FlowBench for 150 to 210 cfm heads - FlowBench Materials

[larrycavan]

[gofaster]

I keep thinking that having a motor that's not wired in is part of the problem. Unless you have a cover or a one way valve on it, it is probably allowing a backflow from the high pressure side of the board to the low pressure side. I think Mouse, John, and Rocco (or Tony?) all came up with some clever one way valve ideas. I apologize if I'm not giving credit to the right people.

[200cfm]

Ok, Happy Days are starting to come in now. I think I am getting closer to a credible bench. One with repeatability and accuracy. Yes, I thought about the issue of back flow on the 5th motor. So today I upped the ante and wired the 5th motor for power and also set it up with variable control. So I am currently at 5 motors with 2 of them variable.

And I installed eight 1/4" T nuts and bolts along the middle section framing and top chamber framing to pull the front board into the areas that I was unsure of. This bench has well over 50 1/4 inch carriage bolts in it and just about that number in number 10 wood screws. In hind sight that is a lot of holes. Once I clamped shut the front panel I could see a much better closure in the mid section.

Double checked my incline calibration and ran the following tests. The givens are: 115 cfm calibration plate installed on top bore entry. All 5 motors running to avoid back pumping loses.
Incline set for 12" rise with 30 inch or 76.2 cm length.

1.950 Orifice Selected:

test depression @ 28 " wc Incline rise to 33.0 cm or 13.0".
% flow mark @ 65.5% for 117.0 cfm flow. Error @ plus 2.0 cfm. Made several pulls and got good repeats.

1.650 Orifice Selected:

test depression @ 28" wc Incline rises to 64.8 cm or 25.50". Percent Flow mark @ 92.1% or 117.8 cfm. Error @ 2.8 cfm Several pulls got similar repeats.

1.300 Orifice Selected:

test depression @12.8 Incline rises to 76.2 or 30" mark.
Percent Flow mark @ 100% or 79.4 cfm.
Error @ 79.4 - 77.8 or 1.6 cfm Several pulls with good repeats.

This is the closest I have ever been on the three orifices and the first 28" wc test on the 1.650 plate. So I think I can say, "in the zone." Both manometers are steady.
I want to add a second coat of outside primer and decide if I should add more T nut bolts on the outside section of the front panel.
How do you "fine tune" the cd of the plate?

[bruce]

Personally, I'd call your cal plate 117 cfm and say you're good to go!!

Yep, blame it on the the orifice machinist for being off those 2 cfm's (not that I think the machinst was off 2 cfm's mind you)



Edited By bruce on 1171162065

[Thomas Vaught]

I agree with Bruce that the plate is repeating very well on several ranges with a 117 cfm flow number. I would also call it good.

You built your bench a little to late to get involved in the pass-it-around plate study but I would not worry at all as several benches were in the same ballpark as you for calibration.

Welcome to the accurate-build it yourself flow bench club. (We allow
members who have store bought benches too! LOL)

Tom V.

[larrycavan]

Good Job

[200cfm]

Great!!! I am one happy backyard racer! And could not have done it without the tutoring feedback and topic discussions of this forum. Now I can move on to the head bore adapter fixture design and gismos to open valves, etc. Hope to flow my first port before March and down the road further add a third manometer with one of Bruces pitot averaging probes etc. to sniff the fps of these antique ports.

Every bench needs a name so I'm calling this one "Turbo 200."

[200cfm]

Ok, have started building a head adapter model to see if I can make this piece. Do I have to keep the bore adapter the same length as the stroke of the engine? The closest bore sleeve size I can come up with is 3.680" and the sleeve is 6 inches long. But my engine strokes are 3.250" and 3.625". Is it ok to have that much bore depth for the air before it gets into the settling chamber? Thanks.

[SWR]

[200cfm]

Ok, that is one less thing to worry about. Thanks for the guidance.

[Stef]

This has been an excellent thread! Gave me some more ideas...

[200cfm]

Ok, have built the cylinder head adapter using trial and error. This is the second version. First prototype was limited and not fully adequate even though it did function for flow testing. Results were very positive. This version has wider leg supports for better hand movement and better bench top connection. And it is white oak for durability. I made the length a full 30 inches to handle the shifting weight of the head. Mock up was built around cylinder number 3 (1,3 5, 7) head. Each cylinder has 6 head bolts for clamping to the block deck but only two were interchangeable with each cylinder as the head was shifted to left or to the right. So two cut off head bolt holds serve as "alignment dowels" for each cylinder as the head is shifted. The other holes are used for clamp down to the top of the adapter. But I am discovering that standard large C clamps offer equivalent sealing.

First design used 1/16 cork rubber gasket siliconed to the top. This sealed very well and offered a nice pad to the deck of the head. Currently testing out the use of the head gasket itself. It seals equally as well. Have made some data flow runs on intake and exhaust and the numbers fall in line with the factory specs. I made up a radius for the inlet. Standard wood with an 1/4" radius. And the flow data on the exhaust tests look in line with what numbers I have for a factory exhaust valve port. This bench is draw thru (suction) on the exhaust and it seems that the exhaust can be flowed backwards for valid cfm readings. I was skeptical at first but no longer.

Down the road I want to improve on the dial indicator control and accuracy. Current one is adequate but needs refinement.

[larrycavan]

Looks like you're all dialed in and running!

You can make another plate with a smaller bore that will sit right on top of the one you have if you need to.

My stand has a 4" bor and I have another plate with a 3" bore that I place on top when I'm working with smaller bore engines.

[Thomas Vaught]

Quote:

"This bench is draw thru (suction) on the exhaust and it seems that the exhaust can be flowed backwards for valid cfm readings. I was skeptical at first but no longer."

Ford Engineering at the Powertrain Operations and Electrical Engineering Building (POEE) has been flowing cylinder heads for many years (on the exhaust) by pulling through the head. The air is still going in the same direction but the suction is not on the combustion chamber side of the head.

In Smikey's book he shows a picture of his bench set-up where he pulled exhaust from the head (with a header or manifold) and read the inlet air going into the head with his laminar flow element attached to a plenum before the exhaust valve/ combustion chamber.

Tom V.

ps What is the "rise" on your inclined manometer?

[200cfm]

That is interesting. Are you saying they pull the air from the intake port side and not the combustion chamber side? Is the intake valve completely removed?

The rise on the incline is 12 inches. Total length is 30.0" or 76.2cm. It is marked in percentage flow but for calculations I go by the metric marks to find the flow number. These heads have sharing exhaust ports on cylinder 3 and 5. Simezed (sp?) I think is the term. I do get a higher reading on port 3 in comparison to exhaust port 1. That seems correct because the entry is much larger and one shared wall is much shorter in length. Exhaust valve is 1.525" and the SSR is slightly more than a 90 degree turn. Not a good design for the floor side of the port.

Should I put a radius entry block on the exhaust flange exit port if a bench flows depression instead of pressure?