Jump to content

What is over boost?


stuarty

Recommended Posts

Over boost is actually a bad thing, when the turbo randomly spikes, I've never really understood it as a sales feature.

That's what I thought Jay. But BMW are marketing the overboost as a good thing!

 

The only thing I can think of is, the the fuelling and ecu allow the car to produce more boost for a short duration of time under hard acceleration, but if it's safe to do that why can't it do so all the time!

Link to comment
Share on other sites

Overboost on newer turbo cars when marketed in the brochures it's basically either a switchable increase in boost pressure or a mapped increase of boost at a certain point depending on gear selection or revs.

Very apt that you should answer that. :D;)
Link to comment
Share on other sites

Overboost on newer turbo cars when marketed in the brochures it's basically either a switchable increase in boost pressure or a mapped increase of boost at a certain point depending on gear selection or revs.

That makes sense! Just noticed your forum name there. Lol.
Link to comment
Share on other sites

R33 GTSTs come with a kind of over boost, it delivers boost in two stages so 0.5bar up to 4000 revs then something like 0.7bar after that - I think having it switchable means when stuck in traffic/around town your car is a bit more drivable on lower boost levels?

Link to comment
Share on other sites

You're all kind of right, more or less.

 

Basically the car will have electronic boost control, so the waste gate will be set to open at say 1 bar under normal conditions. If certain conditions are met (sport mode on, engine oil at right temp, certain throttle threshold reached etc) then the controller will hold the waste gate closed until 1.2 bar, hence the term overboost.

  • Like 2
Link to comment
Share on other sites

I think the new Fiesta ST has overboost. In the states its power is listed as a couple of bhp higher than europe. In the states their rules allow the overboost figure to be the stated power whereas in europe it is not. If I remember correctly the overboost figure is only available for a few seconds at WOT.....

  • Like 1
Link to comment
Share on other sites

Pretty much, yes. Same as with the 911 Turbo/S, you get two power figures and you always need to go on the lower one as the higher one is only ever available briefly.

 

Until they launch a special edition and you can have it all the time ;)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...