Racing Fuel Systems

In what situation would you use these downleg annular boosters? I believe these are Barry Grant from Allcarbs (Allstate)

On a single plane manifold

Where you want sharper throttle response without relying on acute acc pump tuning

Extra midrange torque in a lot of instances. That would lead to economy.

I don't think Barry Grant ever did any like that, but the traditional downleg and annular styles. Allstate appear to be using his concept (that may have been someone else's before him, who knows) and manufacturing these from std downlegs. Is it Braswell or BLP that do a mini annular? I have three Race Demons here, all downleg, and I think I will put a set in the Allstate shopping cart. Have to try them with the gold 1.500" sleeves.

Are not annular boosters usually straight leg is what I'm getting at?

Need some inside and outside diameters

Arrived today. 12 hole. I'll post up some dimensions soon.

Done a rough sketch for dimensions. They use a Holley downleg which is the same outside dimensions as the Barry Grant except thread diameter, Holley being a bit smaller. On the drawing below booster leg i.d is .189” for the horizontal section where the thread is and .158” for the angle section. Entry at the top of the booster is .405” and it tapers to .377” where the series of holes are. The i.d of the insert then expands to .470” to the tail end. X12 fuel exit holes approx .026”-.028” (a little difficult to measure). Tail is exactly level with venturi minor diameter.

Thank you for the detailed information. Will you report how they work?