Turbocharger & Supercharger Info/Questions
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Joined: Apr 2003
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From: Houston
All of the statements made here have exceptions. Here are some examples.
I understand that the turbo itself gets very hot and can glow under hard driving. This is only the exhaust side though. Yes some heat is transferred to the compressor side but it isn't as much as it might seem.
A centrifugal supercharger does have an efficiency range of a good turbo system but the word "good" is the key. There are turbo systems out there that are not as efficient as a good supercharger (centrifugal" and the reverse applies as well. Along the same lines a screw type supercharger can fit in the same boat but on a good day the best screw type is still not quite as efficient (thermally) as a good centrifugal or turbo. But it can be very close. Different roots type blowers have different efficiencies. A Camden blower is a straight cut 2 lobe per rotor blower. This is the oldest and least efficient type of roots. The Eaton blowers use a 3 lobe twisted design that is quieter and far more efficient than the Camden units but still not up to par with the other forms of forced induction.
"Superchargers use the engine to spin up the screws (lose some HP to gain LOTS with no lag)." I'm not sure if I agree with this comment entirely. Yes a supercharger does rob power from the crank to get it spinning. However too many people fail to realize just how much power is lost on a typical turbo system. There are so many turbo kits and cars equipped with turbos that are just plain and simple subpar. Really crappy exhaust manifolds typically feed turbos that are way too small and restricitive. Ever notice how much power can be gained on a naturally aspirated car with a good set of headers? How much worse would it be if you put a restriction like a lousy manifold and a pipe as small as your typical turbo turbine wheel? Power would be much less. Basically there are so any gains that are cancelled out on a turbo car due to poor turbo designs. A good tubo system can actually be very free flowing with minimal loss as well as minimal lag. However in a perfect situation a supercharger still does rob power from the crank. The point is that just because the engine has a turbo does not mean that it couldn't be improved upon with a supercharger and vice versa.
"I would never take a SC over a turbo on anything smaller than 3.0L" Why not? A gain on a small engine is proportional to a gain on a big engine. In terms of a centrifugal supercharger you don't have the low end power on a small engine that you will need when the supercharger isn't really in the picture whereas you can fall back on displacement at lower rpm's on a bigger engine. In this respct I would agree but that was a pretty blanket statement that doesn't apply to other forms of forced induction.
"Air temps are generaly only lower with a turbo because of the use of IC's" Many supercharged cars are factory equipped with intercoolers as well. So that statement also applies to supercharged vehicles as well. While a nonintercooled supercharged car will have higher temps than those with, so will a nonintercooled turbo car. Many of these have been produced as well.
"I dont even see how you can add boost to this car" Well I have a picture of a turbocharged bar stool so I think it is possible! Just give it time. There are already kits in the testing stage.
All engines have "turbo lag". Confused? Turbo lag is best described as "fuel lag". It takes time for fuel to get into the engine after the throttle is depressed. The closer the throttleplate and fuel injectors are to the engine, the less the lag. Throttle response isn't neccesarily much better on a supercharged car especially an Eaton equipped car. Step on the gas, and the car starts to move forward but it takes a second for the bypass valve to react to the change in manifold pressure enough so that it can close and allow the engine to receive boost. Supercharger lag? Even other roots type of systems with the throttle before the supercharger have a slight delay due to the added distance of the throttleplate from the engine. Typically carburated cars have less lag or delay time than fuel injected cars but there is alot to do with the intake design that can change that. Go out to your car and step on the gas and see if the engine rpm rises exactly when you press the gas or if it delays for a second. Trust me, it delays. You just don't realize it. If you don't have forced induction, you still have lag. You just don't get to enjoy the surge of power after it .
Here are some of my guidelines for choosing each type of system.
If you have a small displacement engine and want a moderate power increase for daily driving, you should probably favor a positive displacement supercharger or a good turbo system that can produce boost down low where your engine is lacking any power.
If you have an engine with a very wide powerband, stay away from centrifugal supercharger. Since boost rises exponentially, you don't want 6 psi at 6500 rpm but 11 psi at the 9000 rpm shift point. If your engine only had a powerband that was 1500 rpm wide, this might not be much of an issue since boost stays much more linear. You optimally would like at the same amount of boost across the entire rev range for maximum average power.
For large displacement engines you can go gung ho and do a system that produces tons of power everywhere. However an engine that produces 500 ft lbs of torque at 1500 rpm may be a little difficult to get off the line. You have the option here of falling back on displacement and designing a system that works best at higher rpms. These engines don't typically rev that high so a centrifugal supercharger is just fine. Remember that since output of these superchargers is an expnential increase with rpm, the higher the rpm, the more drastic the gain. With a lower powerband, total power and boost is much more stable.
Just some things to think about.
I understand that the turbo itself gets very hot and can glow under hard driving. This is only the exhaust side though. Yes some heat is transferred to the compressor side but it isn't as much as it might seem.
A centrifugal supercharger does have an efficiency range of a good turbo system but the word "good" is the key. There are turbo systems out there that are not as efficient as a good supercharger (centrifugal" and the reverse applies as well. Along the same lines a screw type supercharger can fit in the same boat but on a good day the best screw type is still not quite as efficient (thermally) as a good centrifugal or turbo. But it can be very close. Different roots type blowers have different efficiencies. A Camden blower is a straight cut 2 lobe per rotor blower. This is the oldest and least efficient type of roots. The Eaton blowers use a 3 lobe twisted design that is quieter and far more efficient than the Camden units but still not up to par with the other forms of forced induction.
"Superchargers use the engine to spin up the screws (lose some HP to gain LOTS with no lag)." I'm not sure if I agree with this comment entirely. Yes a supercharger does rob power from the crank to get it spinning. However too many people fail to realize just how much power is lost on a typical turbo system. There are so many turbo kits and cars equipped with turbos that are just plain and simple subpar. Really crappy exhaust manifolds typically feed turbos that are way too small and restricitive. Ever notice how much power can be gained on a naturally aspirated car with a good set of headers? How much worse would it be if you put a restriction like a lousy manifold and a pipe as small as your typical turbo turbine wheel? Power would be much less. Basically there are so any gains that are cancelled out on a turbo car due to poor turbo designs. A good tubo system can actually be very free flowing with minimal loss as well as minimal lag. However in a perfect situation a supercharger still does rob power from the crank. The point is that just because the engine has a turbo does not mean that it couldn't be improved upon with a supercharger and vice versa.
"I would never take a SC over a turbo on anything smaller than 3.0L" Why not? A gain on a small engine is proportional to a gain on a big engine. In terms of a centrifugal supercharger you don't have the low end power on a small engine that you will need when the supercharger isn't really in the picture whereas you can fall back on displacement at lower rpm's on a bigger engine. In this respct I would agree but that was a pretty blanket statement that doesn't apply to other forms of forced induction.
"Air temps are generaly only lower with a turbo because of the use of IC's" Many supercharged cars are factory equipped with intercoolers as well. So that statement also applies to supercharged vehicles as well. While a nonintercooled supercharged car will have higher temps than those with, so will a nonintercooled turbo car. Many of these have been produced as well.
"I dont even see how you can add boost to this car" Well I have a picture of a turbocharged bar stool so I think it is possible! Just give it time. There are already kits in the testing stage.
All engines have "turbo lag". Confused? Turbo lag is best described as "fuel lag". It takes time for fuel to get into the engine after the throttle is depressed. The closer the throttleplate and fuel injectors are to the engine, the less the lag. Throttle response isn't neccesarily much better on a supercharged car especially an Eaton equipped car. Step on the gas, and the car starts to move forward but it takes a second for the bypass valve to react to the change in manifold pressure enough so that it can close and allow the engine to receive boost. Supercharger lag? Even other roots type of systems with the throttle before the supercharger have a slight delay due to the added distance of the throttleplate from the engine. Typically carburated cars have less lag or delay time than fuel injected cars but there is alot to do with the intake design that can change that. Go out to your car and step on the gas and see if the engine rpm rises exactly when you press the gas or if it delays for a second. Trust me, it delays. You just don't realize it. If you don't have forced induction, you still have lag. You just don't get to enjoy the surge of power after it .
Here are some of my guidelines for choosing each type of system.
If you have a small displacement engine and want a moderate power increase for daily driving, you should probably favor a positive displacement supercharger or a good turbo system that can produce boost down low where your engine is lacking any power.
If you have an engine with a very wide powerband, stay away from centrifugal supercharger. Since boost rises exponentially, you don't want 6 psi at 6500 rpm but 11 psi at the 9000 rpm shift point. If your engine only had a powerband that was 1500 rpm wide, this might not be much of an issue since boost stays much more linear. You optimally would like at the same amount of boost across the entire rev range for maximum average power.
For large displacement engines you can go gung ho and do a system that produces tons of power everywhere. However an engine that produces 500 ft lbs of torque at 1500 rpm may be a little difficult to get off the line. You have the option here of falling back on displacement and designing a system that works best at higher rpms. These engines don't typically rev that high so a centrifugal supercharger is just fine. Remember that since output of these superchargers is an expnential increase with rpm, the higher the rpm, the more drastic the gain. With a lower powerband, total power and boost is much more stable.
Just some things to think about.
mostly harmless
Joined: Jun 2002
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From: Greater Vancouver Area, BC
Originally posted by neit_jnf
don't take wakeech too seriously, he's always like that :p
don't take wakeech too seriously, he's always like that :p
sorry about that TargeT. i sincerely apologize for being so intentionally offensive.
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Joined: Jan 2004
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From: Barely on the road
rotarygod, sounds like you have some experience with SC'd cars but maybe not so much with Turbo cars, I'll try to shed light with what i've picked up from practical aplication on turbo'd cars ( i race em, run em hard & fix em when i break em)
Actualy this is refered to as "heat soak" and the entire turbo, part of the exhaust manifold, and sometimes the heatshield for the turbo will glow in various stages of red/white. you lost a VERY noticeable chunk of your posible HP when your engine becomes heat soaked. (this is also why on older turbos it was VITAL to have a turbo timer on your car, or at least let it run for about 3 min after your done driving so that the oil can continue to cycle through the turbo)
The rest of your post i cant comment too much on, as I am generaly unfamilar with SC solutions in practical application but you dont seem to give turbo systems too much credit
I can see that your SC biased by reading your
where you barely mention turbo's as a viable option.
Small displacement engines generaly produce their power by reving very high in comparison to large displacment engines, losing a lot of potential energy out of the exhaust pipe, energy begging to be harnessed by a turbo
on the same note, most small displacement engines cannot power a blower (Supercharger) big enough to produce high boost levels for BIG HP gains (20+ PSI), or if they do the HP loss due spent driving the SC is unacceptable. This is why i would stick to turbo solutions
Of course, it all depends on your application, Running a 20G turbo ona 2.0L with the right supporting mods will put you into a 11.5 1/4 mile but the turbo lag is nearly unbareable (IMO) you dont get full spool till 4200 RPMs or so
smaller turbo, faster spoolup, but you cant push as much boost (the twin scroll 16g on my Evo gave me full boost at 3000 rpms and started spooling up at 2500)
(as you can tell, im a fan of turbo's)
I understand that the turbo itself gets very hot and can glow under hard driving. This is only the exhaust side though. Yes some heat is transferred to the compressor side but it isn't as much as it might seem.
The rest of your post i cant comment too much on, as I am generaly unfamilar with SC solutions in practical application but you dont seem to give turbo systems too much credit
I can see that your SC biased by reading your
guidelines for choosing each type of system.
Small displacement engines generaly produce their power by reving very high in comparison to large displacment engines, losing a lot of potential energy out of the exhaust pipe, energy begging to be harnessed by a turbo
on the same note, most small displacement engines cannot power a blower (Supercharger) big enough to produce high boost levels for BIG HP gains (20+ PSI), or if they do the HP loss due spent driving the SC is unacceptable. This is why i would stick to turbo solutions
Of course, it all depends on your application, Running a 20G turbo ona 2.0L with the right supporting mods will put you into a 11.5 1/4 mile but the turbo lag is nearly unbareable (IMO) you dont get full spool till 4200 RPMs or so
smaller turbo, faster spoolup, but you cant push as much boost (the twin scroll 16g on my Evo gave me full boost at 3000 rpms and started spooling up at 2500)
(as you can tell, im a fan of turbo's)
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Joined: Apr 2003
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From: Houston
I've got a IHI RH-C7 turbo on a big streetport 4 port 13B that I built myself sitting in my 1st gen GSL-SE RX-7. It was the engine that I had built for my old 2nd gen. I am also about to buy another 2nd gen T-II RX-7 and upgrade the turbo and engine on it. Still think I am biased toward superchargers? I don't have one. Almost all of my experience is with turbo cars. I just know how superchargers work and when to use them if I wanted to.
My personal take is that if you absolutely need to run 20psi on an engine, it is probably for race use in which you would use a turbo anyways due to efficiency reasons. Most people seriously contemplating superchargers aren't planning on running that much anyways but rather looking for a nice gain across the board. Nothing wrong with that. Anyone who needs 20 psi on the street should probably be considering a bigger engine first.
BTW: superchargers get heat soak too. I've never seen any part of them glow red but they do get quite hot.
I love turbo cars and I did indeed leave mention of them out. Lots of people know how to pick a good turbo. Not many people know how to pick a good supercharger or when to.
My personal take is that if you absolutely need to run 20psi on an engine, it is probably for race use in which you would use a turbo anyways due to efficiency reasons. Most people seriously contemplating superchargers aren't planning on running that much anyways but rather looking for a nice gain across the board. Nothing wrong with that. Anyone who needs 20 psi on the street should probably be considering a bigger engine first.
BTW: superchargers get heat soak too. I've never seen any part of them glow red but they do get quite hot.
I love turbo cars and I did indeed leave mention of them out. Lots of people know how to pick a good turbo. Not many people know how to pick a good supercharger or when to.
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From: Barely on the road
Originally posted by rotarygod
I've got a IHI RH-C7 turbo on a big streetport 4 port 13B that I built myself sitting in my 1st gen GSL-SE RX-7. It was the engine that I had built for my old 2nd gen. I am also about to buy another 2nd gen T-II RX-7 and upgrade the turbo and engine on it. Still think I am biased toward superchargers? I don't have one. Almost all of my experience is with turbo cars. I just know how superchargers work and when to use them if I wanted to.
My personal take is that if you absolutely need to run 20psi on an engine, it is probably for race use in which you would use a turbo anyways due to efficiency reasons. Most people seriously contemplating superchargers aren't planning on running that much anyways but rather looking for a nice gain across the board. Nothing wrong with that. Anyone who needs 20 psi on the street should probably be considering a bigger engine first.
BTW: superchargers get heat soak too. I've never seen any part of them glow red but they do get quite hot.
I love turbo cars and I did indeed leave mention of them out. Lots of people know how to pick a good turbo. Not many people know how to pick a good supercharger or when to.
I've got a IHI RH-C7 turbo on a big streetport 4 port 13B that I built myself sitting in my 1st gen GSL-SE RX-7. It was the engine that I had built for my old 2nd gen. I am also about to buy another 2nd gen T-II RX-7 and upgrade the turbo and engine on it. Still think I am biased toward superchargers? I don't have one. Almost all of my experience is with turbo cars. I just know how superchargers work and when to use them if I wanted to.
My personal take is that if you absolutely need to run 20psi on an engine, it is probably for race use in which you would use a turbo anyways due to efficiency reasons. Most people seriously contemplating superchargers aren't planning on running that much anyways but rather looking for a nice gain across the board. Nothing wrong with that. Anyone who needs 20 psi on the street should probably be considering a bigger engine first.
BTW: superchargers get heat soak too. I've never seen any part of them glow red but they do get quite hot.
I love turbo cars and I did indeed leave mention of them out. Lots of people know how to pick a good turbo. Not many people know how to pick a good supercharger or when to.
I like the fact that my lil "4 banger" beats out most V8s with ease
and i still get good MPG (if i stay out of deep boost
hehe) I hope they crack the ECU on this baby so you guys can get some Turbos tossed on it, that would make this car actualy perform pretty well instead of better than the average daily driver, i guess im a bit more of a performance enthusiast and this car isnt for me right now
btw, DROP AN LS1 or LS2 in those RX-7's!! i thought that was the only reason people got those!
good info tho & ur right, not a lot of knowlege about SC out there, but thats just another reason to go turbo, lots of support :D
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Joined: Apr 2003
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From: Houston
Yeah I see alot of people do that but it just escapes me. Then again I don't drag race either and you do admit to some track use. I like to turn! My little first gen will beat most of those V-8 cars throught the twisties. In fact it would do a good job at it with stock horsepower levels. A little suspension work and some power and it is just that much more fun.
I am a fan of the LS1 engines. IF I HAD to have a V-8 that would probably be it. However I own an RX-7 because it is a rotary and that is what I love about it. I wouldn't need an RX-7 if I had an LS1. I'd just buy a Camaro instead. I really don't care how cheap, easy, or fast it is to swap one into a light little RX-7. If it isn't a rotary I personally feel that it doesn't belong in an RX. If I had an LS1 car, I'd probably turbo it too. I wouldn't let a little boosted engine beat ME if I had a V-8!
I am a fan of the LS1 engines. IF I HAD to have a V-8 that would probably be it. However I own an RX-7 because it is a rotary and that is what I love about it. I wouldn't need an RX-7 if I had an LS1. I'd just buy a Camaro instead. I really don't care how cheap, easy, or fast it is to swap one into a light little RX-7. If it isn't a rotary I personally feel that it doesn't belong in an RX. If I had an LS1 car, I'd probably turbo it too. I wouldn't let a little boosted engine beat ME if I had a V-8!
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From: Miami
they already made a turbo kit for the rx-8 i think hks . they dont got a price on it , but so far in the picture the turbo in mounted in front of the alternator and the intercooler a front mount. ill try to see if i can remeber the web page.
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From: Des Moines,WA
Does anyone know if any other aftermarket manufacturers are in the process of making a turbo kit for the RX-8 such as Greddy or Apexi? Also i keep hearing about the HKS turbo kit but when i go to the HKS web site the only aftermarket product they have for the RX-8 is their exhaust. Where do they advertise that kit, is it on their web site or on a seperate site?
In between cars, RX8-less
Joined: Feb 2004
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From: Sydney Australia
I have searched high and low and finally I have found some good news.
RX-8 Turbo Kit
I hope you guys like.
RX-8 Turbo Kit
I hope you guys like.
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Joined: Feb 2004
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From: Lewisville, TX
According to the latest road and track magazine, in which they were discussing the mazdaspeed RX-8, mazda north america is working on a supercharger for the RX-8 and a hydraulic turbocharger (uses a pump intead of engine exhaust). The mazdaspeed RX-8 also has a different exhaust and engine mapping that gives it more low end power and more torque similar to Canzoomer's Stage 1 kit.
The article starts on page 64 of this month's issue so the next time you're in the store, give it a read. It was cool to know that the mazdaspeed RX-8 also had no real engine changes in it's current form and apparently they also have a dual mode hydrogen/gasoline rx-8 on the way.
Ajax
The article starts on page 64 of this month's issue so the next time you're in the store, give it a read. It was cool to know that the mazdaspeed RX-8 also had no real engine changes in it's current form and apparently they also have a dual mode hydrogen/gasoline rx-8 on the way.
Ajax
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Joined: Mar 2004
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From: Monterey Bay, CA
SC Development by BRP
Hi guys, new to forum obivously, I'm a SC'd miata owner (190hp roughly) and eventually will be a RX8 owner. I haven't taken the time to completely read through all these threads so this information may be redundant or old.
Anyways one of the great SC kit manufactures for Miatas recently bought a RX8 and is going to start working on a SC kit for the RX8. This particular thread explains in fair detail as to why the RX8 didn't make good dyno numbers in SCC. This will also be the place for you guys to find updates on what I'm sure is one of the many FI kits being prototyped right now.
thread
Anyways one of the great SC kit manufactures for Miatas recently bought a RX8 and is going to start working on a SC kit for the RX8. This particular thread explains in fair detail as to why the RX8 didn't make good dyno numbers in SCC. This will also be the place for you guys to find updates on what I'm sure is one of the many FI kits being prototyped right now.
thread
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From: PRC
I think that Mazda probably will unveil some new FI technology when they come out for a kit with this be, whether it is a hydraulic or whatever they decide. They already have a trubo Hydrogen Renesis that is spooled at low rpms by an electric motor until exhaust is strong enough.
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Joined: Oct 2001
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From: Boulder County, Colorado
Question is, will they come out with a kit (please please please!) or will they just sell an "extra high performance/Mazdaspeed" version of the car starting with 2005 or 2006 model years? My guess would be the latter. Sadly.
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From: Denver, CO
Originally posted by Omicron
Question is, will they come out with a kit (please please please!) or will they just sell an "extra high performance/Mazdaspeed" version of the car starting with 2005 or 2006 model years? My guess would be the latter. Sadly.
Question is, will they come out with a kit (please please please!) or will they just sell an "extra high performance/Mazdaspeed" version of the car starting with 2005 or 2006 model years? My guess would be the latter. Sadly.
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Joined: Aug 2003
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From: Arizona
The Greddy kit is just about out or already is in Japan. I haven't heard anything about Apexi or HKS. Judging by HKSs track record they ususally take thier time when making turbo kits. It took almost 2 years for a WRX turbo kit to be finalized here in the states so I wouldn't expect to see one from them any time soon,.... though I have been wrong before.
Int'l Man of Mystery
Joined: Jan 2004
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From: Central Florida
Originally posted by RatedR_RX-8
does anyone know wether greddy is starting to make a turbo kit for the RX-8 or if any other companies such as hks or apexi are in the process of making a turbo kit for the car?
does anyone know wether greddy is starting to make a turbo kit for the RX-8 or if any other companies such as hks or apexi are in the process of making a turbo kit for the car?