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Fyi For M35 Owners With Aftermarket Bov

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Equilibrise Community Regular

Equilibrise

Posted
Posted

I recently discovered something interesting regarding aftermarket BOV's and mentioned it in another post, however I thought more of you guys would read this fresh post and possibly benefit from the finding; that is if you don't already know about it.

It is regarding the turbo flutter which seems to happen a lot in many driving styles and situations. Being an auto they do tend to flutter a bit as we don't always come off throttle completely (not in the way you would in a manual anyway). The flutter sound is created by the turbos impeller 'chopping' up back pressure that is not released by the bov. This is not good for any turbo as it creates opposing forces on the impeller and bearings and would most likely reduce the life of a turbo.

The standard pressure hose going to the bov has a restrictor in it. It is about a third in from the end of the hose. The restrictor reduces about 4mm diameter down to about 1mm and would reduce the pressure sent to the bov to actuate it and therefore, having an aftermarket bov which usually have stiffer spring rates and are harder to open will not open or not open enough except when controlling the accelerator with a bit of gusto.

I replaced the hose with fuel line hose and noticed the difference immediately. I'm not sure how much you guys would notice due to us all having different setups, but I thought it would be worth a shot if it means prolonging the life of your turbo and having a more enjoyable ride.

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Brick Mentor

Brick

Posted
Posted

I did this today, I still have a bit of pigeon noise, but from my short brap around the block it seemed less. It does seem to have smoothed out the stutter it had getting off throttle but until i drive along a 100km/h bit of road i wont know for sure.

DaveM35 Collaborator

DaveM35

Posted
Posted

I checked mine by squeezing all along the hose with pliers and couldn't find a restrictor, hose definitely looks factory. It's an Axis so maybe it's not on every model? Mine hardly stutters since I stiffened up the spring rate, it was heaps softer than the stock one before so I set it as close to the same as I could gauge and it made a big improvement with stuttering.

Just in case anyone else is looking for other ways to possibly improve the feel.

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