exhaust back pressure

Not sure if we have exhaust specialists but: My new engine this is being installed has a 2" high rise exhaust elbow. 22 inches away the exhaust hose would enter my wet muffler that is 1 1/2 inch diameter input and exit.

No exhaust expert here buy what problem are you having that would make you want to change anything? I think a 400 HP engine can work with a 2 inch exhaust hose. Add some water and you might need a larger hose but why bother. I had my exhaust system replaced professionally and would get an engine full of water after that. Let me tell you, it is very difficult to start an engine that is full of water. I re-ran the exhaust hose to the highest point in the transom and all is well. I had to learn more than I wanted about exhausts before I did that. It is important that the volume of the exhaust hose after the muffler be less than the capacity of the muffler. Bigger is not always better. Allen On Sun, Jun 12, 2011 at 8:00 AM, Bob Connell <jo… [at] yahoo.com>wrote: > > > Not sure if we have exhaust specialists but: My new engine this is being > installed has a 2" high rise exhaust elbow. 22 inches away the exhaust > hose would enter my wet muffler that is 1 1/2 inch diameter input and exit. > From that exit today there is then a gooseneck (length of hose @ 6 ft) to > get well above the waterline and then to the stainless fitting out the > transom. That fitting is 1 5/8 inches. > > Question: should I replace the muffler with 2 inch input/exit rather than > reduce the short run of hose from 2 to 1.5? If I replace everything with 2 > " but reduce it at the transom to 1 5/8 inches, is the whole reduction thing > for naught? Or must I replace the stainless fitting in the transom too and > if so where would I find something like that? Thanks. > > Bob Connell > "Jollygood!", Cal 31, #59 > Shilshole Bay, WA > > >

Hello Bob, I reduced mine before it entered the muffler. I reduced whatever metric size exhaust hose to a 1 1/2". Works great, however my engine is smaller than yours. Frans On Jun 12, 2011, at 8:00 AM, Bob Connell <jo… [at] yahoo.com> wrote: > Not sure if we have exhaust specialists but: My new engine this is being installed has a 2" high rise exhaust elbow. 22 inches away the exhaust hose would enter my wet muffler that is 1 1/2 inch diameter input and exit.

May I suggest reading this before changing anything http://viewer.zmags.com/publication/066ba269#/066ba269/49 Allen On Sun, Jun 12, 2011 at 8:00 AM, Bob Connell <jo… [at] yahoo.com>wrote: > > > Not sure if we have exhaust specialists but: My new engine this is being > installed has a 2" high rise exhaust elbow. 22 inches away the exhaust > hose would enter my wet muffler that is 1 1/2 inch diameter input and exit. > From that exit today there is then a gooseneck (length of hose @ 6 ft) to > get well above the waterline and then to the stainless fitting out the > transom. That fitting is 1 5/8 inches. > > Question: should I replace the muffler with 2 inch input/exit rather than > reduce the short run of hose from 2 to 1.5? If I replace everything with 2 > " but reduce it at the transom to 1 5/8 inches, is the whole reduction thing > for naught? Or must I replace the stainless fitting in the transom too and > if so where would I find something like that? Thanks. > > Bob Connell > "Jollygood!", Cal 31, #59 > Shilshole Bay, WA > > >