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4 into 1 Exhaust - RV-7 - AWI vs Vetterman

BillL

BillL

Well Known Member
I am sitting on a decision for exhaust system. I have searched here for hours and can not get clear data to move me forward. The considerations are as follows:

Fit: Pipe routing, possible interference with standard components, cable routings etc.

Heating: Only single muff is available, but there are pin-fins on the exhaust pipe to help in heat transfer

Exit: Is the angle and geometery of the exit compatible with cooling area changes like DanH has been doing on his -8? I will do flyoff with standard SJ cowl, and modify later after all else is sorted.

Performance: Mr Vetterman has some good information comparing his units showing basic cruise equality with his best picks for the 4 into 1 pipe with the 2.5/3" dia. I am more weighted to cruise performance (thus efficiency) than low down absolute speed.

Durability: The AWI has seen some fractures (2-400 hr range) and i wonder if these have been resolved by welding processes, design, and/or mounting system.

Anything missed here from your experience(s)?


Thanks in advance for sharing your experience.
 
BillL said:
I am sitting on a decision for exhaust system. I have searched here for hours and can not get clear data to move me forward. The considerations are as follows:

Fit: Pipe routing, possible interference with standard components, cable routings etc.

Heating: Only single muff is available, but there are pin-fins on the exhaust pipe to help in heat transfer

Exit: Is the angle and geometery of the exit compatible with cooling area changes like DanH has been doing on his -8? I will do flyoff with standard SJ cowl, and modify later after all else is sorted.

Performance: Mr Vetterman has some good information comparing his units showing basic cruise equality with his best picks for the 4 into 1 pipe with the 2.5/3" dia. I am more weighted to cruise performance (thus efficiency) than low down absolute speed.

Durability: The AWI has seen some fractures (2-400 hr range) and i wonder if these have been resolved by welding processes, design, and/or mounting system.

Anything missed here from your experience(s)?


Thanks in advance for sharing your experience.
Click to expand...

Bill,

I have basically the same setup as you on my 7. I installed the AWI 4 into 1 and it does appear to be a very nice unit. I'm running the superior cold air induction along with the S.J. cowling. The pipe clears everything nicely so far, although I haven't fitted the cowling yet...but I think everything is going to clear just fine. I guess only time will tell as to any cracking issues that I may have. I'm going to try running the heat muff without the pin-fins, but if heating becomes a problem, I'll send one of the pipes back and have the pin-fins installed.

Mark
 
AWI here

It has been working great for three years (175 hours). However I also hear good things about the Vetterman system.
 
BillL said:
Exit: Is the angle and geometery of the exit compatible with cooling area changes like DanH has been doing on his -8? I will do flyoff with standard SJ cowl, and modify later after all else is sorted.
Click to expand...

I can't speak about -7 geometry. I suspect AWI designed the pipe for the side-by-side models, none of which has the -8's recessed exhaust ramp. For my -8 (and my intentions to eliminate the cowl chute) I sent the pipes back and had them raise everything vertically. I wanted the tailpipe up in the ramp recess.

Durability: The AWI has seen some fractures (2-400 hr range) and i wonder if these have been resolved by welding processes, design, and/or mounting system.
Click to expand...

One crack in the collector, repaired no charge. AWI also asked that I slightly shorten the length of each pipe inserted into the collector....sure, easy mod. No further issues to date.
 
Thanks

Mark, Terry, & Dan, thanks for your responses. I will moving toward the AWI 4 into 1 design. Regarding the clearance at the edge of the firewall and plane of the lower fuse, Dan, I knew from your pictures that there was an exit ramp on the -8 but did not connect your changes with that, specifically. The -7 (as we know) does not have that and I will have to take a different approach to controlling the cooling exit air flow. The prime reason for going with the 4 into-1 is it presents a simpler single shape to deal with.

BTW - AWI has not changed their website pricing for at least a year although they are charging higher prices. $1495 quoted vs $1188.

Thanks
 
Testimonial!

Red Marron and I built 2 RV-6s, 1989-1993. Both had Vetterman's original 4-pipe, mild steel systems. In 1995, I upgraded to his stainless steel tuned crossover system.

The origin mild steel system is still flying on an RV-6 in east Texas, and the crossover system is still on my airplane. To this day I have had not one single problem.

And if I did, I'm very sure that Larry would take care of me!
 
I just received my second 4 pipe system from Larry Vetterman, the first is with the -7 in Oregon. Larry provides a very good exhaust system for RV's, and they do not cost anywhere near $1495.
 
Vetterman

I'm building with Larry's system. I couldn't believe how nice the system was built. The welds are unbelievable. He is an artist.
 
Vetterman 4-into-1

David, I talked to Larry yesterday and he did his best to talk me out of a 4 into 1 system. He also said the collector alone was $500, so I took that as meaning it would be $500 more than his standard 4 pipe system.
 
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BillL said:
David, I talked to Larry yesterday and he did his best to talk me out of a 4 into 1 system. He also said the collector alone was $500, so I took that as meaning it would be $500 more than his standard 4 pipe system.
Click to expand...

I was referring to the 4 pipe system, not 4 into 1.
Sorry for the misunderstanding.
 
DanH said:
I can't speak about -7 geometry. I suspect AWI designed the pipe for the side-by-side models, none of which has the -8's recessed exhaust ramp. For my -8 (and my intentions to eliminate the cowl chute) I sent the pipes back and had them raise everything vertically. I wanted the tailpipe up in the ramp recess.



One crack in the collector, repaired no charge. AWI also asked that I slightly shorten the length of each pipe inserted into the collector....sure, easy mod. No further issues to date.
Click to expand...

Dan, how much flight time since the AWI repair?

Thanks!
Russ
 
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Thanks for the heads up. I see they have a 1 year warranty from the sale date. So the warranty can be up before 1st flight for some people.
 
I have over 800 hours on my airplane, with a Vetterman exhaust. At around 350 hours the tailpipes tried to break free because I added some piccolo pipes. Returned to Larry for repair, cost was barely more than the materials and shipping with several pieces replaced. I managed to spring one of the swivel joints when re-fitting - again fixed at minimal cost. No more problems since. All the problems were induced by me, yet were fixed quickly and at a very reasonable cost.

My view is that the performance of a Vetterman exhaust is on a par with anything else, the fit is excellent, but what I know for sure is that Larry Vetterman's customer service is outstanding!!

Pete
 
Good questions,
What is your main target RPM?
Is this in cruise?
Plan on operating LOP or ROP in cruise?

Exhaust systems can be tuned like a fine piano for that peak torq. @ Requested RPM/ Power settings / @ Density altitude for that day. The Dyno room has shown these results with slight changes @ port exit, primary size, and/or tail pipe size.
An exhaust system is not a choice of a 10 or 15% gain in performance over the other because it looks like a common racecar header.
In a standard application, I would look at:
Over all Reliability/ Fit/ Performance/ Economy and Cabin heat.
Vetterman is my choice.
 
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