Stock Zenith carburettors + Alpina airbox

NilsH

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Hi!

First, I have little knowledge about carburettors so please excuse me if the question is dumb.
Now the question: can the Alpina style airbox be fitted with the Zenit carburettors? If not, which type fits?

I know that the Alpina airbox is very rare and expensive but I really think the original is, hmm, ugly. So I'm looking for options.
Thanks to all!

It is JamesE30's picture of his great car, thanks! https://www.e9coupe.com/forum/threads/from-e30-to-e9-my-3-0cs-with-a-little-alpina.26504/

Unbenannt2.png
 

zinz

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The Alpina airbox in the picture is attached to triple Solex DDH sidedrafts. I don't see how that airbox could be easily fitted to two Zenith downdrafts.

Ed
 

deQuincey

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nothing has be done so far
you must start it as a Project, many questions will arise as if this is posible to fit within the available free height
i can give it a try if you give me an alpina airbox no matter the condition
IMHO a complete overhaul of the alpina airbox will be needed to accomodate this
not very easy
 

NilsH

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Thanks for your input!
I learn something every day and changing carburettors is a too big project for me.
Are there any other airboxes (other look/appearance) that will fit easily without such a large rebuild effort? I haven't seen any so far...
 

deQuincey

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Thanks for your input!
I learn something every day and changing carburettors is a too big project for me.
Are there any other airboxes (other look/appearance) that will fit easily without such a large rebuild effort? I haven't seen any so far...
nope
the stock one is beautiful, you can repaint it in black, red and or yellow ;-)
(if you decide "or" it is the colour of your choice, if you decide "and" is a flag of a great country closely related to the coupe)
 

WALTER

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I agree NilsH, the stock box leaves a lot to be desired IMHO; it's clunky and dominates the engine compartment. The Alpina airbox is more sporty. Just eyeballing the two air boxes, they appear to be roughly the same length and height. Theoretically, the two Zeniths could fit in there albeit with the carbs closer to either end I imagine. What I don't know is how the inside of that Alpina box is set up. Are there separate chambers for each air horn, pairs of air horns, or is it just one big chamber. The other issues I see would be cutting an welding the bottom to accommodate the downdrafts and mounting the air box in a manner in which is not shaking itself loose. Member Daddywad sells a reproduction alpina air box I believe, if you want to give it a go. Don't trust my calibrated eyeball though!
 

WALTER

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Forgot to add, there are sport filters for Weber downdrafts which have small rectangle chromed tops with a freer flowing filter. I have them on a coupe and don't like the look at all. Where the regular filter housing is too big, the sport filters are too small and 'blingy.'
 

zinz

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Those small rectangular Weber filters with the open elements are horrible for air flow.
 

Markos

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FWIW - You are looking at $2K - $3K for the Alpina box. $200 - $400 for a CSI airbox. $150 for the airbox bracket if you can find one. Fabrication time, hood clearance issues. When you are done you have what looks like an alpina performance setup but really it’s just for aesthetics. I don’t think that you have many good options that make sense honestly.

Since you are open to engine bay modifications, why not install side draft carbs?
 

Markos

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As I'm sure you know, Daddywad sells repro Alpina boxes for £525, it would be insane to destroy an original Alpina box for this.

https://www.dropbox.com/s/yfazccaqaaq7voq/CS PARTS BROCHURE[1].pdf?dl=0
Agreed on destroying and Alpina box. Daddywad’s setup is on my short list actually. I mistakenly had his “all in cost” on the brain when mentioning the $2K price. The cheapest original alpina box that I have seen was $3K.

I’ll have to see if we can just buy the box. I may actually be able to afford it then...

Hi Markos

total would be;

3 x manifold adaptors for carbs @ £120.00 = £360.00
3 x airbox elbows @ £120.00 = £360.00
1 x airbox @ £525.00 = £525.00
shipping estimate to WA = £280.00

total; = £1525.00 pounds sterling

thanks

Mark
 

nosmonkey

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Heres my Daddywad manifold mocked up on top of the stock Zeniths.




Physically they fit underneath, but obviously the mounting mounts dont line up. You could cut the bottom mounting flange off and have an flange welded in for the zeniths, or have an adaptor piece made up to mount the two. But at this point I see very little sense in doing so and you may as well just go triple carb, or as i'm doing, ITBs with standalone management.
 

WALTER

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Physically they fit underneath, but obviously the mounting mounts dont line up. You could cut the bottom mounting flange off and have an flange welded in for the zeniths, or have an adaptor piece made up to mount the two. But at this point I see very little sense in doing so and you may as well just go triple carb, or as i'm doing, ITBs with standalone management.
Thanks for those pics. I do agree that it seems like a lot of trouble to do this mod and at the end of the day it's just for looks, but I imagine if your real interest is aesthetics, its got to be cheaper to figure out the mounting than buying a set of triple webers or itb's especially if you are not going to do all the other performance mods that typically go with them (larger motor, better exhaust, etc.).
 

bfeng

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Is t this like putting an AMG badge on a stick W124 300sd? Why not keep
Your car honest and authentic? And I happen to think the stock air filter housing is quick attractive in a German form-follows-function way.
 

Ohmess

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That airbox was designed for sidedrafts, which sit much lower because the carburetors are mounted to the side of the manifold. Downdrafts, whether zeniths or webers, sit atop the intake manifold. I doubt an airbox designed for sidedrafts can be made to fit under the hood sitting on top of downdraft carburetors.

In addition, a downdraft airbox needs to be more centrally located under the hood, which means that you would need to design a way to mount the box in its new location.

Moreover, those airboxes are made of cast aluminum. Cutting and patching the cast aluminum to mate up to different carburetors and to mount in a different location would not be easy.
 

Nicad

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Most people seem to indicate these boxes hold back some power ultimately. They really muffle the intake sound (Which so many find intoxicating). Probably should only mod a fake if you really want to see if this can work. I can't see this having the flow of the stock airbox. I find they look great when refinished with newly plated hardware.
 
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