carb help

[antyates]

I going to buy a mighty demon carb
wondering which one to buy--750--825--850
I have a 393 sbf i my mustang gt (1986) victor jr heads, lunati solid roller cam duration @.050 is int.244 ex.255 lift is int.644 ex.655
5-speed with 410 gears
Barry grant tech line said for my app. and also being a street car go with the 750 but just trying to get other oppions, they said 850 id lose some bottom end.

 

[SublimeRT]

I think it depends on how high you'll be turning the motor. You can use this formula, (CID x Max RPM) / 3456 = CFM, to find the CFM at max RPM in a 4 stroke. The answer will be assuming 100% VE though and will need to be adjusted for your application. Maybe that'll help.

 

[lang williams]

sublime is close u gotta throw volume efficiency in too of about 80% on a street motor. i did the equation with 6500 rpm an came up with 591 or a 600 cfm carb. which sounds small to me. my brother has a built 350 with a speed demon 850 an its way too much carb, he called the tech line an they recommended a mighty demon 650. hope this helps.

 

[93 LX]

I have a 5.0L with some mods and I have a 700 cfm DP. I tried a 600 and 650 but they seemed to cause the engine to struggle to get to 6 grand. With the 700 it gets there in a snap and it has better top end power. I have been told by people the 700 is too much but an pioneer in 5.0 chris kaufmann that with my combo the 700 was just right. See if you can borrow a 650 carb and go from there.

Allen

 

[86bluecobra]

I would think the 750 would be lots. I have a 750 on my 351w and it runs rich. Those extra cubes should be handled easily by the 750. Unless you plan on reving the engine to 8500+rpm that is.