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I am making an active hood vent to extract the heat from the turbos.
Active.
The whole thing, including the 90 degree Gurney flap will close and form a flat surface 2 minutes after I shut the engine off.
They will open 30 seconds after the engine starts running.
I selected the placement based on the best low pressure zones above the turbo+manifold assembly for best heat extraction.
Final shape and placement will take some tweaking, but I am excite.
Teacher: "Four crows are on the fence. The farmer shoots one. How many are left?"
Little Johnny: "None."
Teacher: "Listen carefully: Four crows are on the fence. The farmer shoots one. How many are left?"
Little Johnny: "None."
Teacher: "Can you explain that answer?"
Little Johnny: "One is shot, the others fly away. There are none left."
Teacher: "Well, that isn't the correct answer, but I like the way you think."
Little Johnny: "Teacher, can I ask a question?"
Teacher: "Sure."
Little Johnny: "There are three women in the ice cream parlor. One is licking, one is biting and one is sucking her ice cream cone. Which one is married?"
Teacher: "The one sucking the cone."
Little Johnny: "No. The one with the wedding ring on, but I like the way you think."
I am serious.
Seriously, the hood has curves. Not flat.
Louver frame will distort the curved hood surface.
So....
It's just a matter of duplicating the hood surface and transferring the relevant curvatures on the louver frame.
That way, I can mount everything without any hardware showing on the hood surface.
Here is the proof of concept - trial fit - I have too much time on my hands to play with foamboard doodad...
The frame will be inserted in the hood, but obviously won't be that tall in the aluminum final version. Foamboard is kinda flimsy, and I thought I could trim it to whatever is needed...
Note how the frame follows the hood's contour.
That way, it won't distort the aluminum surface of the hood when secured in place.
Now, I have several options for actuating this louver system...
I could use a solenoid, but the action is too fast, and could cause damage in the long run.
There is the stepper motor + control board option, too. I am told that would not last too long in the underhood environment.
Looks like I will have to use a servo motor and some sort of a controller.
Joe, I really could use your input in that department.
How about a vacuum actuator/dashpot? They're very commonly used for air conditioning and heating flapper doors in cars. They come in many sizes and shapes
Now, I have several options for actuating this louver system...
I could use a solenoid, but the action is too fast, and could cause damage in the long run.
There is the stepper motor + control board option, too. I am told that would not last too long in the underhood environment.
Looks like I will have to use a servo motor and some sort of a controller.
Joe, I really could use your input in that department.
I don't think you have to worry about waterproof under the hood. Most stuff under there isn't water proof.
Heat could be a problem, but you can shield something small easier than you can something large. Just put a thin wall shiny stainless barrier around it.
Just about any linear travel device can be remotely mounted though. Could you mount it in the firewall and have a push/pull rod that actuates it? You don't even need a hard link between the two, the vents just have to engage the actuator rod when you close the hood (just funnel the rod into the correct place so the position of the vent doesn't matter when you close the hood)
Of course if you're a real cool cat, you'll just actuate it directly with nickel titanium (nitinol) wire. It contracts when it gets hot (either externally or by passing a current through it) and is good for moving over a pound of force over millions of cycles at 6% contraction. You can get it in various activation temperatures.
How about a vacuum actuator/dashpot? They're very commonly used for air conditioning and heating flapper doors in cars. They come in many sizes and shapes
Originally Posted by Joe Perez
I'm struggling to think of a servo or linear actuator that is waterproof, will survive the heat under the hood, and isn't insanely expensive.
Would it be possible to use a vacuum motor, such as a cruise control actuator or a wastegate can?
The headlight motor from an NA might work, though the gearbox is fairly large.
What are your thoughts on using a cable between the drive motor and the louvers?
Originally Posted by TurboTim
I was thinking vacuum actuator and dashpot too.
To be perfectly honest, I had been thinking about the vacuum option all along, it's just that I was not able to express myself properly after pulling an all-nighter in the garage.
I was actually trying to ask if electric/electronic based options would be preferable over the vacuum system, which I was going to list last, and which I forgot to type, before I posted that message.
I do have a 3 port vacuum solenoid, and a nifty actuator from the supercharger's bypass setup, so I am pretty much all set.
That vacuum actuator has an internal spring, and has its own dashpot, too.
All I need is a delay circuit, and my friend Hakan (you know, the guy who makes Maxi Gauges) is the go to guy in those matters.
Not the actual one from my MP62, a representative image courtesy of google.
Oh, before I forget, that prototype will be tweaked a lot, like, radiused corners and optimized slat shapes to allow better airflow, better closure, and better blending in with the car's curves.
This is the first time ever I am modifying something on the car's exterior, and the very idea of ending up with an ugly eyesore is just frightening.
08-28-2018, 07:36 PM
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