tuned exhaust for a Lycoming 0320

I'm just having more fun than should be legal and it probably isn't if I look far enough into the County, State and Federal statues, but I am never-the-less. I have pretty much followed the Cafe numbers for header length and the 4-into-one collector. Keeping in mind friendship to my neighbors, I also included a muffler. I purchased the collector and muffler from Barnes Stainless and will be purchasing the header tubing, 321SS from the same source in all likelyhood. A/C Spruce has the tubing listed at $8.75/ft. I've made up some PVC headers complete with flanges glued on and am heating the PVC with a heat gun and bending them until I get the pipes where I want them. The plan then is to take the bent up PVC to a muffler shop that has a mandrel tube bender and have them bend up the expensive 321 SS tubing. I plan on welding in some of the 3-bolt ball fittings to both ease the stresses and make installation and removal easier. My plan is to install the stock exhaust, do a hover and check the MP and then quickly change exhaust systems and repeat. I'm hoping to see a MP improvement. I've had this plan in my "Round Toit" list every since I read the Cafe study.

Dang I sure do like the experimental category. No bureacrats in the way. Stu Well the heating of the PVC wasn't working as well as I hoped so I changed to using PVC elbows. I modified some 45° elbows by cutting out a wedge fron the outside of the elbow and reduced the angle to 30°. I had to drill a couple of holes and use some safety wire to hold the elbow to the 30°. I also turned the PVC pipe ends in the lathe to make them turn a bit easier in the elbows. Needless to say it is a projet in progress.

Stu Well PVC elbows weren't working to well either. Couldn't get equal length pipes to end up in an equal place. Next tried 3/4" steel flex conduit. OK it proves that you can get 4 equal length pipes to end up at the mouth of the 4-into-1 collector. It does prove that the required bends are not simple. However the steel flex conduit is heavy and tries to sag. Next tried some 1- 1/4 flex aluminum conduit. It isn't heavy but it too sags all over the place. One thought was to get the conduit in place with support and then put a bunch of tack welds to make it solid. Yep the conduit is weldable but it will take welds on both sides to make it rigid. Next trick being tried is using an expoxy to coat and stiffen the flex conduit. Also trying some permanent thread locker and some 5 minute epoxy. Sure would be nice to have some medium that was flexible but kinda stiff that could be treated with some easy to apply medium when the proper angles were achieved to derive a stiff pipe that could be copied in SS. Any of you wizards out there have any ideas that might help a sr.citizen having trouble?

Well, I guess you don't even need pipe or tubing. Could be anything that bends easily. What about using ethafoam cylinders the right diameter. Sorta like those floating things kids use in the pool, only smaller in diameter. Shape the pieces and glue them together. Once you like the shape, give each piece a coat of 4 oz fiberglass cloth, using your favorite resin. Maybe ABS plastic water pipe. Cut, notch and bend as needed, then heat weld the joints. Add stiffeners as needed on the inside of bends so they don't get in the way at the mufffler shop.

Pete Stanaitis

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Half-inch electrical conduit and pipe insulation?

You can bend it with a conduit bender if your knee won't do, and the pipe insulation will bulk it up until it's the right size.

I have seen "bendable" as opposed to "flexible" exhaust tubing. It was solid but corrugated. I think JC Whitney used to carry it. In smaller sizes, you could use the corrugated pipes intended for gas appliance or water heater connections.

Be sure your exhaust shop is capable and willing to fabricate from your model. I had no luck getting a small block Mopar Y-pipe duplicated at my local shops. They were willing to build and fit it on the motor only.

Don Young

I have several sets of the ICE systems that have saved me a fortune in fit loss. You may want to take a look

Respects,

Rob Fraser

Fraser Competition Engines Chicago, IL.

Were you asking to get the whole thing done, or just the pipes bent?

I doubt that I'd want to build a header in the air to go onto an engine later -- but I could see bending a bunch of pipes (if I hand a bender) for someone to weld up themselves.

Serious spaghetti there!

Thanks for the ideas. I'm finding that with the flex conduit I can cut 4 equal length pieces and squiggle them around all at the same time and come up with a good solution. To do one pipe at a time it is very hard to get from point A to point B and end up with 4 pipes of the same length. It is a trial and error process that involves many trials. Rob Fraser touted a kit that could help but the kit is $800. If I was in the tuned exhaust business this would be a good deal. Another suggestion invovle "bendable" rather than flexible tubing such as used in hot water heater installations. This sounds good because you can start with 4 pices of equal length and squiggle until you get therm right. I have the engine setting where I can get to it and the 4-into-one attached to the frame and all I should have to do is squiggle them in and then make sure they don't move from there to the tube bender. In theory I should be able to get the headers without any welded joints between the engine and collector.

Stu

Don: Thanks for the "bendable" vs "flexible" that may just be what I need. I just sent my wife to pick up some of the copper "Bendable" tubing used in hot water heater installations. It makes my problem much easier if I can have 4 equal length pieces and squiggle them around all at the same time to fit between the engine and collector. That way the collector location can float a bit so that I end up with a smooth flowing set of equal length pipes. The length has been determined from engine dyno studies and should all be the same within 1/4 inch.

"> Were you asking to get the whole thing done, or just the pipes bent?

Tim: I just need the modelling done for each of 4 pipes. I've found a shop that says they can bend SS tube to match my model. I've got a certain amount of flexibility in the mounting of the collector and very little framing to dodge. The problem has just been that I started with 4 equal length pipes and was trying to determine the bend angles that I needed to start from 4 cylinders in an opposed engine and end up in the collector. I could get one pipe and even two pipes arranged and then the other two pipes would not come close to the collector. It seemed that the bend angles of all 4 pipes had to be determined simultaneously to meet the boundary conditions. The flex conduit did that but how to hold the bends in place long enough to get the pipes bent. Stu

Rob: Thanks. The ICE systems does look like a hot set up. However for just one exhaust system their plastic blocks are a bit pricey @ $800. That coupled with the fact that I need 4 pieces of pipe each about 34inches long would require a minimum of 136 pieces of plastic at 1inch increments. Their $800 "Street Bike" kit only had 55 pieces. There was no indication on their web site that longer straight pieces were available.

Stu

"Stuart & Kathryn Fields" fired this volley in news:OOydnauqP9ZPU6vVnZ2dnUVZ snipped-for-privacy@iwvisp.com: .wescottdesign.com

That's good, because flex pipe doesn't resonate well. You need a good model, and rigid pipe (go with the bender guys).

(Ahhh... the SWEET sound of an un-muffled O-540 with tuned pipes!) (oh... sorry... that's an o-320... a little guy)

LLoyd

Great thing is they will gladly build you a custom kit that won't kill the wallet. In conjunction with Solidworks or CAD you can get a lot of flow dynamics as the individual parts have values established for them. I love em' but cried when I wrote the check! They are really great for high performance development. It's the only show in town I found that works for me on turbo manifolds and funky headers. I tried to offers sponsor space on my funny car and they politely declined. They know they got us by the short & curly hairs....

Respects,

Rob Fraser

Fraser Competition Engines Chicago, IL.

Your experience is in no way unique. I have had countless projects where I needed something done-the places capable of doing it treat you like you're crazy if the project goes .001" outside their normal routine. Example: I needed some 4"X8" copper faced circuit boards screen printed with my traces. Had all the necessary prints for scanning ready to go. 3 shops looked at me like I just dropped in from Venus. This was in no way a difficult thing for them to do. Idiots... JR Dweller in the cellar

D>>I'm just having more fun than should be legal and it probably isn't if I

Super glue the joints-little dab'l do ya. JR Dweller in the cellar

Stuart & Kathryn Fields wrote:

PC board shops are all digital, now. Practically none of them have an enlarging camera, darkroom, etc. like they did in the OLD days of the

1960s, when artwork came in on mylar sheets with black crepe tape and little pre-cut donut pads. If you can't send them a set of Gerber files, they just don't know what to do with it. The screen printed overlay is all generated digitally, the same way. They literally don't have a procedure or the equipment for going from physical artwork to the silk screen, anymore.

Jon

I did some work on an Aero Commander 500C a couple decades ago, with a pair of IGSO 540s. The only muffling was a perforated "basket" around the straight pipe coming out the top of the engine. I wouldn't call it a "sweet" sound, either. Awesome, yes! Still no comparison to the sound of a Merlin idling, though.

Jon

bends and putting it together on the truck (1962 2 1/2T Dodge dump truck with a 360).

Don Young

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