200 CFM Research

[200cfm]

Got a question about reducing dead spaces with filler and how it may or may not aid overall cfm. This weekend I started filling the expansion areas in my port. There is a big expansion zone behind the PRt and a lesser dip zone on the opposite wall leading up to the HBt (head bolt turn). The air speeds along the middle of both walls are better with less fall off swing as you probe down the port. So the pressures are becoming more balanced or better we can say. But the CFM values are about the same after filling the dead spaces. I was hoping I would see a "leap" in CFM but didn't.

Do heads perform better (on the track) with the same CFM from a bench but improved air speeds along (in this case) the PRt wall and the HBt wall? I want to think "yes" but have no proof. I guess I need to know if all the work this weekend has not been in vain. tom c

[49-1183904562]

[jfholm]

Tom,
I have a link that shows how to make those "flow boxes" out of plaster that Rick talks about. I will try and find it for you.

I also remember an article by Larry Meaux where he states that he redid a set of heads for a car and got the velocities correct but did not pick up one CFM and yet the car went .5 seconds quicker in the 1/4 mile and a handful of MPH faster. Yet did not pick up one CFM.

John

[49-1183904562]

Tom,

Sorry not trying to sidetrack your thread but for this WEP is the best thing to use and mold release will work great.

WEP Water Extended Polyester Resin (Basically Fiberglass resin & Water beat to a froth emulsified) makes a dense material that will grind easily and mistakes and mods can be done with any epoxy even body filler.



Rick

[Flash]

[200cfm]

John, that is an encouraging note from Larry M. If anyone would know on experience it would be Larry. Rick, I placed an order for the book you mentioned. Found one listed on Abebooks.com for Practical Gas Flow by Dalton. Should be in my lap for evening reading in 5-10 days.

I have heard of "flow boxes." Maybe Bruce can start a new division section where forum members can discuss and build these. (tom)

[jfholm]

When Rick mentioned the book and then just now when Tom said he ordered it I thought, "hmmm... that sure sounds familiar" Then I noticed this orange book buried on my desk next to me and dug it out, and there it is. I have a copy and it is even book marked on the page on how to make the molds and flow boxes.

This getting old sucks. I am always doing this lately

Thanks guys for jolting my brain back into gear!

John

[Flash]

Its well worth add to any to your library
Vary good and ease to understand book.

I pick it up when it was recommended to some one else on here

[49-1183904562]

[color=#000000]Gordon,

The WEP link I posted is just for education in the past I have used straight polyester resin > MEK as the hardener and H20 just mixed with and electric drill and fan type paint stirrer. The reason I say to use WEP is it molds so well work well with a burr of sanding roll and machines easily so you can try various modifications. An example would be I create a single cylinder copy of my head, intake exhaust and combustion chamber. If I am careful in my alignment of all my plug cores, I should end up with a model that will flow on the bench very close to a stock cast head. You can drill and tap the top to hold a simple valve opener and fit a dowel to create a socket that will replicate the spring seat. Now if you have access to some machine equipment and want to get really fancy one can cut it for guides and seats to make sure my references are measurable. Then out of scrap PVC plumbing fittings make many different combinations of valve seats that will just snap in place to test all the various angle combinations at different point in your progress.

Sort of building a universal trial and error test head, the only real drawback is that you don

[Eagle Eye]

Hi, 200. Was reading your post about cfm and air speed. We realized years ago that high velocity in the intake port will produce more horsepower until it gets too much and gets turbulent and seperates. Low air speed means a lazy port and low power. The higher speed column of air has more inerta and doesn't slow down as much when the valve closes. We always felt that had a supercharging effect. We built some very fast stuff years ago using this theory before we acually had any testing equiptment as we do today. We tried to combine the best flowing port with the most velocity. Just an opinion but I hope it helps you. Jim BTW,I just use a small piece of fine scotchbrite to shine the surfaces back up. Especially in the ports and chamber.

[Flash]

Thanks Rick, for you input.........Hadn't even thought about the valve guide.......or spring seat for that matter :p

Pop in seats is a vary cool idea as well.

Do you have any picture of these mold?

[larrycavan]

[49-1183904562]

Gordon,

I do not have any pictures of my last castings as they were for my 312 Y block motor almost 15 years ago. But I just started on the new project of doing a complete mold copy of Harley EVO heads for just this purpose. Got an unmolested stock set of fleabay this week for this project. So as I start work on it I will create a thread and post. Going on a ride down the Blue Ridge late next week but will start after that.

Rick

[200cfm]

My test head hit 201.5 cfm at .450 lift today. I tested it three times to make sure I was not seeing things. Went to 207 @ .600 which was a record. Went with filler in the roof to make the roof flat. Gave a few cfm gain in the .5 to 2 range at various lifts. Played with filler in the floor but that was a killer. Spent a lot of time on the bowl enlarging it and getting rid of chokes in the bowl before the real throat at the seat. Got the bowl big enough to probe with the sonic tester which normally would never fit. Made experimental flat angle cuts on the SSR to turn the air using angles instead of a radi. Figured if angles could turn air at the valve and seat it might turn it better on the SSR. Yes, the spark plug is in tight. Maybe the bench is leaking again.

John Force is in town. Off to the races tomorrow. :p

[200cfm]

Got the Gas Flow book a few days back and finished it up this evening. He says you can use a flow ball to find the restricted areas in the port. If I followed him correctly you will see an increase in pressure on the manometer. This is where I got lost. Is he referring to a benches test pressure across the port or the static pressure in the port? Why would the presence of a physical object into the port be a valid method of detecting restrictions in the port? It would seem the flow ball mass in itself is taking up CSA and introduces a pressure change.

Anyone able to explain this technique? He illustrates it on pages 38 and 39. (tom c)