Port velocities

[larrycavan]

Thanks Larry but we haven't discussed the initial question I posted regarding the SSR vs L/D and Convergance Lift.

What's your feelings on that?

When you're not lifting over .050 - .100 beyond the convergance lift, how much can one really expect from SSR detail work?

[maxracesoftware]

[hdwgfx]

Forgive my ignorance, can you please define Convergence Lift ?

[maxracesoftware]

[larrycavan]

Thanks Larry....

Here's the port being tested with throttle body in place & OEM Stack.

There's a guy here in Pa. that runs a flowbench forum and does a heck of a job on custom work.....won't mention any names.....

[larrycavan]

more

[larrycavan]

another

[bruce]

Hey I saw that throttle body before! So that's where they go . . . I'm interested to see if that work did any good

[106-1194218389]

Nice pictures Larry C> and nice work Bruce. Ok everybody, here's my dilemma. The Dart 180 cc intakes still have too much velocity to get max horsepower at 6000 or up. I am not sure they will make 5500 as the high HP peak accourding to Pipemax. I am going to try again tonight but I am getting close to that's all she rode boys! These heads are going to end up pushing 195cc. Should I go a little more conservative and keep the HP peak lower which will cause the cylinder CFM to be less than the heads will flow which technically should slow the velocity down. Option 2: I have a set of 200cc Dart Iron Eagles that I think I can get the velocities correct on much easier. They will end up being about 215cc when done with correct velocities. This would be for a 360 cid SBC. What do you guys suggest?

[larrycavan]

[106-1194218389]

Well, Guys, I am close to success with these Dart 180's. I am probably close to 195cc now. I will cc the intake port tomorrow night. I widened port on divider wall side some more. I laid the SSR back some more and lowered the apex height some more. I also noticed that FPS was a little fast on the ramp up to the apex coming from intake manifold mounting surface ao I actually lowered the ramp up to the apex also. I then stramlined the guide boss some more. The port really sounds better. From .050" to .450" stayed the same or picked up slightly. But above .450" lift got better and less turbulance.
.450" lift FPS - pushrod on left and divider wall on right - top to bottom - 2.050" intake valve - Milodon Megaflow valve and not backcut yet.
pushrod SSR
364 335 319 202 226 286
364 319 303 286 303 303
319 303 267 350 391 350
CFM flow at 28"
.050" = 29.5
.100" = 60.7
.150" = 94.6
.200" = 125.6
.250" = 155.0
.300" = 180.1
.350" = 204.1
.400" = 224.4
.450" = 242.9
.500" = 257.6
.550" = 264.5
.600" = 247.1
.650" = 249.8
.700" = 253.6
.750" = 253.6
.800" = 254.2

That is a 42cfm gain over stock

[larrycavan]

[106-1194218389]

[color=#000000]Larry I have been fighting the turbulance demons. The port was one of the worst I have ever had for turbulance to start with above .500" I think it was built for stock cams and low rpm. I just wanted to keep the port cc's down below 200 for this engine. The port is starting to sound much better. At first it sounded like a tornado going through Kansas. Also the way these 23

[larrycavan]

John,

I'm curious about something. If you probe that port with a string, does it tend to turn left and down?

[106-1194218389]

This is a left side port. On a Small Block Chev you have paired ports. This is a left side port and as it gets to the cylinder bears to the left to enter the cylinder. I ran a string down the port this morning at .800" lift and .550" lift. .550" lift is where the most turbulance is. At .800" lift there is turbulance going over the SSR and the string moves to the left when I hold it on the pushrod side at the roof the string bears to the left and jumps all over going over the SSR. At .550" lift it is very jumpy going over the SSR as would be expected from the readings I get, but always bears to the right side of the bowl going over the SSR. This was very interesting as I used a long string so I could hold it away from the port entry so I would not disturb the flow. Very enlightening as I have not done this before. You can visualize the whole flow path and the string curves and follows the air path. Really kind of cool to see the string suspended and curved in the path. I learned a lot from a little piece of string. Isn't it amazing how we can spend hundreds of dollars, or whatever our currency is :;): ) on research equipment and not even a pennies worth of string reveals so much.
ADDENDUM:
I just went and flowed again at .450" lift where I am checking my velocities. This lift has only 1/5th the turbulance as at .550" lift. The velocity is the highest right over the the center of the SSR, 391 fps, the string is always forced over the center of the SSR. The string does not jump around over the SSR as it does at the other two lifts. It does have a little bit of the jitters but not anything like above .500" lift.