Driving with the engine hood partly open

One of my winter projects is to install an actuator in the engine compartment, so I can partly open my engine hood from the driver's seat. I've been driving around with my engine hood propped open five inches and I like how much it cools the upper part of the engine. I'm not sure it has any impact on oil temperatures, but I'm positive it allows more cool air to circulate around the fan and air cleaners.
With the hood propped open I can easily rest my hand on the fan shroud, throttle bodies, alternator, etc., after a spirited drive. That's something I can't do after a 'closed hood' drive.
Presently, I'm trying to figure out which actuator to purchase-mainly how many pounds of force will I need to open the hood six inches at 70 mph. The actuators come in a range of force/pounds-from 8 to 1000.
I'm guessing that 150-200 force pounds would do the trick. What do you guys think? Any idea how much pressure there would be on the hood at 70?

Do/would extra louvers in the hood help at all?

Why not just install an oil cooler?

Not meaning to insult you at all, Ron, but I think the idea of using a propped open lid sucks.

I'd be looking at finding a way to pipe cool air into the engine compartment with ducting , maybe from the fron of one of the rear wheel wells or from under the car with a means to screen the opening wherever it was. Most likely I'd be wanting to duct right to the fan opening in the front of the tin.

Without ducting I'd look to some way to create openings in the tin or the compartment walls to let air in.

I saw you describe that your engine tin gets so hot that you can't rest your hand on it. Could one of the heater output pipes be disconnected under the car so heat goes to the engine tin instead of to your tootsies? There's tubing under the car that feeds your heat into the cockpit - maybe one is cut or disconected or something? If you had one working and one not working you'd still get heat in the car.

sounds very knight-Rider-ish. :)


you could do this with an cylinder actuator (you can get them at princess auto). a small one with an appropriate stroke/strength.

i'd have to agree with focusing on getting cold air into the compartment instead (as much as i love things like this)

A partially-open hood may mask the symptoms, but won't fix the problem. A thorough inspection with the car on a rack would be a good place to start. To me, it makes more sense to invest the time and money into a fix, not a hood actuator. There are lots of folks on here with decades of experience. Snap some pics and post them.

My old Fiat-Abarth's used to be equipped with a means to hold the hood open while driving,however they were water cooled and had their radiators in the rear next to the engine. It supposedly also improved their aerodynamics, but you couldn't prove it by me. Of course they were only 750c.c.'s.

More like a leaf vac's they draw air like crazy.

I was only planning to line the wheel wells as rock guards liners but they evolved in carboard form .

I tranfered that to nylon sheet stock. I got from MCmaster Karr

I had to add rabbit cage baskets in the area under the doors just forward of the rear wheels to keep the leaves out in the fall.. But they do help. You would never notice them unless you put the car on a lift..

I simply glued them in with urethane windhield sealer and used gorilla tape to hold them in place while it sets up. diddo with the baskets.. Im runnining a 1750ish size engine witha T-4 oil cooler in behind the doghouse.. all this was done when i put the milage motor in.. it has never over heated sence

Ron Scribed: "Presently, I'm trying to figure out which actuator to purchase-mainly how many pounds of force will I need to open the hood six inches at 70 mph. The actuators come in a range of force/pounds-from 8 to 1000.
I'm guessing that 150-200 force pounds would do the trick. What do you guys think? Any idea how much pressure there would be on the hood at 70?"

OK, I've been thinking about this, too, and to heck with all you'se party poopers.

A couple of things to consider: (1.) The torque arm of the cover is only about 16 inches or so. I wouldn't think the force multiplier would be too much to worry about. (2.) The air flow downforce at that part of the body shouldn't be too great until you raise the rear lip of the cover above the level of the rear lip of the rear cowl, where it gets more directly into the flow. If you keep it horizontal or below, the force shouldn't exceed your 150-200 force pounds. In fact, I would bet it would be less than that.

I have a power window actuator from Specialty Power Windows that I might use. It is cable driven, can raise/lower the end about 20 inches, total, and should be able to tolerate 75-80 force pounds, depending on where it's mounted from the pivot point of the cover.

Another alternative would be the lever operated GM style actuators, although I haven't looked closely at one to figure out how to mount it. I would anticipate mounting mine on one side of the cover, but that might be in the way of other things, The GM lever-style (I think they were used on Jeep Grand Wagoneers, too) might allow mounting towards the firewall, a bit more out of the way and still provide good leverage to lift/hold the cover.

Either cable or lever versions can be found in most junk yards and they only get about $15 for them around here.

I anticipated that it would be the sole cover opener so it would open all the way up for usual access, or could be stopped/reversed at any partially open point.

Hope this gives you some ideas. Sorry........fluid dynamics and air flow calcs were never my strong suit. I'm afraid I would have to cobble something up, try it out and tweak.

gn

I ran a 4" al. flex duct from the fan inlet to under the pass. side b-pillar. I guess it helps some, but no way of knowing for sure. Haven't had any overheating problems. I have an Empi inlet screen and the duct is screened to keep crap out of the fan.
A new guy who joined in for the Pumpkin Run, Todd El-Taher has an cockpit controlled actuator on his rear lid. Don't know what model.
Of course I can't find any pics, but it was about a 6 or 8" long cylinder from what I could see and was mounted vertically where the latch mechanism would normally be.
~WB

why not fix the problem causing the over heat in the first place? Problems usually don't get better while you are dealing with symptoms..I am just sayin'..............there are thousands of these cars out and about running with the lid down.....

Ken Vila has one on his car and it was pretty cool, no pun intended! Write to him and I'm sure he will provide you with all the details.

https://www.speedsterowners.com/files/thmblist.asp?sf=/WIKD356

Maybe Ron just thinks it looks cool?

You would be surprised what doing this upgrade to the deck lid and a couple of wheel well intake openings will do for cooling. ~Alan

Seriously- what's the big deal with just popping your hood? I've done it, and it's not like it flops around back there. If you don't have a luggage rack, you're golden.

Holey moley, I never said I had an overheating problem.
I originally popped open the hood to cool the fuel pressure regulator, which was getting hot and vapor locking. The fuel pressure regulator has just has been moved out of the engine bay, so I no longer need to have the hood propped open, because my car does not overheat. The car has a large oil cooler and EVERYTHING is attached and working as it should.
I want advice on foot/pounds of air pressure, so I can order the correct actuator, not whether it's a good idea. I like it and I like the idea that I can hit a switch and open the engine hood to give the fan and throttle bodies some extra air when cruising along on the highway at 75 mph on a hot, summer day.
Thanks for the info, Gordon. I never considered buying an actuator that could fully open the hood. Instead of a six inch stroke I could go with something in the 18 inch range.
Here's a link to the six inch actuators http://www.firgelliauto.com/default.php?cPath=74

Hi Ron,

Sorry, I guess I misunderstood your post. You said that you couldn't put your hand on parts of the engine after driving with the hood closed, but you could after driving with the hood open. Sounds kind of like overheating to me, eh?

Ron:

Got to look at mine today, and it has a Nippon Denso motor so I'm thinking it came from a Toyota (probably) or Honda (maybe). I got it from Peter McEwan who is not available for information. It has a coil-cable feeding a lift which slides up and down an upright support. Mount that support near the hinge with a Heim joint connection and it should be able to handle the load, depending on the connecting link used. Put in a power window rocker switch and you're done.

Gn

If your determined to do a lid motor .At least put it at the hinge end with a head light door type arangemet so it will work like a air ram when open.. use a porsche air flap switch and it opens at 45 or 50 automaticly

This situation is very common in early bugs with big motors. Dual carburetors and the doghouse fan can use air faster than the openings in the engine compartment can let it in and this creates a negative air pressure situation. The solution (at least one where you don't have to drive around with the engine lid partly up) is to open up the engine compartment so more air can get in. Holes and ducting to the front breast plate or leaving it off, holes in the side walls of the engine compartment (the bug guys call them "Weber windows" as it makes tuning, and jet and plug changing easier) and modifying the engine lid for more air intake (as Alan Merklin showed) are all ways to get more air to the motor. A simple before and after test (as well as a noticeable drop in oil and head temps) will tell if your efforts are successful; take a long piece of clear aquarium tubing , fasten one end to the coil area and the other end goes in a clear glass of water held by a friend in the passenger seat. At speed it will be obvious when there is more air in the engine compartment. The only concern with leaving the front breast plate off is if a plastic bag or rag gets sucked into the cooling fan. A screened inlet ducted from under the car to the fan intake area (such as Bill suggested) would be more trouble free.

Tom- Putting an extra oil cooler on it is treating the symptom and not the cause, at highway speeds you will have nice cool oil but the heads will still be happily cooking themselves into oblivion. The problem is the heads (and to a lesser extent the cylinders) aren't getting enough cooling air; hence the high oil temps. If you took a car that has high oil temps at speed and mount a good cylinder head temp gauge I'll bet you lunch that after mounting the extra cooler, head temps would still be skyrocketing. High head temps causes faster guide wear and loosening, stretched and broken exhaust valves and seats losing their press fit. If left long enough heads can be unfixable (is that a word?).

Another cause of VW motors overheating at highway speeds is leaving off the bottom "sled tins". I've been told at speed the pressure of the layer of air under the car is as much as 2lbs higher than the air exiting the bottom of the motor. The sled tins exit the air horizontally behind the motor (and away from the car), allowing it to join the under car air stream easily. Without the sled tins the air exits straight down, hitting the under car stream at a right angle, not able to join it efficiently. This causes turbulence and a back up of air around the heads and cylinders, which doesn't remove heat as quickly as it should. They also keep the under car air from over cooling the bottoms of the cylinders and thermostat (which would stay closed way more , if not all of the time).

You would think the Carrera louvers in some engine lids would help, but apparently they do the opposite and suck air out of the engine compartment. The air flows over the raised portion of the louver and creates negative air pressure, taking more out instead of letting it in. This is a good thing if there is an adequate supply of air to start with, but if the motor isn't getting enough air it only makes the situation worse.

Bill- the aquarium tubing manometer (I think that's what it's called...) will tell you if your ducting is working; I'd like to hear your results. And Ron, I agree with Jim; if you can't touch the fan shroud after a spirited run and letting in air by opening the deck lid makes a difference, it's getting hot. What happens if your actuator malfunctions? I think you're attacking this from the wrong angle.

Forgot one other thing I did long ago. I run a 356 pulley on the alternator. It's smaller and spins the fan 10-11% faster IIRC. Good to have a welded balanced fan with this. It also makes great air volume through the heater boxes.

~WB

Can you guys drive your speedsters at 70/75 mph in hot weather (85/90 degrees), then stop, pop the engine hood and rest your hand on the shroud or alternator? If you can then my IM is running too hot.

I doubt it. My oil cap gets pretty hot to the touch too but the dipstick reads 190-200.

That's because 180 deg (perfect for oil) is WAY too hot to touch. The engine is made of metal, and it's air-cooled-- it's gonna' heat-soak and be too hot to touch.

I picked up my IM today from Henry's. I drove the 60 miles home with the engine hood closed. The outside temperature was 32 to 34 degrees F. When I arrived home I quickly grabbed my new digital temperature gun and took some readings. My Gene Berg sump showed 170 F (dash gauge showed roughly 150/160) and the heads showed 280, while my CHT dash gauge showed a shade under 300.