reducing heat in a E32 750 engine room

[shogun]

Q:
Front hood venting?
Message: I was looking at the hood(engine cover) on my spare parts car and was thinking it might be intresting to louver a bit of it and see if it reduced the heat of the 750. Being that German engineering has most of this thought out pretty well, I thought to ask if any one has tried any venting and what the result might be. Lovuers were a hot rod must have of the 50's and one of the local guys still has a press?? Dinan added 3 vents on each side for his Turbo install (intecooler air)and they look good. I think.
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Answers:
The e32 hood doesn't lend itself to Socal custom
Message: Fast & Furious.

Just remove the rear rubber gasket which seals the hood to the forward support for the IHKA blower & windscreen wiper chamber. As you move, suction from the low pressure zone against the windscreen pulls the heat out the back and up/over the top of the car.

It makes a big difference. Also have your exhaust manifolds/down pipes ceramic coated.
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As far as I understand the system and what the German engineers thought of it:
they sealed the system as much as possible, so that no air can escape thru any slots in the hood.
Inside the engine room the air has a kind of pressure from air coming thry the front grill entry, and then the air is pushed to under the car to get out.
If one installs louvers - some are looking very nice, I have seen them on E32 in Germany- the whole system would be not working that good.
Otherwise companies like Alpina or Schnitzer would have installed them too.
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here is a link, they make it
http://www.fredsfab.com/images/ServImages/louver_08wm.jpg
This company is specialized in that.

http://www.fredsfab.com/service_categories.php?id=1

Louvers by Canfield
http://www.frontiernet.net/~dlcanfield/
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"As far as I understand the system and what the German engineers thought of it:
they sealed the system as much as possible, so that no air can escape thru any slots in the hood."

While I agree with you and this might have been a good idea with 6-cylinder engine, my opinion is that with V-engines, there isn't enough air flow through engine bay. When there's more than 50C (120F) in engine bay at constant 50km/h(30mph), there's definetely something wrong when outside temperature is only 20C (68F). Fortunately around here temperatures over 30C (86F) are very rare and winter is long.

Hoses and plastic parts won't survive that for long and as we know, they don't. "What to do" is the question then and frankly, I don't know. I suspect BMW engineers blocked top venting in order to get more (any?) air flow to exhaust manifolds and gearbox, but this is just a guess.

Large scoop on top of hood might help. ;)

(In/out electronic thermometer used for the science part. )

Tuomas
'89 750il 250k (Brand new LAD bombs (Febi) ordered and paid, chistmas time :) )
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Yes, I'm thinking those engineers were too long on the ganja! Prolly the descendants of the messerschmidt team who came up with the Gigant.

If this system works so well, why are many cars coverting to top mounted venting system. Ford Cobra, M3CSL & ALMS race car, Elise & Exige, and many many others.

The available pull of the airstream over the top of the car is far superior to anything happening underneath. Maybe this thinking is why the B12 5.7 has louver panels in the Carbon hood?

================================================== =====

The idea with removing the rear rubber gasket at the rear of the hood seal(partly) is quite interesting.
Plus: Also have your exhaust manifolds/down pipes ceramic coated.

Maybe for some hot climate areas this might be a good idea.

[632 Regal]

I wonder if the thinking was to try and keep the exhaust manifolds cooler without ventalation...wonder how hot they get both ways...this would be an interesting test

[shogun]

That is a good point, Jeff

so you believe the complete sealing at the hood had the idea behind to cool the exhaust manfild cooler?
So then one should also do the other step when removing the seal at the hood:

Also have your exhaust manifolds/down pipes ceramic coated

[632 Regal]

We used to coat headders but it was so they lasted longer and looked cool, I never read anywhere that it helped keep them cooler.


Also have your exhaust manifolds/down pipes ceramic coated

[shogun]

I also posted that on BB and one comment from a guy who is just installing a Chevy Corvette engine in an E32 is:
quote

I'm not sure of removing the rear seal to allow venting, it's always been my understanding that the area at the base of the windshield was a high pressure area. This should put more air into the engine bay- seems like a good idea. The most benefit would be after you park the car, then the heat has somewhere to go.

[winfred]

when i installed the coated headers on my e30 i don't think they put off any more heat then the manifolds did despite the extra surface area and thinner tubing
http://members.cox.net/wdixon27/%20m20%20r%20motor.jpg

[rob101]

I also posted that on BB and one comment from a guy who is just installing a Chevy Corvette engine in an E32 is:
quote

I'm not sure of removing the rear seal to allow venting, it's always been my understanding that the area at the base of the windshield was a high pressure area. This should put more air into the engine bay- seems like a good idea. The most benefit would be after you park the car, then the heat has somewhere to go.
yeah i'd tend to agree with him, for one the discontinuity of the bonnet leading into the windshield is likely to cause an area of recirculation (ie turbulence or an eddy) in that area which would mean it'd be high pressure. don't think it'd go into the engine bay but i don't think you'd get much air coming out from the engine bay.

[shogun]

My friend Reinhard in Germany, the electronic wizzard of E32, develops now for my 750 a system where the aux fan will run after the engine has been switched off till it (engine room) reaches a certain temperature. A temp feeler will be installed in the engine room, and it will switch on the aux fan automatically if the temp exceeds a certain limit.
That will fight the heat in engine room and will be very good for the life of the plastic parts in the V12 engine room.
All will be on a masterboard with all items, this is the layout
http://s71.photobucket.com/albums/i155/shogun_bucket/?action=view&current=Zeitglied_Lueftung.gif

Presently under test run in Germany.

He also developed this iluminated gear shift system

http://img249.auctions.yahoo.co.jp/users/4/4/8/6/soundlabo77-img600x450-1180437815shift.jpg
http://img249.auctions.yahoo.co.jp/users/4/4/8/6/soundlabo77-img600x450-1180437853p1060747.jpg
http://img249.auctions.yahoo.co.jp/users/4/4/8/6/soundlabo77-img600x450-1180438129p1060775.jpg

[bmwrp8]

that aux fan delay thing seems to be helpful but don't you think it'll run down the battery especially in a hot day?? while the engine is not running

[shogun]

don't you think it'll run down the battery especially in a hot day?? while the engine is not running

Has been calculated. Most/many of the 750 have a second battery in the trunk which is for aux equipment and to keep the main battery healthy for starting the engine. There is a separation relay between the 2 batteries.
Usually also there is the parking ventilation which can be operated by timer when engine is off.


Have tested it. The aux fan requires in the low RPM stage 18A, in high RPM 30A. We assume that it needs maybe 10 minutes running of the aux fan after engine has been switched off.
That is quite standard/normal on newer cars with electric fans, that they run for a certain time after the engine has been switched off to cool down the engine/engine room.

[bmwrp8]

I see...never knew some e32 750 has two batteries..wow that'll cost you if you had to replace both:D just imagine how heavy this cars are...planning to trade my e34 for a e32 750 but i'm scared of the maintainance...nice to have that said feature in the e34 though but I guess i'll run down the battery to the point that I might not get it to start

[shogun]

Yes, the maintenance is very expensive for the 750, all is needed twice on the engine.
My Highline has even more complicated stuff:
2 batteries, 1 under rear seat, one in trunk
2 alternators!
2 aircons, 1 for the front, 1 for the rear! The one for the rear sits under the center console in the rear (not the one which is used as armrest and underneath is the cooler box), which has the walnut tray for the Highline glasses.
Passenger seat can be operated by a switch in the center console in the rear, plus many other gimmicks.

[CharlesAFerg]

Yes, the maintenance is very expensive for the 750, all is needed twice on the engine.
My Highline has even more complicated stuff:
2 batteries, 1 under rear seat, one in trunk
2 alternators!
2 aircons, 1 for the front, 1 for the rear! The one for the rear sits under the center console in the rear (not the one which is used as armrest and underneath is the cooler box), which has the walnut tray for the Highline glasses.
Passenger seat can be operated by a switch in the center console in the rear, plus many other gimmicks.

Speaking of your highline, one of these days you should get some more pictures of the interior, engine bay, as well as all of the special "gimicks" as you call them.

[attack eagle]

I also posted that on BB and one comment from a guy who is just installing a Chevy Corvette engine in an E32 is:
quote

I'm not sure of removing the rear seal to allow venting, it's always been my understanding that the area at the base of the windshield was a high pressure area. This should put more air into the engine bay- seems like a good idea. The most benefit would be after you park the car, then the heat has somewhere to go.

He is close to correct. It is a high pressure area and would add lift and drag to the front end when driving, as well as probably reduce cooling effectiveness due to reducing the pressure differential between the highpressure area in front of the car, and the low pressure area of the engine bay. Remember those old cowl induction hoods were designed to take IN air from this area to feed cool air to the carbs, and were sealed to it. They were not to vent heat.
There is also the longer term possibility of distorting any plastics on or near the firewall when the heat vents while stops. I've seen it on several turbo DSMs when an owner removed the rear seal to "vent hot air", though it never occurs when that seal is in place. If you wanted vents, the place to put them would be in the forward 1/2 of the hood, and using a reverse louver.


A good first step to reducing heat in the engine bay, would be to ceramic coat the exhaust headers/manifolds. Unlike "chroming" in the old days, ceramic coatings do a very good job of containing heat within the piping. Coating the up pipes would be a good idea as well. A side benefit is that it might also assist with emissions since the cats would be brought up to temp more quickly. Particularly if your emissions testing seems to be of the "hurry up, sign in, and wait a good while" variety.
Alternatively, if you have cast manifolds, there are 1" header wraps that are easier and less expensive (and uglier), though not quite as effective or maintenance free. Tip: soak em in water overnight, then let them dry till they are damp, but not wet. Then apply. I do not recommend using them on thin walled piping since they do retain moisture and can lead to rusting overtime. I will probably be doing this to my 525 this summer.

Also if not fitted, a simple heatshield bent up from 1/8th sheet aluminum will do wonders in helping reduce heat radiated into the bay. Also something I am looking into.
I would definately try both of the above before adding drag and lift by venting the hood.

[grave77]

well I guess all BMWs vent heat from below, many friends of mine complained when they Stand next to my car and they feel like it's on fire. as for the hood ventilation I once noticed that if you intend to stand still with the engine running then this would make some difference as hot air rises up and builds up more heat, but when the car moves then it's the same. but still Alipna made a nice vents on the hood of the B12 850

[grave77]

I would agree on working with the manifold here, as I have read before that the front air pressure works on cooling the front engine side and the water cooling system has more cooling effect on the the rear engine side, therefore any thing that will drag air up side the engine comp. will mess up with this.

I cannot leave my foot outside the door and throttle the engine .. air comes out there really hot! simply ... I would love to have those infrared meters that senses the heat off hot surfaces.

coating the manifold will reduce heat around 30 degrees only .. that surface is already 240 - 260 degrees, if it goes down to 220 degrees it is still very hot. wrapping them would make more difference I guess. but after all, it's simple physics, the hot air needs to cool down, if you stop that at the front ( manifold ) that will cause the rear exhaust to heat up more and it will rust faster.

[attack eagle]

actually hot exhausts has higher velocity which is a good thing,and if anything hotter exhaust would move the condensation point for water vapor in the exhaust gasses further to the rear, reducing the exposure to condensation in the pipe.

Coatings are to reduce radiant heat, not surface temps, and their purpose simply to get the radiant heat "losses" further downstream where there is airflow, and reduce them in he engine bay to enhance long term durability of plastic and rubber parts.