Stuart's Flowbench

[S2Z]

It's a bit different from the "usual" but I thought I'd post a pdf presentation of my flowbench.
It's constucted out of 1/2" plywood & particle board (top is two layers)
A Nissan Z32 MAF sensor is mounted to the underside of the bench top (Between the layers of particle board).
A dual 36" scale Monometer is centered behind the flowbench.
One of the monometers is attached to the bottom of the MAF, the other manometer tuber is for velocity probes or vacuum source.
The vacuum source is homemade consisting of an old Dayton Shop-Vac canister and lid, a 1.5 HP Router, a 14" dia x 13" pitch RC prop, a 1/2" plywood plenum floor and the speed controller.
2 each 2.5" hoses attach the flow bench to the vacuum source.

Hearing protection is essential! The router and prop combo is absolutely wicked sounding (sounds like a Banshee wailing)

I created an Excel program to convert the MAF sensor voltage to CFM.
Testing thus far has produced 3.111 Volts which equates to 224 cfm (28" wc)!

The next step is to remove the MAF and "calibrate" the meter readings to actual calibrated flow.

Anyone in the Seattle area willing to help?
I'll leave myself wide open for comments... (Good bad or ugly)

[Brucepts]

Interesting design!

Thanks for sharing your project with us, I'm sure discussion will ensue

[Tom Vaught]

Hello Stuart,

It has been a while since I posted on the Flow Bench Forum so you may not recognize my name, not that it really matters.

First off you did a nice job on the bench, (much better effort than my attempt at building a MASS AIR METER flow bench many years ago).

This is what I did:

1) I had a flow bench that used two LARGE "Wet & Dry" vacuum motors. Between the two motors they could pull about 400 cfm at 12 inches of test pressure.

2) I found a Ford Mass Air Meter that was about 45 lbs of air per minute (about 653 cfm when tested at Garrett Turbocharger Temp and Pressure. I had one of my buddies at Ford run the Transfer Function on the Mass Air Meter in 5 cfm increments.

All in all when I was done this is what I found:

A) I could not use House Current and a Battery Charger to get accurate cfm numbers.
The voltage varied too much. I did not try using a 5 volt controlled power supply from a desk top computer as I was not computer literate then and the max RAM on a Desktop computer at that time was 1 MEG of RAM. I suppose that a Power Supply might work much better today.

B) If I had not had "access" to this very accurate flow bench I would not have been able to generate an accurate MASS AIR meter calibration vs CFM.

C) Since then I have built quite a few of the Orifice bench type flow benches and have been very happy with them.

The items above are things to "think about". Nice job again on the bench.

Tom Vaught

[Brucepts]

Hello Stuart,

It has been a while since I posted on the Flow Bench Forum so you may not recognize my name, not that it really matters.

Tom Vaught

Yes, it does matter! We miss your input don't be a stranger!!

[S2Z]

Hey Thanks Tom!
I was almost expecting to get "flamed" on this one!

AHhhh, that would explain!
I had suspected the house current varying too much (especially where I live) so I added a small 12 volt battery from my Radio Control field bench. I noticed that the voltage reading "settles" down a faster than with the battery charger hooked up directly.



I went by the vacuum repair shop nearby my house last week and talked to the owner. That 13" prop is really taxing the 1&1/2HP router! And it's very, very loud! So I'm looking at replacing the vacuum unit with a triple stage vacuum motor. He also has several dual stage units available also for about $69 each. The dual units will pull 110" wc where the triple pulls 155" wc.

I finished cc'ing the head this morning and was very pleased with the results:
The combustion chambers & intake ports have a maximum variance of 0.2 cc
The exhaust ports have a maximum variance of 0.4 cc.

What was surprising to me is that especially with the exhaust ports, the voltage readings at the higher valve lifts were exactly the same at 13 mm!
Also, the Intake ports all read the same maximum readings also (226 cfm) although they did vary at which valve opening gave the maximum flow reading, but only by 1mm opening setting.

There was not a "huge" improvement in the maximum flow numbers (4% increase) although at minimum valve openings, there were significant improvements (14%). The flow improved across the whole valve lift spectrum, but the biggest and most consistant increases were between 1-8mm valve opening settings.

Getting rid of the "howling" noise at 3-6mm substantially increased the flow over the un-modified head. Yes, re-profiling the valves, in conjunction with "sharpening" the divider wall made the noise go away.

Tomorrow, I'm taking my MAF sensor set-up down to Portland, OR to have Mr. Loyning (Loyning Engine Service) "calibrate" the MAF.

I'll post the results when I get back...

A Side Note:
After final modifications and re-testing the head, I had to abort testing 3X due to the clay around the port opening getting sucked into the port!!

[S2Z]

Heh All,
I've been BUSY! I went over to TAP Plastics in Bellevue, and bought a bunch of Polyethylene 1/2" cut stock (they sell it for a couple $ a pound), several different size clear Acrylic Tubing and a 12"x36"x1" Plate.
I modified my bench to allow a head to be installed or removed without opening the plenum. I used 3.50" ID Clear tubing as a Bore Simulator and modified the Head adapter to allow me to change to different sized Bore Adapters. I'm now using a 12v Hanger 9 Starter battery to power the now calibrated MAF sensor. I also added a LED Indicator light, to remind me when poer is on to the MAF Sensor.
Additionally, I built a 230 cc "Graduate" and stand out of a piece of 1&1/8 clear tubing, and several pieces of 1/4" clear acrylic sheet. I attached the tube to the stand and tapped it to accept a fuel petcock.
What took the longest time, was measuring, verifying and re-verifying the graduation marks in 5 cc increments.
TAP also had pre-cut 1/4" thick 4.0" clear Acrylic discs, perfect for ccing combustion chambers with, so I bought 4 discs.
I connect the graduate with clear vinyl tubing and tee to attach a 12 cc Syringe w/ .2 cc graduations.

Using the 1/2" polyethylene plate is perfect fo making port radius plates with.
It cuts and shapes like butter! and doesn't crack or split, etc like plywood.
So I built a set for the VG30 exhaust ports. I had previously made a radius plate for the intake ports that works for all of the intake locations out of plywood, but will probably fabricate a new one out of the plastic plate as well (as time permits).
I also built a "better" set of flow balls, flow wands and additional shaped velocity probes...

[Eagle Eye]

Hello Stuart. My bench uses a maf sensor also. It is a hot wire. I'm trying to find out where it came from. Automotive app. ? If I post a picture of it could you take a look? Maybe you know someone who is familiar with them. Let me know. Thanks, Jim

[S2Z]

Hello Eagle Eye,
I'll do whatever I can to help a brother out...
Post the pic!
My MAF is a Z32 (300ZX), although, I've been keenly interested in what is being used for the Corvette ZR1 (The 638 HP monster), as it's MAF sensor is good for over 1000 cfm!
Now only if I could build a Vacuum source that capable...

[Eagle Eye]

Here's the pic. The sensor is inside a metal tube to protect it. It is the tiny white probe with two red wires and two yellow wires. thanks

[S2Z]

Do you have photos of the housing?
Also there should be some Part NUmber markings on the Circuit board. There aren't allot of suppliers that provide MAF sensors to the industry, so you might be able to track it down from there.
It's kind of hard to tell who made this sensor without the outside housing, as I've never taken the opportunity to take one apart, usually they are Line Replaceable Units. (Just R & R the whole unit), so Can't tell what it is w/o the housing...