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Exhaust system.

Exhaust systems.

I've looked at all info l could find on the net, but came up with a lot of technical stuff that a burnt out old machine operator can't understand.

So I'm back here because of the wealth of expertise l can tap into.

My RV4 has a four pipe cross over system that crosses over behind the sump, one of the pipes runs too close to the throttle control and has burnt the plastic wrap from around the cable.

It surely leaves a lot of heat in the engine bay and a lot of heat l can do without, l have considered a four into one system.

Like a Pitts S1 for example if performance is an issue with a four into one (or two) they wouldn't use it.

Then some guru's are quoting harmonics, back pressure, balance tubes, pipe diameter, and it goes on and on.

I would like to know.

1.Why haven't there been a system like a Mustang or a spitfire just exhaust stubs.

2. Why are these four pipe cross over equal length pipe systems are installed their heavy, noisy, take up room, makes it hard to do maintainable and a lot of heat where there shouldn't be any.

So, the final question is what's wrong with a four into one system on an RV4.

Thank in advance. Thunda.
 
A couple things..

I am must assume yours has a "4-into-2" with crossover system, meaning 2 pipes exit the bottom. I myself have a 4 pipe with no crossovers,4 exit pipes. These two are the most common, each with different pros/cons. The crossovers offer some resonance damping and scavenge benefits, the 4 pipe is a bit louder with a unique sound. I have seen a couple 4 into 1 pipes (best for smoke systems) made by custom vendors, but I believe the are less compatible with the variations of induction systems, ect.. "Stub Stacks" as you refer AKA Spitfire,have been used on a few racer variants like the Cassutt and some other purpose built machines (very raspy sounding), but do not provide means of carburetor heat, and or cabin heat muffs ect..Also, they will keep the side of the fuselage a bit soot covered and make a mess..unless you want to sheet exit area with thin stainless. You will seldom hear of an RV-4 that runs "hot" based on exhaust heat alone. Mine is actually hard to keep up to temps in the cold, and any hot summer heat is directly attributed to oil temps/oil cooler airflow. Others on the forum may offer some good 4 into 1 suggestions, but I doubt you will see temp changes worthy or weight reduction of changing the system , and most RV-4's need weight up front if you carry much in the back.
 
G'day Larco.
Thanks for that.
looks like Spruce has got an answer to everything.
But me thinks it's time for a 4 into 1 system
I may try and make a system up with pvc pipe and see if a local auto exhaust mob will have a go at it.
 
The solution is just put a vetterman 4 pipe system on it. You can't beat that setup and larrys pipes are the best.

Bob burns
Rv-4 n82rb
 
Agree with Bob, though Larry has retired and Clint is now running things. Vetterman exhausts are very well made.
 
I have the Vetterman 4 pipe system, and love it. The sound, I am told, is amazing when I come by at 180 knots.
 
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Thank for the reply's fellas, but a 4 pipe system is exactly what I'm trying to get away from.

1. Too expensive to get to Australia.
2. Not interested in what it sounds like.

Larrys system's may be good but, I'm better off getting a 4 into 1system built here, a lot cheaper and l get exactly what l want.

But thank again for the comments.
 
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