is 420 hp too much for a 670 holley street avenger :confused:

I'll take a stab at this. Carb selection isn't based on horsepower as much as it is by CFM capabilities of the engine. The standard formula I've seen around is this:

Cubic inches x PEAK RPM x Volumetric Efficiency
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3456

Volumetric efficiency is the tough one to figure out. For a performance oriented street engine I think somewhere in the .75 to .85 range is reasonable to assume. A V.E. of 1.0 assumes that the engine can move 100% of the air it theoretically could move. Engines that are super or turbo charged can exceed a V.E. of 1.0.

Using the above formula, I was surprised as to how small a carb I should be using. It came out to less than 525 CFM on a 350 rated by GM at 430 HP at 6,000 RPM assuming a VE of .85.

The Holley Street Avenger is a vacuum secondary carb, and as a rule, they are more forgiving when mis-sized than are mech secondary carbs. I had a 670 Street Avenger on it and it ran great!

I am open to any and all criticism on this, and interested in the opinions of others.

I fully agree with BPOS on both his math reasoning and recommendation. Most tend to over-carb. their engines, which leads to output loss in the lower ranges. Look at flow rates for carb.s used on GM's most killer factory motors, they tend to be smaller than you would first imagine. The 670 should be capable of supporting your engine at max. output. The final jetting numbers may need to be adjusted based on your plug readings, but this will be slight compaired to trying to get to large carb. jetted down to work right in the low and mid ranges. The drivability of the smaller carb. on a street car will be greatly enjoyed.

I have been told that bigger is not always better!
:D

You haven't been talking to my wife. :rolleyes:

Deluxechev, I bought an Avenger 670 for my wifes ragtop and I love the carb.... As far as Holley's go it's one of the more forgiving carbs to works with. As others have stated, you'll need to fine tune it by playing with the jetting to get it perfect. I treated the guy's at the local Jiffy Lube to pizza in exchange for some tune time on their emissons analyzer to get mine dialed in.

Regards,
Tom

thanks alot! you guys are awesome!

Hot Rod stuck a little 625 Demon on a 383 making 355 HP and 450 lb-ft torque a while back.