My LT4 Cylinder Heads were flowed on Charley's Speed and Machine Superflow flow bench.

In both cases:
standard depression of 28 inches of water,
same end cylinder,
contour on the intake port,
as well as without a exhaust tube on the exhaust port.

Intake Port

Lift--OEM--CNC #1
.100 060.5 063.5
.200 123.0 133.9
.300 173.0 194.4
.400 209.5 236.0
.500 240.2 269.7
.550 230.1 279.7
.600 231.9 281.5
.650 233.1 279.5
.700 ------- 277.3

Exhaust Port

Lift---OEM---CNC #1---CNC #2
.100 047.6 058.0 051.2
.200 103.1 108.3 098.9
.300 131.2 140.6 144.7
.400 154.1 161.2 161.6
.500 164.5 172.8 180.3
.550 167.8 177.4 186.6
.600 169.1 179.9 191.6
.650 171.6 181.6 195.8
.700 ------- 183.3 197.8

Notice two tests for the ported version. As you can see the port flow did not improve as well as one might expect and CNC's explaination is a possible core shift. Wish they would have noticed this on the first visit to their facility. I was also running into issues with valve float at a very low 6100 rpm where before the OEM setup ran strong to 6400 rpm (the limiter)! The second visit to Florida, resulted in some hand porting to improve the flow numbers and some investigation to the valve float issues.

Overall, I would not recommend CNC Cylinder Heads in Pinella Pines, Florida. The product did not achieve the advertised numbers, they did improve-no argument, but not to the numbers quoted or expected from $2196.

	Cylinder Head Flows
1996 Corvette LT4 Engine Development Current Modifications Single Mass Conversion	My LT4 Cylinder Heads were flowed on Charley's Speed and Machine Superflow flow bench. In both cases: standard depression of 28 inches of water, same end cylinder, contour on the intake port, as well as without a exhaust tube on the exhaust port. Intake Port Lift--OEM--CNC #1 .100 060.5 063.5 .200 123.0 133.9 .300 173.0 194.4 .400 209.5 236.0 .500 240.2 269.7 .550 230.1 279.7 .600 231.9 281.5 .650 233.1 279.5 .700 ------- 277.3 Exhaust Port Lift---OEM---CNC #1---CNC #2 .100 047.6 058.0 051.2 .200 103.1 108.3 098.9 .300 131.2 140.6 144.7 .400 154.1 161.2 161.6 .500 164.5 172.8 180.3 .550 167.8 177.4 186.6 .600 169.1 179.9 191.6 .650 171.6 181.6 195.8 .700 ------- 183.3 197.8 Notice two tests for the ported version. As you can see the port flow did not improve as well as one might expect and CNC's explaination is a possible core shift. Wish they would have noticed this on the first visit to their facility. I was also running into issues with valve float at a very low 6100 rpm where before the OEM setup ran strong to 6400 rpm (the limiter)! The second visit to Florida, resulted in some hand porting to improve the flow numbers and some investigation to the valve float issues. Overall, I would not recommend CNC Cylinder Heads in Pinella Pines, Florida. The product did not achieve the advertised numbers, they did improve-no argument, but not to the numbers quoted or expected from $2196.
	Comments: tmcarthurs@hotmail.com