Technical N54 Phenolic fibre fuel rail gaskets.

MoreBoost

Sergeant
Jul 27, 2017
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People keep saying the cowel is a heat trap like BMW didn’t do aerodynamic testing on these cars...it is not a heat trap. It closes off the top of the bay and forces the air in the bay to exit on the underside of the car. When you remove your cowel, you upset that flow, create more turbulence/drag, and likely cause higher under hood temps.

That all said, I’m also a perpetrator as I have the M3 cowel that doesn’t seal properly against the non M hood, but that lack of sealing surface is on the list of items to fix.

Heat rises. It's a heat trap. With the cowl off you can see the heat haze coming from the bonnet. Especially when you aren't moving and there's no vacuum to draw the heat out.
Surely you aren't going to argue this.
 

MoreBoost

Sergeant
Jul 27, 2017
361
143
0
Ride
335i
People keep saying the cowel is a heat trap like BMW didn’t do aerodynamic testing on these cars...it is not a heat trap. It closes off the top of the bay and forces the air in the bay to exit on the underside of the car. When you remove your cowel, you upset that flow, create more turbulence/drag, and likely cause higher under hood temps.

That all said, I’m also a perpetrator as I have the M3 cowel that doesn’t seal properly against the non M hood, but that lack of sealing surface is on the list of items to fix.

Think you also assume to much on the aerodynamics. The Non M E9x cars create lift on the front end at speed. They are not that well designed. They benefit from a front air dam.
Also removing the cowl allows far more air flow in and out of the bay. Believe it or not ambient air will be cooler than what's found in a running engine bay. It's simple thermodynamics.
 

The Convert

Captain
Jun 4, 2017
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Heat rises. It's a heat trap. With the cowl off you can see the heat haze coming from the bonnet. Especially when you aren't moving and there's no vacuum to draw the heat out.
Surely you aren't going to argue this.
If you’re sitting still, then yes, I agree completely. While moving, I disagree. With all the air entering the engine bay through the front bumper, It’s hitting the engine, mixing with the engine bay air, transferring heat into that cooler air, then moving down and back through the trans tunnel and out the back. Do you see hot air rise out of your cowel area while driving because I don’t.

If someone wants to tape a bunch of strings on the bottom of their windshield and then go driving with and without the cowel, that would be a great way to find out what’s actually happening. In stock form there is low pressure in that area to feed the hvac system. Would be interesting to see what happens in that area without the cowel.
 

martymil

Major General
Sep 6, 2017
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I can tell you one thing driving around town and hwy I can consistently see.lower temps with the modified cowl.

The only thing that cowl was designed for to provide clean air to the cowl filters

Once you put the factory manifold, airbox and wires that usually run there is stuff all air getting through
 
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TiAgAu

Corporal
Nov 18, 2018
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The only thing that cowl was designed for to provide clean air to the cowl filters

This is the only thing stopping me doing the cowl mod. It looks good and all, but say like your VC or OFHG is leaking and would you notice burning oil smell? since the bms filter is just that. Obviously full cowl is sealed off and charcoal in the filter.

Sorry to get off topic. I like the idea with the phenolic spacer definitely doing this when i have access. It's to simple not too.
 
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derekgates

Lieutenant
Feb 23, 2018
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People keep saying the cowel is a heat trap like BMW didn’t do aerodynamic testing on these cars...it is not a heat trap. It closes off the top of the bay and forces the air in the bay to exit on the underside of the car. When you remove your cowel, you upset that flow, create more turbulence/drag, and likely cause higher under hood temps.

That all said, I’m also a perpetrator as I have the M3 cowel that doesn’t seal properly against the non M hood, but that lack of sealing surface is on the list of items to fix.

I am curious how you are going to fix the sealing issues? Did you find a thicker rubber trim?
 

The Convert

Captain
Jun 4, 2017
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I am curious how you are going to fix the sealing issues? Did you find a thicker rubber trim?
I honestly haven’t done any work on it and likely won’t in the foreseeable future. Too many irons in the fire already. One thing too look at would be if the carbon M hoods have the mating ribs, and if so, see if they could put those ribs on a non-M hood.
 

martymil

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I don't use the torque wrench on these, really not that critical.

Just nip them up with a small 1/4 inch ratchet.
 
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martymil

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Just resurrecting this thread, been doing a bit of research and came across the safety data sheet of 98ron fuel.

https://www.google.com/url?sa=t&rct...ON-14945.pdf&usg=AOvVaw3jeHEvwY4_Oa6730ckj-3l

I'm no expert on this but fuel boiling point starts at 37.5c or 100f which is quite low.

In a closed pressurised system the boiling point would be quite higher but still can't see any drawbacks of running the fuel cooler.

Still on the to do list is the Mercedes fuel chiller but that might be a summer project to be able to see real benefits..