some old lady around here was told by her "mechanics" that they had to fabricate double y joints on her f250 460ci 1979 exhaust, and charged her out the ying yang they did....as far as my knowledge goes you can use 2 inch pipe off headers or stock manifolds to what ever mufflers you want, providing there is sufficient back pressure......they said it was a "heat" issue...never heard of such a thing...so i looked under the truck and there was only a single y colllecting off the manifolds into one pipe into a stock muffler...now my question is...is there any special "voodoo" to consider when dual exhausting a propane big block?

 

Not that I've ever been aware of. My 89 460/propane has had duals with the factory manifolds since the first it's first muffler job. I don't know what to say man, my drivers side pipe is bent in between the flywheel cover and oil pan but I doubt that cost a whole lot. Who is the 'some old lady' and how did you get involved... if it's that gross of an injustice and they charged out the ying yang for something they didn't do then a call to the police is probably in order.

 

I think someone is feeding you a load of crap. Propane burns better than gasoline, so there really is no reason for you not to be able to use a dual exhaust setup. It's just like high octane gas.

 

all of the dual fuel vehicles I have ever seen have a single exhaust, as far as I am aware, propane runs a shade cooler as it is more efficient. If it was a heat issue, they would require stainless exhaust, not a separate exhaust. Somebody's pulling a fast one. For an example, consider forklifts, they run inside closed buildings for hours, and the exhaust on them is the same thing you see on regfular automotive stuff, and if the exhaust was hotter, it would be hotter coming out, and OSHA would have some kind of ruling on that too, but it doesn't come out any hotter that I ever noticed...

 

The only thing I would do for a dual exhaust is add a cross over tube as close to the headers as possible to add more low speed torque.

 

a what?...not like a y....

 

No.
A "Y" would be 2 into 1 for a single exhaust.

If you have 2 separate exhaust tubes, one for each side it's called dual exhaust.
If you add a tube connecting the two, it effectively doubles the available area for the gases to go when one valve on one side or the other opens reducing back pressure.

It does not seem like it would be much, but it is.

High performance race cars once used a double crossover tube in an "X" pattern to make the flow as smooth as possible at extremely high Rpm's.

 

my 79 propane 460 has dual exhaust off of the stock manifolds... runs great

 

Add a crossover tube and you get more torque without losing any HP at all!

A rather cheap performance upgrade!