why do turbos lag

[MRJDM]

i know that a turbo forces air into the engine. so why is there lag?

[fueltank]

Turbo lag refers to a short delay before the turbocharger develops sufficient boost.

it happens when the impeller and turbine wheels are not spinning fast enough. it takes time for the exhaust gases to bring the turbocharger up to operating speed.

[MRJDM]

thanks fueltank that makes sense.
someone told me that the reason turbos lagged was because the turbos have to fill the intercooler with with compressed air. any truth in that.

[fueltank]

yes but before it can start filling it with compressed air, the turbo has to actually start spinning fast enough to start compressing.

[wynode]

Bigger the turbo, the more exhaust gasses you require to spin the turbine.

[**Ghost**]

and from how i understand it...turbo cars feel slow when "lagging" cos they have to run lower CR right?

[wynode]

Throttle response is less because you have to wait for the turbo to spool up.

[pornstar]

so many myths...

[Morkz]

should go to www.howstuffworks.com they got lots of cool shit there, everything is explained very simply with diagrams :thumbsup:

[A'PEXi]

thats what twin turbo's are for :D smaller turbo for low rpm

[fueltank]

[QUOTE="ALOL...then how come my turbo kicks in earlier than a GTR?

[bumthology]

cos u have a small one
eheh

[wynode]

thats what twin turbo's are for :D smaller turbo for low rpm

Actually thats what sequential turbos are for

[fueltank]

thats what twin turbo's are for :D smaller turbo for low rpm

Actually thats what sequential turbos are for
TT Supra's do run sequentially.
Same with the B4 Liberty.

It's just a name.

[A'PEXi]

thats what twin turbo's are for :D smaller turbo for low rpm

Actually thats what sequential turbos are for
TT Supra's do run sequentially.
Same with the B4 Liberty.

It's just a name.

you still have 2 turbo's in a sequential yeh?

[fueltank]

yes they don't spool up at the same time.
and suprisingly, they are both the same sized turbo!

[wynode]

THey are?

[fueltank]

THey are?
yes they are.

[Weq]

lag is commonly referred to the period of time when a turbo car feels slow.. while making alot of induction noise... lol

Then it comes in in a woosh of fury as the compressed air fights it way outa the intercooler into the intake manifold. U can think of NA cars as having inifinate lag.

Large intercools, badly designed charging piping (to many bends, thickness etc) turbo exhaust side size and engine capacity all contribute to 'lag' factors.

[wynode]

U can think of NA cars as having inifinate lag.


Errr I don't think so Tim :P.......not sure what you're getting at there!

[poid]

lag nowadays seems to refer to how long it takes to come on boost (ie, the turbo comes on at 4000rpm, so there is lag up to 4000rpm), but it used to refer to time it takes from when you hit the throttle to when the car responds to it. This is what i still understand it to mean as well.

So with NA, you have snappy throttle response. With turbo's there is generally a lag between when you mash the accelerator and when you see boost. This can be virtually eliminated though if you want a nice street car with near instant response. The WRX if i remember right used to have a huge amount of lag until Subaru cured it in one of the updates/facelifts.

Many of the factors have been listed that contribute to it, however there are others such as compression ratio that havent been mentioned

[wynode]

used to refer to time it takes from when you hit the throttle to when the car responds to it

Thats my take.