4 into 1 exhaust

[hoyden]

I would like to install a 4 into 1 exhaust on my IO-320 RV-9 project.

I read about 4 into 1 exhaust on VAF but cannot find the thread. If you have a 4 into 1 can you share your experience? Any downsides or issues?

[DanH]

https://awi-ami.com/4-1-exhaust

https://awi-ami.com/pub/media/pdf/4-...dan-horton.pdf

About 1150 hours now.

[Thermos]

Originally Posted by DanH

https://awi-ami.com/pub/media/pdf/4-...dan-horton.pdf

Slightly off topic, I really like those cable isolators that AMI includes and would love to get rid of the rubber-and-stainless isolators that came with my Vetterman exhaust. There are plenty of companies that make cable isolators but the trick would be determining which ones would isolate the exhaust without making the whole assembly too rigid.

ds

[David Paule]

Any chance one of you guys might post a photo of the cable exhaust hangers?

Thanks!

Dave

[dpansier]

Here’s a few photos of the cable hangers on the AWI exhaust system.

[hoyden]

Dan H, I saw your post a few months ago and the pointer to AWI. That post sparked my interest.

Dan P, your picture answers one of my questions: can the 4 into 1 be installed without the channel in the aft airframe. What engine are you using?

Another couple three questions, is there room for heat muffs? Are there any difficult or challenging issues installing the system? Things that must be considered?

My RV-9 kit includes the RV-6 cowl, which Van's says is the right cowl for an IO-320 vertical draft fuel injection.

[DanH]

Originally Posted by David Paule

Any chance one of you guys might post a photo of the cable exhaust hangers?

If the aircraft has inboard motor mount points, it's easy to hang the cable mount base from a cross bar. If it doesn't have inboard mounts, just attach up through the bottom skin and angle, behind the firewall.

I was an early adopter, 15 years ago. Initial fitting of the pipes and cowl had contact as shown. I made measurements, sent it back to AWI, and they changed it, no problem. Mostly it just needed to move straight up, which required cutting off the exhaust port flanges and welding new flanges to shortened headpipes. I do not know if it became the new standard.

My cable loops are also shorter than typical, but recall my long term goal was to reduce the exit area, so I needed the tailpipe as high as practical.
.

[BillL]

Originally Posted by dpansier

Here’s a few photos of the cable hangers on the AWI exhaust system.

Mine looks similar for a 7. I have the 360 and it must sit aft about an inch because it is displaced and closer to the firewall/fuse corner. The exhaust pipe is not square but has a turndown at the end. Due to the exhaust pipe angle, it is tight between the fuse corner and the cowl exit for the IO james cowl. It may not be a factor for the Vans cowl as it is ~1" lower than the SJ/IO.

I thought the steep rake of the exhaust pipe might add some drag so had it modified to lessen the angle. FWIW - there was no measurable drag reduction. Speed remained the same.

Internally - -The #4 exhaust pipe is nearly touching my cowl chute on a James Cowl. Not sure about how it would be on the Vans, but would expect it to be close. Remember that the 8 has a recessed tunnel that helps this situation. I got mine after Dans modification but don't know if what he is using is production.

[dpansier]

Originally Posted by hoyden

Dan P, your picture answers one of my questions: can the 4 into 1 be installed without the channel in the aft airframe. What engine are you using?
.

No mods to the RV7 airframe to install the 4 into 1.
Engine is a IO390

[hoyden]

Thanks everyone for sharing your experience with the 4 into 1. I am hopeful I can get one for my RV-9.