Brad,

We are almost neighbors, . I'm in Lorton right now, .. but just sold my house and am moving down to Henrico Ashland area in a few months. Close to Richmond.

Selling the $600K house for a $190K house on 2 acres where I can build a new 40x60 shop. $1800 a month for 1000 sq. ft shop space is just stupid around the DC area, .. so I'm outa here.

I have two flow benches, .. I have a SF110 that I use for small stuff, 4 cylinder road race heads, quick jobs, etc. I also have a custom that flows 900 cfm at 36" h2o for the pro stuff. The big bench is up in Maryland since I don't have room here right now .. moving shop.

Jim Justice at Justice race engines in Frederick has a FlowData that will hit 800 cfm at 28", .. but I don't know
if he has run it lately.

The difference between the two is often less then a cfm if I use the same bore adaptor and intake radius.

The MOST important thing with a sf-110 is all the corrections. You HAVE to do temp & barometric pressure corrections to get accurate cfm numbers.

I use the Performance trends Port flow analyzer software, .. have a flowcom on the bench that feeds info right into the computer, .. and it's dead on. The other advantage to the Port flow software, .. and more important then flow numbers is it does all the flow coefficient math too.

I just had a set of small block chevy 12º comp heads that flowed a peak of 388 cfm @28" I flowed them on the 110 at 7", .. then checked it on the other bench, .. corrected numbers within 1-2 cfm.

You have to remember a flow bench is a test tool, .. you test always with the same machine, .. and can't really compare to other machines. ( although the magazines have blown this CFM flow thing way out of proportion. )

What I would be more concerned about is turbulence in the port. Like a short turn can flow real nice and sound sweet at a 7" vacuum, .. but run it 32" and it turns into a category 5 twister.

Curtis

I just had a thought, .. yea , yea I know, .. it's rare.

While talking about "stage" porting, etc, .. THE MOST important part of this level of modification has not been talked about, ..
the valve job. With limited port work the valve job is the larger portion of what you should be paying for at this stage, ..
so porter dudes, .. what are you doing for valve jobs?

Just the standard 3 or 4 angles, .. custom cutter sets, .. ?????

This is by far the most neglected area. I get these CnC heads in from name companies, .. AFR, Dart, etc, .. don't want to
pick on the CnC porting cause it's often fairly good, .. but the valve jobs often SUCK! A few hours on the seat machine, touch up with a grinder and the heads pick up a bunch, .. other experience ??

Curtis

wow, this porting stuff really gets pretty intense, really making me rethink my "home" ported "j" heads and wheather they are worth a crap or not, now I have another reason to pull the motor this winter.

hey you think thats bad....the 906's on my 383 didn't even get any porting!!!

if i let the bench run long enough for the temps to stabilize, my bench reads 80% exactly with the calibration plate......always(the correction factor for my bench is 1.035).
thats what its read every time ive checked it in the
last 11 years.
winter, summer, humid, dry ..... 80%.
i rarely even bother checking it anymore.

what i did discover however was it matters which way the plate is oriented on the bench.

fast68, ..

interesting, .. so if you do the math with temp corrections to get a CFM number it always comes out the same?
My bench, .. like with themp corrections, . if the intake and discharge temps are different, .. when I do the corrections I get the same CFM, .. and the inclined always reads the same, ..
but if I don't do the temp correction the CFM number is wrong, ..

I tried the same thing with a Baro correction and it had an effect, .. VERY minor but it did seem to have an affect.

Could it be I'm being too anal????

I'm not worried about the final CFM number as much as I'm worried about the curtain area coefficiants.

Curtis

Curtis,
i just do it the way the owners manual says.
wait for about a 25deg spread between thermometers....take a reading....determine the correction factor.
they dont say to use the temp correction for determining the bench correction factor, so i never have.

since the reading has always been 80%, i rarely check the bench anymore.
i mostly check the calibration if ive tested a head and the numbers seem off from what i was expecting.
then i'll stick the orifice plate on to verify the bench isnt doing something "strange".
it's never been a problem with the bench.....it always checks at 80%.

to my way of thinking....the orifice plate just becomes the test piece.....and on my bench anyway, the repeatability for that particular test piece has always been right on the money.
regardless of whether you should use a temp correction for testing the orifice plate or not, the fact is the bench always shows it as 80% flow.
i'm satisfied with that kind of repeatability.

I guess the reason that I am taking an interest in this post is that there is a local builder that has a superflow 110 (i think) and I would like to get him to do some work for me, but I never knew a fair labor rate and kinda would like to know what improvement or detrement that I made, that being said,I have no idea what stock "J" heads flow, and I know there is no black and white answer to that, just an average, and I have no idea what would be a good flow number, the only other thing that has been done to these are the addition of 2.050 manley nail head chevy valves, and a 4 angle valve job, I guess the thing that I need to do is get some facts together and learn about a flow bench so we can sit down and talk this out and I wont get confused when he lays out some figures and technical jargon, and this forum seems to help me do that,,, and yes, from what I have heard ryanj is the man on the small block stuff, so his input would be well recieved, as well as yours and dwayne's,, thanks guys this is a good post.

dartman, the fact is....the only numbers you really need to be concerned with from the flow bench are the corrected flow numbers.

for a mildly ported J head with SBC type valves, tested on a 4" bore adapter....if you're in the 250+ cfm range(corrected flow @ 28"), you're doing pretty well.

most SB Mopar "home port" type work ive tested is usually in the 220's and 230's, although mid-240's is really pretty easy to attain, and doesnt really require much material removal....if you take it out of the right places.

thanks dwayne, that gives me a ballpark area as to what I need to talk to him about, from what I have heard from several other people that he has done work for, he is very good at what he does and very concious about his work,, from what conversation I have had with him, and what I have read from your posts, you two would get along quite well.

dwayne, what size bench do you have? just curious.. i have a superflow 600, and im looking to get a 1020 soon. i go along with dwayne on the porting small block stuff, ive done some nhra stocker small block stuff and think they are around 190/150 with a 1.88 and 1.60. ive done s/s stuff that flows 260, 240 at .400 lift that goes fast. with those things, as with alot of things, the low lift numbers mean alot.

jeff

I was never aware of any barmetric correction associated w/ the SF-110, either, although I know of certain benches (e.g. FlowData) that require it. I've never seen any noticeable variations when running a calibration check against the supplied plate, either.

Unlike Dwayne's, my calibration tests don't seem to care which way the plate is oriented. However, I have seen a small (but consistent) difference in calibration factors between tests run at 10" and 8"; I check for both, since those are the most common test pressures I use, and adjust the results accordingly.

As far as factoring in the intake / exhaust temp differential into the final calculation, I've done that... but really haven't seen much added value in taking that extra step. Since the consistency w/ the inclined manometer readings has always been good when retesting known ports, the only thing that the temp differential adjustments seemed to do was lower the final intake #s a few cfm and raise the final exhaust #s a few cfm. I really didn't see any improvement in test-to-test consistency with them...

"I guess it's a matter of the head porter to be "up front" with the customer & having an informed conversation with the fellow to see what he really needs"

Exactly.

I'd like to think that I had a little to do with this post. Dwayne and I had quite a talk and MAN, did he ever learn me. This whole post is very "enlighteneing" to the guy {like myself} that doesn't really know much about head flow and porting and such. I, too, appreciate the unbiased comparisons between different porters. It's really helpful to us all... Here's to you guys..

You'll, hopefully, be hearing from me soon,Dwayne...

blowfish, my feelings exactly, this has been one of the better forum's that has taken place on this board for some time, very enlightening informative and understandable, cheer's and 's

Jeff,
just a lowly SF-110 here.
the repeatability is excellent, but i dont think it provides a very realistic comparison between heads with vastly different port cross sections, especially the bigger heads.
the lower test pressure, and with that, lower velocity, just isnt able to saturate the bigger heads, so gains that might be made from increases in cross section either dont show up....or hardly show at all.

it seems as though on heads that flow 300ish or less (@ 28") the numbers parallel the numbers from a SF600 pretty closely, but on something like a Dart 360 BBC head or a B1, the numbers just seem to be too low.

yes.....i know i could stand to have a bigger bench.