Rotrex Supercharger
01-09-07, 10:52 PM
#1
Rotrex Supercharger
So as some of you might know I have been looking at purchasing a supercharger for my SP 12A. With only the Camdem as an available option, I thought i'd look at different models so that maybe I can fab up my own. This one looks very promising and would seem fairly easy to install (much like the installation of a turbocharger)
This is the HKS model of it for the 350z.
You should be able to futher see the resemblance of that to the turbocharger. So you could basically (i'm assuming here) use it as a blow thru type supercharger on a carb. From the rotrex website I see that they have basically 3 sizes.
1) C15
50-200Hp
201,500 rpm max impeller speed
1 : 12.57 gear ratio
2) C30 (The one that I might opt out for)
100-400hp
120,000 rpm max impeller speed
1 : 9.49 gear ratio
3) C38
300-630Hp
90,000rpm max impeller speed
1 : 7.5 gear ratio
Fabbing up a bracket to this would seem fairly easy to do, and could be mounted where the AC/PS units used to sit. This would eliminate one big problems that i've seen with the camdem which is hood clearance issues. (unless you go with side draft webers or so but that really isn't all that cheap especially custom making the piece to go from the weber to the supercharger. Let me know what you guys think about this idea. I'm pretty much a noob with boosting and stuff so let it out.
This is the HKS model of it for the 350z.
You should be able to futher see the resemblance of that to the turbocharger. So you could basically (i'm assuming here) use it as a blow thru type supercharger on a carb. From the rotrex website I see that they have basically 3 sizes.
1) C15
50-200Hp
201,500 rpm max impeller speed
1 : 12.57 gear ratio
2) C30 (The one that I might opt out for)
100-400hp
120,000 rpm max impeller speed
1 : 9.49 gear ratio
3) C38
300-630Hp
90,000rpm max impeller speed
1 : 7.5 gear ratio
Fabbing up a bracket to this would seem fairly easy to do, and could be mounted where the AC/PS units used to sit. This would eliminate one big problems that i've seen with the camdem which is hood clearance issues. (unless you go with side draft webers or so but that really isn't all that cheap especially custom making the piece to go from the weber to the supercharger. Let me know what you guys think about this idea. I'm pretty much a noob with boosting and stuff so let it out.
01-09-07, 10:56 PM
#2
This option would probably also work much better than a camden, since you could run a turbo intercooler in line to help with the heat issues that come with compressors if you ran into any.
I personally think its a great idea, now it just needs to be tried!
Only problem, is it has to be treated like a turbo, no drawthrough setups here, so the fuel system will have to be adressed.
I personally think its a great idea, now it just needs to be tried!
Only problem, is it has to be treated like a turbo, no drawthrough setups here, so the fuel system will have to be adressed.
01-09-07, 11:02 PM
#3
wheres the water goin?
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heres what ive been looking at to doing to my 7!!!
http://www.gatorsuperchargers.net/photos/photos.htm
http://www.gatorsuperchargers.net/photos/photos.htm
01-09-07, 11:09 PM
#5
Originally Posted by Gen1onr
This option would probably also work much better than a camden, since you could run a turbo intercooler in line to help with the heat issues that come with compressors if you ran into any.
I personally think its a great idea, now it just needs to be tried!
Only problem, is it has to be treated like a turbo, no drawthrough setups here, so the fuel system will have to be adressed.
I personally think its a great idea, now it just needs to be tried!
Only problem, is it has to be treated like a turbo, no drawthrough setups here, so the fuel system will have to be adressed.
The fuel issue would have to be adressed no matter what the upgrade it lol.
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01-10-07, 04:15 PM
#12
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All it is is a centrifugal supercharger. You should be able to find a ton of info on them. Setting up your carb isn't really gonna be the same as setting up for a turbo, because a centrifugal supercharger doesn't boost the same way. But, i agree that it's a very superior setup to the camden one. I like centrifugal superchargers, very precise and predictable airflow in a pretty linear fashion.
01-10-07, 05:34 PM
#13
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You have to look at your expectations for a supercharger. You can think of a centrifugal supercharger as all of the advantages of a turbo with all of the advantages of a roots supercharger or you can think of a centrifugal supercharger as all of the disadvantages of a turbo with all of the disadvantages of a roots supercharger.
A centrifugal supercharger will tend to have weak boost at low and mid RPM with a huge surge of boost at high RPM (not at all the same thing as turbo lag).
However a centrifugal supercharger is much more efficient than a roots supercharger and it doesn't have the tremendous heat of a turbo.
There are definite advantages to each type of boost but I like the boost delivery of a roots supercharger. It is faster to deliver boost, more consistent across the rev band, but it is less efficient.
You should investigate the pluses and minuses and decide for yourself.
By the way, a centrifugal supercharger must be properly sized for your engine just like a turbo. Make sure that Rotrex makes a size that is compatible with the rotary.
A centrifugal supercharger will tend to have weak boost at low and mid RPM with a huge surge of boost at high RPM (not at all the same thing as turbo lag).
However a centrifugal supercharger is much more efficient than a roots supercharger and it doesn't have the tremendous heat of a turbo.
There are definite advantages to each type of boost but I like the boost delivery of a roots supercharger. It is faster to deliver boost, more consistent across the rev band, but it is less efficient.
You should investigate the pluses and minuses and decide for yourself.
By the way, a centrifugal supercharger must be properly sized for your engine just like a turbo. Make sure that Rotrex makes a size that is compatible with the rotary.
01-10-07, 11:50 PM
#14
Ya i have been comparing the 2 side by side and I think i'm leaning more towards this setup. I have sent out a couple of email out today to compnies that produce them asking them a few questions regarding the rotary, but from reading the c30 might be the way to go, a c38 would probably need a half bridge or larger port i think.
01-11-07, 09:57 AM
#15
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boost
The belt driven centrifugal supercharger will not give you the low/mid power of the roots type or even a turbo. It would work best on a constant high output application like a ski boat. It is easier to mount and will add less heat to the charge than the Roots type. You will need to calculate the drive ratio both to avoid over speed and to hold peak boost to the desired limit. You may want to check out "coolmist" as a means of charge cooling. It could be an interesting project. Keep us posted on your progress.
01-11-07, 02:19 PM
#16
The amount of power you'd loose driving a centrifugal type blower at a decent boost level coupled with the lag from a nice intercooler and the original lack of torque from a rotary to start with makes this idea seem like a "One step forward and two steps back operation."
The Camdon blowers are "roots" style for a reason. They move a tone of volume at low rpm. The centrifugal blowers need lots of rpm to start moving big volume.
Not that it couldn't be done, but why not go the turbo or N20 route? It would be more efficient IMO.
The Camdon blowers are "roots" style for a reason. They move a tone of volume at low rpm. The centrifugal blowers need lots of rpm to start moving big volume.
Not that it couldn't be done, but why not go the turbo or N20 route? It would be more efficient IMO.
01-11-07, 03:22 PM
#18
Originally Posted by vxturboxv
The amount of power you'd loose driving a centrifugal type blower at a decent boost level coupled with the lag from a nice intercooler and the original lack of torque from a rotary to start with makes this idea seem like a "One step forward and two steps back operation."
The Camdon blowers are "roots" style for a reason. They move a tone of volume at low rpm. The centrifugal blowers need lots of rpm to start moving big volume.
Not that it couldn't be done, but why not go the turbo or N20 route? It would be more efficient IMO.
The Camdon blowers are "roots" style for a reason. They move a tone of volume at low rpm. The centrifugal blowers need lots of rpm to start moving big volume.
Not that it couldn't be done, but why not go the turbo or N20 route? It would be more efficient IMO.
For power loss, just like tranquil said it can't be more than what I was loosing from running those 3 belt driven items,
As for the "lag", as I mentioned before this was possibility of adding an intercooler, but if it means I have to sacrafice a bit in the low and gaing about 10 -15 more hp in the top i might be willing to sacrafice a little bit of the low.
Either way, intercooler or not, a gain in HP and torque would be gained over my current N/A setup. The goal that i'm opting for right now is somewhere around 210rwhp, It may not be big HP number, but that is not what I would like to atcheive. I just want something that would still be very driveable, and controlable without having to spend thousands more on upgrading other things. i'm still a college student (still going to university after that probably too) so I'm just setting up a very realistic budget figure and HP figures along with that.
01-11-07, 03:37 PM
#19
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for a horsepower number like that, i think a small turbo would work better and could probably be pieced together with t2 parts for cheap. And then you just have your carb upgrades, plumbing and exhaust, both can be done cheap enough..
01-12-07, 02:37 AM
#21
Originally Posted by dj55b
I don't want another thread about about turbo vs super ...
For power loss, just like tranquil said it can't be more than what I was loosing from running those 3 belt driven items,
As for the "lag", as I mentioned before this was possibility of adding an intercooler, but if it means I have to sacrafice a bit in the low and gaing about 10 -15 more hp in the top i might be willing to sacrafice a little bit of the low.
Either way, intercooler or not, a gain in HP and torque would be gained over my current N/A setup. The goal that i'm opting for right now is somewhere around 210rwhp, It may not be big HP number, but that is not what I would like to atcheive. I just want something that would still be very driveable, and controlable without having to spend thousands more on upgrading other things. i'm still a college student (still going to university after that probably too) so I'm just setting up a very realistic budget figure and HP figures along with that.
For power loss, just like tranquil said it can't be more than what I was loosing from running those 3 belt driven items,
As for the "lag", as I mentioned before this was possibility of adding an intercooler, but if it means I have to sacrafice a bit in the low and gaing about 10 -15 more hp in the top i might be willing to sacrafice a little bit of the low.
Either way, intercooler or not, a gain in HP and torque would be gained over my current N/A setup. The goal that i'm opting for right now is somewhere around 210rwhp, It may not be big HP number, but that is not what I would like to atcheive. I just want something that would still be very driveable, and controlable without having to spend thousands more on upgrading other things. i'm still a college student (still going to university after that probably too) so I'm just setting up a very realistic budget figure and HP figures along with that.
But your right, it will work and you will gain HP. But why not get the most power out of your money? I helped build a 12A engine with a roots blower off an xr-7 cougar (roots). The motor was sweet sounding and rev'd like a sport bike. But would still get whooped on by your basic TII rx-7.
I'm just saying theres a reason those blowers aren't usually put on rotarys. They don't work very well....
I'm not trying to bash your idea, just explain why cent. blowers aren't commonly used on rotarys. More power to you for doing something different. Keep us updated with pictures.
Good luck! :cheers:
01-12-07, 07:33 AM
#22
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From Superchargersonline.com...
The centrifugal supercharger compresses the air primarily at the point that the air leaves the supercharger impeller and is forced into the supercharger scroll. At this point the air is pushed through a venturi shaped bore. The compression peaks at the apex (narrowest point) of the venturi before being released into the scroll for discharge. This compression method allows the centrifugal supercharger to enjoy a fairly high degree of thermal efficiency, however, in order to produce significant amounts of boost, the centrifugal supercharger impeller must spin at very high rpms. In fact, the amount of boost produced by a centrifugal supercharger is proportional to the square of its impeller speed, which enables the centrifugal supercharger to make very high amounts of boost in the upper half of the engine's powerband.
Due to the design of the centrifugal supercharger and it's discharge scroll, the supercharger compressor can be mounted far away from the air intake. A discharge tube can be used to carry the compressed air from the supercharger compressor to the engine's air intake, or to an intercooler, making it very adaptable and easy to install. Also, because the centrifugal supercharger essentially acts as a high-speed fan, air can flow backward through the compressor under certain circumstances like quick deceleration or while shifting gears (rather than a fixed-displacement supercharger - roots, twin screw - which only allow air to flow in one direction). Supercharger manufacturers exploit these benefits by easily making the mounting hardware (hoses, discharge tubes, etc.) for a wide variety of vehicles at a very affordable price, without requiring the throttle body to be moved or modified as is the case with fixed displacement systems.
While the centrifugal supercharger is efficient, easy to install, adaptable, and cool (produces fairly cool air charge), there are several drawbacks that should be noted. First, because the compressor's impeller is gear-driven and spins at very high rpms (40,000+), centrifugal superchargers tend to be noisier (more whistley) than their fixed displacement counterparts (Powerdyne's Silent-Drive superchargers eliminate much of this noise by using an internal belt to drive the impeller rather than a gear-drive system). This whistley noise doesn't bother most people - in fact, we find that most of our customers like to hear their superchargers in action. The biggest drawback of the centrifugal supercharger is it's inability to make high levels of boost at low engine rpms. Typically, a centrifugal supercharger will make it's maximum (quoted) boost at the engine's redline rpm and nearly nothing at 1500-2000 engine rpm. Boost builds exponentially with engine rpm, meaning that boost comes on very quickly in the upper half of the powerband. While this normally isn't a problem for lighter cars with manual trannsmissions, it poses a significant problem to heavier vehicles, towing vehicles, or vehicles with automatic transmissions. If you have a truck, towing vehicle, or an automatic transmission, you may want to consider a screw-type supercharger, which makes full boost as low as 1500 engine rpm.
So the only question is...are our cars considered a light car? Also will a lighter flywheel help a centrifugal supercharger by letting the engine rev up much faster?
Another thing to think about is. Do you want boost all the time? Cruising under boost wastes gas. So it might be nice not to have full boost at the bottom end and full boost up top, kinda like NOS.
Im just throwing some ideas. Im not an expert in this area.
So the only question is...are our cars considered a light car? Also will a lighter flywheel help a centrifugal supercharger by letting the engine rev up much faster?
Another thing to think about is. Do you want boost all the time? Cruising under boost wastes gas. So it might be nice not to have full boost at the bottom end and full boost up top, kinda like NOS.
Im just throwing some ideas. Im not an expert in this area.
Last edited by 2wankel; 01-12-07 at 07:47 AM.
01-12-07, 08:20 AM
#23
Originally Posted by vxturboxv
Um.... U guys are smok'n the crack if you think the load of those accesories are anywhere near the load a blower puts on a motor. The gearing system in even the small cent. blowers spins the compressor upwards of 60,000rpm, the race models 80,000+. Thats why they use such huge ribbed belts... We don't see little v belts on many super chargers do we?
But your right, it will work and you will gain HP. But why not get the most power out of your money? I helped build a 12A engine with a roots blower off an xr-7 cougar (roots). The motor was sweet sounding and rev'd like a sport bike. But would still get whooped on by your basic TII rx-7.
I'm just saying theres a reason those blowers aren't usually put on rotarys. They don't work very well....
I'm not trying to bash your idea, just explain why cent. blowers aren't commonly used on rotarys. More power to you for doing something different. Keep us updated with pictures.
Good luck! :cheers:
But your right, it will work and you will gain HP. But why not get the most power out of your money? I helped build a 12A engine with a roots blower off an xr-7 cougar (roots). The motor was sweet sounding and rev'd like a sport bike. But would still get whooped on by your basic TII rx-7.
I'm just saying theres a reason those blowers aren't usually put on rotarys. They don't work very well....
I'm not trying to bash your idea, just explain why cent. blowers aren't commonly used on rotarys. More power to you for doing something different. Keep us updated with pictures.
Good luck! :cheers:
(Actually I was woundering how much HP loss there was from those units, I tried posting in the one Gilmer Drive thread that poped up not too long ago but I had no reply from there. if someone could chime in on that, that would be great.)Still waiting replies from companies ... grr I hate waiting ..
01-12-07, 08:27 AM
#24
Originally Posted by 2wankel
From Superchargersonline.com...
The centrifugal supercharger compresses the air primarily at the point that the air leaves the supercharger impeller and is forced into the supercharger scroll. At this point the air is pushed through a venturi shaped bore. The compression peaks at the apex (narrowest point) of the venturi before being released into the scroll for discharge. This compression method allows the centrifugal supercharger to enjoy a fairly high degree of thermal efficiency, however, in order to produce significant amounts of boost, the centrifugal supercharger impeller must spin at very high rpms. In fact, the amount of boost produced by a centrifugal supercharger is proportional to the square of its impeller speed, which enables the centrifugal supercharger to make very high amounts of boost in the upper half of the engine's powerband.
Due to the design of the centrifugal supercharger and it's discharge scroll, the supercharger compressor can be mounted far away from the air intake. A discharge tube can be used to carry the compressed air from the supercharger compressor to the engine's air intake, or to an intercooler, making it very adaptable and easy to install. Also, because the centrifugal supercharger essentially acts as a high-speed fan, air can flow backward through the compressor under certain circumstances like quick deceleration or while shifting gears (rather than a fixed-displacement supercharger - roots, twin screw - which only allow air to flow in one direction). Supercharger manufacturers exploit these benefits by easily making the mounting hardware (hoses, discharge tubes, etc.) for a wide variety of vehicles at a very affordable price, without requiring the throttle body to be moved or modified as is the case with fixed displacement systems.
While the centrifugal supercharger is efficient, easy to install, adaptable, and cool (produces fairly cool air charge), there are several drawbacks that should be noted. First, because the compressor's impeller is gear-driven and spins at very high rpms (40,000+), centrifugal superchargers tend to be noisier (more whistley) than their fixed displacement counterparts (Powerdyne's Silent-Drive superchargers eliminate much of this noise by using an internal belt to drive the impeller rather than a gear-drive system). This whistley noise doesn't bother most people - in fact, we find that most of our customers like to hear their superchargers in action. The biggest drawback of the centrifugal supercharger is it's inability to make high levels of boost at low engine rpms. Typically, a centrifugal supercharger will make it's maximum (quoted) boost at the engine's redline rpm and nearly nothing at 1500-2000 engine rpm. Boost builds exponentially with engine rpm, meaning that boost comes on very quickly in the upper half of the powerband. While this normally isn't a problem for lighter cars with manual trannsmissions, it poses a significant problem to heavier vehicles, towing vehicles, or vehicles with automatic transmissions. If you have a truck, towing vehicle, or an automatic transmission, you may want to consider a screw-type supercharger, which makes full boost as low as 1500 engine rpm.
So the only question is...are our cars considered a light car? Also will a lighter flywheel help a centrifugal supercharger by letting the engine rev up much faster?
Another thing to think about is. Do you want boost all the time? Cruising under boost wastes gas. So it might be nice not to have full boost at the bottom end and full boost up top, kinda like NOS.
Im just throwing some ideas. Im not an expert in this area.
So the only question is...are our cars considered a light car? Also will a lighter flywheel help a centrifugal supercharger by letting the engine rev up much faster?
Another thing to think about is. Do you want boost all the time? Cruising under boost wastes gas. So it might be nice not to have full boost at the bottom end and full boost up top, kinda like NOS.
Im just throwing some ideas. Im not an expert in this area.
Thanks alot for this post, I'm pretty sure that our car is considered light vehicle (unless they mean like motorbike??) As for the flywheel, not so sure about boosting it quicker, but from reading the part that it want flow backwards, it might be a point down. If they say that decelerating or shifting gear would do that, a lighter wheel looses its inertia faster hence could make air flow backwards moreoften.
I would like to know too about the cruising under boost things ... this is kinda like a daily driver, and i mentioned before money is an issue here especially with gas prices now a days.
Thanks everyone for contributing and keep it coming
01-12-07, 09:58 AM
#25
http://www.w2wpowertrain.com/images_...ger_range1.pdf
I found this off one of the site while browsing ... the one that I was considering is the c30-84 which flows .30kg/s is that enough air for our air thirsty rotaries?
I found this off one of the site while browsing ... the one that I was considering is the c30-84 which flows .30kg/s is that enough air for our air thirsty rotaries?