Question about twin charging

[Failali]

i know in a twincharged engine, usually there is a supercharger and a turbo charger which gives you instaneous power from 1-5k rpm and then the power band dips , then the turbo takes over.

 

Is there such a thing that in a twin turbo setup, there is a small turbo and a big turbo

 

suppose they could be engineered in such a way that the small turbo spools up instaneously for takeoff and when it reaches the point that the powerband dips, the turbo stops spooling and the bigger turbo takes over?

 

thanks

[Latioboy]

Oh my god. There u go again.....

[Cerano]

i know in a twincharged engine, usually there is a supercharger and a turbo charger which gives you instaneous power from 1-5k rpm and then the power band dips , then the turbo takes over.

 

Is there such a thing that in a twin turbo setup, there is a small turbo and a big turbo

 

suppose they could be engineered in such a way that the small turbo spools up instaneously for takeoff and when it reaches the point that the powerband dips, the turbo stops spooling and the bigger turbo takes over?

 

thanks

 

yes...

this is called sequential turbocharging which removes turbo lag. but this is quite costly and needlessly complicates the system. i believe BMW 335i's turbos work in this fashion. Nowadays manufacturers prefer variable geometry turbos

[inlinesix]

Go & do ur reading on the net.

[Failali]

yes...

this is called sequential turbocharging which removes turbo lag. but this is quite costly and needlessly complicates the system. i believe BMW 335i's turbos work in this fashion. Nowadays manufacturers prefer variable geometry turbos

 

 

what are variable geometry turbos? are they built strategically in the engine block to remove turbo lag?

 

 

[Thespark]

BMW's 3 litre turbocharged petrol found the the 335i uses 2 small turbochargers for each of its 3 cylinders to reduce turbo lag. For small turbo + big turbo application perhaps can look at mercedes benz's new turbodiesel in the new E250 CDI which uses a small turbo in the low rev range and a larger one in the higher rev range.

[Failali]

Oh my god. There u go again.....

 

 

aiyah. i had this theory in mind after reading about twincharging in the Jetta.

But need the engine be reinforced if the original engine block is all aluminium?

 

[Failali]

BMW's 3 litre turbocharged petrol found the the 335i uses 2 small turbochargers for each of its 3 cylinders to reduce turbo lag. For small turbo + big turbo application perhaps can look at mercedes benz's new turbodiesel in the new E250 CDI which uses a small turbo in the low rev range and a larger one in the higher rev range.

 

Diesel engines usually use sequential turbocharging to aid in torque off the line? is the powerband of diesel cars similar to supercharged cars? where the powerband dips after 5000rpm?

 

 

[Cerano]

BMW's 3 litre turbocharged petrol found the the 335i uses 2 small turbochargers for each of its 3 cylinders to reduce turbo lag. For small turbo + big turbo application perhaps can look at mercedes benz's new turbodiesel in the new E250 CDI which uses a small turbo in the low rev range and a larger one in the higher rev range.

 

E250 is CDI?

 

E250 should be turboed petrol not diesel.

[inlinesix]

BMW's 3 litre turbocharged petrol found the the 335i uses 2 small turbochargers for each of its 3 cylinders to reduce turbo lag. For small turbo + big turbo application perhaps can look at mercedes benz's new turbodiesel in the new E250 CDI which uses a small turbo in the low rev range and a larger one in the higher rev range.

BMW 3L turbocharged petrol uses 1 small + 1 big turbo. For diesel, BMW N47 also has widest range of turbo application for the small. For 118d, it use 1 turbo. For 120d/320d/520d, it uses VTG. For 123d, it uses 1 big + 1 small turbo.

[Cerano]

BMW 3L turbocharged petrol uses 1 small + 1 big turbo. For diesel, BMW N47 also has widest range of turbo application for the small. For 118d, it use 1 turbo. For 120d/320d/520d, it uses VTG. For 123d, it uses 1 big + 1 small turbo.

 

so i'm right about the sequential turbos?

[Ithunk]

for turbo the bigger the cc the better i reckon

[Cerano]

for turbo the bigger the cc the better i reckon

 

im not sure if the capacity has anything to do with turboing

 

but one thing is for sure. forced induction be it supercharging or turbo is the way the industry is going

[Cerano]

Diesel engines usually use sequential turbocharging to aid in torque off the line? is the powerband of diesel cars similar to supercharged cars? where the powerband dips after 5000rpm?

 

sequential turbocharged vehicles or variably geometrically charged veh. have a power band similar to those of supercharged veh in the way that both are linear. however, turbos tend to get hotter and they extend to redline

[Failali]

BMW 3L turbocharged petrol uses 1 small + 1 big turbo. For diesel, BMW N47 also has widest range of turbo application for the small. For 118d, it use 1 turbo. For 120d/320d/520d, it uses VTG. For 123d, it uses 1 big + 1 small turbo.

 

 

do you you mind sharing why sequential turbocharging is very complicated? is there alot of wiring to do in the engine bay ?

[Failali]

sequential turbocharged vehicles or variably geometrically charged veh. have a power band similar to those of supercharged veh in the way that both are linear. however, turbos tend to get hotter and they extend to redline

 

 

does it mean reliability issues can come up ? can it be aggravated by the type of ball bearings and material of the blades eg(ceramic) or cast iron?

[Kyojin]

heard of Google?

 

it's not as easy as slapping two turbochargers.

 

do a simple search. a lot of stuff covered out there.

 

[Cerano]

do you you mind sharing why sequential turbocharging is very complicated? is there alot of wiring to do in the engine bay ?

 

err common sense.

 

2 turbos will cost more and be more complex than one.