Throttle and boost?

[andrewrx7]

To those know, this may have a pretty obvious answer....but do you only get max boost when you have WOT? (i.e. is the amount of boost you generate dependant on the throttle position?)

:confused:

Cheers!

[fro]

No, it\'s not directly related to the throttle position. It\'s more load dependant - you\'ll not get much (if any) boost in 1st gear at half throttle but in 5th you can easily get full boost with half throttle because the engine is under greater load.

[andrewrx7]

Hmmm.... so what determines the load? :confused:

[fro]

Lots of factors

When you\'re accelerating in first gear on a  level road, it\'s quite easy for the engine to push the car along so it won\'t produce much exhaust gas to spin the turbo up.
In fifth gear, up a hill with the same throttle position the engine is under much more load so produces more gas.

This site is pretty handy:

http://auto.howstuffworks.com/turbo.htm

used it the other day to work out how a fridge works (to see if refridgerated trousers were possible)

[fro]

I forgot EGT (exhaust gas temperature)...

under load the exhaust gas will be much hotter

[zevans]

Prolly won\'t get max boost under certain revs either, I would imagine, because again there\'s not enough exhaust coming through to generate that much.

And of course there\'s lag...