Expansion chamber exhausts for WB820s running alky

[philrock]

I recently bought a couple of WB 820s. They are in good condition, ported, modern ignition, Tillotson HR 194 carbs (one per engine) set up for methanol. I currently have GEM cast aluminum can mufflers, which are limiting performance significantly. I want to go to expansion chamber exhausts, but have no experience with this.

I normally run at a track that’s a little tighter than the Adams Riverside, CA track. I’m told to expect the engines to max out at around 12,500 rpm. I’m using Horstman DXL wet clutches.

Questions:

1. What is the correct flex length?

2. How much adjustment in flex length should I allow for fine tuning?

3. What is the correct size for the header tube? The cross sectional flow area of the exhaust manifold on the engine block is about the same as the cross sectional flow area of a 1.50” o.d. tube.

4. What is the standard wall gauge for header tubes? 16? 18?

5. Any suggestions on off-the-shelf expansion chambers that are suitable and available?

6. Do I need / want to use silencers?

7. Any suggestions on good papers, books, or articles that will help educate me on the subject?

[VirgLove]

http://usmotorpower.com/820.htm#parts

[philrock]

Bingo on the pipe! Thanks VirgLove! Good price, too: $112. U.S. Motor Power part no. 300-820. Anyone have any experience with this pipe?

The header shown in the picture is not available. Any ideas on a header? I understand that RLV and Dave Bonbright are stumped on this, too.

[louie figone]

Contact Scott Wiggington at ASW Inc. 408-748-6949, he and Bubba are working on a header for the West Bends for use with a pipe. That pipe that U.S. Motor has is for the WKA spec class, dry clutch and spec length. You may want to talk to Art at RLV about the correct pipe to be used with the oil clutches.

Louie

[Tom Smith]

I don' think there are any pipes readily available for the West Bend engines. Most of the kart pipes I've seen are not too with it anyway.
The best kart pipes I've have seen were on an Anderson Kart running a Yamaha. Someone in Sacramento builds them for about a grand.
I was going to try out a set of professional racing pipes on a pair of West Bends coupled together once but never got around to it.
The old style box mufflers or the Horstman mufflers work fine on decent motors.

pipes.JPG

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[Bill Johnson]

The RLV Pro 80 pipe works good on a WB820.

[philrock]

Thanks for all your help, guys.

I heard recently that RLV's Mac 101A pipe works well with this engine. They still sell the pipe, but the header remains a challenge.

[louie figone]

Randy Holt has been making a few of these for himself, give him a call, he may do a couple for you.
661-400-3468

Louie