LilJayV10

iTrader: (5)

I have read threads on this before, and have tried to so a search just for that topic. I didn't know were else to post this, so it might get moved.

My question is this, for example, AFR ported 195 v AFR 220. Both have about the same flow numbers. but which is better? is it dependendt on what motor its going on?

Lets say they flow 300cfm at .600, is that 300cfm the same coming from a 195 compared to 220? I know port velocity is going to be better at 195 because you are shoving or pulling, more air through a smaller area compared to a 220.

One of the reasons I am asking is I am in the process of trying to decide what heads to get for my 406. I had protopline 220's on before, the car ran mid 7's in the 1/8 traction limited, and was just as streetable and fun to drive as my stock 305 TBI.

I have seen several people on this board, 87_TA is one of them, who runs 10's with a 406 and the ported 195's.

thanks for any info.

Jason

89Nighthawk

Flow is important, velocity is important but overall it is the quality and quantity of the charge that matters most. You can have a head that flows 300 cfm on the intake but the chamber is crap and you have a lot of unburnt fuel going out your exhaust, meaning the power doesn't equal what is expected given the flow rating. That is why some heads defy conventional thinking on flow equals horsepower because they are MORE EFFICIENT than typical heads. This usually means high velocity and great swirl and a very efficient combustion chamber. I'm fairly sure the new AFR Eliminator heads will prove this to be true.

Picking what port size you want is dependent on displacement, rpm range and the cam you're going to run. When you match all of your components then you will get a great running engine. Typically use the smallest port for your engine that you can for the highest velocity.

shaggy56

I know it drives me nuts on how big block heads with their big old ports make so little power compared to small block heads. You know if you compare not just Chevys but every engine ever made that the small block port is rather small to begin with compared to other engine head ports that have been made in history.

contact

do other engines have the insane
multiple choice / intake-port-volume,
like the SBC ?

it would seem to me that there is...
...concerning the intake manifold..
.
--> a matching 'cross-section-area' <--
.
.
or maybe not,
please enlighten me
.
and if so,
what is it

I'm kinda tired of,
I've got a secret