Intake Flow w/o Valve??

[Rick360]

I saw a fairly well know and respected cylinder head porter, while analyzing a head ported by someone else, flow a intake port normally, then remove the intake valve and flow it again without the valve. He didn't really explain why he flowed the port without the valve.

Questions:
Why would you want to know the flow without a valve in the head?

What can be learned from this?

What would be good or bad flow numbers without a valve, as compared to with a valve?

By the way - great site

Rick

[speedtalk]

Hi Rick, Thanks for joining the site. Whenever I'm looking for more high lift flow I'll test without the valve. I'm not totally confident in what the numbers mean, but I feel if you pull the valve and the high lift doesn't pick up, you can ignore the bowl and chamber.

[bill jones]

-one example I have is BBC Dart 320 head that flows 357(good port) and 343 (poor port) flow 375 and 354 without valves but with the stems holes plugged with a pilot that protrude several inches towards the valve seat.
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-Darin Morgan and Larry Meaux both probably has some insight on this subject

[maxracesoftware]

Thanks Bill for your other Post on Port Lengths
here's 1 more =

Dart 320cc Good-Port-Direction
7.200"=Roof
4.840"=Floor

6.020"=Port CenterLine Length using Scotch 3M #218 Fine Line Tape

and maybe a thinner Automotive/Paint-Body PinStripe tape would be better to use than the 3M#218 ??
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you would Flow Test the Heads without the Intake valve ..as to create a sort of Port Flow Coefficient to compare the Flow Curve "with" a valve -vs-what the Heads Flow "without" a valve...sort of shows what Flow might be possible

you could also make a comparison or judgement about
Port Flow Coefficient -vs- Curtain Area Coeff or Valve Area Coeff
all based upon the theoretical Flow CFM possible for a given area and differential pressure

[Adger Smith]

It also helps to show your customer what to expect out of his cores. You can then explain that you can spend a bunch of time & money working the port CC's larger or make what he has more efficent.
I have never been able to make a 320 /2.250 head flow as much as a 360/2.35 head. It also helps to show them how proper valve seat angles can increase flow through the lift curve.
I hate the customer mentality that Bigger is better & all they want is a big # at hi lift. Must be a male thing! :~) Can you say Testosterone poisoning?

[maxracesoftware]

Hi Adger, a few Chrysler Port CenterLine Lengths you might like =>

W8 alum SBC (ported shape)
Intake Roof= 7.325 Floor= 4.605 Length= 5.965
Exhaust Roof= 4.660 Floor= 3.150 Length= 3.905

P5-Hemi (Ported shape)
Intake Roof= 7.660 Floor= 4.915 Length= 6.288
Exhaust Roof= 4.880 Floor= 3.160 Length= 4.020



here's a few more GM SBC Port CenterLine Lengths =>

LS-1 (ported shape)
Intake Roof= 6.400 Floor= 4.575 Length= 5.488
Exhaust Roof= 4.240 Floor= 2.390 Length= 3.315

GM # 12555690 LT-4 (ported shape)
Intake Roof= 6.285 Floor= 4.580 Length= 5.433
Exhaust Roof= 3.840 Floor= 1.915 Length= 2.878

GM #034 cast-iron Bowtie heads (ported shape)
Intake Roof= 6.200 Floor= 4.620 Length= 5.410

GM #292 cast-iron Turbo heads (ported shape)
Intake Roof= 6.090 Floor= 4.300 Length= 5.195

GM Dart-Buick alum 10 deg SBC (ported shape)
Intake Roof= 7.200 Floor= 4.770 Length= 5.985

GM Chevy 18 deg SBC alum (ported shape)
Intake Roof= 6.800 Floor= 4.370 Length= 5.585

ProAction/ProTopLine cast-iron 285cc 14deg (ported shape)
Intake Roof= 6.860 Floor= 4.475 Length= 5.668
Exhaust Roof= 4.430 Floor= 2.510 Length= 3.470

GM SBC Canted-valve alum (ported shape)
Intake Roof= 7.420 Floor= 4.570 Length= 5.995
Exhaust Roof= 4.410 Floor= 2.300 Length= 3.355

AFR 210cc (ported shape)
Intake Roof= 6.165 Floor= 4.500 Length= 5.333
Exhaust Roof= 3.865 Floor= 1.935 Length= 2.900

LS-6 (ported shape)
Intake Roof= 6.480 Floor= 4.525 Length= 5.503
Exhaust Roof= 4.385 Floor= 2.400 Length= 3.393

[Adger Smith]

Thanks Larry,
It's nice to have the data when you need it. Sure will be a time saver.
I have just taken on a couple of old race buddies work. Got any data on Briggs engines? lol Yes, they are old racers that are into the grand kids JR dragsters. I'm going to set up the flow bench on a few of these & see what making power in them is all about. Looks like there is a bunch of areas to inprove them. I saw one "Name" built engine with ex ports about 20% larger than the intakes. ????? These flat heads might be an interesting challenge. Larry, or Any one have any thoughts?

[bill jones]

-One thing I found about flowing flathead intake is to: do NOT use any restraint in the intake valve, just turn on the flowbench and the valve will open to the best AIR flow point, then hold the valve in that position and determine that lift.
-That has always showed me the EXACT max lift point for AIR.
-I would then investigate the intake the same way using wet spray testing.