pronger44

are aluminum AFR 220cc heads too much for a 350 even if it's supercharged?

BlownBird

Contrary to popular belief, no head is too much for a supercharged motor. The more volume you can push in, the more power you will make.

89ProchargedROC

True, but you cant put in a baby cam......so that has to be considered also

paul_huryk

Actually, that is not entirely true. For a roots (or positive displacement supercharger), yes - you force air in. For a vortech/paxton/powerdyne/ATI - no, it needs to spin higher to give boost (compressor type supercharger and turbos).

I'm not even mentioning the fact that if a blower is too small for a motor (a 144 on a 500hp 383 for example), it may actually be hurting performance.

The rule of thumb should be (regardless of supercharging/turbocharging) for picking heads - pick the smallest cc head with the highest flow in the range you are operating (.700' lift flow #'s don't matter if you are running a .500" cam). For example, a 180cc head that flows 250cfm is a better choice than a 210cc head that also flows 250cfm. The smaller head will produce more bottom end TQ with the same hp, which makes faster acceleration.

You should check exh/int flow % on the heads you wanna buy. If it is above 80% then you can run a single pattern (or dual); below 80%, run a dual pattern (supercharged/turbo/N2O).

pronger44

so with a super charger it's all about the cfm's not cc's?

paul_huryk

pronger,

The answer is yes (in most cases), but that also applies to NA motors too. The exception is when you need to run big ports in order to get to a certain RPM level (using a super Victor for 8000rpm), which is typically rare on a streetable motor.

Maybe I went off in a tangent with my last reply, but the idea is to get a nice flat powerband, which includes a good low-mid range TQ presence. You can't get good low end on a 350 with 235cc heads, but you can with 1800cc ones - and you probably never be able to use all the flow the big heads have on a sub 8000rpm motor.

I would say go for the 190cc heads and a supercharger (if you want it). AFR has dyno tests of some motor combos on their web site - take a look.

Guido

Good thoughts there fellas.

The smaller the port, the higher the air velocity; hence your low end torque production.

BlownBird

Sorry for the bad info guys... I was thinking on the lines of max power. Guess i better build a larger motor for my heads

89ProchargedROC

No you dont.....your motor is setup very well

87_TA

When building a blower motor the larger intake runners the more volume the charger has to fill there fore losing boost and velocity.
You dont need super high flowing intakes because you are forcing your air in,the exhaust side of a head is the area that needs to be concentrated on with a blown motor to eliminate self EGR,ing.

89ProchargedROC

That is true and it isn't........you dont NEED a better flowing intake

BUT

it will allow you to make the same horsepower with LESS pressure (boost) because it flows more air

--Also, on a side note.....if you are worried about losing velocity in the heads with a blown car you are one sandwich short of a picnic

87_TA

Better flowing,yes..
bigger,no..
read the post,and i will keep my sandwich.

89ProchargedROC

huh?

chew a little more and respond again please

logikal6785