18HP Vanguard need more power!!

[fulleraviation]

Exhaust Theory

Roger,

Good article. Here are some pictures of Small engine exhaust built for the racing guys such as the Jr. Dragsters.


Look arround this site. They have some dyno charts and exhaust kits.
Kart Pipes - Your Go Kart Pipe Home

Another site:

http://www.bmikarts.com/shop/?cart=1754853&cat=169&

EC Dist:
Exhaust Systems : EC Distributing, Your Online Racing Store!

And Carts Plus:
Golf cart exhaust kits

[Bw6]

Great Links

Fuller, thanks for the links, may come in handy soon.

[fulleraviation]

Not sure how the conduit will hold up in the long run. I think some others have used it in the past and can chime in, but might consider some 4130 tubing from Aircraftspruce for a final product.

4130 ALLOY STEEL ROUND SEAMLESS from Aircraft Spruce

[Roger S]

The conduit has held up great. I had to cut those big radius 90's into several pieces and grind/fit a 2 into 1 with a collector. Had an exhaust shop weld it all up. The galvanized caused their wire feed some problems. Maybe it can be removed before welding? The big radius of the 90's seems to work well for the maxIV.

Anyone using the conduit, welding/burning galvanized creates serious toxic, poison fumes. Do it outside, stay upwind or use a fan.

There is another source or two for pre bent pipe kits, I think Micmac has it in his exhaust article.

[fulleraviation]

He used BMI Carts. I put it in the in my post above in links.

Hey Roger! How about a picture.

[Roger S]

Being on the cutting edge of technology, I don't own a digital camera it could happen but is hard to see inside the argo anyway. As far as the collector, I brought the pipes together at a low angle, cutting and grinding a tapered slice off of each. Like 4 inches length and around half the diameter on the end. I joined them to 1.5" pipe. I took masking tape and wrapped around the 1.5 to find the circumference of the collector. Took the tape off, cut it in half, transfered one to each header pipe to show how much circumference to leave on the sliced header pipe cuts. Then I hammered out what was left of the pair of smaller dia header pipes to fit the larger collector dia, when brought together.

How the pipes come together, the internal shape of the collector, and what comes after it is supposed to affect things a lot. I don't have a welder so have not experimented, but even the pros who build exhaust say trial and error is what it comes down to. As cheap as the conduit is, I'd prolly use it for experiment on the IV.

[fulleraviation]

EC Dist. told me that at the 5,000 rpm and less, exhaust scavenging with a collector would not be much of a factor. They say the higher the RPM's the more a 2 into 1 would be effective. The principle of the creating a vacuum to help suck the exhaust makes since or Low pressure. Other then seat of the pants, I have to leave it to the lawnmower guys with the Dyno's.

It sure is fun to play arround with though!

[Roger S]

That's about opposite of what that exhaust article says about 2 into 1 making more touque at a lower rpm than duals.. mainly making a wider torque curve than duals. Length and diameter is supposed to determine where in the rpm range the exhaust makes torque. It's all cobble and test, though what you stick on the end of the pipe changes everything.. it's a crap shoot.

When was a kid with a mini bike, about 14, a friend who's Dad raced sports cars bought 3 lengths of 1/2" plumbing pipe, and we tested each length on our little 2-3 hp briggs and tecumsehs. Longer pipe, low end, short pipe, top end. We settled on 5" for a nice compromise. Just enough time for the police to be waiting for our last test drive and an escort home.