2 of the links have my flow #'s. They are max port. No current dyno numbers.

Jeff D.

 

"I agree the LT1 stacks up well here, esp. with the full port. Acc'ding to Lloyd, the LT4 will go up a bit higher ultimately, to a little over 290 at "full port," but it sounded like it wrecks the low end of the powerband."

that's probably not far from the truth. head porters usually get a raw deal. they have to put out high numbers for the public because that's what those who don't know any better believe makes all the power. so you get what you "want" instead of a head better suited to your needs.
if the head only flowed 260 cfm you'd likely find another porter regardless of the fact that the head made an average 10 hp and 10 ft lbs more power than what most were getting with better/higher numbers. this is often times the case but it all gets lost in the misconceptions.

my last engine was hydraulic cammed with afr 195s hand ported to 271 cfm at peak. not as impressive as a 290 cfm head but this engine made 527 hp 455 ft lbs at the flywheel before any power adders.

JB

 

Jeff what flow would you recommend for a cc305 cam?

 

The one thing that I have seen in several places is that on a street engine, you want to keep the intake ports on the small side. Apparently that improves low-end torque and throttle response. Given that the LT4, even in max port form, doesn't flow THAT much better, I don't see the benefit on a street engine. That last bit of performance is awfully expensive. LT4 heads stock cost about what I paid for my heads.

The most interesting part was the as-cast numbers. The LT4s fairly kill the LT1s in that sense. But ported, the numbers aren't that much better.

BRAD

 

Aggiez28, I just had them given a "street" port job b/c I drive this thing everyday. Maybe later I'll pay extra to go "full port," but right now I'm only gonna be spinning 6200 rpm's and then only once in a while. I'm still fairly new to modifying and I don't want to go overboard at first and do something irreversible. But my intent was to get a good set of heads that I could "grow with."

Incidentally guys, Lloyd sent me the correct .1 numbers. They *were* .05 before. Here is the new set:

Int. before/after
.100 62/66
.200 125/132
.300 177/186
.400 218/233
.500 243/270
.600 240/283

Exh. before/after
.100 45/49
.200 89/99
.300 123/131
.400 144/152
.500 158/167
.600 163/175