FLOW Bench / Optimum Valve Lift - Chevelle Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Search this Thread Display Modes
post #1 of 13 (permalink) Old Aug 31st, 19, 12:00 AM Thread Starter
Team Member
Nelson
 
Join Date: Jun 2019
Location: Miami
Posts: 41
FLOW Bench / Optimum Valve Lift

Ok got a question, not sure if my theory is off but hoping someone can clear this up for me.

I built a diy flow bench. Couple details first cause I know itís important to note. Iím pulling 25w.c. With my 858 square port heads with intake valve open to .600Ē not to bad for now. I may add a fourth wetvac, got one more at the farm.

Oh and Iím using an old vane anemometer, but going to use a newer hot wire cfm meter going forward.

Ok hereís my question.

Im looking to determine at what lift the head alone with intake or exhaust open the head flows best. My thinking is for example if the intake flow stops increasing at .500Ē lift and the exhaust stops increasing at .470Ē why pick a cam with more lift if itís not going to mathematically offer any performance gain??

In my case Iím limiting other variables to 65deg overlap. While maximizing duration to what ever that overlap allows me to.

I guess what trying to say is, the flow bench can dictate what max lift cam I shoul target. Any excess lift would just kill the effective stroke.

Thanks
Nelson

Pics of my Mickey flow bench.
Attached Thumbnails
Click image for larger version

Name:	5CB786CF-F2CD-4A95-AE6F-175365E2C3BC.jpg
Views:	26
Size:	123.8 KB
ID:	601942   Click image for larger version

Name:	D0713C70-EBAD-417F-ADEB-6F53F6F7C0CD.jpg
Views:	24
Size:	121.1 KB
ID:	601944   Click image for larger version

Name:	0E7DC654-1019-469E-A02A-BA00EA35B95C.jpg
Views:	25
Size:	127.5 KB
ID:	601946   Click image for larger version

Name:	5016E859-F46C-4E48-9A19-A33F9374C4CB.jpg
Views:	25
Size:	109.6 KB
ID:	601948  

68C427GO! is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old Sep 3rd, 19, 4:26 PM
Tech Team
 
Join Date: Sep 2002
Location: USA
Posts: 905
Re: FLOW Bench / Optimum Valve Lift

Ideally you would want the valve to lift to the flow point at which flow stops increasing, and hold it there for as long as you need it. But practically, that is not possible. So you then have to go to a lobe profile that is more reasonable (the lift derivatives are finite) which includes some sort of parabolic shape. That sometimes involves lifting past the point at which flow stalls, it's not necessarily a bad thing, you don't get additional flow, but you get the duration you need at the valve opening points where flow is a maximum

Sent from my SM-T817V using Tapatalk

Scott
70GS455 is offline  
post #3 of 13 (permalink) Old Sep 4th, 19, 1:04 PM
Lifetime Premium Member
Beth
 
Join Date: Oct 2010
Location: Nashville TN
Posts: 1,529
Garage
Re: FLOW Bench / Optimum Valve Lift

I think you're overlooking a very important limitation.

The intake valves are very large and heavy.

Going much higher than .600" lift gets into cubic dollars.

You will probably see improvements in flow way beyond .600", but what's the point ?

BTW rectangle port heads might perform well on a bench but they are too big for most street engines.

67 Chevelle convertible, 138 vin, original 4 speed, bucket seats, Marina Blue with black interior
nashville beth is offline  
 
post #4 of 13 (permalink) Old Sep 8th, 19, 3:05 PM Thread Starter
Team Member
Nelson
 
Join Date: Jun 2019
Location: Miami
Posts: 41
Re: FLOW Bench / Optimum Valve Lift

Ok so your basically picking a higher lift even if it donít flow more just so you can hit the max flow point twice. In essence your like extending duration in a vertical plane vs a horizontal. Sorry Iím sure that terminology isnt used in cam talk, but canít help viewing this as a tactic to add more duration at at max flow. I say this cause Iím not sure if once a max flow/lift is found that lifting valve more can in some unknown case flow less. In which case, I would think you donít want to hit a max flow point twice if between those points you actually flow less. My reasoning is your first max flow point hit was on the way up the intake lobe ( I would imagine there is some static regain to benefit from as the intake runner diameter changes benefiting velocity) and the second hit is on the way down the lobe. I would suspect that flow on the second hit would have been disrupted by the decrease in flow/vel. I canít imagine air flow and much less velocity re-establishing to the level it was prior to the first hit. That second hit I think is only seen on a flow bench type reading. Iím not trying to debunk any theoryís sorry if it may sound like it.

Please please feel free to step in Iím sure My thinking is full of holes. Iím new to this and the moment I heard flow your heads I was like ok here something tangible I can work with. Im looking forward to learning all about this very important step in engine building.

Nelson
68C427GO! is offline  
post #5 of 13 (permalink) Old Sep 9th, 19, 2:15 PM
Senior Tech Team
 
Join Date: Apr 2012
Location: Yerington, Nevada
Posts: 1,694
Re: FLOW Bench / Optimum Valve Lift

Well, dry flow air is completely different than what should be done, a metered air/liquid wet mixture flow bench.

I built mine over a decade ago, keep updating it, and get real world results. I also have a very nice dry flow bench, so I get both results from a project.

Dry flow is OK, I guess, but the heads I have done after dry flow, on my wet flow worked a lot better.

Just my take on flow benches.

Always remember one thing about custom head porters that live by the flow bench, you get the head that had a reduction in flow efficiency just after the best reading.
Dave Ray is online now  
post #6 of 13 (permalink) Old Sep 9th, 19, 7:56 PM
Boldly procrastrinating
Tom Terrific II
 
Join Date: Oct 1998
Location: Glendale, Az
Posts: 28,195
Garage
Re: FLOW Bench / Optimum Valve Lift

Nelson, if your port maxes out at .500 then running a lift higher than .500 will have the open .500 or more for a longer time. increasing flow velocity also helps. Many porting tricks that increase flow at higher lift kill off flow or velocity at low lift. It will pay you to realistic about usage. If this car is going to streetable and actually driven how much of the real world drive time will be around 6000RPM? Think about seat of the pants torque instead of high RPM horsepower. You still can't drive a dyno or roast the tires on a flow bench..

just my $.02.

Tom Terrific or Terrible Tom, depending on the phase of the moon, passing cosmic rays or other factors not fully understood except by my wife.
Tom Mobley is offline  
post #7 of 13 (permalink) Old Sep 9th, 19, 8:11 PM
Lifetime Premium Member
Jim
 
Join Date: Nov 1999
Location: International Falls MN
Posts: 6,193
Re: FLOW Bench / Optimum Valve Lift

The heads I got ported from Eric were tested to 1 inch & flow kept going up.

Jim

77 Monte
421 Profilers ported by Eric Weingartner, Straub HR 3200 conv. from Jake 200-4r w/ 3.73's
Machine work by Torvinen's machine
11.93 @ 112.7 & tuning
67 Imp.SS for the wife 275 hp 327-TH350
77 cruiser is online now  
post #8 of 13 (permalink) Old Sep 9th, 19, 9:16 PM Thread Starter
Team Member
Nelson
 
Join Date: Jun 2019
Location: Miami
Posts: 41
Re: FLOW Bench / Optimum Valve Lift

Dave. Hadnít even thought of wet flowing not really sure what one consists of. Would love to look into that at some point (wonít lie sounds messy...lol) for now Iím still trying to wrap my head around the deficiency in my diy bench. For one thing the accuracy of the hot wire anemometer Iím using is pointing out that velocity in the 6Ē pipe Iím using now are not uniform enough to trust for repeated reading. So Iím going to grab a medium static variable speed blower drive package I have up stairs ( I have a lotta crap in the shop 30yrs storing crap) and try to make something more legit. Which by the if you wouldnít mind would like to what you made for dry flowing. See Iím currently just interested in being able to flow engine components in an effort to establish a base flow point max flow and uniformity between ports.

Tom. Appreciate your points. As for adding a little more lift beyond the max flow point measured ( totally agree) but I guess that little bit more is a guesstimation. Iíll probably gauge the little extra lift based on overall valve events. Key limiting factor will be 60 to 65 overlap I want to stay within.
Iím being honest I know itís gonna be a street car with hopefully a little attitude. But overall I just donít want to leave any performance on the bench. I like knowing how things work, then I can live with the outcome.

I guess I may have drifted a little from original question. At this point I guess I need to build a reliable flow bench before I can share readings and get your feedback/advice

Thanks
Nelson
68C427GO! is offline  
post #9 of 13 (permalink) Old Sep 14th, 19, 8:12 PM Thread Starter
Team Member
Nelson
 
Join Date: Jun 2019
Location: Miami
Posts: 41
Re: FLOW Bench / Optimum Valve Lift

So far this is where Iím at with the new flow bench. I repurposed an old work table. but made it so I can remove 4Ē pvc pipe if Iím not using it. Currently Iím working on adding a air straighten to the 4Ē pipe. I made one out of a eggcrate grille but Iíd like something with smaller holes.

I might have to post few times to show all pics.
Attached Thumbnails
Click image for larger version

Name:	9FCCC73E-70D5-42C3-B24B-EBDECE25E5CC.jpg
Views:	6
Size:	74.1 KB
ID:	603382   Click image for larger version

Name:	2BF849E6-50B6-47F7-9F4F-129CEFF0349A.jpg
Views:	6
Size:	76.4 KB
ID:	603384   Click image for larger version

Name:	F1A51581-20E2-4BA0-818A-C46AD324CDAC.jpg
Views:	5
Size:	78.4 KB
ID:	603394   Click image for larger version

Name:	58ED4A13-349A-4F7B-A535-192333536EDE.jpg
Views:	4
Size:	69.3 KB
ID:	603396  

Click image for larger version

Name:	783A2CE7-372E-43F5-8534-A9C9B391949B.jpg
Views:	4
Size:	61.3 KB
ID:	603398   Click image for larger version

Name:	B2CC82A7-B04F-42C4-AAAA-653579DD887D.jpg
Views:	4
Size:	54.9 KB
ID:	603406   Click image for larger version

Name:	700E3E1D-9A2D-44B8-898C-8CFE27438938.jpg
Views:	6
Size:	59.5 KB
ID:	603420   Click image for larger version

Name:	D68E5DF7-EFA9-4215-B639-439BECEF17C4.jpg
Views:	6
Size:	90.0 KB
ID:	603422  

Click image for larger version

Name:	7AAED1D5-C473-4749-BC14-696FE5A71879.jpg
Views:	6
Size:	57.8 KB
ID:	603424   Click image for larger version

Name:	C0D45E29-F736-4AB9-BAEB-5C0004EE3502.jpg
Views:	6
Size:	70.1 KB
ID:	603426  
68C427GO! is offline  
post #10 of 13 (permalink) Old Sep 15th, 19, 12:56 PM
Senior Tech Team
 
Join Date: Apr 2012
Location: Yerington, Nevada
Posts: 1,694
Re: FLOW Bench / Optimum Valve Lift

Nice work, keep going.
Dave Ray is online now  
post #11 of 13 (permalink) Old Sep 16th, 19, 12:15 AM
Senior Tech Team
 
Join Date: May 2006
Location: SoCal
Posts: 10,906
Re: FLOW Bench / Optimum Valve Lift

Have you tried talking to Rich??? at PTS?

Quote:
This post is a duplicate of a post that you have posted in the last five minutes.

To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
cuisinartvette is offline  
post #12 of 13 (permalink) Old Sep 16th, 19, 8:03 PM Thread Starter
Team Member
Nelson
 
Join Date: Jun 2019
Location: Miami
Posts: 41
Re: FLOW Bench / Optimum Valve Lift

Thanks Dave.

Who is Rich? PTS?
68C427GO! is offline  
post #13 of 13 (permalink) Old Sep 17th, 19, 7:56 PM Thread Starter
Team Member
Nelson
 
Join Date: Jun 2019
Location: Miami
Posts: 41
Re: FLOW Bench / Optimum Valve Lift

Ok got it. PTS. Flow bench website. Thanks
68C427GO! is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevelle Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address. Note, you will be sent a confirmation request to this address.

Email Address:
OR

Log-in










Thread Tools Search this Thread
Show Printable Version Show Printable Version
Email this Page Email this Page
Search this Thread:

Advanced Search
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome