boosters
01-31-2004, 05:53 PM
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Car: 1991 RS
Engine: 305 LO3(TBI)
Transmission: TH-700R4
boosters
i am looking at demon carbs in the summit catalog and i was wondering what the difference is between downleg boosters and annular boosters?
01-31-2004, 08:10 PM
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Car: '94 Corvette
Engine: LT1
Transmission: 4L60E
Annulars provide a better signal to draw fuel from the main circuit (Has opening all the why around the booster), while the downlegs have the least restriction to air flow.
Annulars tend to behave better at lower rpm with giant crabs, with the trade off being more restrictive. So annular are great for smaller CIN engines that require huge cfm carbs.
Here a pic of both side by side.
https://www.thirdgen.org/techbb2/sho...hreadid=184671
BTW: both are great for race.
Ron
Annulars tend to behave better at lower rpm with giant crabs, with the trade off being more restrictive. So annular are great for smaller CIN engines that require huge cfm carbs.
Here a pic of both side by side.
https://www.thirdgen.org/techbb2/sho...hreadid=184671
BTW: both are great for race.
Ron
01-31-2004, 10:36 PM
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Car: 86\92 Mutant
Engine: 355CI 430HP
Transmission: T-5 with mods
Axle/Gears: 7.625", Eaton Posi, 3.73
I converted my Holley 3310-1 from the " good " down leg boosters to Annular boosters ( Primary side only ) some years ago. The difference was astounding. Throttle response was much, much crisper and I was able to jet down two sizes immediately and still keep the same fuel curve.
01-31-2004, 11:02 PM
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Car: '94 Corvette
Engine: LT1
Transmission: 4L60E
Can't really answer that, but If ProForm had a choice between the two, I would of picked the Annular version. (ProForms bodies only come with downlegs)
In fact I ran an 830CFM Annular at 6300 feet on a 350CIN (Idle vacuum was about 7PSI
), and the fact the car even ran is a testimony to the design. I did have a wicket lean spot that (2) 50cc pump couldn't even correct. At this altitude an 830cfm behaves like a 1200cfm would at sea level. My only recourse was to swap out my Holley 830 body with the smaller ProForm body, and the lean/bog gone
You can’t go wrong with the Annulars ‘1fast91rs’. You’re just going to give up a little airflow, but not much.
I wonder what Nascar teams go with? I know they have to use a 4150HP – 830CFM, but I believe they have a choice with Annular or downlegs…
Ron
In fact I ran an 830CFM Annular at 6300 feet on a 350CIN (Idle vacuum was about 7PSI
), and the fact the car even ran is a testimony to the design. I did have a wicket lean spot that (2) 50cc pump couldn't even correct. At this altitude an 830cfm behaves like a 1200cfm would at sea level. My only recourse was to swap out my Holley 830 body with the smaller ProForm body, and the lean/bog gone You can’t go wrong with the Annulars ‘1fast91rs’. You’re just going to give up a little airflow, but not much.
I wonder what Nascar teams go with? I know they have to use a 4150HP – 830CFM, but I believe they have a choice with Annular or downlegs…
Ron
02-01-2004, 02:02 AM
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Car: 86\92 Mutant
Engine: 355CI 430HP
Transmission: T-5 with mods
Axle/Gears: 7.625", Eaton Posi, 3.73
Originally posted by ronterry
Can't really answer that, but If ProForm had a choice between the two, I would of picked the Annular version. (ProForms bodies only come with downlegs)
In fact I ran an 830CFM Annular at 6300 feet on a 350CIN (Idle vacuum was about 7PSI), and the fact the car even ran is a testimony to the design. I did have a wicket lean spot that (2) 50cc pump couldn't even correct. At this altitude an 830cfm behaves like a 1200cfm would at sea level. My only recourse was to swap out my Holley 830 body with the smaller ProForm body, and the lean/bog gone
You can’t go wrong with the Annulars ‘1fast91rs’. You’re just going to give up a little airflow, but not much.
I wonder what Nascar teams go with? I know they have to use a 4150HP – 830CFM, but I believe they have a choice with Annular or downlegs…
Ron
Can't really answer that, but If ProForm had a choice between the two, I would of picked the Annular version. (ProForms bodies only come with downlegs)
In fact I ran an 830CFM Annular at 6300 feet on a 350CIN (Idle vacuum was about 7PSI
), and the fact the car even ran is a testimony to the design. I did have a wicket lean spot that (2) 50cc pump couldn't even correct. At this altitude an 830cfm behaves like a 1200cfm would at sea level. My only recourse was to swap out my Holley 830 body with the smaller ProForm body, and the lean/bog gone You can’t go wrong with the Annulars ‘1fast91rs’. You’re just going to give up a little airflow, but not much.
I wonder what Nascar teams go with? I know they have to use a 4150HP – 830CFM, but I believe they have a choice with Annular or downlegs…
Ron
Nascar Teams have been using nothing but Annular Boosters for years. The fuel atomization is just so much better...and that increases fuel milage. Same for TransAm and most Pro GT1 cars. The Annular booster wins hands down....and with the latest designs, airflow restriction is minimal...if any.
The gains in torque curve, fuel milage and throttle response with an Annular booster out way any slight decrease in airflow.
And really, if you look at the Pro Levels of Drag Racing such as Pro Stock...what are they using? Dominators with Annulars I believe.
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