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Old 12-14-2010, 12:58 AM
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Default DIY cowl scoop

Had a hard time figuring the best place for this as it could fit engine, exterior, but it's also a DIY so here it is.

You ever have one of days where some idea just pops into your head while you were doing something else.

There I was going through my pile of "good used stuff" looking for some metal pipe I had removed from my Jazz and I spotted an old broken plastic stool that I had tossed on my pile.

I had been thinking of having my wife buy me a cowl scoop for Christmas and had been looking at photos of them and whamo it hit me ..... with a little work I could make a scoop out of this.



There was a broken leg from being old and the rubber buttons on the legs get worn off and if you sit on one on surfaced concrete like they use here it's so slippery the legs have no grasp and spread apart to the breaking point.

But I can't throw away good plastic so I cut off one end and presto potential scoop.



As you can see it had a crack that I filled with epoxy (black line on the left) and all that internal bracing had to go so out came my good old dremel tool and the braces were cut out.

Put it up on the car and it looked right so then "how do I hold it in place" got me thinking.





So I thought how about something else from my junk pile.....



So I opened my hood and thought Hmmmmmmmmm what about all that potential water coming in right on top of my master cylinders?

So a slight segue into making a "Cover" for the master cylinders. Back to the junk pile and this old clip board was just right.



A few minutes to cut and fit it into place and presto master cylinder cover. But then it looked ugly so how about some of this.........



I got Mrs Claymore to separate the foil from the foam on some of my favorite foil insulation and then I had some nice foil that matched my other engine parts to cover the cover.

The cover is held in place by some of those twisty ties that hold stuff to the cardboard when you buy something new. So a couple of holes were drilled and it was finished being shaped just right and I applied some contact cement to the foil and plastic cover and done no nasty water dropping onto my master cylinders.



It matches the other stuff in my engine bay and can be removed in less then a minuted just by untwisting the twisty ties.



So now that the cover was done back to the problem of holding the scoop into place.

How about some lengths of that old aluminum coat hanger epoxied in place. Yep works fine.



Note my cool "high tech" work area.

Those long ends were cut off and bent and they fit perfectly into the original holes in the cowl used by the stock cowl cover. They also align the new cowl scoop left to right so it can't move around.

Ok the rear is set so it's onto making sure the new scoop is cut, fitted, and filed down so it mates to the stock cowl just right. This fitting took the longest of anything it was try it cut a little here, try it again, cut a little there, back and forth several times until it was perfect.

Sorry this photo is a little out of order but I forgot to get a photo of the inside front brackets, also made from the old coat hanger and epoxied in place, before I painted it but you can see what they looked like finished in this photo.



Again there was a lot of trial and error cutting, bending, and holding everything in place back and forth made worse because the two sides of the original cowl hole are not the same shape or size and they had to be held in the correct position with super glue first then epoxied to the new scoop in the correct position.

But it got done on the part stuck to the scoop ....but what about the bottom end??



Hey they work for Honda so I thought they would work great here. Holes were marked out and drilled and new Honda pop buttons that hold various parts of the Fit/Jazz were put in place and work just great as you can see here.



More bending and fitting was done to make sure the scoop would clear the hood when it was opened and closed (Forgot about that in the beginning)

OK time for paint and on the bottom edge I happened to see some hard foam rubber that they sell in the supermarket to go on the bottom of chairs to keep the legs from marring floors so I bought some.

Using a metal ruler and a nice new sharp razor cutter a section was cut that is just wide enough to cover the bottom edge of the new scoop so it won't mark the cowl. The foam came with sticky tape applied to the bottom so it was an easy job to peel the tape and stick it on the bottom of the new scoop.

Well here it is all painted and held by it's new brackets and it even has non-scratch foam on the bottom.



Has the right angle with the hood and windshield. It took some more trail and error and looking at it from all angles to get it where it looked correct with both the hood angle and cowl angle.







While I was taking photos of my handiwork I noticed my wiper arm was looking a little funky so I gave that a fresh coat of flat black while I was working.




So there it is my "cheap" DIY cowl scoop made from a broken one of these.



With the use of the pop buttons from Honda the good news is it takes less than 20 seconds to pop the buttons and remove the scoop and put the original cover back if you get into very heavy rain sometime. So I'm carrying the stock cover in the space with the spare tire in case I ever get caught in the heavy downpours we get around here.

I'm sure some people out there are wondering why go to all this bother when you can buy one with a lot less trouble. The answer is I ENJOY working with my hands and tools and nobody else on the planet has a scoop just like this one.

As for "cheap" yep I used as lot of junk parts but on my last job I was making $100.00 per hour so if you add up my time this probably is worth $1,000.00 in my time.

Now to the bottom line "how does it WORK" .........

This thing is SWEET my car has the lowest engine temperatures I HAVE SEEN SINCE I PUT IN MY GAUGES. While it is low the reduction in engine temperatures is helped by the removal of the rear hood rubber seal also.

If you live in a hot area or during the summer months I would remove that seal RIGHT NOW if I had known how much this reduced engine temps I would have done it years ago. With just the seal removed temps were down 5-10 degrees when the car was moving.

But with the scoop installed temps were down a further 10 degrees AND it keeps working while the car sits still or is moving slowly not just at speed.

And even if you get stuck in traffic the temps climb hotter much SLOWER with the scoop. It seems to be the coldest at about 60-70 mph on the expressway but faster than that it is still cooler than normal.

And it cools off the car faster when you stop after driving the car. I was messing around with the wiper arm and happened to put my hand near the scoop after a long trip and it felt like putting my hand near a hot air outlet in a home heating system hot air was moving out the new hole made by the scoop even after 1/2 an hour of the engine being turned off.

Bottom line GET ONE NOW.

Last edited by claymore; 12-14-2010 at 03:36 AM.
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Old 12-14-2010, 05:03 AM
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Default Nice Job!

Quote:
Originally Posted by claymore View Post
...But with the scoop installed temps were down a further 10 degrees AND it keeps working while the car sits still or is moving slowly not just at speed...
...And it cools off the car faster when you stop after driving the car. I was messing around with the wiper arm and happened to put my hand near the scoop after a long trip and it felt like putting my hand near a hot air outlet in a home heating system hot air was moving out the new hole made by the scoop even after 1/2 an hour of the engine being turned off...
Nice Job claymore! Not only does it look good, but it works too! You have given me inspiration to try something as well. It is good news to hear that your cowl allows the hot air to escape whether moving or still. Knowing now the characteristics of your mod, do you think fabricating a simple mesh grill would also help cool things down?
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Old 12-14-2010, 07:32 AM
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If you mean putting mesh over the hole after taking off the stock piece I would think that should work fine when stopped or moving slow. Not sure how it would work moving fast if air would move right over the hole with nothing to stop it or does the air get forced out from the bottom anyway.

I think a little experiment with some yarn taped to various parts of the scoop and open hole should determine whether or not the air is coming out the hole or going in from the scoop.

If the air is coming out the hole from the bottom would a scoop facing the rear work even better.

Doing this got me thinking of the front seal on the hood. I'm going to wait and make sure how the removal of the rear seal and scoop averages out on the engine temp then I'm going to try removing the front of the hood seal also to see if that makes any more decrease in temps.

The only reason I could think of that would make it not work is if removing the seal cool air then goes under the hood and not through the radiator but that would still drop under hood temps anyway

I wish I had another indoor/outdoor thermometer so I could take the sender and check the temps in different areas under the hood.

When driving today I was watching the engine temps so close I forgot to keep an eye on my intake air temps at the TB to see if there was any effect but for sure I will be checking that too.

Good times with lots of "Stuff" to investigate.
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Old 12-14-2010, 05:37 PM
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Very interesting!
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Old 12-14-2010, 08:26 PM
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Thought of something more. EDIT: I keep forgetting that you guys in the USA have the hole on the other side but it would still help the hot air get out anyway even if it's not directly over the turbo or supercharger. This would be the perfect mod for Fits with TURBO or Superchargers. Because of where it's located, right above the turbo or supercharger, all the excess heat produced by them would be reduced and it still works after the engine is shut off. The heat hanging around after shut off is what slowly kills turbo bearings and a scoop gives an exit for that trapped heat to escape.

Now I have a little problem ...... I have to think of something else to tell Mrs Claymore to get me for Christmas

Last edited by claymore; 12-15-2010 at 11:56 PM.
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Old 12-20-2010, 02:29 AM
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finally got around to my weekly wash and thought how the heck am I going to keep from flooding the engine compartment with that big gaping hole right in the middle?

Then another great idea popped into my head... I took one of my new car wash sponges and wrapped it in a plastic shopping bag and presto instant cheap scoop blocker.

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Old 12-25-2010, 07:58 PM
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You know that scoop is not going to do anything other than adding some crazy wind drag right? That area between the windshield meet the hood is suppose to create a small vacuum already (where do you think your interior get fresh air from?)

By putting a scoop there, it will only generate wind drag, unless, you are direct the flow directly towards your intake or turbo inlet, then it might've help. Also, your scoop cannot be "straight", your inlet must be smaller than the inside... meaning the scoop should be like this \ /

edit: ok, wrong pic, but here is my mspaint version:


Another method would be using the NACA duct design.

Last edited by codenamezero; 12-26-2010 at 12:05 AM.
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Old 12-25-2010, 10:50 PM
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Dude it is not scooping air in using the higher pressure all the time at slow speeds and when stopped it's letting hot air out. If you notice it's not hooked to anything needing more air. "The inlet needs to be smaller that the inside'" ?? Dude even your illustration doesn't have an inlet smaller than the inside?

Since this is a high pressure zone because of air building up against the windshield there will be only a minuscule increase in drag because the air is building up in this area anyway.

Bottom line if you read the post is it WORKS GREAT even if it doesn't meet your unproven theory. Proven reductions in engine temperature while at speed and standing still indicates that it works very well thank you.

And as for my intake air that is taken care of with another DIY cold air intake system that delivers outside air temperatures to the TB can't get any better than that.

Last edited by claymore; 12-26-2010 at 12:02 AM.
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Old 12-26-2010, 12:34 AM
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ok wrong illustration i've updated my previous post with my poor mspaint drawing, what i mean is that, if we want to get the air in, the inlet should be smaller than the inside area, so that it will allow the air to get in properly.

i am not saying all hood scoop is bad, i am just saying that perhaps your particular design might be bad. i'm just saying the scoop your inlet seems to be much larger than the hole itself. in addition, nearly half of the scoop is not directing the air properly. look, nearly 40% is directing the air into a dead end.


so the air won't be able to get in and bounce back out. unless you have your intake position right there, which would continuously sucks in the incoming air such as:

or


Quote:
Quoted from the web

Scooping air from the hood to cool the engine bay is not reasonable due to the MUCH higher pressure under hood than above. The air will want to come OUT of the vent.

Scooping from the hood to provide the intake cool engine air is reasonable and best done as far back on the hood as possible.
you can do whatever you want to your car, but if you are claiming that this design works, you should back it up with facts, perhaps temperature reading from before and after the scoop... or just put some paper strip around the scoop and video it to see how the paper strip flow (inward or outward). my take on the scoop like that will just create more drag than anything else.

ps: this is just a friendly discussion
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Old 12-26-2010, 01:26 AM
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Dude did you read the whole thread before commenting? The temperature data FACTS you are looking for are posted in the thread as I always do and before you doubt my data be advised that I have gauges installed including an engine coolant temperature gauge and an intake air thermometer sensor at the TB which you would have known about if you had read some of the threads already posted before commenting.

And so what if the air is trapped there the air that is needed is going in the hole and working fine as you would see if you bothered to read the post.

And you are missing the whole point of installing this particular scoop. It was installed as a path for cold air the enter and exit the whole engine bay NOT ANY PART OF AN INTAKE SYSTEM.

As for drag that area is a high pressure area naturally to begin with and any air flow coming into that area is disturbed already as air gets trapped and stacked up against the windshield which makes it a higher pressure area so adding this scoop in the path of air getting trapped by the windshield wiper causes virtually no impediment to said air flow
meaning virtually nil increased drag.

This is my DIY cold air intake that is taking care of the intake air and it works just fine also reducing incoming air charge to ambient air temperatures at the TB and you can't get any better than that unless you wanted to add an airconditioner to the intake system.


Last edited by claymore; 12-26-2010 at 01:29 AM.
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