Two friends two different sets of heads. Each is selling for relatively the same price -1k. Which would work best on a 350 LT1 a4 motor with a custom cam which will be designed for whichever set I buy? I know this is a subjective thread but lets assume the port work is top notch for both and the ports are shaped appropriately. Hard to compare exhuast numbers b/c of pipe and no pipe but really want to compare intake only so assume exhaust flows the same.

First set 185cc intake 2.00 1.56 Manley race flo 918 springs

.100 - 87
.200 - 153
.300 - 211 / 159
.400 - 250 / 178
.500 - 271 / 185
.600 - 276

*exhaust flowed with NO pipe. 28" depression 4.00 bore SF600

Second Set 195cc intake 2.00 1.56 Manley race flo 918 springs

.100 70.01 59.9
.200 136.9 112.2
.300 201.2 159.8
.400 242.4 193.3
.500 273.01 210.6
.550 279.9 217.2
.600 286.7 223.9

*exhaust flowed with 1.75 pipe. 28" depression 4.00 bore SF600

 

Mid lift numbers are better on the first set. I'm no expert, but I would pick those.

 

thats what I thought as well but I am no expert either. hopefully at least one will chime in.

 

Are those intake volumes after porting? What is the minimum CSA of each head? Were they tested on the same bench under the same conditions? To decide, that's what you need to know among other things.

Rich

 

Assuming everythings equal (same bench same conditions) it would depend a lot on your cam, with the first set you'll be able to run a tamer cam, which would make things more street able as well as keeping your valve train alive longer.

 

intake cc volume after porting. Not tested on the same bench (but assume they were) both benches were sf600. I know that doesn't mean much. A lot of variables here but I really like the mid-flow numbers on the first set as I those are the highest I have seen on a ported stock casting. I was wondering if it is better to have more powerful midlift numbers than at .500 and up and what 10cc's less on the intake could have on power (assuming csa is the same or very close)?

 

IF the head volumes are as stated (I am suspicious because of the round numbers - those sound like preporting specs) the 185cc head would likely be better for reasons already stated.

Rich