charger question?
Discussion
ive done a search and found nothing, im not very good knowledge wise with supercharges as i have only ever had N/A cars and no how to tune etc them1
my bro's mate swears blind that his vectra gsi has twin superchargers on it, i told him this wasnt possible as each one would not be able to bolt on to the engine! but i wasnt sure hence this question.
i asked him to show me his engine bay or take me for a spin to prove hes not bullsh1tting but he made some excuse so he cudnt!
alot of my mates have turbo'd cars and i have picked up a gerneral knowledge about turbos from helping them with there cars. but from wot i gather S'chargers are completly different!
any help and knowledge u can share with me would be much appreciated!
may thanks davo
>> Edited by davo172cup on Saturday 1st April 12:58
>> Edited by davo172cup on Saturday 1st April 12:59
my bro's mate swears blind that his vectra gsi has twin superchargers on it, i told him this wasnt possible as each one would not be able to bolt on to the engine! but i wasnt sure hence this question.
i asked him to show me his engine bay or take me for a spin to prove hes not bullsh1tting but he made some excuse so he cudnt!
question said:
is it posible to have twin superchargers?
alot of my mates have turbo'd cars and i have picked up a gerneral knowledge about turbos from helping them with there cars. but from wot i gather S'chargers are completly different!
any help and knowledge u can share with me would be much appreciated!
may thanks davo
>> Edited by davo172cup on Saturday 1st April 12:58
>> Edited by davo172cup on Saturday 1st April 12:59
You can do it but IMHO its pointless.
The point of Twin turbo is to reduce spool time. Be it by reducing this distance of the turbo from the exhaust manifold, or by having 2 different sized turbos to give a smoother boost transition.
(I suppose that if the capacity of engine is large enough multiple turbos may be required for the large flow rates.)
The point of Twin turbo is to reduce spool time. Be it by reducing this distance of the turbo from the exhaust manifold, or by having 2 different sized turbos to give a smoother boost transition.
(I suppose that if the capacity of engine is large enough multiple turbos may be required for the large flow rates.)
I would say your 'mate' is telling porky pies..
But thats not to say you cant twin supercharge an engine. I do remember seeing some years ago a twin supercharged V8 BMW engine. This wasnt the type of superchargers you'd expect though and were esentially belt driven turbo's, may have been vortex chargers but i'm not sure.
Your mate is more likely to have a twin inlet system that has dual tracts in the inlet manifold that is controlled via extra throttle butterflies in it to open and close at different revs to give a wider torque band.
But thats not to say you cant twin supercharge an engine. I do remember seeing some years ago a twin supercharged V8 BMW engine. This wasnt the type of superchargers you'd expect though and were esentially belt driven turbo's, may have been vortex chargers but i'm not sure.
Your mate is more likely to have a twin inlet system that has dual tracts in the inlet manifold that is controlled via extra throttle butterflies in it to open and close at different revs to give a wider torque band.
Might be revealing to find out what sort of supercharger he is referring to. Fitting proper superchargers is a difficult and expensive engineering challenge. But if he's just wasted a couple of hundred quid on those cute little cooling fan gadgets then it's possible that he just indeed have twin superchargers fitted. And its probably 20 bhp down on standard as a result. 
The only car I can think of that had twin superchargers was the old Aston Vantage, the chargers themselves apparently consumed 200 bhp just to run them...
Presumably the only reason for the twin chargers was that a large enough single supercharger wasn't readily available from Eaton (IIRC they used Eaton blowers).
There's negative benefit to using two smaller superchargers over one big one - two belt driven pumps simply eat up more power in friction losses.
Packaging will also be a problem since those sort of blowers are big. Your mate is almost certainly bullshitting, but even if he did have a supercharged engine, no Vectra has a big enough displacement to need two Eatons. The biggest off-the-shelf Eaton blower has enough capacity to force feed a tuned 5 litre V8, and I doubt your mate has one of those in his Vectra.
Presumably the only reason for the twin chargers was that a large enough single supercharger wasn't readily available from Eaton (IIRC they used Eaton blowers).
There's negative benefit to using two smaller superchargers over one big one - two belt driven pumps simply eat up more power in friction losses.
Packaging will also be a problem since those sort of blowers are big. Your mate is almost certainly bullshitting, but even if he did have a supercharged engine, no Vectra has a big enough displacement to need two Eatons. The biggest off-the-shelf Eaton blower has enough capacity to force feed a tuned 5 litre V8, and I doubt your mate has one of those in his Vectra.
It can be done....
Although drive belt losses will be higher, 2 smaller blowers would have less inertia than a single large one, if you wanted massive power. Similarly with turbos.
One large one can take an awful lot to spin up, whereas 2 smaller ones are easier.
So while belt drive losses might be higher, drive losses to actually spin the blower might be less...
But for 99% of applications, one blower should be plenty for most people.
>> Edited by stevieturbo on Saturday 1st April 20:56
Although drive belt losses will be higher, 2 smaller blowers would have less inertia than a single large one, if you wanted massive power. Similarly with turbos.
One large one can take an awful lot to spin up, whereas 2 smaller ones are easier.
So while belt drive losses might be higher, drive losses to actually spin the blower might be less...
But for 99% of applications, one blower should be plenty for most people.
>> Edited by stevieturbo on Saturday 1st April 20:56
stevieturbo said:
It can be done....
Although drive belt losses will be higher, 2 smaller blowers would have less inertia than a single large one, if you wanted massive power. Similarly with turbos.
One large one can take an awful lot to spin up, whereas 2 smaller ones are easier.
So while belt drive losses might be higher, drive losses to actually spin the blower might be less...
But for 99% of applications, one blower should be plenty for most people.
>> Edited by stevieturbo on Saturday 1st April 20:56
Errr.... WTF is the point of that?
There is no way that those turbos are going to spool fast enough driven by that belt. (unless there is some magic gearbox stuff inside)
Also you have the mass of the face plate to deal with. You need exhausts anyway so why not mount the turbos on the exaust and use them the way they were inteded.
That just looks redneck to me.
(prepares to be proven wrong)
Toast King said:
Errr.... WTF is the point of that?
There is no way that those turbos are going to spool fast enough driven by that belt. (unless there is some magic gearbox stuff inside)
Also you have the mass of the face plate to deal with. You need exhausts anyway so why not mount the turbos on the exaust and use them the way they were inteded.
That just looks redneck to me.
(prepares to be proven wrong)
They aren't turbos, they're standard centrefugal blowers. I expect there'll be an epicyclic step-up gearbox inside.
Thats similair to what i have seen before.
Superchargers come in various forms not just the roots type of blower commonly associated with a supercharger. Its all in the internals and impellor design.
Toast King said:
Errr.... WTF is the point of that?
There is no way that those turbos are going to spool fast enough driven by that belt. (unless there is some magic gearbox stuff inside)
Superchargers come in various forms not just the roots type of blower commonly associated with a supercharger. Its all in the internals and impellor design.
Mikey G said:
Thats similair to what i have seen before.
Toast King said:
Errr.... WTF is the point of that?
There is no way that those turbos are going to spool fast enough driven by that belt. (unless there is some magic gearbox stuff inside)
Superchargers come in various forms not just the roots type of blower commonly associated with a supercharger. Its all in the internals and impellor design.
Yeah there are many types..... that just looks.... Wrong. Also what is the point on mounting 2 centrifugal compressors? The boost created is non linear, which is the whole point of a supercharger.
"Ok had a look and ROTREX make superchargers
There is a planetary gear system inside.
Still not convinced by the system though!"
>> Edited by Toast King on Saturday 1st April 22:52
cyberface said:
There's negative benefit to using two smaller superchargers over one big one - two belt driven pumps simply eat up more power in friction losses.
There may be some point to it if you're using superchargers with a fixed amount of internal compression (eg. Lysholm screw, Shorrock) since these are most efficient when the internal compression matches the amount of boost you want to generate. So if you want a lot of boost it may be better to run two in series. I have a feeling that some aero engines did this.
Pigeon said:
There's negative benefit to using two smaller superchargers over one big one - two belt driven pumps simply eat up more power in friction losses.
There may be some point to it if you're using superchargers with a fixed amount of internal compression (eg. Lysholm screw, Shorrock) since these are most efficient when the internal compression matches the amount of boost you want to generate. So if you want a lot of boost it may be better to run two in series. I have a feeling that some aero engines did this.
I'm no engineer, but surely putting two fixed-volume chargers in series would be a waste of time? I'm assuming here that the 'outer' supercharger can only pull in (and compress) a fixed volume of air for each revolution. Therefore the maximum inlet volume of air will be limited by the outer supercharger, regardless of whether the inner supercharger can compress this air to a higher pressure. How would the inner supercharger be helping matters? You may be able to increase output pressure, but at the expense of volume, and surely pumped volume of air is the essential aspect i.e. more oxygen for more fuel.
I can see how the centrifugal types may work (as they're turbos in disguise), but again, not in series unless they are of completely different sizes and one is well off the efficiency curve when the other is really pumping air (the efficient one would have to be able to drag air through the big one at this point though...)
I'm not trying to be a smart-arse here, just very interested as I love superchargers and their power delivery (I have an Eaton M90 sitting on top of my 911 engine). Given this reasonably 'heavy' charger (second biggest Eaton make for general purchase IIRC), only one is needed for my engine, and it produces big torque from tickover. The 'torque from low revs, big power at high revs' argument for twin turbos is meaningless with this sort of charger - you'd only need two if the engine was simply so big that the charger couldn't pump enough air.
I expect the ones in that picture would be arranged in parallel, but if you were arranging blowers in series I think you would need different flow/pressure characteristics. For example the efficiency of the Eaton blowers goes through the floor when you raise the boost, so if you were after bonkers power it might work better with two smaller blowers in series rather than one big one. Not that it would be sensible to use Eatons for that sort of thing, but if you did then you might look at series arrangements.
Toast King said:
Yeah there are many types..... that just looks.... Wrong. Also what is the point on mounting 2 centrifugal compressors? The boost created is non linear, which is the whole point of a supercharger.
"Ok had a look and ROTREX make superchargers
There is a planetary gear system inside.
Still not convinced by the system though!"
>> Edited by Toast King on Saturday 1st April 22:52
Do you have a clue what the point of a supercharger is for ???
I couldnt give a toss what my boost curve is like. I want good useable power from my blower, and thats what Ive got. Boost curve is irrelevant. Its power delivery that matters, and boost is only a measure of restriction within the engine anyway. You could have several blowers create the same boost, but very very different power outputs.
I dont want a shitload of torque at 2000rpm that will go up in tyre smoke. I want a good controllable spread of power and torque, climbing as the revs climb.
A rootes or twin screw wouldnt do it for me, and neither would turbos. A CF blower works great though.
And with your reference to mounting 2 units ???
Why do Aeroplanes not all use 1 engine ?? Im sure thre are plenty of single engines that can fly most planes ??
Perhaps its because multiple engines are more efficient. Same goes for many things. Old saying "Many hands make light work"
This isnt so different. The builders simply believe using multiple units is a better way of doing it.
thanks all! learnt alot bout chargers that i didnt no! guna go find some more info on them from the net and books etc, really interesting and wudnt mind learning more! any recomendations on info etc would be good!
spoke to my bro's mate tonite, he still wudnt show me his engine and still ssware blind it had twin superchargers but i watched him pull away from the pub and there wasnt any 'whining noise' that u get from a charger and he floored it and it didnt seem very quick at all, im quite doubtfull that its even a gsi now as it was quite slugish(not that the gsi's are that quick anyway!), prob just a 1.8 with the relevent bodykit! class A bullshitter!
did ask him if he had on of those joke 'turbonators' u can get from ebay etc that cos $69 and apparently produce an extra 35hp????????? he said no but he looked at them cos there really good!
he obvrously doesnt have a scooby doo about cars or much for that matter!lying little toe rag!
davo
spoke to my bro's mate tonite, he still wudnt show me his engine and still ssware blind it had twin superchargers but i watched him pull away from the pub and there wasnt any 'whining noise' that u get from a charger and he floored it and it didnt seem very quick at all, im quite doubtfull that its even a gsi now as it was quite slugish(not that the gsi's are that quick anyway!), prob just a 1.8 with the relevent bodykit! class A bullshitter!
did ask him if he had on of those joke 'turbonators' u can get from ebay etc that cos $69 and apparently produce an extra 35hp????????? he said no but he looked at them cos there really good!
he obvrously doesnt have a scooby doo about cars or much for that matter!lying little toe rag!
davo
cyberface said:
There's negative benefit to using two smaller superchargers over one big one - two belt driven pumps simply eat up more power in friction losses.
There may be some point to it if you're using superchargers with a fixed amount of internal compression (eg. Lysholm screw, Shorrock) since these are most efficient when the internal compression matches the amount of boost you want to generate. So if you want a lot of boost it may be better to run two in series. I have a feeling that some aero engines did this.
I'm no engineer, but surely putting two fixed-volume chargers in series would be a waste of time? I'm assuming here that the 'outer' supercharger can only pull in (and compress) a fixed volume of air for each revolution. Therefore the maximum inlet volume of air will be limited by the outer supercharger, regardless of whether the inner supercharger can compress this air to a higher pressure. How would the inner supercharger be helping matters? You may be able to increase output pressure, but at the expense of volume, and surely pumped volume of air is the essential aspect i.e. more oxygen for more fuel.
It's not volume which is important, but mass. The volume delivered is fixed (by the engine capacity) but the supercharger, by increasing the pressure, increases the density and therefore the mass. The supercharger pulls in a fixed volume of air per crank rev which is larger than the volume the engine itself would pull in, and crams it into the smaller volume.
The outer supercharger does indeed limit what you take in but the manner in which it is compressed is important. It's considerably more efficient to compress the air inside the supercharger to manifold pressure (as opposed to "paddling" it in without compressing it internally as a Rootes/Eaton blower does), but since the compression ratio of the supercharger is fixed, this only works properly at a particular boost level, and most internal-compression superchargers have a modest compression ratio to suit the modest levels of boost that most people use. If you try and create more boost than this with one supercharger the efficiency drops right off as it reverts to "paddling". So if you're running silly boost levels it can make sense to have two units in series to achieve the required compression. Since the second unit is handling air at a higher density than the first, it would need to be smaller.
Pigeon said:
There's negative benefit to using two smaller superchargers over one big one - two belt driven pumps simply eat up more power in friction losses.
There may be some point to it if you're using superchargers with a fixed amount of internal compression (eg. Lysholm screw, Shorrock) since these are most efficient when the internal compression matches the amount of boost you want to generate. So if you want a lot of boost it may be better to run two in series. I have a feeling that some aero engines did this.
I'm no engineer, but surely putting two fixed-volume chargers in series would be a waste of time? I'm assuming here that the 'outer' supercharger can only pull in (and compress) a fixed volume of air for each revolution. Therefore the maximum inlet volume of air will be limited by the outer supercharger, regardless of whether the inner supercharger can compress this air to a higher pressure. How would the inner supercharger be helping matters? You may be able to increase output pressure, but at the expense of volume, and surely pumped volume of air is the essential aspect i.e. more oxygen for more fuel.
It's not volume which is important, but mass. The volume delivered is fixed (by the engine capacity) but the supercharger, by increasing the pressure, increases the density and therefore the mass. The supercharger pulls in a fixed volume of air per crank rev which is larger than the volume the engine itself would pull in, and crams it into the smaller volume.
The outer supercharger does indeed limit what you take in but the manner in which it is compressed is important. It's considerably more efficient to compress the air inside the supercharger to manifold pressure (as opposed to "paddling" it in without compressing it internally as a Rootes/Eaton blower does), but since the compression ratio of the supercharger is fixed, this only works properly at a particular boost level, and most internal-compression superchargers have a modest compression ratio to suit the modest levels of boost that most people use. If you try and create more boost than this with one supercharger the efficiency drops right off as it reverts to "paddling". So if you're running silly boost levels it can make sense to have two units in series to achieve the required compression. Since the second unit is handling air at a higher density than the first, it would need to be smaller.
Gotcha. Fully understand now - I was thinking too much of Rootes-type blowers. Presumably in these situations the outer blower takes in a big load of air in high-flow, low compression, and the inner blower deals with lower flow and higher compression, allowing a much higher density of charge at the manifold? It'd be interesting to see how much efficiency gain from this method is lost through the increased frictional losses from two units.
Cheers for that - no idea how you manage that level of clarity of explanation at 10 to 4 in the morning
Either you're a night owl, live on the other side of the planet or have been at the modafinil.stevieturbo said:
Yeah there are many types..... that just looks.... Wrong. Also what is the point on mounting 2 centrifugal compressors? The boost created is non linear, which is the whole point of a supercharger.
"Ok had a look and ROTREX make superchargers
There is a planetary gear system inside.
Still not convinced by the system though!"
>> Edited by Toast King on Saturday 1st April 22:52
Do you have a clue what the point of a supercharger is for ???
I couldnt give a toss what my boost curve is like. I want good useable power from my blower, and thats what Ive got. Boost curve is irrelevant. Its power delivery that matters, and boost is only a measure of restriction within the engine anyway. You could have several blowers create the same boost, but very very different power outputs.
I dont want a shitload of torque at 2000rpm that will go up in tyre smoke. I want a good controllable spread of power and torque, climbing as the revs climb.
A rootes or twin screw wouldnt do it for me, and neither would turbos. A CF blower works great though.
And with your reference to mounting 2 units ???
Why do Aeroplanes not all use 1 engine ?? Im sure thre are plenty of single engines that can fly most planes ??
Perhaps its because multiple engines are more efficient. Same goes for many things. Old saying "Many hands make light work"
This isnt so different. The builders simply believe using multiple units is a better way of doing it.
I was not questioning the number of units in that picture, more the point of centrifugal units. My question was.... If centrifugal is what you want, why not use a turbo. Scavange the free energy that is ejected down the exhuast.
Also.. I would have thought aeroplanes have more than 1 engine due to pacakging and backup constraints.
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