How to transitions from air intake scoop

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PostPosted: Tue Apr 19, 2016 2:26 am
I'm building a midengine kit and brainstorming how to transition from this upper airscoop to the intake. This is fiberglass which I believe is gelcoated. Will either need to create an airbox on each side or just inline pod filters that are closed to engine bay (like k&n apollo). After the filters/box, will likely be using 4" aluminum tube to the y adapter/throttle body. I had hoped that I might be able to slip something over it like a silicone adapter...but I think the top angle is to large and will slide off. Would appreciate some ideas.

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PostPosted: Tue Apr 19, 2016 8:49 am
Okay, with kit car building one thing it has taken about 40 years or so to figure out is.... I never let the body design dictate how I feed my engine with air for combustion or air for cooling. First, what is your engine/tranny combo here...4, 6, 8, rotary???? How about some pic.s of the outside body overall and where these "intake" opening are.... and I wouldn't even call those things intakes....
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PostPosted: Wed Apr 20, 2016 1:36 pm
Engine is a cammed LS1 E85...mild head work. Shooting for low 400hp ish. Here is a photo of the air scoop from the outside of another car. Porsche G96 transaxle.

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I was hoping that the two pipes combined would feed enough air but I agree the opening as is now, is fairly small, but could be cut back some to inlarge. I could also use air from the lower scoop as well but I didn't want to complicate things. I will have setrab oil and transmission coolers behind those.

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PostPosted: Wed Apr 20, 2016 4:45 pm
Okay, that makes a lot more sense now.... yeah, you've definitely got several options here. It's too bad they didn't dive those cut ins deeper so you could get a little more "rammed" effect to your air supply at speed. The LS motors you see installed in Factory Five's GTM usually end up using two 4 inch tubes for intake. On my rotary set up I have a metal Y at the intake going off to two 4 inch (I run an insulated jackets on those flex tubes) flex tubes terminating into large cone filter just ahead of each wheel. Because mine are low mounted I also run Injen micro outer filters to prevent hydrolock from any water which might splash in there. You may end up going that route. Only other way is going to be to get some yellow sheet foam and create a rather slender box that would cut down to a 4 inch ring adapter to pickup each side hose and go inline filter. I think I would at least try the cone filter route.
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PostPosted: Thu Apr 21, 2016 11:13 am
I had thought about using a cone filter like you describe (one thing about the GTM's alot of them look like dual intake tubes with the "y" but they block off one side and continue to use a MAF....pointless). But I'm concerned about taking hot air. If I'm going to be blocking in the area to keep the cold air close I was thinking it may be nearly just as easy to build a small attached airbox and maybe get some ram air affect.

This may seem like a ridiculous idea and I'll easily be talked out of it but I had two possible options to make this somewhat easier. First make a fiberglass cone filter airbox using a flower pot to mold from/and clay, and transition from the air scoop to the airbox on the perpendicular side of pot/box for a straight shot to the TB/y. Second and similarly to the first I'm considering a heavy duty locking lid tupperware (large cylinder type). It could either be covered/skinned or just engine paint but it should hold up fine (plenty of plastic in an engine bay). Then I wouldn't have to create a lid for the box and the filter could easily be changed.

My biggest questions/uncertainty is how to mold that air scoop exit and how to attach the airbox to it after it's all been made into one piece. Another thought was to use a short section of like that large diameter brake ducting to transition but I still don't know how to attach it.

Just for an idea of the general shape
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PostPosted: Thu Apr 21, 2016 11:46 am
I'm leaning towards the fiberglass airbox idea. With a long boot to slide over the scoop outlet. Then affixed with a couple light duty latches.

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Credit for fiberglass airbox with pot. Obviously I'll try to make it cleaner.

https://www.youtube.com/watch?v=xSCtRNhb6JE



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PostPosted: Thu Apr 21, 2016 12:52 pm
http://www.thumper300zx.com/modifications/freshairintake/freshairintake.htm

Plastic container airbox example.

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PostPosted: Thu Apr 21, 2016 5:30 pm
It's your car so you've just got to experiment. One of the problems we always run into with the VW, Subaru, and Rotary forums is the definition of how a "cold air" intake really functions. They are really inappropriately named since all they take in is ambient air. So that is a starting point... we want to make sure they cannot "inhale" any hot air which is especially of concern with both mid and rear engine layouts. While I do think the cone or cylinder style filter should be isolated I think a complete box to fit it in is a bad idea. It's been shown many times in engine forums that the reality of ramming air near the mid or back of a car can be quite difficult as you or I don't have a wind tunnel to show where turbulent air is occurring. The big manufacturers can spend the time and money to figure all that out, us.... not so much. An enclosure will make it have to "suck" air if it is truly not being rammed in.... If you do end up really wanting a custom box, I'd make it like a pro.... get some yellow block foam (you can make your own with yellow sheet foam from a Home Depot) and make a single carved item that you can overlay with your fiberlglass. Just use some PVC to carve in those tubes for attachment. When it's hard just flip it over and dissolve your foam with acetone, you're done... Need two just carve mirror image blocks. Not saying you can't do what the guy did in the video, but man, looks like extra work to me to end up with something not so custom. Again, it's your project, your car....
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PostPosted: Fri Apr 22, 2016 12:45 am
Thanks for the response. All points well taken about the airflow. I'll mull this over. Probably will take your first advice and just run the cone filters and box it off somewhat to keep hot air out best as possible. It's certainly the easiest. If IAT's are bad it can be dealt with later. If I decide to make a box I'll use the foam and pull air from the top and bottom scoops to make sure not to suck air through one smallish hole.

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PostPosted: Fri Apr 22, 2016 8:14 am
Ohh, and I completely forgot about this.... In our industry antique woods are very sensitive to environment. We especially find this to be true in old drafty poorly sealed historic buildings which not only house valuable antiques but must allow constant public traffic flow. We are hired to not only work on those items but to determine how we can either stablilize those environments or at least move pieces to more stable parts of these buildings. We use these small (1/2inch thick 3 x3 inch) things called digital recording Thermo Hygrometers which we can put in place for a month or so and actually see the highs and lows in both moisture and temperature. When I first laid out my system I duct taped these just inside where my cone and flex pipe came together. I'd drive for a week and pull and read the device. I found that by just moving the cone a few inches here or there and running minor back shielding that I could get near ambient temp.s all the time in both cones even in my hottest weather. I am running a rotary which can have exhaust temp.s in the 2000+ degree range so getting those things in the right place was much more critical than most app.s. We used to get those units just at Radio Shack for about $25 each. Might make tuning your system a little easier.
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!
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