Vented hood mod for E34

[ktteoh]

folks, has anyone done this before either on existing original hood or hooded replacements?

what are the best options?

what are the cons (engine bay gets rusty easily, wet electronics etc?)

[AngryPopTart]

Define vented. Do you simply want to vent more hot air or do you want to take in more cold air? Best options for what? I don't think adding vents will significantly change how wet the engine compartment gets. It gets wet in rainy weather even without additional vents, scoops, ducts, what-have-you.

If you're toying with the idea of some form of cold-air-induction, just see what others have done... which is essentially, leaving it alone because it's already tuned, unlike your neighbors compact econo-car.

[ktteoh]

yes, shogun's assumption is what i wanted - a cooler engine bay thru getting rid of the trapped hot air.

I assume he wants to get the engine room more cooled as he lives in Malaysia.
Mt theory is:
BMW designed the system in such a way that the engine room is almost completely enclosed, and the air is forced by the fan into the engine room, cooling the engine and then it should pass out under the car to also cool the transmission or the manual gear.
That is why the also installed the tight sealing under the hood.
If you install vents, air would come out on top (maybe) and with the effect that the tranny is not cooled enough.
Easiest to try this is to remove the rubber sealing between hood and chassis, so air will have space to leave between hoof and chassis, mainly in the area where the windshield is.
I have seen some E32 with louvers, but that is more cosmetics and not effective. Even high powered Alpina cars never had this or needed it.

[attack eagle]

remember unless you have something (like a big louver) sticking up in front to induce a low pressure area about mid hood,you will not get air flowing OUT of the engine bay at speed.
front edge and the rear edge are both highpressure zones

[shogun]

I assume he wants to get the engine room more cooled as he lives in Malaysia.
Mt theory is:
BMW designed the system in such a way that the engine room is almost completely enclosed, and the air is forced by the fan into the engine room, cooling the engine and then it should pass out under the car to also cool the transmission or the manual gear.
That is why the also installed the tight sealing under the hood.
If you install vents, air would come out on top (maybe) and with the effect that the tranny is not cooled enough.
Easiest to try this is to remove the rubber sealing between hood and chassis, so air will have space to leave between hoof and chassis, mainly in the area where the windshield is.
I have seen some E32 with louvers, but that is more cosmetics and not effective. Even high powered Alpina cars never had this or needed it.

[Ferret]

instead configure the fan (or have it configured) to run based on temp even if the engine is off. that will give you some cooling when not in motion after shutdown, when running, if you still have a mechanical fan, there is no need for additional cooling airflow... and make sure you have your underhood pad still in place.

It's routinely 110 here and i have yet to discover anyone who really needs a hood vent...

+1 on this

If you're any good with electrics it might be worth setting up a split charge type system with a second battery (if you're worried about the primary battery discharging) and then have a system that runs the A/C fan for 15-20 minutes after you pull the key out of the ignition - or until the temp drops sufficiently.

[attack eagle]

yep, that only works when parked (and possibly off). Won't work in motion, because there is nothing to uinduce oiair flow out form under the hood, in fact it might negatively impact cooling as it would reduce the pressure differential across the radiator.

If you have any plastics you don't want to get damaged, do nto removethe rear hood seal.

I have seen many DSMs who think it will help, and wind up warping plastics
instead of helping.

instead configure the fan (or have it configured) to run based on temp even if the engine is off. that will give you some cooling when not in motion after shutdown, when running, if you still have a mechanical fan, there is no need for additional cooling airflow... and make sure you have your underhood pad still in place.

It's routinely 110 here and i have yet to discover anyone who really needs a hood vent...

[Jon K]

Hood vents look ricey

[Incantation]

con - your car doesn't need it so it looks about as gay as having an m-badge on a non m-car

[bubba966]

If you want to lessen the underhood temps get your exhaust manifolds ceramic coated. That should drop your underhood temps by a good 60 degrees.

And as others have said, venting an E34 hood doesn't work to reduce underhood temps.