. I am proud to say that the production car is much faster everywhere in the powerband. It still isn't a rocket by any means but it feels very nice. Anyone used to the turbos on the 3rd gen will be dissappointed but it will still outrun any stock T-II.
08-08-03, 10:13 AM
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Originally posted by peejay
Note: Didn't say anything about larger displacement, just a smaller eccentricity and wider rotors to compensate.
Also note that between the 10A to the 12A to the 13B in the 70's, torque was rising out of proportion to displacement. I wonder why that is.....
Note: Didn't say anything about larger displacement, just a smaller eccentricity and wider rotors to compensate.
Also note that between the 10A to the 12A to the 13B in the 70's, torque was rising out of proportion to displacement. I wonder why that is.....
the torque rises out of proportion when you add the 6 ports (133hp and 133lbsft) or a turbo
mike
08-08-03, 10:59 AM
#81
Remeber that the early engines back in the early 70's weren't choked by emissions standards that they are now. Power started falling off when emissions standards came along. Torque is directly proportional to horspower so to accurately compare numbers we really need all of the specs to be at the same rpm and with each engine set up identically to the other minus the displacement differences.
08-08-03, 11:01 AM
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Originally posted by rotarygod
Remeber that the early engines back in the early 70's weren't choked by emissions standards that they are now. Power started falling off when emissions standards came along. Torque is directly proportional to horspower so to accurately compare numbers we really need all of the specs to be at the same rpm and with each engine set up identically to the other minus the displacement differences.
Remeber that the early engines back in the early 70's weren't choked by emissions standards that they are now. Power started falling off when emissions standards came along. Torque is directly proportional to horspower so to accurately compare numbers we really need all of the specs to be at the same rpm and with each engine set up identically to the other minus the displacement differences.
mike
08-09-03, 12:51 AM
#83
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Actually the 10A's had peak power at 7000rpm.
The Cosmo 10A's also had no emissions equipment.
Torque is directly related to displacement, HP is directly related to displacement and RPM range. Things like thermal efficiency and volumetric efficiency trim it up or down.
The Cosmo 10A's also had no emissions equipment.
Torque is directly related to displacement, HP is directly related to displacement and RPM range. Things like thermal efficiency and volumetric efficiency trim it up or down.
08-09-03, 02:20 AM
#84
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Originally posted by rotarygod
Remeber that the early engines back in the early 70's weren't choked by emissions standards that they are now. Power started falling off when emissions standards came along. Torque is directly proportional to horspower so to accurately compare numbers we really need all of the specs to be at the same rpm and with each engine set up identically to the other minus the displacement differences.
Remeber that the early engines back in the early 70's weren't choked by emissions standards that they are now. Power started falling off when emissions standards came along. Torque is directly proportional to horspower so to accurately compare numbers we really need all of the specs to be at the same rpm and with each engine set up identically to the other minus the displacement differences.
08-09-03, 04:37 AM
#85
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Um,..........no
5 ft/lbs of torque at 9000 rpm would be 8 hp,..
If you had 1000 rwhp you would be going somewhere very fast, no matter what rpm/torque it occurs at.
Thats why they invented a little device we like to call the transmission. If you had 5 ft/lb of torque, you would need ~1,000,000 rpm to make 1000 HP, now you run that thru your transmission with a 500:1 gear ratio and you get 2500 ft/lbs of torque with a very useable 2000 rpm shaft output to go into the rear end 4:1 sound good? that makes 10,000 ft/lbs of torque, with the wheels spinning at 500 rpm
that gear would be good for 65 mph btw, youd get more effective torque if it was lower.
f1 cars only make about 240 ft/lbs and id say their pretty fast.
HP is not fictional, it is a measure of power, which is work over time, torque is a measure of work alone.
power is a much more useful rating then work, because power is a good representation of how much work a motor can do, where as torque is an instantanious measurement of its rotational force, which would only really be useful if no one had invented transmissions.
5 ft/lbs of torque at 9000 rpm would be 8 hp,..
If you had 1000 rwhp you would be going somewhere very fast, no matter what rpm/torque it occurs at.
Thats why they invented a little device we like to call the transmission. If you had 5 ft/lb of torque, you would need ~1,000,000 rpm to make 1000 HP, now you run that thru your transmission with a 500:1 gear ratio and you get 2500 ft/lbs of torque with a very useable 2000 rpm shaft output to go into the rear end 4:1 sound good? that makes 10,000 ft/lbs of torque, with the wheels spinning at 500 rpm
that gear would be good for 65 mph btw, youd get more effective torque if it was lower.
f1 cars only make about 240 ft/lbs and id say their pretty fast.
HP is not fictional, it is a measure of power, which is work over time, torque is a measure of work alone.
power is a much more useful rating then work, because power is a good representation of how much work a motor can do, where as torque is an instantanious measurement of its rotational force, which would only really be useful if no one had invented transmissions.
08-09-03, 06:35 AM
#86
Old [Sch|F]ool
You're both right.
As the RPM range goes up, your ability to accelerate is increasingly affected by the rotational inertia of the engine and drivetrain. Meaning, if you have two 500hp engines but one of them has less rotational inertia, the "lighter" one will accelerate the car harder. Pull a steady load up a hill, and they will be identical, though, because they both make the same HP.
Power is work over time. Torque is not work, however. Torque is force. Picture this - you have a ratchet on a difficult bolt. Let's say you have a 2' long ratchet on an RX-7 flywheel nut, and you are applying 100 pounds of force on the end of the ratchet. This is 200lb-ft of torque, which is force. But the nut is not turning, because they are complete bastards, so no work is done because there is no motion, so you are putting out zero HP. For an example of work, imagine pushing a wheelbarrow up a hill. No matter how fast or how slow you do it, it takes the same total amount of work to move it up the hill. How *fast* you do it, is power. To move that wheelbarrow up twice as fast, you need twice as much power.
Break the figures down... Torque times revolutions per minute is horsepower. Torque is rotational force, revolutions are rotational distance, minutes are time. Force times distance is work. Force times distance per unit of time is a measure of power. (One horsepower, in fact, is the ability to lift 550 pounds one foot in one second)
This turned out longer than I thought, but I hope this helps...
As the RPM range goes up, your ability to accelerate is increasingly affected by the rotational inertia of the engine and drivetrain. Meaning, if you have two 500hp engines but one of them has less rotational inertia, the "lighter" one will accelerate the car harder. Pull a steady load up a hill, and they will be identical, though, because they both make the same HP.
Power is work over time. Torque is not work, however. Torque is force. Picture this - you have a ratchet on a difficult bolt. Let's say you have a 2' long ratchet on an RX-7 flywheel nut, and you are applying 100 pounds of force on the end of the ratchet. This is 200lb-ft of torque, which is force. But the nut is not turning, because they are complete bastards, so no work is done because there is no motion, so you are putting out zero HP. For an example of work, imagine pushing a wheelbarrow up a hill. No matter how fast or how slow you do it, it takes the same total amount of work to move it up the hill. How *fast* you do it, is power. To move that wheelbarrow up twice as fast, you need twice as much power.
Break the figures down... Torque times revolutions per minute is horsepower. Torque is rotational force, revolutions are rotational distance, minutes are time. Force times distance is work. Force times distance per unit of time is a measure of power. (One horsepower, in fact, is the ability to lift 550 pounds one foot in one second)
This turned out longer than I thought, but I hope this helps...
Last edited by peejay; 08-09-03 at 06:37 AM.
08-09-03, 11:59 AM
#87
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This is the worst subject to argue about EVER! 
Check this link out:
http://www.stanford.edu/~voloshin/lhowwhy.html
Blake
Check this link out:http://www.stanford.edu/~voloshin/lhowwhy.html
Blake
08-15-03, 02:54 PM
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Just to clarify guys we have a Dyno Dynamics Dyno here at Vishnu, not a Dynapack(we don't have a pit crew here or the time to mess with that dyno) You can read about the dyno at www.dyno.com.au. This dyno does read lower than the dynojet by approx 17% in 2WD mode. For Rice Racing the RX-8 made 117KW at the wheels on our Dyno Dynamics Dyno. I am sure that you have used plenty of those back home in Australia.
For comparison a Acura Integra Type R made 153 wheel horsepower, and a Honda S2000 made 185 wheel horsepower with both cars being stock on our dyno. Just wanted to clear that up fella's. Take care guys.
Brett Payne
Vishnu Performance
For comparison a Acura Integra Type R made 153 wheel horsepower, and a Honda S2000 made 185 wheel horsepower with both cars being stock on our dyno. Just wanted to clear that up fella's. Take care guys.
Brett Payne
Vishnu Performance
08-16-03, 05:39 PM
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Yeah well here is my argument.
When are youg guys gonna get over the fact the rx8 isnt a dragger or a sports car? It is a sporty sedan.
Who cares how fast it goes down the strip?It's not made for that.You all sound like a bunch of Honda Accord owners trying to race your 4 door grocery getter.
Now when someone needs to get mad or upset is if the rx7 comes out andit cant even produce 250 hp,280,or 300.
And the only thing that the rx7 needs to compete with is the same car its been competing with its whole life, the Supra.
What i want to hurry up and see is a decked out Renesis Turbo and see how it compares with a 13b-rew.
Please do not say anything about compression being to high. I will slap you.compression can be lowered.
Say for instance a streetported t78 13b-rew versus a street intake and exhuast ported t78 13-msp-re.Seeing as the new engine does not have a peripheral exhuast,not as much heat, but has better "piston like" effeciency. I'm sure the exhuast ports can have different style porting(i.e. street, bridge) for different flow characteristics.You also gotta look at if a huge turbo is placed on the engine, it may not spool the turbo as fast as a peripheral exhuast 13b-rew, but the stock rpm band 2k rpms higher. Plus that is limited by ecu.The stock redline was 10k.More of a power band to play with.
When are youg guys gonna get over the fact the rx8 isnt a dragger or a sports car? It is a sporty sedan.
Who cares how fast it goes down the strip?It's not made for that.You all sound like a bunch of Honda Accord owners trying to race your 4 door grocery getter.
Now when someone needs to get mad or upset is if the rx7 comes out andit cant even produce 250 hp,280,or 300.
And the only thing that the rx7 needs to compete with is the same car its been competing with its whole life, the Supra.
What i want to hurry up and see is a decked out Renesis Turbo and see how it compares with a 13b-rew.
Please do not say anything about compression being to high. I will slap you.compression can be lowered.
Say for instance a streetported t78 13b-rew versus a street intake and exhuast ported t78 13-msp-re.Seeing as the new engine does not have a peripheral exhuast,not as much heat, but has better "piston like" effeciency. I'm sure the exhuast ports can have different style porting(i.e. street, bridge) for different flow characteristics.You also gotta look at if a huge turbo is placed on the engine, it may not spool the turbo as fast as a peripheral exhuast 13b-rew, but the stock rpm band 2k rpms higher. Plus that is limited by ecu.The stock redline was 10k.More of a power band to play with.
08-18-03, 04:07 PM
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Originally posted by CCarlisi
A member of the rx8 forum had their car dynoed at pettit and put down around 170rwhp. What kind of dyno does pettit have?
A member of the rx8 forum had their car dynoed at pettit and put down around 170rwhp. What kind of dyno does pettit have?
08-19-03, 07:03 PM
#93
Originally posted by twint78
Say for instance a streetported t78 13b-rew versus a street intake and exhuast ported t78 13-msp-re.Seeing as the new engine does not have a peripheral exhuast,not as much heat, but has better "piston like" effeciency. I'm sure the exhuast ports can have different style porting(i.e. street, bridge) for different flow characteristics.You also gotta look at if a huge turbo is placed on the engine, it may not spool the turbo as fast as a peripheral exhuast 13b-rew, but the stock rpm band 2k rpms higher. Plus that is limited by ecu.The stock redline was 10k.More of a power band to play with.
Say for instance a streetported t78 13b-rew versus a street intake and exhuast ported t78 13-msp-re.Seeing as the new engine does not have a peripheral exhuast,not as much heat, but has better "piston like" effeciency. I'm sure the exhuast ports can have different style porting(i.e. street, bridge) for different flow characteristics.You also gotta look at if a huge turbo is placed on the engine, it may not spool the turbo as fast as a peripheral exhuast 13b-rew, but the stock rpm band 2k rpms higher. Plus that is limited by ecu.The stock redline was 10k.More of a power band to play with.
08-21-03, 10:54 PM
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Wow...86 mph thats pretty strange. Here is what someone got with their gtech.
http://www.rx8forum.com/showthread.p...&pagenumber=18
I really dont know how inaccurate it could possibly be. Even half a second off would still yield the fastest time any magazine got. I dont konw about the 101.4 mph trap speed though, im guessing he would need around 215ish at the wheels? Anyway, some of the other things that it calculated are strange but worth looking at.
nearly forgot...its at the bottom.
http://www.rx8forum.com/showthread.p...&pagenumber=18
I really dont know how inaccurate it could possibly be. Even half a second off would still yield the fastest time any magazine got. I dont konw about the 101.4 mph trap speed though, im guessing he would need around 215ish at the wheels? Anyway, some of the other things that it calculated are strange but worth looking at.
nearly forgot...its at the bottom.
Last edited by crazyfool; 08-21-03 at 10:59 PM.
08-22-03, 10:19 PM
#97
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Well, it's official. Mazda downgraded the hp to 238 BHP. They lied again!!!! I am convinced they inflated the actual HP by 5% or so to arrive at 238HP. They are still trying to get away with whatever they can.
08-22-03, 11:37 PM
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Even with 238hp it should still be over 200rw....actually with 15% loss it would be 202rwhp. Thats still 20-30RWhp off from what people are actually getting. If they are averaging 180rw on the dyno that would be right around 210hp.
Supposedly they had to change the ecu's out at the last minute when they went thru customs. Sounds like the 250hp wasnt measuring up to the emmissions standards and they had to change the tuning or something.
STEPHEN
Supposedly they had to change the ecu's out at the last minute when they went thru customs. Sounds like the 250hp wasnt measuring up to the emmissions standards and they had to change the tuning or something.
STEPHEN
08-23-03, 02:04 AM
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The fact that the European spec RX-8 is rated at 228 hp in the latest Evo magazine from England should be noted. If the RX-8 is making 175 wheel horsepower on a dynojet dyno and 157 wheel horsepower on a dyno dynamics dyno then this leads me to beleive that the car is only delivering around 210 horsepower to the flywheel. 115 pound foot of torque at the wheels at 6300 rpm is not very impressive either, and certainly not what was quoted by Mazda.
Overall Mazda has once again screwed the pooch and the fact that they are not offering to fix the lost horsepower and once again throwing $500 to owners is quite pathetic. What happened to the 280 horsepower this motor was making in pre-production cars? Thank goodness the new RX-7 will have a 1.6 litre motor as it is "rated" at 300 horsepower. Perhaps that motor will make the 250 horsepower this Renesis is rated at.
But we will probably never get to see the RX-7 as the RX-8 will likely die a quick death because of this scandal. The 6 speed RX-8 is not making 250 or even 239 horsepower, but 210 just like the automatic. That is unacceptable and Mazda should find the missing ponies. Or tell everyone that it made a huge mistake and drop the price $5000 and try to sell it as a 210 horsepower car. That would at least be honest.
Brett.
Overall Mazda has once again screwed the pooch and the fact that they are not offering to fix the lost horsepower and once again throwing $500 to owners is quite pathetic. What happened to the 280 horsepower this motor was making in pre-production cars? Thank goodness the new RX-7 will have a 1.6 litre motor as it is "rated" at 300 horsepower. Perhaps that motor will make the 250 horsepower this Renesis is rated at.
But we will probably never get to see the RX-7 as the RX-8 will likely die a quick death because of this scandal. The 6 speed RX-8 is not making 250 or even 239 horsepower, but 210 just like the automatic. That is unacceptable and Mazda should find the missing ponies. Or tell everyone that it made a huge mistake and drop the price $5000 and try to sell it as a 210 horsepower car. That would at least be honest.
Brett.
08-24-03, 02:34 AM
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Does anyone know what the RX8s in Japan are doing?
Remember that the Japs have 100 octane fuel on the pump, would be very interesting to see what they are up to....
Remember that the Japs have 100 octane fuel on the pump, would be very interesting to see what they are up to....