anyone getting 100" out of their bench?

[robssm]

Just want to size up.. I overbuilt the daylights out of my MSD style flowbench (thankfully I did everything structurally correct in the days before the PTS bench invention) and I want to see what problems folks came up with.

I realize I may need to switch to a heavy duty paxton blower in there possibly at some point, and that vac motors might not be able to do it.

Figure since I am rebuilding it, might as well put in a few extra reinforcements, etc etc.

[Tony]

A hundred inches is roughly 3.6 psi, a walk in the park for a Paxton.

But a hundred inches is also around 514 Lbs per square foot of pressure, and a one foot cubed bench is kind of small.
If you can build it to withstand the pressue, go for it.........

[Brucepts]

The PTS style flowbench build is not rated for 100", it's designed to use 28" as a test pressure.

If someone is going beyond that test pressure they are on their own with the design, I clearly state that on my website and anyone I talk to about building a flowbench.

As Tony already said it's not something to take lightly, you are dealing with some serious pressure that can have some serious failures!

[robssm]

that being said, how accurate is it to use the 100" digital manometer at, say, 40"??

Is it accurate? Or will it be too far out of its range?

I just don't want to buy the manometer twice...

[Brucepts]

Well the only DM that will work is the 100" sorry to say. The 40" one will top out around 36" it's designed to use with a 28" PTS Style flowbench.

The 100" will work fine at or above 28" below that say around 10" you are only using 1/10 of the scale so not so good. It will work but it's not the desired application.

[Tony]

I just don't want to buy the manometer twice...

You need to select the right tool for the job.
If you are building a conventional type of flow bench to test at the standard 28 inch test pressure, the 40 inch manometer is perfect for that.

Many people starting out sometimes decide they would like to build a 100 inch 1,000 CFM flow bench, which is entirely possible if you hove the electrical power source available that can drive about a 60Hp electric motor.
Thats going to be something like 250 Amps at 230 volts by the way.

If you only have maybe 25 amps available, you could still build a 100 inch 100 CFM bench, but is that going to be useful ?
Might not a 33 inch 300 CFM bench be better suited for flowing most types of common cylinder heads ?

If you have a bit more power available, say 50 Amps you could either decide that doubling the flow to 600 CFM might be more useful than doubling the test pressure.
And that is about what most of us have decided we can do with the electrical power we have.

Unless you have a vast source of electrical power available, the standard PTS bench filled with as many motors you have power to run, cranked up to the standard 28 inches test pressure has worked out pretty well for most of us here on the Forum.

[HCCH]

I've tested a few small block heads up to 60". I have not exceeded that yet. I did add a fair amount of bracing to my bench though.

[1960FL]

This is a topic I will chime in on, since I have had a little to do with the history of the PTS bench and have one myself, I will make some statements that some may like and others may turn there nose up at.

One. Can the PTS bench as designed flow at 100” of depression/pressure NO! In no way would I or any sane person with engineering background stand in the same room with that box as someone turns the dial toward 100”…

Two. If you really want to test at 100” and use the PTS “Style” of bench then YOU will need to redesign it with the proper framework and sheeting to hand 520 Lb/Sq foot and that is not really the truth as that is only the pressure in the test plenum and not the motor side of the box (100” + DP + Losses). My bet is your pushing 600Lb/Sq Foot on that side of the box.

Three. I have been porting and playing with heads for many years and to date I do not have a Dyno and I do not have regular access to a Dyno, with that though my heads that end up on Dyno’s I get the data but it is not a regular opportunity. Why do I say this? If you don’t have a Dyno and can’t go from bench to Dyno to bench I see little or no value in testing at 100”. Yes this is a broad statement but the fact is if you have the above situation then you are much further along than most of us here on the forum. And thus the need is high and cost to do so is secondary.

The solution is then a Extensive Metal Skeleton 1”+ Sheeting Nut & Bolt with adhesive built Flowbench, powerd by a roots supercharger connected to about a 15HP 3phase motor running on a VFD.

Four. If the above does not apply then continue with the low hanging fruit. My personal generality looks at it like this in the realm of flow gains potential. 28” 80%, 36-40” +5%, 60” +3%, 100” +1%. I built my PTS Bench with a 1” X 1” full oak internal skeleton, glued and screwed I feel safe testing to in short runs to 36-40”. What I know and have learned is when I have enough knowledge to get the full 85% gain from these testing’s I will put my energy in another flow bench, A WET Flow Bench! I think there is more knowledge to be gained there than at 100” but then again to some Size Matters….


JMO

Rick

[Malvin]

A WET Flow Bench!

That is my next project I have all ready started to gathering materials to build!

http://www.wood-database.com/wood-artic ... f-rupture/

[larrycavan]

My personal generality looks at it like this in the realm of flow gains potential. 28” 80%, 36-40” +5%, 60” +3%, 100” +1%.

JMO

Rick

Where did you come up with that ?