difference between pitot and orifice

[larrycavan]

[maxracesoftware]

[racehead]

Bruce,Now I am stuck with your pitot tube flowbench.
Well , I am learning the hard way

[Tony]

Ha-ha, we are all learning. I am on bench design number four right now. Flow benching is like a compulsive addiction.

Once you build your first flow bench, there is no escape....

[whtrthanu]

Max, a good friend of mine who also does some of my machine work to help me out has a converted 300 bench(600 now), we often send head back and forth to check the benches, the low lift number are very close, but after .350 lift the bigger bench is about 1-2.5 cfm higher than the 110....mostly on the bigger flowing heads, it could be that my motors are weaker, or just my power supply isnt getting 120 volts.......but as far as the exh flow the are almost identical....
my bench was built in 99 so it probably has some different internals than your old 110 did

[whtrthanu]

Larry, how do I go about getting the wiring figured out, is there a schematic available?, or am i gonna be like fire marshal bill and just hope for the best...........

[larrycavan]

[thomasvaught-1]

Quote:

"Water guages are fine and dandy except when you're porting a lot of heads. To make them is relatively inexpensive. You get what you pay for or put the effort into designing properly.
They're fine for the average guy just tinkering in the garage. If you spend considerable time actually using your flowbench for porting heads, you'll probably want to move on up to a good electronic setup. I've never talked to anyone who did and regretted it."

Ford Research uses (as many on this board knows if they were involved in the "Plates" study) a several million dollar electronics package to read and document test results.

That being said, our "Flow Lab" for the majority of the normal work we do every day still uses fixed orifice plates in a large drum type plenum ( with an access door) and rubber stoppers. The benches are one direction benches. They ALL use water manometers for the orifice flow numbers on large length inclined meters. We did swap out the mercury pressure manometers for digital stuff but the rest of the bench stayed the say. Why? Because they worked and worked well.

The lab guys don't get paid by the hour so they can take more time and they only run the test once. LOL!

Tom V.

[whtrthanu]

Ok so now i have alot of my bench project figured out....
Onto the head dvelopment questions!!!!

How come most of these engine development programs are geared towards car type engines...Even the flow program you sent me Larry, it doesnt jive with my dyno results.....
Most of my builds are bike motors, inline 4 cyl, 4 valves...
I seem to always figure on .4hp per cfm per cyl...depending on the compression and the cams it can go up or down between .36-.42..........The power always seems to be off from these programs.............

[larrycavan]

[larrycavan]

[whtrthanu]

Larry, i port differently than the conventional copy cat bike shops out there...
There are alot of shops filling ports like you said, Ive been down that road, always the wrong way in power on the big motors.....
Most of the guys will talk about a critical choke point, and velocity, and keep shrinking the port until it is just a turd.......
Im my opinion, there are alot of ways to skin a cat, as long as you are getting good results keep on going down the same road of development.....
Now, about the air speed in the port
where is the most critical area to hurt the port?
would it be along the short side radius,or by the mcsa?

Mike

[larrycavan]

[sleeper sedan]

Guys, I'm new to the forum but have been lurking for a short while now but I got to tell you... Thanks for you contributions. I've got a bit more research to do, that's without a doubt and the title of this post certainly gave me a quick pro/con of flowbenches.
I've got a SF600 at my disposal and have used it over the years with great success but, I've got an every increasing need for a larger capacity flowbench... Right now I'm thinking 1,300 cfm @ 20.4" Is this doable...? Dunno. Will I have to step up and use a 30 HP belt belt driven GMC 6-71? <chuckling> I'm going to find out.
In the end it's a learning thing for me, the wife calls it an obsession. I've got money to buy some nice pieces (accuracy and electronics are good) but looking for something more than just writing a check for a newer, larger commercial flowbench.

Clark