Check out this Supercharger
12-01-2006, 04:53 PM
#26
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I am no expert, but the S2000 guys have been using similar chargers; breaking the 350 RWHP easily. As far as I know, the S2000 is not a torque monster car either....
On the other hand, with the "turbo kits" out there for the RX8; why look for something else?
On the other hand, with the "turbo kits" out there for the RX8; why look for something else?
12-01-2006, 06:01 PM
#27
[QUOTE=epitrochoid]You can't simultaneously make a claim that power increases between 6 and 9k are acceptable and that you have a greater area under the curve. you have to look at the entire torque curve.
the only curve that counts is the torque curve. hp is actually the area under the curve from 0-X rpm (not quite, but you obviously know calculus so you know what i mean). and the slope of the HP curve is torque. while yea, gains from 6-9k are alright for racing, you're still going to have a sloped torque curve at the point, which only leads to a more sloped hp curve. if your particular setup can support XXXft/lbs of torque, and you only had that at exactly 9000 rpm (ignorning airflow properties of the motor here), you would get beat by the same car that had the same torque at 3500 rpm and held it to 9000 rpm.
[QUOTE]
Agree that lower down the rpm range this setup will not match up with turbo car but it is still a lot quicker than stock . You make it sound like a stock NA car would pwn this supercharged car down low (which it absolutely would not).
As far as higher up the rpm range (and racing) it does not matter a toss how much torque you have below the shift points. If you have ever ridden a two stroke motorcross bike you will know what I mean .
I do agree that the car will not be as quick as a turbo with the same peak out put .
However :
Extrapolating the S/C curve to 350 hp would give roughly 315hp average from 6-9k .
From this (and looking at your hp curve) I would expect this car to be as quick as a turbo car producing 320-330 peak hp.
the only curve that counts is the torque curve. hp is actually the area under the curve from 0-X rpm (not quite, but you obviously know calculus so you know what i mean). and the slope of the HP curve is torque. while yea, gains from 6-9k are alright for racing, you're still going to have a sloped torque curve at the point, which only leads to a more sloped hp curve. if your particular setup can support XXXft/lbs of torque, and you only had that at exactly 9000 rpm (ignorning airflow properties of the motor here), you would get beat by the same car that had the same torque at 3500 rpm and held it to 9000 rpm.
[QUOTE]
Agree that lower down the rpm range this setup will not match up with turbo car but it is still a lot quicker than stock . You make it sound like a stock NA car would pwn this supercharged car down low (which it absolutely would not).
As far as higher up the rpm range (and racing) it does not matter a toss how much torque you have below the shift points. If you have ever ridden a two stroke motorcross bike you will know what I mean .
I do agree that the car will not be as quick as a turbo with the same peak out put .
However :
Extrapolating the S/C curve to 350 hp would give roughly 315hp average from 6-9k .
From this (and looking at your hp curve) I would expect this car to be as quick as a turbo car producing 320-330 peak hp.
Last edited by Brettus; 12-01-2006 at 07:00 PM.
12-01-2006, 06:58 PM
#29
Originally Posted by knonfs
On the other hand, with the "turbo kits" out there for the RX8; why look for something else?
This is just my opinion which is not necessarily based on the facts so please tell me if you have FACTS to disprove any of this.
*more reliable
*Boost is the same for a set rpm so your tune should be more stable
*Less lag
*more civilized as a daily driver
*easier to bolt on - less to modify
*smoother transition to boost - so more drivable in the wet especially.
*easier on motor & drivetrain due to lower peak torque & smoother transition to boost.
Last edited by Brettus; 12-01-2006 at 07:06 PM.
12-01-2006, 07:07 PM
#30
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This is cool and all I guess, but personally if I had the money to spend, I'd just wait for one of the twin screw kits to come out (average HP > peak HP), I think Petit is getting pretty close. Waiting sucks, but getting a lesser product and then living with it for several years sucks more.
12-01-2006, 07:26 PM
#31
Originally Posted by BaronVonBigmeat
This is cool and all I guess, but personally if I had the money to spend, I'd just wait for one of the twin screw kits to come out (average HP > peak HP), I think Petit is getting pretty close. Waiting sucks, but getting a lesser product and then living with it for several years sucks more.
12-02-2006, 06:11 PM
#32
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Originally Posted by Brettus
good point - have to struggle to find an answer to this .
This is just my opinion which is not necessarily based on the facts so please tell me if you have FACTS to disprove any of this.
*more reliable
*Boost is the same for a set rpm so your tune should be more stable
*Less lag
*more civilized as a daily driver
*easier to bolt on - less to modify
*smoother transition to boost - so more drivable in the wet especially.
*easier on motor & drivetrain due to lower peak torque & smoother transition to boost.
This is just my opinion which is not necessarily based on the facts so please tell me if you have FACTS to disprove any of this.
*more reliable
*Boost is the same for a set rpm so your tune should be more stable
*Less lag
*more civilized as a daily driver
*easier to bolt on - less to modify
*smoother transition to boost - so more drivable in the wet especially.
*easier on motor & drivetrain due to lower peak torque & smoother transition to boost.
More reliable..not so much. OEM vs OEM I'd have to put my money on the turbo setup being more reliable. Fewer moving parts with a turbo, especially when compared to a roots type blower or anything using a clutch to engage/disengage. On the other hand, turbo's are giant heat traps and can cause problems if not designed properly. Although, technology has come a long way.
Consistent boost. A properly set up turbo and EMS with a MAP sensor will be just as consistent.
Less lag. No, not with a centrifugal blower. Defining lag as the time it takes to reach the torque plateau, a centrifugal blower pratically lives its life in lag. While I've never ridden in a large turbo RX8 (yet) I have ridden in/driven a host of large turbo'd cars including RX7's. You can feel the lag, and after awhile you start to dislike it (although it can provide a unique rush, and impresses the ladies
). A positive displacement blower has no lag though.More civilized as a DD. Yea, I'd have to agree. Diamler Chrysler halo cars are known for being monsterously powerful and retaining their streetability (IMO to the point of it getting in the way of performance, but to each his own), and they for the most part all use blowers in the halo AMG line. OEM turbo cars are easy to drive as well though, and with the right setup there's no reason a boosted NA car couldn't be the same.
Easier to bolt on. Depends quite a bit on the motor and the car, but the problems of tuning, physical space, drivetrain strength are similar across both set ups.
Smoother transition to boost. In a limited traction environment, it's all in the driver's right foot. If anything, a bit of lag might actually help you to get rolling before the big torque comes in. In the turbo case, you can ease the transition to boost with an electronic valve controller, and most people use them on modified cars. Positive displacement blowers can use an electronic or vaccum operated clutch to hold off any boost below a set RPM, load, speed, etc etc. Centrifugal blowers have no torque down low, so it doesnt matter
Easier on motor/drivetrain. Yes, it is easier since you're only stressing the motor at high rpm's. However, if you have the build the car for 350hp it's much more effective to be able to use the corresponding torque across the a greater powerband rather than only at redline. Goes back to my original point.
Richard Paul's blower is interesting because it splits the difference between a parasitic roots blower and a laggy centrifugal blower. I'm no jet engine mechanic (but IIRC Richard Paul is), but you can read his lengthy thread and learn more than you'd even want to know. In the end though, as always, it comes down to the particular use of the car and the driver's personal preferences. I'm no fan of drag or dyno queens, so providing power that the driver can convert into quick lap times is what wins it for me.
12-02-2006, 08:23 PM
#33
Some good points there Epi . Like I said - those were my opinions & the reason I lean towards the SC .
Probably the main objective to me is to have a considerably more powerfull car that does not compromise the stock drivability too much.
My feeling (rightly or wrongly ) is that a S/C will better meet these needs.
Your point about the AFSC is exactly why I'm leaning to that option .
However you still can't deny that the Cent. S/C car with the stage 2 kit will be a beast capable of matching it (in flat out acceleration) with most of the turbos out there today.
BTW I always thought lag was defined as the time it takes to get into boost after depressing the accel. While the cent S/C will not have much boost at low rpm what boost it does have will be practically instant . When drivng "in the twisties" this is exactly what you want - yes ?
Probably the main objective to me is to have a considerably more powerfull car that does not compromise the stock drivability too much.
My feeling (rightly or wrongly ) is that a S/C will better meet these needs.
Your point about the AFSC is exactly why I'm leaning to that option .
However you still can't deny that the Cent. S/C car with the stage 2 kit will be a beast capable of matching it (in flat out acceleration) with most of the turbos out there today.
BTW I always thought lag was defined as the time it takes to get into boost after depressing the accel. While the cent S/C will not have much boost at low rpm what boost it does have will be practically instant . When drivng "in the twisties" this is exactly what you want - yes ?
Last edited by Brettus; 12-02-2006 at 10:03 PM.
12-03-2006, 11:21 AM
#34
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Well, once full boost is reached, you've reached you're torque plateau (not necessarily the torque peak, but it will be close). In the curves it's too hard to say what's better. If you ask me, I'd rather a more predictable torque curve that is the same at any RPM as opposed to a centrifugal curve which at 6000 will be double what it is at 3000
12-16-2006, 09:42 PM
#35
Just found a magazine article on it from January this year.
You can just read it if you go to full screen . Not sure how I can get it big enough to read easily without going over max. file size.
You can just read it if you go to full screen . Not sure how I can get it big enough to read easily without going over max. file size.
Last edited by Brettus; 04-28-2013 at 04:07 PM.
12-17-2006, 04:04 AM
#37
The whole point of a supercharger to me is to give instant boost at low rpms. Otherwise, go turbo if your goal is max HP.
The RX-8 needs instant boost at lower rpms to get its 0-60 and 1/4 mile numbers lower. The right supercharger should do the trick. But of course, we are all still waiting on the twinscrew and AFSC... and final price and performance numbers.
The RX-8 needs instant boost at lower rpms to get its 0-60 and 1/4 mile numbers lower. The right supercharger should do the trick. But of course, we are all still waiting on the twinscrew and AFSC... and final price and performance numbers.
12-17-2006, 08:39 AM
#38
Momentum Keeps Me Going
I so would like to try this SC. Such a clean and simple looking install! PNP harness... nice! Wonder why that mag spent so much time explaining the thing and so little on (none!) about any real performance numbers?? A bit strange considering a stopwatch or even second hand on a watch would some indications of improvement. And one would think they might own a G-TECH or some datalogger.... ummmm.
Also I don't get the numbers assuming they're comparing RWH... 74% increase ??... (my car) 178HP dyno x 1.74 = 310HP but they're saying 267HP? or 267HP-178HP = 89HP 89/178 = .5 or 50% Where do they get 74%?
Also I don't get the numbers assuming they're comparing RWH... 74% increase ??... (my car) 178HP dyno x 1.74 = 310HP but they're saying 267HP? or 267HP-178HP = 89HP 89/178 = .5 or 50% Where do they get 74%?
12-17-2006, 10:16 AM
#39
To be honest, I have problem with a number of these kits not putting down HP and performance numbers.
The G-Tech and the G-Timer (GT2) are pretty cheap. They will allow you to see 0-60, 1/4 mile times, and HP numbers.
Also, the point of these kits is to go faster. I expect people to say.... "Hey, after spending $6,000 dollars, my RX-8 can do 5.0 in 0-60 or 13.8 in the 1/4 mile." Don't just put down some HP figures, put down complete performance numbers of the test car.
Its really weird that you can not get complete performance numbers for the kits and test cars with these kits for the RX-8.
Where are the sub 13 second (ok sub 14 is cool too) or sub 5 second RX-8's (close is cool too) with their native engine (not 20b or Rx-7 transplants)? You got a kit putting down an extra 100 HP, so put up all the numbers.
The G-Tech and the G-Timer (GT2) are pretty cheap. They will allow you to see 0-60, 1/4 mile times, and HP numbers.
Also, the point of these kits is to go faster. I expect people to say.... "Hey, after spending $6,000 dollars, my RX-8 can do 5.0 in 0-60 or 13.8 in the 1/4 mile." Don't just put down some HP figures, put down complete performance numbers of the test car.
Its really weird that you can not get complete performance numbers for the kits and test cars with these kits for the RX-8.
Where are the sub 13 second (ok sub 14 is cool too) or sub 5 second RX-8's (close is cool too) with their native engine (not 20b or Rx-7 transplants)? You got a kit putting down an extra 100 HP, so put up all the numbers.
Last edited by sosonic; 12-17-2006 at 10:20 AM.
12-17-2006, 11:33 AM
#40
Originally Posted by sosonic
The RX-8 needs instant boost at lower rpms to get its 0-60 and 1/4 mile numbers lower.
12-17-2006, 11:42 AM
#41
Originally Posted by Spin9k
I so would like to try this SC. Such a clean and simple looking install! PNP harness... nice! Wonder why that mag spent so much time explaining the thing and so little on (none!) about any real performance numbers?? A bit strange considering a stopwatch or even second hand on a watch would some indications of improvement. And one would think they might own a G-TECH or some datalogger.... ummmm.
Also I don't get the numbers assuming they're comparing RWH... 74% increase ??... (my car) 178HP dyno x 1.74 = 310HP but they're saying 267HP? or 267HP-178HP = 89HP 89/178 = .5 or 50% Where do they get 74%?
Also I don't get the numbers assuming they're comparing RWH... 74% increase ??... (my car) 178HP dyno x 1.74 = 310HP but they're saying 267HP? or 267HP-178HP = 89HP 89/178 = .5 or 50% Where do they get 74%?
The reason they prefer to quote % increase is that Dyno numbers are so erratic. Our dynos down here (Dyno Dynamics ) typically show 10-15hp less than US Dyno Jets .
12-17-2006, 12:10 PM
#42
Originally Posted by sosonic
Where are the sub 13 second (ok sub 14 is cool too) or sub 5 second RX-8's (close is cool too) with their native engine (not 20b or Rx-7 transplants)? You got a kit putting down an extra 100 HP, so put up all the numbers.
The best turbo 1/4 mile i've seen is a 13.1 from Adrian - all the others I've seen are high 13s low 14s.
Maybe people think thier setups are too fragile to risk that sort of abuse ?
12-17-2006, 12:22 PM
#44
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Originally Posted by sosonic
To be honest, I have problem with a number of these kits not putting down HP and performance numbers.
The G-Tech and the G-Timer (GT2) are pretty cheap. They will allow you to see 0-60, 1/4 mile times, and HP numbers.
Also, the point of these kits is to go faster. I expect people to say.... "Hey, after spending $6,000 dollars, my RX-8 can do 5.0 in 0-60 or 13.8 in the 1/4 mile." Don't just put down some HP figures, put down complete performance numbers of the test car.
Its really weird that you can not get complete performance numbers for the kits and test cars with these kits for the RX-8.
Where are the sub 13 second (ok sub 14 is cool too) or sub 5 second RX-8's (close is cool too) with their native engine (not 20b or Rx-7 transplants)? You got a kit putting down an extra 100 HP, so put up all the numbers.
The G-Tech and the G-Timer (GT2) are pretty cheap. They will allow you to see 0-60, 1/4 mile times, and HP numbers.
Also, the point of these kits is to go faster. I expect people to say.... "Hey, after spending $6,000 dollars, my RX-8 can do 5.0 in 0-60 or 13.8 in the 1/4 mile." Don't just put down some HP figures, put down complete performance numbers of the test car.
Its really weird that you can not get complete performance numbers for the kits and test cars with these kits for the RX-8.
Where are the sub 13 second (ok sub 14 is cool too) or sub 5 second RX-8's (close is cool too) with their native engine (not 20b or Rx-7 transplants)? You got a kit putting down an extra 100 HP, so put up all the numbers.
12-17-2006, 01:21 PM
#45
Momentum Keeps Me Going
Originally Posted by mysql101
I can tell you why I don't have any 0-60 times. Because this isn't a drag car and I have no interest in doing that sort of thing.
How about some 50-70 mph, 50-90 mph numbers in 3rd or anything to show mid-range strength? It doesn't have to be apromise or a guarantee, just some anecdotal numbers on some test car!
Or how about ANY 4th gear numbers? I think mid range in-gear numbers are the real point of any performance enhancement. Here even on this forum, a yr or two after the turbo kits are out, I'm still looking for this.....perhaps I've just missed it?
On track at an HPDE, where I would make use of any power bump, 100s of times I've found the 8 weak from 50-70 in 3rd, and any speed in 4th gear like 85 and above. When I have a nice long straight... ok 60-80 is pretty decent, nothing to write home about compared to many other cars, but as soon as 4th is taken, it's speedometer creep time. Others simple fly by and around, losing any advantage I've made in the twisties. It's damn depressing is what it is.
Now drag racing is not what the 8's about for sure, bragging rights about 0-60 is lame, but it is a benchmark. However gathering a bit of speed on a track on a straightaway is basic, and that's where I'd like some numbers from anybody to reassure me that spending $4-10K depending on what kit is going to get me something... anything worthwhile. That's what I interested in. And no supplier as yet gives any guidance... in fact no numbers of any type are available...
.
12-17-2006, 01:56 PM
#46
Originally Posted by mysql101
I can tell you why I don't have any 0-60 times. Because this isn't a drag car and I have no interest in doing that sort of thing.
How do you find the turbo for around town driving . Do you think the low down torque is a major advantage in stop start driving ?
12-17-2006, 02:37 PM
#48
The times I enjoy driving the 8 the most is on windy roads . A lot of the time I just stay in 3rd gear & am constantly on & off the throttle between 5000 & 8000 rpm . With a small turbo (ie Greddy) how much turbo lag would there be . Do you think it would be annoying ?
12-17-2006, 02:43 PM
#49
Its one thing to say you are not interested in drag racing your car, so you don't care about 0-60 or 1/4 mile times. That is understandable that you do NOT spend $4000 to $10,000 dollars for a kit. Why pay that much for a kit if you don't care about straight line performance?
Saying the car is only good for the turns and twisties, sounds like a "spin" by Mazda marketing. There are no good reasons why the RX-8 can't improve its short distance and straight line performance. The RX-8 is a great car and this is one of its few weak areas, so a good kit would help in that area.
Also, I think Mazda is disappointing its fans and bringing down a great car like the RX-8 by not coming out with a Mazdaspeed version, not have come out with a Mazdaspeed version sooner (if one ever come out), or not doing more to help pro-tuners trying to help the situation.
If you are about to spend $7,000 dollars on a kit, I would think MOST people want to see short distance and straight line performance numbers. Why not? Also, G-techs and G-timers are kind of cheap.
It would be silly to spend that kind of money and not see any worth while performance gains.
As for boost at lower rpms...
You want the boost to come as soon as possible for it to have an effect. If you have a lot of lag, then your performance is going to suffer. If you are sitting at a stop light and the boost does not hit until 6,000 rpm than its going to take a while to get up to speed. On the other hand, if boost hits at 2,000 rpm than you are going to feel it right away. Plus this type of boost helps in slow down and speed up driving through traffic.
Another point is that the RX-8 has got TOP SPEED. You can go 140 and up, so its not that you can't get up in speed, its how SOON you can get there.
Continual boost from the lower rpms to the higher rpms range is a plus for your kit. To have the boost come in at lower rpms and just drop off is the issue with the quasi roots blitz supercharger. Having to wait for boost to kick in at a higher rpm range, lag, is the knock on turbo. Thats why I think a lot of people are showing interest in the AFSC, Twinscrew supercharger kits. Even the Centrifugal Superchargers are going to get interest as they might have some advantages over turbo (which would be a debate), as you might get boost a little sooner, it would be easier to install as oppose to turbo, and/or performance numbers that are closer to turbo.
Bottom line, a kit should produce performance numbers that justify the MONEY. Also, just HP numbers can be deceptive, because of when and where the boost is coming in. Thats why people will argue to see the test car, that has the kit on it, be put to the test. If the kit is as hot as it says, than publish the 0-60 and 1/4 numbers. Good numbers would justify the cost of the kit.
Saying the car is only good for the turns and twisties, sounds like a "spin" by Mazda marketing. There are no good reasons why the RX-8 can't improve its short distance and straight line performance. The RX-8 is a great car and this is one of its few weak areas, so a good kit would help in that area.
Also, I think Mazda is disappointing its fans and bringing down a great car like the RX-8 by not coming out with a Mazdaspeed version, not have come out with a Mazdaspeed version sooner (if one ever come out), or not doing more to help pro-tuners trying to help the situation.
If you are about to spend $7,000 dollars on a kit, I would think MOST people want to see short distance and straight line performance numbers. Why not? Also, G-techs and G-timers are kind of cheap.
It would be silly to spend that kind of money and not see any worth while performance gains.
As for boost at lower rpms...
You want the boost to come as soon as possible for it to have an effect. If you have a lot of lag, then your performance is going to suffer. If you are sitting at a stop light and the boost does not hit until 6,000 rpm than its going to take a while to get up to speed. On the other hand, if boost hits at 2,000 rpm than you are going to feel it right away. Plus this type of boost helps in slow down and speed up driving through traffic.
Another point is that the RX-8 has got TOP SPEED. You can go 140 and up, so its not that you can't get up in speed, its how SOON you can get there.
Continual boost from the lower rpms to the higher rpms range is a plus for your kit. To have the boost come in at lower rpms and just drop off is the issue with the quasi roots blitz supercharger. Having to wait for boost to kick in at a higher rpm range, lag, is the knock on turbo. Thats why I think a lot of people are showing interest in the AFSC, Twinscrew supercharger kits. Even the Centrifugal Superchargers are going to get interest as they might have some advantages over turbo (which would be a debate), as you might get boost a little sooner, it would be easier to install as oppose to turbo, and/or performance numbers that are closer to turbo.
Bottom line, a kit should produce performance numbers that justify the MONEY. Also, just HP numbers can be deceptive, because of when and where the boost is coming in. Thats why people will argue to see the test car, that has the kit on it, be put to the test. If the kit is as hot as it says, than publish the 0-60 and 1/4 numbers. Good numbers would justify the cost of the kit.
Last edited by sosonic; 12-17-2006 at 03:09 PM.
12-17-2006, 07:02 PM
#50
Originally Posted by Brettus
The times I enjoy driving the 8 the most is on windy roads . A lot of the time I just stay in 3rd gear & am constantly on & off the throttle between 5000 & 8000 rpm . With a small turbo (ie Greddy) how much turbo lag would there be . Do you think it would be annoying ?
Originally Posted by sosonic
Its one thing to say you are not interested in drag racing your car, so you don't care about 0-60 or 1/4 mile times. That is understandable that you do NOT spend $4000 to $10,000 dollars for a kit. Why pay that much for a kit if you don't care about straight line performance?
Saying the car is only good for the turns and twisties, sounds like a "spin" by Mazda marketing.
It would be silly to spend that kind of money and not see any worth while performance gains.
Good numbers would justify the cost of the kit.