All the bonnets I've seen have basically the same design. The inlet faces perpendicular to the bores, with a small plenum like area on top, like so:



It seem to me there are some design improvments to be made, as hood clearance isn't a problem for me (5" cowl). I was wondering if a 3", 90 degree elbow, could be placed directly on the top of the bonnet. That way, incoming air is going directly down the bores. I imagine this would work much better, or am I wrong?

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

The problem with using a 90 deg mandrel bend is that the the mass air flow will be against the outside of the bend. This makes *much* more air flow through the carb barrels near the bend's outside, and little air on the short side radius. Using a bonnet, it acts as a plenum, effectively giving you equal flow for all carb bores.

I guess the one thing to consider is how much flow loss the sharp transition in the bonnet gives, compared to the bad flow distribution with the mandrel bend.

If you use a throttlebody instead of a carb, flow dist doesn't matter as much since there is no fuel involved. HTH!


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Andris Skulte
Skulte Performance Designs
Z28tt-89 IROC T56 DFI Twin Turbo
http://www.skulte.com

 

Thank andris...I was wondering later how big a downfall the bad distributuion would be.
guess that answers that

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

all the guess work has been done for you already. make one with a smooth 90 deg. bend if the one from the carb shop is not in your budget and hood clearance is not a problem. it's been proven not to have distribution problems though.