Head flow and power differences question / discussion

OldmanRick said
Kinda depends on what you have here. For a street car i wouldn't spend the extra coin to update to the 325's if you already have the 293's.

100%!

273 said
With the 2hp per cfm rule of thumb, 293 cfm = 586 hp, now it can make more than 2hp:cfm but if it making a lot over 586 hp you’re probably under headed.

How so? Big call considering there is no other information.

If everything here is getting you well under 2hp:cid eg.. 475-500 hp with the 293 cfm/586 hp head the 325 cfm might not add anything or not much, if making 550-600+hp the 325 probably add a decent amount depending on cam.

Flow curve dependent.

if making well under the 325 hp 2hp:cid probably effects throttle response, but probably make the 293 cfm heads hp + with lesser cam, which makes for worse driveability large cam or heads?.

Could you clarify this?

Richard Holdener has tried to find out if you can over head size and flow on the dyno, he has found bigger generally don't lose power but there's point where gains are smaller and smaller to not at all, but as for real world performance and driveability that question is still up in the air, with a 416 I think you have less chance of side effect especially if 550+hp is the goal.

Engine masters did the same. Freiburger claims he failed since the test of, “Is there such thing as too large of a cylinder head” test didn’t show what he was after. Darn shame.

Maybe some day I’ll try it myself.

coloradohill said
Sounds like I should stay with the highest flowing head I have.
Thanks

IMO, not knowing anything else except this is an”Street car,” I’d stick with the 293 heads. I have a set of TF heads on the wife’s car. The small super efficient port is really quite good and super drivable. Provides a good top end charge and excellent low speed torque with feeling any dead spots down low in the rpm range, good pedal feel on tip in from idle and at any point driving.

RAMM said
If anyone has already mentioned it , I apologize. I didn't read every single post closely.

Part throttle and "tip-in" is where you will see the biggest differences, with the TF being superior over the Indy's. You might make more power with the Indy's but considering where the engine will spend 98% of its time unless you are an avid racer--I'd go TF and sell off the Indy stuff. Just my two pennies. J.Rob

While I don’t know if I’d sell off the Indy stuff so quickly, I agree 100%.