Measuring port velocities

[4v6]

Thanks for that Craig, it’s just as well I didn’t order it then!
My bench is based on the FlowQuick measuring electronics as you’ve correctly guessed and as you know doesn’t have any provision for measuring such thing's as velocity so an add-on device is the only option at this point.
I was seriously considering acquiring a Superflow bench like Guy's, to improve my capabilities, even the price hasn't really put me off, it's just other equipment must take priority at this point, this is getting serious!

May I ask what equipment you’re considering for measuring velocity with yourself?

Tony

[CraigAPD]

I built my OWN bench using FlowQuick hardware about 6 months ago.

Prior to that I was using a large SF bench, the 600 i think it was. I had free access to it whenever I wanted, but it usually meant taking at least half a day out of the workshop.
I will tell you that the results I’ve gathered from my bench are pretty much spot on with what was gathered from the SF. And the repeatability is superb. That aside its percentage gain you are ideally interested in, and repeatability is the key for this.

The main benefit, figures aside, is the time taken to test a head. It would take me approx 45mins to test each side (one port), up to say 12-13mm. this was entering percentage into a pre-made excel spreadsheet. The same test with the FlowQuick takes about 10-15mins!!! And with the same level of accuracy. Plus there’s then no graph plotting afterwards, as its all software generated!

So I really would try the FlowQuick first before splashing out. I’ve got good experience with both, and my conclusions are totally impartial.

For those not familiar with this set-up, it uses a digital measuring unit that displays CFM. You can then connect the measuring unit to laptop, and running the software they sell, you can plot CFM versus lift (as well as many others, percentage, l/d, etc), as it logs the measured value. So you simply set lift, adjust depression (not even necessary, as the unit corrects back to pre-set depression value, but its more accurate if you are at THAT depression), then press the hand held button! Hey presto - the data is logged. It then automatically moves onto the next lift site, ready for you to press the button again.
It’s amazingly quick...

[4v6]

Ive had pretty much the same experience with mine Craig.

Its extremely rapid to use, i can log and compare a full set of lift figures from 1mm to 10mm on a four valve head ( intakes) in just a few minutes.

The only small criticism i have is the stability of the display ( on mine at least) tends not to be exactly stable, so theres a little interpretation of the figures required, in that case i try to go down the middle of the "extremes" displayed.
Its not ideal for measuring the effects of valve seat modifications for that reason i feel, however it may be that my particular bench needs the pipework to and from the electronics re-arranging to even out turbulence that may be present and creating this issue.
Otherwise, its a fantastic item to have.
Ive learnt so much from it in such a short time ( Guy has pointed me in the right direction more than once) and i wouldnt be without it now.

[robert kenney]

In the event that the equipment supplier doesn't off add on apparatus. Why not build a device to allow reading relative airspeeds. You could use a impact tube gauge sizing of your choice as size doesn't matter as there is no flow in the pitot system and an aircraft airspeed indicator. As long as the system is a true pitot/static setup where it the static air references ambient air within the test area barometric correction(DA/temp)is applied to the readings You would have real velocity data. I have DA/airspeed charts from my aircraft experience if any body desires

I believe only relative readings would be necessary. Some one could correct me but the exact airspeed would only be needed to correlate testing on multiple pieces of equipment?

A digital PTD could also be incorporated and calibrated to a known airspeed gauge.

Robert

[Guy Croft]

Without wishing to divert from things currently under discussion member Martin Faulks drew my attention to some work he was engaged in using a sonic probe for port airflow evaluation (or something like that, typical of him - all very clever stuff).

If he reads this perhaps he would engage..

G

[tmvolumex]

This is an interesting discussion. I have a hand held wind speed meter that utilizes a small (apx 1 inch) diameter bladed propeller for measurement. As I recall it can measure air speeds up to 100 mph. A small, direct readout meter, such as the one I have could give you relative data quickly. It would be average port velocity since it would sample the entire port at once. I paid a little over $125 for the one I have, their are less expensive ($35 on an internet auction site) ones from China, but I would doubt their accuracy. Their are also hot wire models available for a a few hundred US dollars.
I was going to try this meter out for measuring the relative efficiency of 2 different exhaust systems. By utilizing a 1 hp air blower, blowing into the exhaust system and by measuring the system back pressure and exit velocity, I could get some comparitive data at simulated high exhaust flows. The blower I have is capable of a few hundred CFM.

[CraigAPD]

The problem I can see with that is physically fitting it in the port? You have to remember you may be in a section of port which is only 25-30mm in diameter. You want to be able to plot velocity at points only a few mm apart perhaps. Therefore the Pitot tube with its extremley small head will be ideal.
Mine should be here any day now. I'll post some pics.

The display Ive gone for displays velocity outright digitally, no number crunching. You could do it alot cheaper with a simple manometer to give a differential figure from which you could calculate velocity.

[CraigAPD]

Tony,
Sorry I hadnt realised you already had the flowquick up and running. The fluctuation of the depression can be annoying, you may know this already, but if you depress the button for several seconds it logs an average cfm value. I usally find my flickers within a window of 1cfm either side of the logged value. I'm planning on trying different positions of the depression take-off on the plenum to stop the fluctuation, I'll let you know how that goes.

Craig

[Guy Croft]

Could someone please publish good photos of the rig and its various controls please? With head on test and bare unit.

GC

[CraigAPD]

I'll take some when I get my digi camera back..

[4v6]

Craig, yes ive had mine up and running for around 2 years or thereabouts so im pretty familiar with it now.

Guy, as requested, some photos and a brief description of the system.

This is the flowquick unit.
The controls on the front panel allow rapid comparisons between imperial and metric measurements eliminating the need to do any calculations to convert between different depressions.

Front Panel.

flowquick (1224 x 918).jpg (146.3 KiB) Viewed 11781 times

The side panel comprises two switches which are used to tell the unit to expect either exhaust or induction pressures. Simply set them to the direction necessary.
I manually reverse the flow through the heads by simply swapping the vacuum pipe over on the shop vac and flipping the switches over, takes only a moment.

Flow direction selector.

intake-exhaust selector (1224 x 918).jpg (144.85 KiB) Viewed 11781 times

The calibration orifice that is supplied with flowquick has a known flow rate of 80.9 cfm@ 28 inches depression which is placed over the test bench and vacuum or pressure applied through it.
Its simply a case of setting the controls on the front panel ( i tend to use the metric scale) and adjusting the calibration on the rear panel to match the known flow test rate.
I do a leak test first just to ensure as little error as possible.

Homebrew testbench.

basic setup (1224 x 918).jpg (186.39 KiB) Viewed 11781 times

Flowquick is equipped with a serial port connector so it can simply be attached to a laptop and the software is then able to create graphs, allow comparisons between curves, give readouts on screen of actual depression, swirl and printouts etc.
As you raise a valve to a particular lift point, simply press the data logging button on the attached flylead and the unit takes the reading instantly. From there, just move to the next lift point.

Quattro head.

ontestBPF (1224 x 918).jpg (193.3 KiB) Viewed 11782 times

Example of graphs produced.

screenshot1 (1224 x 918).jpg (240.29 KiB) Viewed 11787 times

All in all, a very useful piece of equipment.

[superbike]

I use an FP1 digital box connected to my bench. It does have a cfm guestimator where you dont have to maintain any certain test pressure. It would make a job quicker but i do not use this function as i have found descrepencys between real and guestimated pressures (obviously normal) higher pressure more separation=lower reading)

For velocity or air speed on bench i now use a pitot probe. For example on one model i work with 335fps on bench down the ports centerline in each choke at 80 percent valve lift with x amout of flow gives me 148hp. I log this data then make sure i meet these numbers again on the next head. The pitot tube is also good for finding where the air travels around the port. I test i conducted about 2 years ago (thank you Deano) wich involved opening up the splitter section by a large amount gained me zero flow but ruined on bench measured velocity . It also lost 8hp everyware in the range over a standard head. Well actually it lost more see below

Normal stock head 170cfm = 133hp
Routine ported head with 185cfm= 144hp :)
Routine ported head with 185cfm plus splitter enlarged to the max = 125hp approx 19hp loss and this was only opened 2mm in diameter extra in each choke. Going a little off the subject but advancing the inlet cams on this engine by 15 degrees over standard gained back about 8hp putting this over ported head back onto the stock hp level of about 135. Since then i pay big attention to my measured bench airspeed and even weld up ports (make smaller) to gain power but then again i only really work with one brand and all there ports are proved to big for there cams lift.