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PostPosted: July 3, 2019, 8:26 am 
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I did the HPDE event at NJMP over the weekend, I remembered to switch my dash to display IAT. One nice thing about having a Can/BUS dash is that I can display anything the ECU knows. I was surprised I was seeing 50 degree over ambient at the end of the sessions, that is too high. so an air box and some nice cool external air inlet is a must. I used to use a forward facing inlet manifold with the air filter just behind the radiator next to the exhaust, I am sure the new setup is better but 50 degree is much to high. Checkout viewtopic.php?f=4&t=19374

I have found a Aluminum NACA duct on Ebay that is on it's way, it looks like I can just extend the ECU cover upwards to seal to the bonnet and add a duct. Sounds simple.

Graham


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PostPosted: July 3, 2019, 8:39 am 
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Yo, G-Man!
Cooling the intake air is a good thing. An old friend of mine who works on Triumphs and Jags showed me a Jag "tuning manual" from their competition department that said if you could cool the intake air 100 degrees it would equate to a 15% increase in horsepower. I built an airbox for my MGB based on the Jag info, and could actually tell a difference in the power with the "seat of the pants" dyno. YMMV, etc...

I don't remember 'zackly what your hood looks like, but you might also cool things down by venting some hot under-hood air from the header region with an "air extractor" type vent over the exhaust. Would that work with your hood?

I used these: https://www.westmarine.com/buy/west-marine--slotted-ventilators--P012_363_002_500?recordNum=4

Note: You can turn 'em around and they'll scoop air into the engine bay, if need be.

:cheers:
JDK

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PostPosted: July 3, 2019, 8:55 am 
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I agree, I did some work on a motorcycle to build an air box, it was not pressurized but just getting cool air into the engine made a noticeable difference. My can is full of louver vents.

Graham


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PostPosted: July 3, 2019, 10:51 am 
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My brother's Stalker has an LS-3 with a rear-facing intake manifold and he ran the air inlet into the glovebox area, which makes for a very clean installation. Since he wears earplugs anyway, any increase in noise wasn't noticeable.

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PostPosted: July 3, 2019, 11:35 am 
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Doesn't the NACA duct require laminar airflow across the duct to function?

I'd start by insulating that nice shiny metal tube running from the filter to your TB. That can't be good. And moving the air intake to the LH side of the engine would also get it away from that big heating radiator called the exhaust header.

Then there is always what I did, move the air cone filter OUTSIDE the engine compartment. As far forward as possible IMO to keep from picking up heat while flowing across the bonnet.

Those are just a few ideas. :cheers:

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PostPosted: July 3, 2019, 5:44 pm 
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I'd make a mount for the air filter and use a longer hose than can flex with engine movement or mount the filter directly to the tb and remove it when you need to top off brake fluid if it prevents using a funnel.

I'd fit a heat shield that blocks most of the flow past bell housing to protect everything behind there as well by helping to force the hot air out the side of the hood and body louvers.You can fit silicone baffle material (1/8x3x9 feet is a common size) to the edge near the hood and use the rest around the radiator. I'd use .050 steel sheet since it will also serve as a washer on the header flange though you could avoid bolting it to the header by using tabs under the valve cover fasteners. Another option is to wrap the tubes but that will cause the tubing to overheat and fail eventually. Yet another option is to hang a blanket of heat shielding fabric insulation tied with stainless straps or safety wire but it wont be as effective and a good fitting shield. You could also have the header ceramic coated to insulate but you must also have the inside coated also or it will still overheat the tubing like a wrap.


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PostPosted: July 3, 2019, 8:40 pm 
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Joined: December 1, 2013, 10:48 pm
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Location: Atlanta GA
I’m planning something similar but going to seal the intake filter to a housing with the inlet in the passenger footwell. Hopefully it keeps the iats down


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PostPosted: July 4, 2019, 7:22 am 
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Do not use metal to extend the foot well air box. Conducts to much engine bay heat. [think fiberglass] Consider moving the cold air inlet to the center of the windshield as for inboard into the scuttle as possible. You could probably get 2/3s of the air box thru the top fire wall area. Put the air inlet opening at the base of the windshield, that's a high pressure area which should improve the design and pick up out side cooler air. My cold air box made a big time improvement. Davew


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PostPosted: July 4, 2019, 10:41 am 
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All good opinion, I like your idea Davew to not use metal, so lets expand on that. As I see it I have two options a flat sheet material that I can use a metal like construction, by that I mean pop rivets construction. Or make a form and fiberglass over it, it's a one time shot so I am not making a mold look at http://www.usa7s.net/vb/showthread.php? ... abrication and you will get an idea.

So what non metalic flat sheet material can I use?

Graham


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PostPosted: July 4, 2019, 3:21 pm 
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Graham
No need to make a form, just use flat sheet fiberglass and just lay up new glass on the corners to construct. Just three sides and a bottom then seal against the top of the scuttle. Here a similar design [with curved glass ] that seal against the top of the nose cone. Davew


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PostPosted: July 5, 2019, 6:29 pm 
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I had a spare remote thermometer and put the sender on the inner fenderwell of my '68 F100. Going down the road it would run about 10F over ambient (huge grille, lots of ground clearance, and a gigondomundous radiator). Sitting still on an 80 degree day, it would run about 160F. After shutting the engine off, it would spike as high as 240F before dropping back down; I suspect a lot of that was heat coming off the exhaust manifolds and other hot bits.

I don't know that it proved anything in particular, but it was interesting to see the spike after shutoff.


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PostPosted: July 12, 2019, 7:10 am 
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I have a similar condition with my cold air system. Once you stop the engine, i.e. park for a short period, allowing the intake to heat soak. There is a noticeable drop the HP. It than takes a long time to re-cover. If the ambient temp is higher then 85-90F, you are SOL. You can not move enough air thru the engine bay to cool the system down.
Davew


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PostPosted: July 12, 2019, 1:40 pm 
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I like the ideas people have put forward, I think I am going to use a combination. I am going to start with a fiberglass airbox built over a wire mesh form. I have two reasons; one it allows a more organic shape that sheet construction. But the major one is it's a construction form I have not used in the past and I think it will be useful. I have picked up some wire mesh and will try making form tomorrow and see how that goes, if I can make a suitable form I will continue with the fiberglass process.

Graham


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PostPosted: September 4, 2019, 10:00 am 
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My airbox project is complete and tested. We had some ups and down and it changed path along the way but I am very happy with the outcome. I used it at the 3 day event at Mid-Ohio over the Labor Day weekend. I was able to use RaceChrono and a Bluetooth OBD2 dongle to datalog to my phone. I went from 50 degrees over ambient to about 12 degrees. I huge improvement, I think that is about as low as I can go as I am running a heated inlet manifold. There is a conversion kit to change to a dry inlet manifold, I might install that over the winter.

The process

1. Made a box out of wire mesh from the hardware store.
2. Wrapped the box in 3" wide dry wall tape.
3. Fiber-glassed the box.
4. Decided to cut the box in half to allow access to the filter.
5. Added teeth to the 2 half's of the box so they would locate each other.
6. Found I made the box to tall, I did not calculate the height of all the dry wall tape and fiber-glass correctly.
7. Decided to go to a top loader and seal it to the hood under side.


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File comment: Wire mesh box
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File comment: Dry wall tape
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File comment: Grrrrrr
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File comment: Working out the actual size of the NACA duct was tough. So I used a heavy coat of black paint and printed it on a piece of card. Worked great
IMG_20190811_091752.jpg
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File comment: Underside of the hood
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File comment: Hood looking good, was worried about cutting the hood, did all cutting from the underside just in case of a slip.
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File comment: Completed, used gold foil from Pegasus Racing
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IMG_20190823_194017.jpg [ 521.46 KiB | Viewed 594 times ]
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PostPosted: September 5, 2019, 2:00 am 
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Joined: January 18, 2015, 2:34 am
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Location: Los Angeles
I went the route of glassing over an old ITG sausage filter and running it forward and next to the radiator. I added a sock style filter. The duct is 3” id. I didn’t measure the before and after temps but it certainly seems to help the performance. It also seriously reduces intake noise.


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