Generator Exhaust Hose - Different I.D.'s

As long as you got the hose on far enough to double clamp it I don't see why it would create an unsafe condition. I can't picture the hose splitting. I would think after several heat cycles the hose would take a "set" and be fine.

I would not do it. The larger flange will push the wire through the hose because of the extra force put on the smaller hose and it will prematurely wear out. Just but the right size hose.

While I really don't think it would be an issue, I'd still use the correct size hose if you can.

Why not just do the job properly and buy a reducing fitting?

Centek Industries - Products

Why add another part/fitting into the equation and another thing that could cause a problem when the correct size hose is easy enough to come by and cheap enough to do it right and keep it simple......

The reason the discharge side of the muffler is larger, is so that the exhaust is quieter less pressure out the exhaust and also so that the exhaust/water mix loses velocity and doesn't shoot 2' out of the thru-hull in the side of the boat..........

Hi,

An 1/8th inch difference will make what is commonly known as a poofteenth of difference to back pressure, velocity etc.

You are being a scare monger.

I guess I misread the OP and took it as the outlet of one was smaller than the inlet of the other or vice versa and the misfit ends had to be connected.

If the generator exhaust elbow is the same size as the muffler inlet (2-1/2") then that is the size of hose to use. If the outlet from the muffler to the through hull is 2-3/8" then that is the size of hose to use.

It is not good practice to try and force a smaller hose on the fittings just to save less money than might be spent having a beer or three after the job is over.

It depends on the length of the run. The longer the length, the more difference that 1/8" will make. Over a 3' run, probably a proofteenth of a difference. Over a 20' run, probably a noticeable difference.

There is about a 1mB difference between 2.375 and 2.5 inches over a meter and about 5mB difference between them over a 6 meter run.

That is based on the exhaust flow of a 12kW generator at 60Hz and full load.

Not enough difference to try to kludge a smaller tube over a larger fitting just to save a couple of dollars.

Hose

Read the op again, the inlet into the muffler / water trap is 2.5" and the discharge is 2.375", kind of blows (sorry for the pun) your velocity theory away.

Now if it was the other way around I could see your thinking however (as usual) you are blowing hot air out of you know what.

Use the correct size hose for each fitting if for no other reason that if it failed and sunk the boat you may get a smart insurance company surveyor noticing your fix and try and deny the claim.

I have seen very very few AWAB hose clamps fail in all of my years. They are a very very good hose clamp......ABA is close as well..... but both of these will outlast a standard shields or Breeze hose clamp etc 3 times over and doesn't cut into the hose. I replace all broken hose clamps with AWAB.

I misread which was used on which side, but depending on what you want to achieve as long as it stays within manufacturers specs. The smaller size can be used to increase exhaust velocity and restrict chances of backflowing into the generator if the exhaust comes out on the transom. Ever see a generator where the exhaust water shoots out 12-24" out of the exhaust? Ocean yachts did this on many of their SF. increasing exhaust size not only increases flow, but the water doesn't shoot out as far, and it does quiet it a tad as Marmot mentioned.

To the OP If I remember correctly, Onan's size on the Elbow is 2 5/8" for some strange reason on those gens.