Carb size opinions

[Paul57]

What size carb would you run on a street driven LQ9???
It has a very mild cam so my shift points should not be over 5500, if that.
I ran the numbers on the carb calculator and came up with 580 cfm.
Does a 600 carb seem ridiculously small for this motor or do I just need to realize the math is more accurate than my ego (bigger is better)???

[Paul57]

Someone must have some suggestions or thoughts on this???

[Pop N Wood]

Everyone is still sleeping off last night's Holloween parties. Give it time.

In the mean time try using the search button to view some existing info

carb'd ls1 database

Anyone tried a carb intake and dist on a ls1?

Seems like the most common carb size is a 750 CFM. These motors flow more air than the first gen motors, so different rules apply.

[Paul57]

Thanks for the links.
I knew these motors flowed more air...however, I did put 100% VE in the calculator to come up with that figure (580 cfm).

[Dickie-311]

i'd say atleast a hp750 carb

[forcd ind]

i pretty much run 750's on everything 350 ci and bigger

[ramdaspadhye]

If you're not spinning over 5500, a 650 will be fine.... 750 is really overkill unless you're running a large cam and spinning over 6k. Any cam under like 228 duration will be fine with a 650 carb

[NemeSS]

i reccomend you check out the holley HP street carbs.
the vac. sec. 650 will be adequate for your build. and is less than 400$ new

[juced211s]

See link below regarding why the carb calculator gave you a smaller number than logic dictates See link below regarding why the carb calculator gave you a smaller number than logic dictates....http://www.carcraft.com/techarticles/selecting_right_carb/index.html
To sum it up, Carbs are rated at 1.5-in Hg pressure drop. At wide open throttle your engine should be between 0 and 1-in Hg. Hope this helps. By the way, as stated previously, a 650 DP or a 750 Vacuum Secondary would work well on that engine in that truck.