Flow figures for 87 "128" Heads ?
Racer
Joined: Jun 2000
Posts: 294
Likes: 0
From: WA
Re: Flow figures for 87 "128" Heads ? (CorvetteZ51Racer)
No, I don't have a swirl meter. I use multiple manometers connected to pairs of very small copper tubes mounted radially in a 4inch diameter plexiglas cylinder. Each pair faces in opposite directions to increase the sensitivity of the monometer and indicate direction. It works well for evaluating changes to a head but obviously my manometer readings can't be compared to strain gauge or rpm type swirl meters.
I also visually look at swirl & tumble by connecting a wet vac to the clear cylinder and spraying water with dye into the port and watching what happens in the cylinder. This also helps to identify where fuel droplets are likely to form and I dimple the chamber in those areas. I do this with an intake manifold bolted on and spraying in from the injector bung.
The shrouding of the intake valve I'm talking about makes the flow biased toward the long side chamber wall and toward the center of the cylinder. With biased flow it's easier to get swirl because the flow has direction. You can point the flow at/with the chamber wall and cylinder wall so that it swirls. If the flow leaves the valve equally in opposite directions it tends to not form swirl.
Do you have a swirl meter? If not, how are you measuring swirl? From a flow standpoint, you want 0 swirl in the port, and rely on the piston crown and combustion chamber to generate the swirl. Simply speaking, swirl kills flow.
I also visually look at swirl & tumble by connecting a wet vac to the clear cylinder and spraying water with dye into the port and watching what happens in the cylinder. This also helps to identify where fuel droplets are likely to form and I dimple the chamber in those areas. I do this with an intake manifold bolted on and spraying in from the injector bung.
The shrouding of the intake valve I'm talking about makes the flow biased toward the long side chamber wall and toward the center of the cylinder. With biased flow it's easier to get swirl because the flow has direction. You can point the flow at/with the chamber wall and cylinder wall so that it swirls. If the flow leaves the valve equally in opposite directions it tends to not form swirl.
Do you have a swirl meter? If not, how are you measuring swirl? From a flow standpoint, you want 0 swirl in the port, and rely on the piston crown and combustion chamber to generate the swirl. Simply speaking, swirl kills flow.
Drifting
Joined: Dec 2002
Posts: 1,861
Likes: 4
From: Houston TX
Re: Flow figures for 87 "128" Heads ? (JoBy)
Well, I just got back from the shop, where I flowed a set of 113s on the same flowbench I flowed my 128s on. In both cases, the chart JoBy found was optimistic on the exhaust side flow, but far less optimistic on the 113s than on the 128s. I don't happen to have the full flow chart in front of me (it's in the car), but the peak numbers for the 113s were:
Intake: 196.5 cfm @ 0.600" @ 28" H2O
Exhaust: 150 cfm @ 0.600" @ 28" H2O
Intake: 196.5 cfm @ 0.600" @ 28" H2O
Exhaust: 150 cfm @ 0.600" @ 28" H2O
