Very nice write-up. Should be helpful to most.
I disagree with this stement:
Originally Posted by 03OrangeSVT
Turbo LAG... modern turbos do not have turbo lag, older ones did the newer ones do not. What alot of people PERCIEVE as lag is the way a turbo comes on, as soon as you hit the throttle you can see boost on the boost gauge so that alone tells you there is no lag.. BUT turbos hit so hard they feel like it all comes at once and most people dont even notice that the boost starts building immediatly.
When most refer to lag, they are talking about
: a) when the turbo begins to spool and, b) how long does it take to reach full boost.
a) Can be many different places in the rpm range depending on what mods are done and the engine. Cams, free flowing exhaust, downpipe size, exhaust housing size, all contribute to spool characteristics.
b) It is a fact that some turbos do take longer to spool. Yes, you are correct that as soon as a load is placed on the engine and more exhaust gas flows, the turbo begins to spool as it comes out of vacuum. Some of the larger turbos can take 1000's of rpms to reach full boost, where as some of the smaller turbos with lighter wheel configurations take only 100's of rpms. The trade off being top end power and low end torque.