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MG MGB GT V8 Factory Originals Technical - Air scoops ... shaker-style??
|Has anyone tried a shaker-style hood scoop on a BV8? (I simply mean a scoop that's attached to the carb top and pokes up through a hole in the hood, rather than being part of the hood). I am totally convinced that a hood scoop is what is needed performance-wise. All you get with the stock bonnet is air that's way too hot, and there's much too little of it to boot (you can see the car richening up at high rpms on the A/F meter -- but this doesn't happen with the bonnet open and the air cleaner removed). But I haven't seen many scoops I can stand. I was thinking that maybe a cast aluminum shaker-type scoop, reversed so as to open rearward and gulp air from in front of the windshield, would look good, even if that sounds kind of over the top! I like the installations I've seen on other cars where there's a ~6" round hole in the hood, and you can't see it with the scoop attached. Only downside to that is, of course, you have to remove the scoop to open the hood.|
Any pictures of scoops, etc.?
|I thought about using a shaker hood scoop from a Mach 1 Mustang but they seem hard to find and expensive. I don't like most hood bulges seem clumsy but had thought of trying to make a RV6 type but open at the rear.|
|Interesting, Richard ... I thought of trying to do the exact same thing. The only problems I foresaw are (i) the RV8 hood would look fundamentally different, and I think not for the better, if it was open in the rear, and (ii) while I agree that the rear of the hood is an absolutely perfect place to suck in air, the car's fresh air vent is right behind it. I hardly want to be inhaling hot, smelly air which would no doubt happen, e.g. if you were going slowly and had the blower fan on. I now think a cast-alloy hood scoop that wasn't actually part of the hood would look much better than trying to fair a scoop into the bonnet.|
|Sorry to intrude here as I have not even begun the planning stages on my conversion. |
Ted, you said "while I agree that the rear of the hood is an absolutely perfect place to suck in air, the car's fresh air vent is right behind it. "
Why not convert the fresh air vent, or at least convert a section of it ?
|Richard, is there clearance for a Mach 1 shaker assembly? I assume you're talking about the kind of rig they put on some '70 Mustangs ... if it'd fit, good heavens it would be simply killer, although it's a rather complex unit with lots of parts. The part that protrudes through the hood is pretty small and generic-looking and it'd look fine on an MG. I didn't think our hood clearance was sufficient.|
|I never got past the look at pictures stage. On the Mustang I think there is some kind of rubber seal between the hood and the shaker part and it does not have to be removed to open the hood. I ordered some Mustang parts catalogues but no shaker hoods were in them just the rubber seal. Some one on the list did use the vent intake for his carb but of course has no heater. I did mean RV8 not RV6. I don't like the idea of the rear opening just because of looks but had thought of louvers on the side of the bulge for exhaust of hot air and some sort of cold air feed from the side of the radiator. Just ideas.|
|The shaker is a "complex" unit. BUT the easies wa to think of it is like an old fashioned air cleaner with a housing around it and a scoop on the top. I thikn wou will find major clearance issues trying to fit a true shaker on, thay are pretty tall assemblies.|
I have seen a cobra jet scoop on a B, it looked pretty good, it was mounted to the bonnet and had a big foam ring mounted on the underside to seal to a 14" air filer base... The only difficulty is getting a air filter in the package.
Check this link for some pictures;
|I think this is a really interesting thread. As some know, I like 'em bone stock-looking, but I must admit that an old Hilborn-style alloy scoop -- I think they were about a foot long and maybe five inches high, might look really terrific on an otherwise stock-looking car. The Gasser look!! |
I have a friend who is quite an eminent architect and he says that sometimes the best way to hide something is to make it obvious. I detest the MGB hoods I've seen whose sheet metal has been grotesquely defaced. But a plain hood, perfectly finished, with an old-style alloy scoop poking through it? ... might be really killer.
What you want, no doubt, is something that puts the air filter _above_ the hood ... as Larry said, if you tried to fit one of those Mustang-style shaker assemblies, it's going to be a disaster space-wise. It looks like the fellow that Larry mentions with the Ford conversion didn't fit the whole setup, so he doesn't get filtered air, which of course you'd need on a road car/daily driver.
Certainly you're right that the induction could be overwhelmingly improved with this mod. It could be a winner. In the spirit of open-mindedness, maybe I'll get an old hood and try it out myself. (So they make scoops that attach right to the neck of the carb? From whence do they come? If so, this would be trivially easy.)
|Go down to Home Depot and get some small size 90o heater duct and make a plate to fix it to the carb. If you don't like the galvanized sheet metal look, paint it to match your car.|
|L. J. Howser|
|There are easier fittings for the carb. K&N Makes one they call it a plenum, it is 9" diam, 3 1/8" vertical clearance. I then has a 6" round inlet on it. I have seen them used for twin turbo 351's etc. Face that opening back and then have a scoop which you attach to this plenum with a 180deg bend tube... might just work..|
I plan to use something like it with an air box similar to a mustang and then rout in a cold air supply from under the front of the car.. Now my secret is out...
|At first I used one of the Mustang scoops sold by JC Whitney, which looked ok from a distance. Next time around I used .032 sheetmetal and made one up that suited me, but that was for the Olds turbo engine and was a bit wider than you would need. One thing that I considered for a time was to take a scrap hood, remove the skin, and use that for a scoop which would match the existing lines. Since I didn't do it I can't say how hard that would be, but it could be done. Of course, this time around there will just be a somewhat large hole in the hood, at least to start with.|
I'm less familiar with the Mustang shaker than with the one on the Hemi-Cuda, and am much more familiar with the Olds 442 scoops and cold air induction. It can be as simple or complicated as you want to make it. The nice thing about the Olds system was that it still used manifold heat for a fast warm-up. The bad thing was that under full accelleration the trap door opened and dumped unfiltered air into the engine. The main problem you face with a shaker hood is filtering the air. If it weren't for that it would be a piece of cake to fabricate one. Here is where I have to question the idea of the fuelie scoop. If there is any provision for a filter it would have to be a darned small one, and that isn't a 'good thing'.
Back to the shaker. Since you apparently do have room for a short air filter under the hood the issue becomes one of routing the air through it. Here is a possible approach. Place the scoop opening(s) either in front, back, or to the sides of the filter element but not directly over it. Use an air filter housing which fully encloses the element, remove the snorkel and mount the scoop at that point, then perforate your hood. A piece of black vinyl edging will trim out the hole quite well if done carefully. Voila, shaker hood scoop. This approach has several advantages which should be apparent, and is pretty simple to accomplish.
I would also not recommend the rearward facing scoop due to fumes and such.
|>Here is where I have to question the idea of the >fuelie scoop. If there is any provision for a filter >it would have to be a darned small one, and that >isn't a 'good thing'.|
I think the fuelie scoops have 10" x 3" air filters; shouldn't be too bad. I mean it looks like that mighty "Cobra Killer" with an SBC mentioned in one of the other threads isn't running a very big filter either. And that motor must suck an incredible amount of air! The fuelie scoop would give you cold air in abundance, and pipe it straight into the carb rather than making it slither into a low-rider underhood unit. I mean with the low-low-rider setup that a lot of us use, sure we get an adequate sized filter on there but then we make the air do contortions to squeeze its way up over the choke tower and down into the car. Seems to me that's the root of much evil here.
I think you're right that forward-facing would be better though.
|Another note and possibility,|
I got this from Bill Jacobsen, so full credit goes to him. He took the scoop off a Pontiac GTO, then cut, fit, cut fit, cut fit until it had the shape he wanted. It really turned out awesome. While his is not ducted to the carb and is more for looks and cooling, it couldbe accomplished without to much trouble...
There are pictures of bills car in the photo gallery section of my website.
|I hear ya Ted. On my 302 conversion I had such lo clerances that I decided to remove the choke tube entirely! I used a hacksaw to take the majority off then a dremel to round and clean up the remaining. This will greatly improve flow. The downside is no choke to help when cold, but I will have to make due.|
ANOTHER shaker idea is made my BANSHEE here in the US. It is designed to give a late model EFI stang a shaker set-up, but I am willing to bet it could be modified in some way to work. If i have the $550 to drop I would consider looking into it...
|Relevant to this thread: does anyone know if there is a supplier of some sort of foam or rubber sealing ring to seal the _bottom_ of a conventional 4-barrel 14" air filter against the bottom of the bonnet? I have rigged a scoop and filter above the bonnet, and my intention is to use only the lower plate of the filter, and seal it against the underside of the bonnet in this way. However, I can't figure out how to do this exactly ... surely there's some sort of foam ring or something for this purpose?|
|Re the fuelie scoops ... I think you may want to be aware of the turbulence issue ... the air coming into that scoop will be very turbulent (comes right over the grille and up the hood ... flow is messy ... this is why F1 cars have their air scoops sticking way up there into the smooth air flow) and the mixture may be thrown off quite a bit. The way to resolve this issue, if you can figure out a way to make everything fit, is probably just to rig an air box or plenum. E.g. if your fuelie scoop filled a decent-sized air box and _that_ air was ducted to the carb, I think you will be happier. That shouldn't be hard to rig, if your motor is in basically the stock location ... you just put the scoop a few inches back from the carb neck and build a box ... whether the scoop is part of the hood, and somehow seals down onto the box when you close the hood, or attached to the box with a hole in the hood is up to you. Don't get me wrong, I totally agree with the age-old adage that a hot engine breathing cold air will make the most power. I forget the figures, but's it's quite significant, like a 1% power increase for every 17 degrees F that the incoming air is cooled. Given that your MG is probably snorting underbonnet air at near 200 degrees, going down to 80 degrees could make a huge difference. If you do this right you will need to add richer jetting and in fact that's the whole point of the exercise.|
This thread was discussed between 06/10/2001 and 11/10/2001
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