The area in gray, not the long but the vertical sheet metal which is next to the battery. Just on the other side is the upper wheel well. I was looking at installing electric fans on each side. I would not remove all the area just a 9" circle. I would weld in some extra support but aren't sure how important that area is.

*** The picture is for reference only not the my project ***

Engine bay sheet metal

I don't think you'd hurt the structure much, but I'd think you'd lose some targa bar rollover protection effectiveness. The bigger risk is there are probably some people who would keel haul you for doing it to a real six.

The car in the picture is just an example no my car



Any other opinions on the subject?

Are you having cooling issues?

Do you think you really need extra fans?

By opening up that area you will allow a lot of water and dirt from the road into the engine compartment.

Why not do fans on the engine grill like on Howards car?

what's the purpose?

But the short answer is, No it's not structural, cut away.

I am looking at ways to vent the engine bay because the airs natural flow is up through the engine grill and with the top off the hot air is drawn into the cab. I want seal off the engine grill and vent the hot air out the sides. The fans on the engine grill work against natural flow while driving. I would like to also look at finding an air deflector to help channel the air through the engine grill vent in a rear direction not up and over the targa bar. If I can find something that would fit over the engine bay grill that would work as well.

Do you intend to keep an air-cooled engine? If so, sealing the top engine lid grill and exhausting air with fans through the fender wells will result in no airflow for the engine cooling fan. You will have three fans fighting for air with no inlet.

I guess I don't really understand the problem with the stock arrangement. The engine cooling fan draws air into the engine compartment through the engine lid grill. While the engine is running this airflow is always into the engine compartment and through the engine. This airflow picks up the heat that is radiated or conducted into the upper engine compartment before it is forced through the engine to cool the oil cooler, heads and cylinders. It then exits the bottom of the engine. The only time air naturally flows in the opposite direction, up through the grill, is when the engine is not running, and natural convection causes hot air to rise.

Do you still have the rubber deflectors on the bottom of the car? These cause a low pressure area and actually suck air from the top to the bottom. I would think that yours might be missing causing the heat to enter the cabin.

Just a guess...

The engine conpartment is a low pressure area due to the engine fan sucking tons of air. If the stock tin and rubber sealing bits are installed the fan pulls air thru the grill off the low pressure area behind the rear window.

Cutting holes for fans, hmmm, I think the fans couldn't keep up with anything and would disturb the engine cooling. Also all the road dirt off the tires would end up clogging the fans.

If you want more cooling go to a GT style engine grill as it let more air in.

Try this for a test:
Drive around on the freeway until the engine gets hot, then pop the engine lid. Wow, oil temps drop 10F atleast. More air in plus the engine lid distrubs the airflow over the targa top so there is a bigger low pressure area at the engine bay so air can flow in.

Also if you have the raintray installed remove it during the summer.

Take a close look at his avatar.. looks like a big V8. Since it's water cooled, I don't see why the engine compartment needs venting at all.. just plumb in a source of cool intake air and seal off the lid.

"Try this for a test:
Drive around on the freeway until the engine gets hot, then pop the engine lid. Wow, oil temps drop 10F atleast. More air in plus the engine lid distrubs the airflow over the targa top so there is a bigger low pressure area at the engine bay so air can flow in."

I run I GT lid and a front cooler, but I am always looking for extra "insurance". Does interupting the airflow over the targa bar really help that much? If so, why couldn't I make a small lip that attaches to the ski/baki rack holes on the underside of the targa bar? It would hardly be noticable - just enough to interrupt the air flow.

Sorry for the hijack - but I am really interested in this.....

I looked at you car (like everyone else ) at Slit's flesh roast. Didn't get a chance to talk to you.

The extra heat you mentioned with the top off happens. Mine is that way too. It's like the heat from the rad. I can feel it on my arm out the window (vents out the wheel wells like yours).

They make fans the push or pull depending on your needs. I'm thinking of a GT style engine grill to open up the air flow better. The cross sectional area of the air intake (the bottom of the engine) is larger than the exaust cross section area (engine lid). By evening them out with a GT lid, it should speed up the air exchange, which helps with cooling. I'd be worried about trapped heat in the bay if you close the top compleatly even with your opened up trunk/engine bay. It might even be another reason for the heat wafting....the heat builds in the trunk and rolls forward causeing it to come over the targa bar as opposed to in a stock engine bay where it dosen't have a chance to build as much. The only way to know for sure is to measure temps at the top of the bar against a "stock" V8 car. By closing off the engine grill and putting a fan in the area you mentioned will only lower temps in the bottom area of the engine bay and only the bottom of the engine. Cool air flow to the carb and intake builds HP. Getting it too hot only boils the gas making measurment within the carb harder. Unless your planning a cold air intake and hood to keep the carb and intake manifold cooler you might be looking for trouble.

Having access to a wind tunnel where you could introduce smoke into the trunk/engine areas while the car is a "speed" would answer some of these questions.

Oh, yes... That awesome machine... I too often forget who has what car.

With no trunk floor whatsoever, I suspect that you'll get quite a bit of airflow around your engine even with a sealed engine lid. Only way to know for sure is to try it and see. 10 minutes and some duct tape should tell you all you need to know. (oh, and a thermometer with a remote display)

John,

I had a simlar question in regards to packaging my Intercoolers

Given /6 oil tanks are mounted in the fender with two 3" or 4" holes the 9" shouldn't be a structural problem. Mounting fans to exhaust heat in engine compartments is not uncommon. What temp is it at and what are you trying to achieve? Sounds like you are trying to keep the heat out of the passenger compartment with the top down so maybe flow is the bigger issue...

I am not having any engine cooling issues at all, In 100 degree weather if I leave my fans on it will still draw down below 180. I get some heat over the targa bar and in hot weather who wants that?
I did drive the car for a short time without the engine lid and I didn't seem to feel much heat over the targa bar. I don't have the lower air deflectors in the engine bay and I should look into trying that. With the lid closed off my intake air temps often get over 160 and thats no good at all. I was looking at putting a long scoop like cover that would still vent but at the back edge of the engine lid grill, with that I could install some fans to push up and out of the engine bay. SBC engines like most like a cool air charge so looking at that is important. I think conventional engines get air via the radiator and other sources which helps cool the intake and exhaust. In this case an exit is needed. I also like the idea of a small deflector under the targa bar as stated using the ski rack fasteners. You know how it is, try a lot of things and find out what works. I'll tell ya next year I will have AC for sure. My cab is heavily insulated at the fire wall and I don't get much heat at all. Even when my intake temps were in the high 160s I could not feel much heat on the material. I'll keep screwing around with the suggestion and see what comes of it.
I have a big alternator (150 amp) but running to many fans can load down your electrical system. My Twin turbo RX7 had 5 fans and my alternator didn't like that much.

Are you saying that the heat from the engine bay is going against the wind and sucking into your cabin? Because the heat from your radiator exiting out the wheels geting sucked into your cabin is much more likely to happen.

Put those $5 plastic pieces under your car.. They really work wonders for cooling the exhaust and getting good airflow around your engine. As for cold/fresh air for the intake, A simple tunnel ram is your best bet...

As for closing off the engine grill to keep the heat out....

I would think that a guy looking for pure drive-ability like you, should be looking at a full body (front suspension and rear drivetrain at least) underbody... Add scoops for under, vents out the back, louvers and fans out the engine lid, and you'll have a super efficient very clean, VERY stable car, especially at high speeds... I'd guess 2mpg more.. WAY more control on the track (im talking way way more...) and a much cooler ride....


This is my plan... A removable underbody. As for the suspension, You can only box it in so much. Dzuts fasteners for easy removal...

Its on my list for next year.

Andrew

Andrew,
Thats an ambitious plain to build an smooth under-body, I like it
The air is really coming from the engine lid/bay. I can reach just over the front edge of the bar and feel the heat swirling around. I had different mufflers/pipes and could also smell the exhaust at over 40 mph. You have some nice ideas, I'm sure to look into them. The smooth under-body is appealing, given the 914s aerodynamics.

Great ideas

Odd..

With my hood vent, I can reach my hand up and feel the heat from the radiator... Its about 100deg.. on an 85 day... and I cant feel it in the cab... so im not worried about it.. Besides I have a sweet idea for removable a/c...

Ice cooled... (heck yes!!) In place of centerconsole for me.. Could be placed on the pass floor, moveable vents, and powered by the lighter... Place some ice packs in it, and turn on the fan... Bam, cold ac for an hour! Keep a igloo for extra ice... No power draggers or added weight for the track!!!

im rambling.

Andrew,
Politicians ramble, Your thinking out-loud

lol

thanks... I got some good thoughts sometimes..

FYI.. my heater will be my oil cooler on under my cowl vent with ducts to the factory controls with a fan..

Oops! Didn't notice the V8. Forget what I said. Does not apply. Obviously.