Smoke flow?

[rusty105]

For a lack of a better term, has anyone smoke flowed their ports on the bench? The smoke I am talking about is the stuff they use in wind tunnels to see air flow over the body of a car. Would this help to see where the flow sticks to the port floor, or pulls away from the floor, goes turbulent, etc.... I am not sure what you could use for a smoke source that wasn't toxic, or smelled real bad, it's just an idea.

[gofaster]

I have NOT tried it yet, but it has been in the back of my mind for quite some time. Here's a link for a site where I found smoke emitters:



I simply have not had time to act on the idea. If you get around to it before I do, I would like to know how it works out for you. I think it may have less potential for making a mess than wet flow tests with flourescent dye. I think the ideal thing to do is rig a camera so the test could be recorded and played back at a slower speed to find out exactly what is happening.

With wet flow you have the advantage of introducing a suspended liquid with a similar specific gravity to gasoline, so it may tell a truer story than smoke.

[bruce]

Pick up one of those simple Halloween smoke generators they sell in Walmart. I have one, used it a few times, be ready for your shop to fill with smoke if you don't vent it outside Try and find the smallest tubing you can for your testing wand. They make alot of smoke!

I like the thread on a wand myself alot less mess. (Till I get a wetflow setup built)

[86rocco]

I'm not sure how well this would work in a flow bench but I've used ammonium chloride "smoke" to check for drafts. It's really easy to produce, get few cotton swabs, soak some of them with hydrochloric acid, the rest in household ammonia, stuff them into a plastic turkey baster and every time you squeeze the baster, a puff of smoke comes out. BTW, it's actually smoke, it's fine particles of ammonium chloride suspended in the air.

[larrycavan]

I've tested with a minimal amount of smoke from a cigar or cigarette lots of times. What I've seen is the same thing I see with a string in the port. I haven't tried it with anything that emits a significant volume of smoke and that may show different tendancies. So far though, the smoke, even when introduced from below, to either side or from above, has always found and shot right down the center of the port runner.

I personally feel a length of string and a pitot will allow you to determine the characteristics of the port's ability to deliver and direct the air.

Less we forget that directing the flow is a very important aspect of the port shape as well as it's volumetric and linear speed characteristics.

A method I've used for many years now and it helps me to see the port shape [no valve installed] effects is to run water through the port. It's suprising sometimes what happens to the flow. I've seen situations where bowl shape and guide boss shape will cause the water to approach from two opposing sides and head for one exit point. The two converging streams actually meet and fight each othe for exit real estate. Now...how scientific or significant is that....draw your own conlusions.

Also, it's shown me [valve installed] what the shape of the SSR does to the flow characteristics. You might think two ports have pretty much identical SSR and valve shapes......then find out the don't behave the same at all. It's not something that a CFM number would always reveal.

I tend to get outside the box and improvise for specialized equipment that I don't have. In any case, there's a goal to uncover a theory or to simply look for tendancies. I personally feel all of the home made methods we come up with are useful in one way or another....

JMO

[Greg]

Has anyone tried dry ice and water? it makes a pretty decent fog and isn't toxic or flamable.

[SWB]

Greg,

That was my thought as well. I figured to make a container to put it in with a hose going up to the port opening. I think Larry is right in that a smoke stream in the port is going to look similar to how a string will go. On the chamber side however, that is where you will learn something.

I have used various mediums in the air and viewed the discharge from the cylinder side. It is very revealing. I highly recommend it.

SWB

[86rocco]

[larrycavan]

[Thomas Vaught]

The water test is a valid way to evaluate flow in a head.

I was fortunate to know the famous Henry "Smokey" Yunick and he told me he used water as well as smoke. He even build a special smoke flow bench (called a Smoketron I believe) to evaluate valve shapes.

Smokey also told me he "ported" Hudson Hornet heads using a slurry of abrasive material and water pumped through the head much like the "extrude hone" process is done today to improve port flows. Smokey was a very smart racer.

Tom V.

[DaveMcLain]

I bought a pipe and some pipe tobacco to use for some smoke testing and it worked out well. Get the pipe burning and then use the end of it to direct a small stream into the port. I use a hand held flashlight to put light down into the port and if you get it just right the smoke will sort of light up and you can see it very easily. It can be quite fun and revealing but be prepared for the pipe to get quite hot! And for your bowl of tobacco to not last very long. It does make the shop smell rather nice. What I don't understand since I don't smoke is how a pipe can smell good but taste absolutely terrible???

[1960flh]

I like this idea masks the smell of the honing oil, does the smoke light up under Black Light?

What's next a pitot probe connected to a Hooka?

[DaveMcLain]

I never tried using a black light on the smoke, I don't know if that would help or not.. A Maglite flashlight works pretty good if you get the angle just right.