4 Into 1 Exhaust

[Brad Gould]

Is there room to put heat muffs on the 4-into-1 in the RVs?

Also, does placing a heat muff on less than all the exhaust pipes alter cylinder horsepower, and therefore smoothness or tuning, by cooling the exhaust pipes differently? I know that there are many non-tuned exhausts with this setup, and I'm guessing it would have an insignificant effect if any.

[flyeyes]

Is there room to put heat muffs on the 4-into-1 in the RVs?

There's plenty of room, and I have one the left side, but it's almost perfectly worthless. I haven't yet flown the plane with an OAT under about 28F, but the heater just puts out copious amounts of lukearm to cool air. I haven't yet tried the doorsprings/stainless steel wool etc. because it isn't a real priority for me. It doesn't affect the balance of the cylinders as far as I can tell.

James Freeman

[penguin]

Flyeyes,

You may be getting vibes through the floor because the angle your tail pipe exits at is too shallow. I had that problem on my 6 and angled the tailpipes to make a 25 to 30 deg angle from the bottom of the fuse - much easier on my feet. Can Aircraft Exhausts change the tailpipe angle to point a little more down? You also have to be careful not to stick the tailpipe too far out from the bottom of the cowl, as well as increasing drag it loads up the ball joints in the exhaust causing them to wear alarmingly.

Pete

[13brv3]

Originally Posted by fodrv7

As George says, the Four into one has a lot going for it.
Does anyone know why Mr. Vettermann doesn't make one.
Pete.

I was wondering the same thing, but I just looked at the Van's webstore, and the description says 4 pipe and crossover systems are available. When you look at the configurations available for purchase, you only see 4 pipe systems for the RV-3 and RV-4. Seems odd he would only make them for the -3 and -4.

I also tried to find a web page for Vetterman, and can't. Does he have a page, or is it phone only? I think I saw a phone number on one of the google hits.

[Tandem46]

James,

I should have asked this the other day, how much? Their website doesn't show exact price. Just wondering if it's at least competitive with Vetterman price wise.

Tobin

[flyeyes]

I should have asked this the other day, how much?

I don't remember exactly, but it wasn't cheap. Around $1100 IIRC, definitely more than the Vetterman.

There is a lot more work in the collector though, and it shows. It appears, to my eye, to be much better constructed than the other 4-into-1 exhaust on an RV at my field.

I do remember it being cost competitive with the other 4-into-1 systems I priced, and I talked to a pleased customer who sent me photos of the exhaust on his RV-8 (Ray Parker? I can't remember his name off the top of my head)

James

[13brv3]

Correct on the price. I was told $1099 when I asked about a system for the RV-8. I've sent another email with questions about the performance improvements. Mainly, I'd like to know if this system has been tested, and shown to be stronger, or if it's just theoretically better.

I had the Vetterman's crossover on my old RV-8, and the only complaint I had was the hangers that kept breaking. That's been a few years ago, so hopefully, they've fixed this by now. If not, I'd have to come up with something to use in place of those squashed stainless tubes.

If the 4 into 1 system doesn't use hangers, that's one less thing to worry about. Of course then you'd worry about cracks in the pipes themselves perhaps. 321 SS is pretty strong stuff, and Lycoming's don't really push the limit on temp for it, so probably not an issue.

I'm seriously thinking of trying one of these systems.

[gmcjetpilot]

I do not want to speak for Larry's Vetterman but he posted on a Yahoo group he did not feel, in his opinion the 4-into-1 was much better. I don't share that feeling. The thing is he has the X-over system down and sells a boat load I am sure, so I don't think he is going to develop a new design. However the fact is people who have done a before and after, having a x-over and than later switching to the 4 in 1, notice the increased power, prop over revving and of course faster climb and higher speeds.

(Floor thumping)
ON the similar note, FLOOR THUMPING comments are few. I have only heard of one complaint of more floor vibration after installation of a 4 into 1 on a side by side model. First, any RV floor vibrates anyway. My RV-4 shook all the time. If you ask that person who says their floor vibrates more with the 4 into 1, they will say the performance gain was very apparent, so I think it is hard to complain with the gains and don't think its an issue. As was suggested pipe angle, collector length and floor insulation / damping all affect the situation. ON the RV-8 with the narrow floor I don't think it vibrates as much as the side-by-side anyway. The side-by-side has the large flat floor to move. I have a longer stinger (collector) on my custom 4 into 1 pipe. I know the stock off the shelf ones are a little shorter, but at a steaper angle from the belly. I think they did this for looks more than anything. The best collector length is 19.5-30 inches long, which most don't want, but I have a 19.5 collector at a shallow angle. The shorter collector looses a little performance but not much. Really to take advantage of a 4 into 1 you would use a custom CAM, and the breathing would really open up, but even without a custom CAM the 4 into 1 is like free HP.

(X-over, 4 into 1 and 4 into 4)
Larry does make a 4 into 4, 4 separate pipes. This is a cool system and works well, From the Cafe foundation the 4 into 4 separate pipes has some good characteristics, like even or balanced power, low back pressure with some but small savaging. In word it has no bad habits but is not a huge plus. You could do WAY worse, like Y-pipes, 2 into 1 on the same side, with odd pipe length.

(Heat muff)
I found on my exhaust technologies 4 into 1 pipe, making room for a long heat muff a little bit of a challenge. Remember "Tuned" pipe lengths or equal lengths requires some bends and curves. I had custom 4 into 1 exhaust made from a pattern I sent them, which is something they still do. So the way I designed my "Headers" was a little tight (see picture below). I only left room for one heat muff. This was before Exhaust Technologies had the stock off the shelf unit. Now they have off the shelf units and I am sure they allow pipe runs that are stright long enough to fit a heat muff or two. I am sure they have accounted a little better for the heat muff. THE COOL thing or should say the HOT thing is they can weld on studs as an option to the pipe to increase the heat muff efficiency by a huge margin. This is a process they use in aerospace heat exchangers. The impressive thing about this company is they do have high tech aerospace manufacture abilities with stainless steel stuff, for all kinds of certified aircraft applications.

I recommend Aircraft Exhaust Technologies, but I do think the installation is not as compact as the cross over. The cross over is NOT bad but it does suffer one physical draw back. If you measure the pipe lengths, primaries, collectors for every cylinder they very from jug to jug, so you don't have "Balanced pipes". What does that mean. It means the power from each cylinder will not have same "scavenging" and the power from the individual cylinders very. The savaging is there but not the to the extent or timing you get with the 4 into 1. Exhaust Technologies also makes a cross over system as well!! They also have a cool Heat muff/ Muffler (noise) combo. http://www.aircraftexhaust.net/

Click on pictures to enlarge, you can see the heat studs, the "cover" of the heat muff in not installed. I found plenty of room on #1 pipe. I did not really have room for more heat muffs the way I designed the pipes, but you can design them anyway you want. As I said the stock ones look like they used longer straight sections so heat muffs are not an issue.

[RudiGreyling]

Thanks guys, I'm learning a lot. Regards, Rudi

[arffguy]

You can have a "A" model RV with a 4 into 1 system if you are willing to engineer and build it. Big "if." This RV-6A has a Lycoming O-320 with a custom built four into one mild steel exhaust on it. It sounds real smooth too. The owner loves it. It was built by a gentleman in my local area who now has built four exhausts for RV's on my home airport alone. He does each one by hand and has no ideas to make plans or a jig to manufacture these. He did this just for fun. His newer design on his own RV-6 has the collector facing the other direction he says. It took me a long time to get these pictures. When I see his other system I will post those too.