Alright, I know this sounds stupid, but I've never understood this phrase. Does this mean that if a turbo doesn't engage until 5K, it lags more than one which engages until 3k? Or is is just that when you reach 5k it takes two seconds until you go to 5.1k, or what?! SO CONFUSED!

 

Its generally refered to the delay from when you press the gas to when boost comes on.

 

nope, you are talking Turbo Threshhold

Lag is the time taken to reach 'certain boost level'? once you are above the turbo threshhold rpm.

Most people think turbo threshhold is actually LAG, when it most certainly isn't

 

so i was right, lag is just time it takes to reach 5k rpms or something

 

You don't quite understand yet.

If you are cruising at 5K RPM under light throttle (no boost) and then mash the throttle, turbo lag is the time it takes for your boost pressure to rise to the maximum level. Say it takes 1 second before you hit your maximum boost of 15 psi. That is turbo lag. It doesn't have much to do with engine RPM.

If you mash the throttle at 1000 RPM, you won't get any boost. But if you keep your foot on the floor, there will be some RPM at which you reach your maximum boost. That is NOT turbo lag, but rather the threshold thing that HWO is talking about. Again, this is NOT turbo lag.

-Max

 

wow, no wonder I never understood what people were talking about when they mentioned lag. I allways thought it was from NA to when the turbo "began" to kick in.

 

you will find people talking about their turbo being laggy, when in fact they dont even know what turbo lag is

 

See what I mean? The phrase is easily tossed around but no one knows what it correctly means! BTW, does anyone have any videos of their car with turbo lag? Just to see it and understand it... Thanks!

 

It is very easy to experience... just follow the procedure in the second paragraph of my last post. Cruise at 5000 RPM (no boost) and then stomp on the gas pedal. The tme between the stomp and reaching maximum boost is the lag. Do you have a boost gauge? That will help illustrate what you are experiencing.

Generally, though, I agree that the term is used loosely. Car magazines often use "lag" to describe when the boost comes in (threshold). The two things are also somewhat related -- turbos with a low threshold often have less lag than turbos with a high threshold. It is also hard to quantify, and thus compare from turbo to turbo. Lag changes with the weather, RPM, etc.

-Max