[LoveHorsepower]

I've searched online and couldn't really find an answer... What are the advantages to twin screw vs centrifugal superchargers? (I know how they're different, don't know why though)

 

[ByByCavalier]

If I am correct, twin screw deliver maximum airflow at a low rpm and maintain that maximum across the rpm range. So they start at say 10 units @ 2000 rpm, and still blow 10 units at 6000 rpm. This is good for low down torque since maximum deliverable air is applied at low rpm, a figurative "+1" for screw types.

Centrifugal type blowers are more linear, and pressure builds as rpm do. Its a direct correlation between engine speed and pressure built. Starts at 2 psi @ 2000 rpm, ends at 8 psi @ 6000 rpm. This means that power developed due to a centrifugal blower is "peakier" than screw types. This may be a benefit at higher rpm, as this blower may be able to deliver more air at higher rpm than screw type.

I have always seen centrifugal blowers as the mid point between turbos and roots type or screw type blowers as they contain characteristics of both F/I types. Its basically a belt driven turbo.

Please anyone correct me if I am wrong, I'm just going off old memory.

 

[renxwar]

You got it right. The only thing to add on is that twin screws are pedal dependent as well. You can have 10% throttle and 10% boost (for example) or go WOT for max boost.

Placement is a pro and con, too. Twin screws are easier and cheaper, with less parts than a centri.. but sometimes a twin screw can't fit.

 

[AKGC]

screw type = volume, but requires more torque/effort to spin.

centrifugal = less parasitic loss, smaller/lighter, but less CFM and harder to chang out the wheel

 

[phase autos]

If I am correct, twin screw deliver maximum airflow at a low rpm and maintain that maximum across the rpm range. So they start at say 10 units @ 2000 rpm, and still blow 10 units at 6000 rpm. This is good for low down torque since maximum deliverable air is applied at low rpm, a figurative "+1" for screw types.

pa.....partially correct as in they flow down low yes! as to the rest i think your confused eg: @100% efficiency lets say its 100 ci per rev. @ 6000 revs its still 100 ci per rev. = 600,000ci

Centrifugal type blowers are more linear, and pressure builds as rpm do. Its a direct correlation between engine speed and pressure built. Starts at 2 psi @ 2000 rpm, ends at 8 psi @ 6000 rpm. This means that power developed due to a centrifugal blower is "peakier" than screw types. This may be a benefit at higher rpm, as this blower may be able to deliver more air at higher rpm than screw type.

pa....as per roots or the more efficient screw type charger the centrifugal too has a known displacement eg: 100ci per rpm but its efficiency varies dramatically this can be as little as 10% at 1000rpm upto 60-70% at 6000rpm

I have always seen centrifugal blowers as the mid point between turbos and roots type or screw type blowers as they contain characteristics of both F/I types. Its basically a belt driven turbo.

pa....please don't use turbo's in the same sentence!!! lol

Please anyone correct me if I am wrong, I'm just going off old memory.

ok i did!

screw type = volume, but requires more torque/effort to spin.

centrifugal = less parasitic loss, smaller/lighter, but less CFM and harder to chang out the wheel

akgc??? you got me lost???

screw type uses more to drive infact upto 150hp out of every 500hp possible
http://www.sprintex.com.au.cust.webinabox.net.au/sprintex/wp-content/uploads/2010/10/sprintex_s5_335_dyno_chart.png

centrifugal use less hp are easier to fit and plumb and change wheels (easier than lengthening screws anyway! so?) but totally inefficient

also good to note that 150hp used to drive the charger was to produce a mere 710cfm the air temp raises to 100c / 195f (way hot too hot to use)

hence why for now you will never see me with one!

 

[N2OInferno]

pa....please don't use turbo's in the same sentence!!! lol

Why not? Many sources document that a turbocharger is a type of supercharger. Makes sense, since a supercharger is defined as "a compressor that forces increased oxygen into the cylinders of an internal-combustion engine." They are just powered differently.

OP, since most of the technical stuff was covered already, the most important thing to remember here is that positive displacement superchargers sound amazing. The rest are just ok.

 

[ByByCavalier]

PA, sorry I wasn't basing my numbers off of any real math, I was being lazy and just using an example to clarify operation, but thanks for clearing that up!

N2O, well said and very true. FWIW obv. turbos are mechanically very differently to superchargers, what I was saying is that characteristically a centrifugal super is closer to a turbo in operation than a screw type. Where screw type blowers have "screws" that mesh together to compound air, centrifugal supers and turbos have turbines that create pressure. Other than both using a turbine, they are completely different.

centrifugal use less hp are easier to fit and plumb and change wheels (easier than lengthening screws anyway! so?) but totally inefficient

agreed

 

[phase autos]

Why not? Many sources document that a turbocharger is a type of supercharger. Makes sense, since a supercharger is defined as "a compressor that forces increased oxygen into the cylinders of an internal-combustion engine." They are just powered differently.

pa...notice the all important lol at the end? IT WAS A JOKE! i was implying that he degraded / insulted turbos by mentioning them in the same sentence!!!

OP, since most of the technical stuff was covered already, the most important thing to remember here is that positive displacement superchargers sound amazing. The rest are just ok.

remember that next time an idler bearing annoys you!!! LOL

as to turbo's they can be classed as variable drive superchargers or akin to variable pulley drive on a supercharger!

 

[phase autos]

PA, sorry I wasn't basing my numbers off of any real math, I was being lazy and just using an example to clarify operation, but thanks for clearing that up!

Obv. turbos are mechanically very differently to superchargers, what I was saying is that characteristically a centrifugal super is closer to a turbo in operation than a screw type. Where screw type blowers have "screws" that mesh together to compound air, centrifugal supers and turbos have turbines that create pressure. Other than both using a turbine, they are completely different.



agreed

its all cool it just came across as 10 cfm @ 2000 rpm and 10 cfm @ 6000 rpm or units what ever you said?

just a bit more info

roots blow air and it compresses in the manifolds as do cent. and turbo's

where a screw builds pressure between the screws heating the air!

roots also due to inefficiency heat the air more than screws

turbo's are good at keeping air near ambient but tucked in near manifolds the ambient is not as cool as the weather outside!

cent, chargers heat the air up the least pitty they suck at efficiency!

 

[ByByCavalier]

PA, thanks for the info. That being said, I have a few questions regarding supers that you or others might be able to answer, as it pertains to the original topic.

What type of solutions exist for cooling the intake charge when using superchargers? Can contemporary intercooler (aftercooler) systems be used with both types of superchargers? I know most turbocharger systems utilize intercooling, but lots of supercharger systems don't mention intercooling. Is this due to the lower maximum boost pressures of superchargers, or because it is simply ineffective/unattainable?

I ask because I know that screw type blowers are prone to heat soak and I am curious as to what can mitigate this issue.

 

[N2OInferno]

In very simple terms, higher boost = more heat. You'll use an aftercooler/intercooler with a supercharger for the same purpose you'd use an intercooler with a turbo. Depending on your application and space constraints, you can go with air to air like a traditional turbo intercooler, or an air to water aftercooler, which uses water to cool the air charge instead of air flowing through it like a radiator. However, you have setups like what Vortech uses that uses a radiator to cool down the water for their air to water aftercooler, so I guess that's an air to water to air setup.

Here's an air-to-water setup on a Mustang:

 

[phase autos]

PA, thanks for the info. That being said, I have a few questions regarding supers that you or others might be able to answer, as it pertains to the original topic.

What type of solutions exist for cooling the intake charge when using superchargers? Can contemporary intercooler (aftercooler) systems be used with both types of superchargers? I know most turbocharger systems utilize intercooling, but lots of supercharger systems don't mention intercooling. Is this due to the lower maximum boost pressures of superchargers, or because it is simply ineffective/unattainable?

I ask because I know that screw type blowers are prone to heat soak and I am curious as to what can mitigate this issue.

sorry went to sleep after my last reply!

ok there are many inter / after cooler set ups 1 you can see in the previous post used with a centrifugal this set up can be used with turbo or remote mounted roots/screw the issue is engine bay room

then you get fools making cooler kits inside the manifold although these are better than nothing they almost do nothing!

ill write a tech article on coolers like i did dyno's!!!

 

[J_Tex]

Well a Centrifugal needs more RPMS to make power, much like a turbo. While a Screw type will need a bit more torque to get the screws spinning. However there are different types of each that offer advantages over the other and vice versa. IMO and experience...

Larger engine- better for Screw type (low end peak power and torque)
Smaller engine- better for Centrifugal type (high end peak power and torque)

In all, two ways of achieving the same goal. It comes down to wether or now you want to rev out your motor to make power or do you want more lowend grunt.

 

[N2OInferno]

I suppose it depends on the application. I don't think I'd put a centrifugal blower onto a smaller vehicle, especially one that doesn't make power until it's up high anyway (like most Hondas, for example.) It depends on where you want your power to be, yes. We've left the roots blower out of the discussion so far (I think) and it generally seems to work very well for small displacement engines.

Back when Speed Options was around (yeah, waaay back in the day) there was a guy that had the Vortech centrifugal setup on his V6 Cougar and wasn't happy at all with the power delivery. I imagine if you already lack low end, it might lead to an upset.

 

[Quartermaster]

Twin screw or don't bother.

Centrifugal ONLY if you simply CANNOT fit a screw type in teh engine bay, or you've given up on turbos.

Back in the Tiburon days I recall RIPP Centrifugal superchargers blowing up a whole grip of 3G DSMs, Tiburons etc and ever since I learned about how peaky they can be and difficult to control, I wouldn't ever go with one unless it was the only option.

 

[J_Tex]

Quartermaster- agreed.

Look this is one of those questions that we can all argue about "which is best" for years at a time. It all comes down to how you want to make power. Personally, I would rather have torque than horsepower.

 

[phase autos]

Quartermaster- agreed.

Look this is one of those questions that we can all argue about "which is best" for years at a time. It all comes down to how you want to make power. Personally, I would rather have torque than horsepower.

me too thats why tt for me i can have both best low down torque and better power all the way up!!!

but as you say its what rocks your boat for some!!!

 

[Suns_PSD]

The car has plenty of torque to spin the wheels at low speeds. Not sure why anyone would desire torque over hp in a V6 sports car. I'd enjoy more roll on power for sure but it's adequate now and I can downshift when I really need to get going.

Just an all around well balanced single street turbo set up is ideal as far as all around performance vs. cost. 400 rwhp is a real kick in the pants man!

I'm still very eager to find out how much hp Tex's 4.2 stroker makes however w/ a cam and head porting. Who knows, that might be a $5K 400hp NA solution right there which wouldn't be too shabby.

 

[phase autos]

The car has plenty of torque to spin the wheels at low speeds. Not sure why anyone would desire torque over hp in a V6 sports car. I'd enjoy more roll on power for sure but it's adequate now and I can downshift when I really need to get going.

Just an all around well balanced single street turbo set up is ideal as far as all around performance vs. cost. 400 rwhp is a real kick in the pants man!

I'm still very eager to find out how much hp Tex's 4.2 stroker makes however w/ a cam and head porting. Who knows, that might be a $5K 400hp NA solution right there which wouldn't be too shabby.

see the beauty of turbos its a key stoke away from what ever boost you like at what ever rpm you like and inherently whatever load you like! without trying to change pulleys on the fly!!!

as mentioned in the electric s/c thread i'm waiting on electric motors to catch up as thats the only thing holding them back i have already got electronic control that is fully mappable 16 rpm x 16 load or the cheaper 9 x 9 with full timming and fuel control (piggy back) for most cars! otherwise these to you can adjust at a key stroke with the benefit of lower intake temps too!

before you ask the best electric motor i can find atm can only render me 5kg thrust and 600 cfm this is fine for 4-6 psi on a 3.8! calculated not tested! i am currently trying to package it smaller as the assembly is currently 6" diameter 5" long my 4" can only do 1-2 psi at best on a 3.8 more testing soon!

i never said much before as every mention of this has brought ridicule but hey you guys do that anyway so heres more fuel for your fire!!!!

 

[Odelagt]

Twin screw or don't bother.

Centrifugal ONLY if you simply CANNOT fit a screw type in teh engine bay, or you've given up on turbos.

Back in the Tiburon days I recall RIPP Centrifugal superchargers blowing up a whole grip of 3G DSMs, Tiburons etc and ever since I learned about how peaky they can be and difficult to control, I wouldn't ever go with one unless it was the only option.

Agreed a third time. I personally think conglomerate max power and drivability would be attained by a turbo setup due to the system sapping the least power from the engine and delivering the most possible flow of compressed air by weight. However, in normal driving situation, I think max FUN will come from the instant-on torque of a twin screw. Lets face it, low end torque is almost always desirable and makes all of us grin. Yeah I like poppy fast spinning rev machines, but that's not what I bought...