Body / Glass: Avanti Cowl Induction Hood??!!

[sweetolbob]

Progress on the 74 has been a little slow as my painter found himself gainfully employed this year. That's good news, for him and I'm happy for him. It just sets me back until next spring for paint.

In the meantime, I've busied myself on a project I've wanted to do since I bought the 83 Avanti, build a cowl induction hood for one like the one in the SNM.

They don't make one the correct size so I found that was 30" wide and 54" long. Too long and too narrow but the height was right, so the challenge was to make it fit.

Original glass induction scoop setup.



So I shortened it, split it down the middle and framed in the center.



The problem was how do I glass the center and get it to release afterwards from the base. From a previous life I figured Glass resin wouldn't stick to HDPE very well so I bought a couple of 24"X48" sheets of black 1/8" and used it on the form to lay up the glass and glass mat layers. The hood released with little effort when mat was laid.



After a fair bit of sanding and minor filler addition it looks like this.



The base (original hood) looks like this with the hole for the air cleaner and a gasket in place. Gene R. got me thinking about hot air extraction with his post so I decided to put a gasket between the scoop and hood to let me pull hot air out from behind the radiator without letting it leak into the cool air stream. The gasket is from a W31 Olds Ram Air setup and will be the same one used to seal the air cleaner to hood gap.



Put both halves together with West Six10 adhesive and a jillion screw along the hood edge. Three days later we have this.



Setting on the Avanti



Question?? Should I extend the cowl back about 4-6 inches to cover part of the cowl? I'm currently going to leave it like this but the extension is under serious consideration.

The last picture is the cab top seal. I found a Firebird setup on Craigslist and modified it to provide the sealing area for the carb to hood gasket.



Ther's still a lot of work to do to finish it, design and cut the air vents (suggestions welcome as I have a couple of Ideas but nothing concrete) and get the final mounting done.

Bob

[grobb284]

Good concept and good implementation!

[SN-60]

It would look better if you extended it back nearer the windshield....but it looks pretty heavy now, and extending it would add even more weight.

[PlainBrownR2]

It will probably work alright for the application that's its being used in. I'm guessing you're not taking it to Bonneville and the engine is not a high horsepower monster so airflow to the aircleaner isn't a major issue. But with that being said, usually with a cowl induction scoop, you want it as close to the windshield as possible. The windshield is your source for high air pressure, as the air is hitting the windshield and being diverted into the scoop, so the closer you can get the scoop, the better off and the less turbulent the air will be. I did a little bit of that kind of engineering on the '55's scoop, but I didn't want it kissing the windshield either, on the account that it'd interfere with the wipers.

[PackardV8]

The Avanti has the intake for the HVAC at the base of the windshield. A functioning ram air intake will be channeling much of the considerable full-throttle intake roar right into the passenger compartment.

FWIW, since many new cars have have to meet Japanese and European exhaust noise regs, some manufacturers actually have a flap-operated tube which connects the intake plenum into the passenger compartment. At full throttle, the flap opens and the intake roar is presumed to sound like powerful exhaust roar.

The next step was to just record a louder exhaust onto a solid state chip and install it into the audio system. VW/BMW and others, get on the loud pedal and it's a recording the driver is hearing.

jack vines

[junior]

Lookin`good Bob. IMO I think it would look better if you matched the trailing edge of the scoop to match the angle of the windshield...but as for effectiveness of the actual cowl induction I don`t think it matters too much. IIRC the 68/69 z/28's cowl induction hood ended right over the cowl grills and the next year Chevelle with that pop-up cowl induction thingie popped up right about where your scoop ends...so they must both end in effective areas. Love the idea of venting the hot air too, just wondering if that air will get reintroduced to the engine at the windshield? Regardless cool idea... Off the top of my head, remember the air-extractors on the second gen Trans-Ams?? Could two of those be placed in the forward corners of the hood? I also figure going old school like the venting on the old can-am cars ( McLarens etc)with the front radiator would be cool too. Have fun with it...I personally love working with 'glass when creating. cheers, junior

http://www.google.ca/imgres?imgurl=http%3A%2F%2F2.bp.blogspot.com%2F_KeVf2uZIxYE%2FSVPmXyRlg-I%2FAAAAAAAAAOM%2FsROChaaqMT4%2Fs1600-h%2FMcLaren%252BM6%252BB.JPG&imgrefurl=http%3A%2F%2F143modelcollection.blogspot.com%2F2008%2F12%2Fchaparral-mclaren-m-12-built-from.html&h=900&w=1200&tbnid=1Ab-KfUGfKOiiM%3A&zoom=1&docid=AI5bCo3axxcQSM&ei=FmFEVKyuMsfRiQK9kYGABQ&tbm=isch&ved=0CB0QMygAMAA&iact=rc&uact=3&dur=676&page=1&start=0&ndsp=6

http://www.google.ca/imgres?imgurl=http%3A%2F%2Fthumbs3.ebaystatic.com%2Fd%2Fl225%2Fm%2FmL-P0vD-0-kKHaTnPRx23Kw.jpg&imgrefurl=http%3A%2F%2Fwww.ebay.com%2Fitm%2F70-81-74-75-76-77-FIREBIRD-TRANS-AM-SHAKER-AIR-CLEANER-SURVIVOR-%2F291109137060&h=169&w=225&tbnid=_3GcYObdW_3fMM%3A&zoom=1&docid=ZfdkMh_9yvHVyM&itg=1&ei=gmJEVKL9DqKrjAL114CABQ&tbm=isch&ved=0CB4QMygBMAE&iact=rc&uact=3&dur=1051&page=1&start=0&ndsp=8

[j.byrd]

sweetolbob, we had a 64 Ranchero that we built a 4 inch tall cowl facing hood for (out of a 61 Galaxie hood so it would have the little "bump" up the middle). I stopped the bottom of it at exactly the rear of the hood, and cut the angle to the top surface of it to match the windshield angle. That's probably a 4 to 6 inch air space between the opening and the windshield, and that rascal would suck a wet leaf off the top of the hood and into the "scoop" above about 35 mph.

I don't know how much good it actually did me with a hopped up 260 two barrel engine, but it looked cool. The only draw-back was that the drag strip in Huntsville, Alabama moved me up a class so I could lose more often, ha ! I was running a 4:57 rear gear back then, so a good top end downhill on a windy day was probably less than 90, but hey, who needed a speedometer, and it was the year the 55 mph speed limit thing happened anyway, so we drove it like that for a couple of years.

[Xcalibur]

Simpler yet, and "cleaner"... go into the "vent" intake below the windshield. Requires some mods but doesn't show while using a well established high pressure area. I tried to get Ron Hall to do so for 1989, to no avail. I mention this because I suspect it is his B'ville car (with later mods) at the Museum to which you refer.

[grobb284]

Simpler yet, and "cleaner"... go into the "vent" intake below the windshield. Requires some mods but doesn't show while using a well established high pressure area. I tried to get Ron Hall to do so for 1989, to no avail. I mention this because I suspect it is his B'ville car (with later mods) at the Museum to which you refer.

There was a Wagonaire with an R2 in Kettering, Ohio that did that year's ago, and it looked factory installed.

[silverhawk1958]

That looks great. A lot of work but looks like it will pay off. I agree with the others above, extending it back toward the windshield and matching the angle of the windshield would add even more to the looks and increase functionality.

[sweetolbob]

Thanks for the feedback, folks. The more I look at it the more you'all are correct. It needs a lip over the cowl.

Junior - My first thought on venting was much like yours, Can-Am style but just to much hot air over the top so I'm looking more at the newer 'vette ones that exhaust more to the side. I know the difference is irrelevant on the street but that will also keep warm air away from cowl intake.

Xcaliber - My first thought was to use the cowl and duct it into a custom spiral air cleaner much like the early Camaro's but just not enough enough street pop so the hood it was. Performance is not the biggest issue as I don't this thing doing 170 at Bonneville but the 383 SBC will get all the cool air it can use. This is my hommage to the late 60's mucle era.

As far as noise level, let it try to overwhelm the exhaust note and if it builds in crescendo as I row through the T56, then so much the better.

Again thanks for the comments and observations, On to phase deux.

Bob