What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

4 into 1 exhaust

hoyden

Well Known Member
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?
 
Here’s a few photos of the cable hangers on the AWI exhaust system.
 

Attachments

  • IMG_3494.jpg
    IMG_3494.jpg
    280.6 KB · Views: 249
  • IMG_3492.jpg
    IMG_3492.jpg
    216.8 KB · Views: 202
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.
 
Last edited:
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.
.
 

Attachments

  • Cowl Pipe Contact.jpg
    Cowl Pipe Contact.jpg
    217.9 KB · Views: 138
  • Exhaust Ramp Finished.JPG
    Exhaust Ramp Finished.JPG
    47.7 KB · Views: 119
  • Exit Panel 4 Variable.jpg
    Exit Panel 4 Variable.jpg
    347 KB · Views: 134
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.
 
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
 
Thanks everyone for sharing your experience with the 4 into 1. I am hopeful I can get one for my RV-9.
 
I only used the single AWI supplied, but would recommend two muffs from the start for better heat. Maybe you could get them to add the transfer studs to a second pipe. I have the IO360M1B 180hp, and since a second muff is not fitted can not make a location recommendation.
 
How hard is it to attach heat muffs? Ideally for MN winter I would like to have two muffs.

I have two muffs which attached very easily, they are configured in series with one position having the welded studs. With two muffs you will have plenty of heat as long as you minimize the airflow thru the known spots.
 
I just bought an RV-7 with a Sky Dynamics 4-into-1 exhaust and their cold air intake.

I realize the OP is inquiring about RV-9 installations and I don't have much to offer with regard to the installation but the Sky Dynamics 4-1 definitely sounds very nice! :)
 
I sent an inquiry to Sky Dynamics for my RV-9. Thanks for the pointer.

I just bought an RV-7 with a Sky Dynamics 4-into-1 exhaust and their cold air intake.

I realize the OP is inquiring about RV-9 installations and I don't have much to offer with regard to the installation but the Sky Dynamics 4-1 definitely sounds very nice! :)
 
Would you mind sharing how you secured the cable loops?

Done looks like they gave a crushed tube on the end, like a swage. The stock AWI I received simply recommended to use a center punch and stake the holder from the outside.

IMG_2330.jpg
 
Would you mind sharing how you secured the cable loops?

I had to shorten the loops a bit for proper clearance, after adjustment, crimped on a short piece of Alum tube on the end of the cable.
Used a standard terminal crimper to make the crimp.

Correction, I used Stainless tube.
 
Last edited:
I had to shorten the loops a bit for proper clearance, after adjustment, crimped on a short piece of Alum tube on the end of the cable.
Used a standard terminal crimper to make the crimp.


Correction, I used Stainless tube.
 
Does anyone know if there are other manufacturers of 4 into 1 besides AWS and Sky Dynamics? My bit of looking has not been successful. I don't need one right this minute but if one was available I would seriously consider purchasing it.
 
Quick update....

I really like the cable hangers, as compared to the bent tube and hose contraptions on most RVs. Light, compact, simple, but of course I've been curious about how long they might last. Well, I finally broke one. It took 1100+ hours.

I have a crimper, cable stops, and cable. 10 minute fix.
.
 

Attachments

  • Cable Hanger.jpg
    Cable Hanger.jpg
    72.2 KB · Views: 73
Back
Top