AWI 4 in 1 exhaust

[Wicked Stick]

Originally Posted by DanH

Dave, does that pipe bottom out in the collector socket, i.e. with the link disconnected you can't shove it in any further?

Hi Dan,

Where are you going with this ? Even if there's room for it to go deeper, it's locked into that position from the welded bracket attach point. The other pipes have some reasonably straight sections near that area where the welded bracket is located, but this pipe is very close to the bend. I'm taking an educated guess here, but I think the combination of the bend and weld may have left that area a little thin and pre-maturely caused it to start cracking there. It's not cracked all the way around (yet), so it must have started in the area near the welded bracket.

[Toobuilder]

Just as a data point, I made my own 4-1 with 30 inch primaries and a slip fit collector. I have one of the primarily tubes welded solidly to the collector and the other three are retained to the collector by the often seen tabs, bolts and compression springs. I have one solid link hangar at the aft side of the sump bolted to a tab welded on a primary in front of the collector. It should also be noted that I have ZERO ball joints anywhere in the system and the flanges are welded to the primaries (no slip fit at the head) and the whole system is mild steel. In other words, its built just like drag race headers have been done for the last 50+ years, and I have not had a single crack in 400+ hours of service.

...and I also have about $200 worth of materials and a weekend of fabrication wrapped up in the whole thing.

[DanH]

Originally Posted by Wicked Stick

Where are you going with this ? Even if there's room for it to go deeper, it's locked into that position from the welded bracket attach point.

Trimming the pipe so the pipe could not bottom in the socket was an experiment suggested by AWI after a crack repair on my collector. The idea was to add a little flexibility, and some room for thermal expansion. In this case thermal expansion would create a high tension stress in the link (runs cooler, extends less than the pipe itself), which would load the tabs right at the crack location. Any truth to the explanation? I dunno. Mine hasn't given any more trouble.

[g zero]

Originally Posted by Toobuilder

Just as a data point, I made my own 4-1 with 30 inch primaries and a slip fit collector. I have one of the primarily tubes welded solidly to the collector and the other three are retained to the collector by the often seen tabs, bolts and compression springs. I have one solid link hangar at the aft side of the sump bolted to a tab welded on a primary in front of the collector. It should also be noted that I have ZERO ball joints anywhere in the system and the flanges are welded to the primaries (no slip fit at the head) and the whole system is mild steel. In other words, its built just like drag race headers have been done for the last 50+ years, and I have not had a single crack in 400+ hours of service.

...and I also have about $200 worth of materials and a weekend of fabrication wrapped up in the whole thing.

I made a set of 4 straight pies for my Skybolt out of swimming pool hand rails. 304 stainless , .049 wall . Cut out the bends you need and tig them together . I had a slip joint with springs about half way up the system . 200hrs no problems .

I considered making the one for my 8 but the cost of the collector and flanges added up to close to $500. I purchased the AWI system for about $1200 .

I will check the clearance of the pipes to the collector before the first startup .
Tom

[Bubblehead]

Originally Posted by DanH

Trimming the pipe so the pipe could not bottom in the socket was an experiment suggested by AWI after a crack repair on my collector.

I now have 400 hours on my AWI 4 into 1 without any cracking. I will do an extra good inspection at the next oil change.

I trimmed the two upper pipes about 1/2" so that the collector would ride up a little higher in the tunnel. Without doing that they were bottomed out in the collector and the collector was closer to the lower cowling than I wanted.

[Wicked Stick]

Originally Posted by DanH

Trimming the pipe so the pipe could not bottom in the socket was an experiment suggested by AWI after a crack repair on my collector. The idea was to add a little flexibility, and some room for thermal expansion. In this case thermal expansion would create a high tension stress in the link (runs cooler, extends less than the pipe itself), which would load the tabs right at the crack location. Any truth to the explanation? I dunno. Mine hasn't given any more trouble.

Dan,
I see now what you were getting at, and it does make sense, the other 3 pipes going into the collector did have a little wiggle room depth wise, but I remember the #3 pipe having to be shoved all the way in to line up.

Last week I sent my collector and the #3 pipe back to AWI so they could inspect it. They told me that they no longer put those attach brackets on the upper two pipes any more and that my #3 pipe did seem to be a little tight in the end of the collector, so it very well may have been caused by the weld, near the bend and no room for flexing.

To AWI's credit, they promptly replaced my #3 pipe with a brand new one free of charge. (I only had to pay for the shipping) The new one didn't have to go so deep into the collector this time either. It was also suggested by my local A&P IA to apply a high temp Anti-Seize compound (the silver colored stuff) to the ends before inserting them into the collector.

Though it seems there's been some issues, I would still recommend AWI as a great company who provides great service and support's their product.

[grayforge]

gnuse mentioned that if one had heard a 4 into 1 exhaust, they wouldn't ask about the advantages over a 4 pipe system. What is the audio difference?

I'm about to pull the trigger on an exhaust and am deciding between Vetterman 4 pipe or AWI 4 into 1. I have an ECI IOX-370. Their cold air sump only allows the use of the Vetterman 4 pipe system. AWI 4 into 1 is supposed to work too.

I'm a bit concerned about the cracking issues in AWI systems, though those were older posts and maybe they have those bugs worked out.

Thanks!

[Russ McCutcheon]

Originally Posted by Toobuilder

Just as a data point, I made my own 4-1 with 30 inch primaries and a slip fit collector. I have one of the primarily tubes welded solidly to the collector and the other three are retained to the collector by the often seen tabs, bolts and compression springs. I have one solid link hangar at the aft side of the sump bolted to a tab welded on a primary in front of the collector. It should also be noted that I have ZERO ball joints anywhere in the system and the flanges are welded to the primaries (no slip fit at the head) and the whole system is mild steel. In other words, its built just like drag race headers have been done for the last 50+ years, and I have not had a single crack in 400+ hours of service.

...and I also have about $200 worth of materials and a weekend of fabrication wrapped up in the whole thing.

Any chance of some photos, sounds like a fun project!

[grayforge]

After more research, it looks like the AWI 4 into 1 is taildragger only... true?

[BillL]

Originally Posted by grayforge

After more research, it looks like the AWI 4 into 1 is taildragger only... true?

Probably, I have a TG and AWI 4-1. I don't know about the clearance needed for the nose gear. I can take a picture when I get mine reassembled. Right now , the engine is off and being used (self imposed) as a "prize" to get the cabin wiring completed. I have of focus on my peas before eating the carrots.

If you really, really need it, I will hang up the engine and add the pipes. Just let me know.