EGR, Intake Manifold, Blanking, etc. etc.

tadaska · 02-19-2017, 01:05 AM

I have been thinking of having a walnut blast and a new intake manifold for a while now but decided to look into the blanking option too. And the more videos I watch on it the more confused I feel about it. None of them give any important relevant information. So I here I go with my questions...

I want to understand the whole functionality of the intake manifold before I can make up my mind whether to blank it or not.

From looking at the pictures it has the hole for the EGR valve on it's side, four square holes underneath where the flaps are and another four round holes at the top. Also 4 extra holes if the swirl flaps are removed. And I just learned that it is the latter that gets blanked which made me even more confused.

Can some one explain to me very simply what goes on in the intake manifold and what is the purpose of all those holes? Keep in mind my engine knowledge is less than basic and try not to use technical terms if possible.

Thank you!

Digitalize · 02-19-2017, 05:53 AM

You don't want to blank where the EGR enters the intake, you'll get no air!

Where the EGR enters is the main air intake from the intercooler, 4 of the holes are for outlets in to the cylinder. The swirlflaps holes are a secondary intake, to be honest I'm not entirely sure from where. The last hole when removing the swirl flaps is just a mounting hole, it gets plugged when you blank them.

You can't blank your intake manifold, you can blank the swirl flaps and EGR, EGR will need to be mapped out otherwise it will cause an error.

tadaska · 02-19-2017, 06:09 AM

So blanking the swirl flaps is just plugging the holes that are left after the swirl flaps are removed? I guess that doesn't stop the soot going back to the engine? I am so confused... I take it the EGR valve is where the air and soot get mixed then? I wish some one could explain fully what actually happens in the intake manifold and what do the swirl flaps do etc.

Digitalize · 02-19-2017, 06:37 AM

From what I can tell the swirlflap is another place where exhaust gas is recirculated in to the intake to aid combustion. They create turbulent air to aid combustion at low RPM but once above 2000rpm they're fully open. People blank them as they either get stuck or fall apart and get stuck in to the engine bay. It seems to be more for emissions purposes than fuel economy or performance.

EGR stands for Exhaust Gas Recirculation, it's the main place that the compressed air from the turbo and exhaust gas are mixed. You can blank it off with a smooth pipe but I'm guessing the swirl flap intake will still be mixing some exhaust gas in to the combustion chamber.

tadaska · 02-19-2017, 08:22 AM

I think I know why the manifold has 8 holes, if the youtube videos are to be believed. It's to do with the Variable Intake Manifold stuff. It looks like the round holes go into the cylinder head cover and are a longer path for air to travel into a cylinder. The square holes go into the cylinder head itself and is the shorter way for the air to travel to the cylinders when the flaps are open. Longer way means more torque at low rpm, shorter way means more torque at higher rpm. It looks like it's best to leave the valves in place. Providing they are strong enough and won't break and damage the engine of course.

Digitalize · 02-19-2017, 10:14 AM

I took my swirl flaps out on Friday after being in for 211k, along with the rest of the inlet it was filthy with carbon build up and oil but they didn't show any signs of failing.

I basically did it because I needed glow plugs changed and it's sort of something you may as well do, there's no real downsides, I haven't noticed any difference at low RPM yet but admittedly haven't driven it much. After 2000RPM they're fully open so will be no different.

tadaska · 02-19-2017, 11:42 AM

I'll take the manifold off when I get a chance and see how it looks. I'll make the decision then.

If the EGR is the only way for the soot to get in then removing the vacuum hose off the valve would leave the valve closed. I know in theory EGR reduces mpg and power so cutting it off should make the engine either more powerful or economical or both. But of course in reality our engines weren't designed that way. But has anyone tried doing it?

Digitalize · 02-19-2017, 12:53 PM

In theory yes removing the vacuum hose is the same as replacing it with a blanking tube, but either way it will throw an error on the dash without being mapped out.

I think you are right that there is 1 inlet and 8 outlets, so blanking the EGR should stop all exhaust gas being introduced.

02-19-2017, 01:05 AM	#1
tadaska Major 114 Rep 1,001 Posts Drives: 2006 E90 320D ES Join Date: May 2016 Location: Eastbourne iTrader: (0)	EGR, Intake Manifold, Blanking, etc. etc. I have been thinking of having a walnut blast and a new intake manifold for a while now but decided to look into the blanking option too. And the more videos I watch on it the more confused I feel about it. None of them give any important relevant information. So I here I go with my questions... I want to understand the whole functionality of the intake manifold before I can make up my mind whether to blank it or not. From looking at the pictures it has the hole for the EGR valve on it's side, four square holes underneath where the flaps are and another four round holes at the top. Also 4 extra holes if the swirl flaps are removed. And I just learned that it is the latter that gets blanked which made me even more confused. Can some one explain to me very simply what goes on in the intake manifold and what is the purpose of all those holes? Keep in mind my engine knowledge is less than basic and try not to use technical terms if possible. Thank you!
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02-19-2017, 05:53 AM	#2
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	You don't want to blank where the EGR enters the intake, you'll get no air! Where the EGR enters is the main air intake from the intercooler, 4 of the holes are for outlets in to the cylinder. The swirlflaps holes are a secondary intake, to be honest I'm not entirely sure from where. The last hole when removing the swirl flaps is just a mounting hole, it gets plugged when you blank them. You can't blank your intake manifold, you can blank the swirl flaps and EGR, EGR will need to be mapped out otherwise it will cause an error.
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02-19-2017, 06:09 AM	#3
tadaska Major 114 Rep 1,001 Posts Drives: 2006 E90 320D ES Join Date: May 2016 Location: Eastbourne iTrader: (0)	So blanking the swirl flaps is just plugging the holes that are left after the swirl flaps are removed? I guess that doesn't stop the soot going back to the engine? I am so confused... I take it the EGR valve is where the air and soot get mixed then? I wish some one could explain fully what actually happens in the intake manifold and what do the swirl flaps do etc.
	Appreciate 0 Quote

02-19-2017, 06:37 AM	#4
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	From what I can tell the swirlflap is another place where exhaust gas is recirculated in to the intake to aid combustion. They create turbulent air to aid combustion at low RPM but once above 2000rpm they're fully open. People blank them as they either get stuck or fall apart and get stuck in to the engine bay. It seems to be more for emissions purposes than fuel economy or performance. EGR stands for Exhaust Gas Recirculation, it's the main place that the compressed air from the turbo and exhaust gas are mixed. You can blank it off with a smooth pipe but I'm guessing the swirl flap intake will still be mixing some exhaust gas in to the combustion chamber.
	Appreciate 0 Quote

02-19-2017, 08:22 AM	#5
tadaska Major 114 Rep 1,001 Posts Drives: 2006 E90 320D ES Join Date: May 2016 Location: Eastbourne iTrader: (0)	I think I know why the manifold has 8 holes, if the youtube videos are to be believed. It's to do with the Variable Intake Manifold stuff. It looks like the round holes go into the cylinder head cover and are a longer path for air to travel into a cylinder. The square holes go into the cylinder head itself and is the shorter way for the air to travel to the cylinders when the flaps are open. Longer way means more torque at low rpm, shorter way means more torque at higher rpm. It looks like it's best to leave the valves in place. Providing they are strong enough and won't break and damage the engine of course.
	Appreciate 0 Quote

02-19-2017, 10:14 AM	#6
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	I took my swirl flaps out on Friday after being in for 211k, along with the rest of the inlet it was filthy with carbon build up and oil but they didn't show any signs of failing. I basically did it because I needed glow plugs changed and it's sort of something you may as well do, there's no real downsides, I haven't noticed any difference at low RPM yet but admittedly haven't driven it much. After 2000RPM they're fully open so will be no different.
	Appreciate 0 Quote

02-19-2017, 11:42 AM	#7
tadaska Major 114 Rep 1,001 Posts Drives: 2006 E90 320D ES Join Date: May 2016 Location: Eastbourne iTrader: (0)	I'll take the manifold off when I get a chance and see how it looks. I'll make the decision then. If the EGR is the only way for the soot to get in then removing the vacuum hose off the valve would leave the valve closed. I know in theory EGR reduces mpg and power so cutting it off should make the engine either more powerful or economical or both. But of course in reality our engines weren't designed that way. But has anyone tried doing it?
	Appreciate 0 Quote

02-19-2017, 12:53 PM	#8
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	In theory yes removing the vacuum hose is the same as replacing it with a blanking tube, but either way it will throw an error on the dash without being mapped out. I think you are right that there is 1 inlet and 8 outlets, so blanking the EGR should stop all exhaust gas being introduced.
	Appreciate 0 Quote