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Hi i wonder if anyone could help,ive recently bought and focus st everything great,its just i have a question about the turbo boost gauge,sometimes when i accelerate in 1st and 2nd gear the boost gauge does not pass the 1/4 mark no matter how many revs i give it, and other times it does,it does how ever pass this mark when iam going around 70 mph and i drop down a few gears,has anyone else had a similar problem? is this ment to happen?
 

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Hello this was my question followed by troy45's response which may help

Hi All

Being fairly new to the Turbo world, I think I'm beggining to understand a few things now having read some of you hints and tips.

I read somewhere about holding onto the boost pressure (I think in a forum discussing intercoolers) so having been out for a blast I think I get it.

Q: Looking at the boost guage whilst flooring it in gears 1 to 5 a few times I notice the boost pressure would peak just over 1 bar in gears 1,2 & 3 then drop to 0.5 bar soon after before being at the end of the rev band, however it maintained 1 bar a lot longer in gears 4 & 5.

Is this normal? is this what was being explained in the forum?

Let me know chaps and chapesses

Troy45'5 reply which was great for me

Couple of things going on that you're seeing - first off depending what map you're running there is a degree of torque limiting going on in the lower gears to protect the drivetrain from the bigger torque loads. Also the ECU can see it's torque targets hit then back things off to some extent. Plus if you're running a decent spec map without an uprated intercooler the ECU will back things off if the turbo inlet temps get too high. Dunno if this will happen at this time of year with it being colder?

Also in the lower gears you're more likely to get the engine into the range where the small turbo runs out of puff at higher revs - it reaches the limit of how much air it can pump into the engine and the engine 'uses up boost' rather than having the boost pressure force feeding the engine. Boost is air pressure the engine isn't consuming. You'd need to be seriously shifting to feel the same effect in the higher gears.
 
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