Cutting and gutting dpf.

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Cutting and gutting dpf.

Post by Knubbsael » Mon Jun 26, 2017 1:07 pm

Hello bmw lovers. first of all sorry for bad English i am from sweden 😀
But my question is not how to open it thats obvious.
what ive heard is that catalysator and dpf is found in the same round muffler looking box.
ive seen People empty the whole box.
my question is isnt it better to keep the cat part to keep a small amount of back pressure to stop the turbo from spinning with out oil when you stop engine?
if this writing doesnt make any sense let me know

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Re: Cutting and gutting dpf.

Post by jonners » Mon Jun 26, 2017 6:58 pm

You will need a remap if you do remove the contents of the DPF. Surely this can assist with the spin up of the Turbo and Oil etc...?
2011 E82 118D Sport Coupe - Black with Orange Seats

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Re: Cutting and gutting dpf.

Post by Knubbsael » Tue Jun 27, 2017 5:38 am

Hi the spin up and remap is irrelevant in my question. question is the spin "down" once you stop engine the turbo Will keep spinning for maybe a minute and since the engine is stopped the oil circulation is stopped as well and the turbo Will keep spinning with no oil for a moment.
If id spare the catalytic part there Will be a slight "resistance" aka back pressure to prevent the turbo from spinning to many roatations after engine is killed.

Any proffesional opinion ? cheers

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Re: Cutting and gutting dpf.

Post by jason@bwchiptune » Tue Jul 25, 2017 8:17 pm

1st if you remove the dpf you will gain around 8-10bhp top end but loose lower end torque
Lower end torque is felt more and needed
If you keep the cat side it will help

There is no need to remove the dpf on bmw cars to try and get more power
If it's remapped well it will still make good gains with the dpf still fitted

If you look at the size of the dpf on a 123d 204bhp which tunes to 250bhp or 120d 177bhp which tunes to 225bhp dpf then compare it to a 335d dpf 286bhp which tunes to 350-360bhp all still with the dpf still fitted

As for the turbo still spinning
When you turn the engine of at idle they do stop spinning in seconds even if the dpf and cat is removed

You would need to hold it revving at 4000rpm then turn the ignition off for it to spin for a lot longer

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