I’ve noticed that aftermarket supercharging seems to be the method of choice for increasing HP/TQ for the NSX. It got me to thinking that, both turbocharging and supercharging basically compress the air charge to the compustion process. However, turbocharging demands a lower compression ratio, hence internal engine modification. Why does this not seem to be the case with supercharging?
Supercharging Versus Turbocharging?????
- Thread starter Gramps
- Start date
Gramps said:
Gramps,
I've noticed you on here quite a bit lately:wink:. Most on here supercharge for a couple reasons;
1. Safest source of power
2. Comptech supercharger doesn't void factory warranty
3. Easier installation then a turbo
4. Cost less then turbo
Turbocharging;
1. More expensive=MORE HORSE
2. TIME CONSUMING
3. Harder installation, usually custom fabricated
4. DId I mention...more horse?:biggrin: :wink:
I still do not understand why superchargers can be used without changing compression ratio, and turbocharging usually requires this.
There are quite a few informative threads on this topic that are full of relevant discussions. Search and check them out... hopefully you can get the information you were looking for out of them. Due to the fact it has been discussed so many times, you may not get as many replies as you would have 2 or 3 years ago.
Depends on the level of boost.Gramps said:
Gramps said:
Turbo charging does not require changing compression. Most of the turbo setups being done these days are in the 500+hp club.... this is a different ball-game than slapping on a Comptech SC and running around on average at 330-375hp. Most supercharged setups that are running big power have low compression builds too.
Sig said:
I was going to respond, but Sig summed up everything I was going to say perfectly. Like he's reading my mind or something. So Sig, what am I having for lunch today? :biggrin:
I discussed this with au-nsx on another thread. The reason is that the SC is running low boost. If you turbocharge at the same boost levels, no need for lower compression. But you are defeating the benefits of a turbo. A turbo can easily give you MEGA amounts of boost, more so than a supercharger (the relavent superchargers being discussed for our application). So to gain the benfits, you need to lower the compression.
If you are going to run low boost, a SC is a better device, especially one like the Comptech Autorotor as its intake air temps are cool. Because of the nature of a turbo, intake air temps are high. You have an impeller spinning at higher speeds and the turbo itself heats up as exhaust gases are passing on the turbine side. This raises the air temps, and therefore, without an intercooler, provides less power at the same boost levels. Air pressure may be just as high, but the heated gas is packing less oxygen molecules in the same space.
If you had a low boost turbo setup that magically provided the same temps at output as a low boost supercharger, the turbocharged motor would probably provide more power because it has less parasitic drag on the motor. But its power "curve" would still be different. More up top, a bit less down low.
So the conclusion is that for a low boost non-intercooled application the autorotor just works a lot better than a turbo would. When you want to produce 500HP, and are willing to intercool and all that jazz that goes along with it, then its better to use a well sized turbo and reduce the factory compression ratio so you don't blow it all to pieces.
If you are going to run low boost, a SC is a better device, especially one like the Comptech Autorotor as its intake air temps are cool. Because of the nature of a turbo, intake air temps are high. You have an impeller spinning at higher speeds and the turbo itself heats up as exhaust gases are passing on the turbine side. This raises the air temps, and therefore, without an intercooler, provides less power at the same boost levels. Air pressure may be just as high, but the heated gas is packing less oxygen molecules in the same space.
If you had a low boost turbo setup that magically provided the same temps at output as a low boost supercharger, the turbocharged motor would probably provide more power because it has less parasitic drag on the motor. But its power "curve" would still be different. More up top, a bit less down low.
So the conclusion is that for a low boost non-intercooled application the autorotor just works a lot better than a turbo would. When you want to produce 500HP, and are willing to intercool and all that jazz that goes along with it, then its better to use a well sized turbo and reduce the factory compression ratio so you don't blow it all to pieces.
TURBO2GO said:
not true...
typically, specifically on the NSX the turbo has produced more power and more TQ lower that the SC systems. This is really dependand on the turbo though on NOT what kind of FI system it is.
It is also not tue that a SC is Safer...
It is also not true that a SC is Cheaper...
These are opinions, not facts....
There are a lot of myths about turbos and many of them are untrue and/or founded in very old information. A turbo application's power curve can be varied with the use of different turbocharger configurations. Most turbochargers will accept a myriad of compressor and exhaust wheels. You can build a 1/4 mile monster that doesn't develop boost until over 4K RPM but provides crazy boost (and with a *relatively* cool intake charge because of the turbo running well within it's efficiency island) or a quickly spooling turbo that develops max boost far below 3K RPM but runs out of steam and can't hold that boost at redline.
Turbo systems really are very flexible, reliable and make strong power when it's done right. And to do it right doesn't *have* to be expensive (okay, everything on our cars is expensive, but you all know what I mean) if you do it right once and know what you're doing. The one and only thing that kept me from going turbo on my car is that there aren't any (that I know of) that are CARB legal/compliant. I've played the "remove all your illegal stuff every few years to get your smog certificate" game and I'm tired of playing and wouldn't want to play it with my NSX.
IM(not so:biggrin: )HO people who don't like turbos are either ignorant to what they can do or have witnessed a poorly configured setup.
J
Turbo systems really are very flexible, reliable and make strong power when it's done right. And to do it right doesn't *have* to be expensive (okay, everything on our cars is expensive, but you all know what I mean) if you do it right once and know what you're doing. The one and only thing that kept me from going turbo on my car is that there aren't any (that I know of) that are CARB legal/compliant. I've played the "remove all your illegal stuff every few years to get your smog certificate" game and I'm tired of playing and wouldn't want to play it with my NSX.
IM(not so:biggrin: )HO people who don't like turbos are either ignorant to what they can do or have witnessed a poorly configured setup.
J
01blacks4 said:
yes, there a million configurations and factors. You can make the argument against almost any setup. But I am not sure it helps answer Gramps's question.
Gramps, you will need to lower compression at a certain boost level regardless of the FI method. That's the bottom line. The rest of it is just arguments of supercharger versus turbocharger, each of which has benefits and drawbacks within their intended applications. If you want to carry on that debate, you better open up a lot of free time. :smile:
TURBO2GO said:
Question answered!
Vega$ NSX said:
I'm going to guess Chicken Sandwich and French Fries.
Close enough. I had some dim sum with some chicken in it. :biggrin:Sig said:
I had a chicken sandwich!!...damn Sig..your good!
o1blacks4 has a very soft spot in his heart for turbos...And I for one love hearing about his turbo research.
IMO..the reason you see many Turbo cars with complete engine builds with lower comp pistons is because turbos for NSXs are not mass produced in the way that CTSCs and to a lesser extent BBSCs were..so for most people if they are going to go to all the effort of a custom build for a turbo or twin turbos you are prolly going to take the time to "GO BIG" and do the whole job from the ground up including the motor build.
As for the "safety" there is some truth to the statement that superchargers are safer because the (generaly) do not provide big boost at low RPM the way turbos (can), however like some have noted there are many differnt turbos avval with varied performance at differnt RPM ranges.
The cold hard truth IMO is that Turbo set ups are more complicated with more parts and pieces..and more Red hot stuff under your engine cover.
if your only looking to add some HP and not MEGA HP the supercharger is the way to go IMO..if you wanna GO BIG and get MEGA HP than a Turbo may be an option you want to look into.
o1blacks4 has a very soft spot in his heart for turbos...And I for one love hearing about his turbo research.
IMO..the reason you see many Turbo cars with complete engine builds with lower comp pistons is because turbos for NSXs are not mass produced in the way that CTSCs and to a lesser extent BBSCs were..so for most people if they are going to go to all the effort of a custom build for a turbo or twin turbos you are prolly going to take the time to "GO BIG" and do the whole job from the ground up including the motor build.
As for the "safety" there is some truth to the statement that superchargers are safer because the (generaly) do not provide big boost at low RPM the way turbos (can), however like some have noted there are many differnt turbos avval with varied performance at differnt RPM ranges.
The cold hard truth IMO is that Turbo set ups are more complicated with more parts and pieces..and more Red hot stuff under your engine cover.
if your only looking to add some HP and not MEGA HP the supercharger is the way to go IMO..if you wanna GO BIG and get MEGA HP than a Turbo may be an option you want to look into.
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Also something to consider when speaking of turbo & boost:
"X" psi on a small turbo is not the same as "X" psi on a big turbo. A better way to look at if lowering compression of the engine would be required is to look at how much horsepower is in mind; not how much boost is to be applied. :wink:
"X" psi on a small turbo is not the same as "X" psi on a big turbo. A better way to look at if lowering compression of the engine would be required is to look at how much horsepower is in mind; not how much boost is to be applied. :wink:
j/w.. isn't superchargers carb legal?? compare to a turbo which it isn't.. and also for smog purposes..
darknezz_ghost said:
The comptech is carb legal, off the top of my head, i think that's the only one that is carb legal out of all the FI products.
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