Alpha 1 Exhaust Restriction

[bazza]

Does the Alpha 1 leg restrict the exhaust in any way? The exhaust baffle failed at the weekend. Top speed was up 5mph and the engine generally felt more responsive.

Does this mean that there is a blockage in the leg somewhere causing an increase in back pressure? Prior to the baffle failing performance was below par. Now it performs as it should!

Engine is a 5.7 litre Mercruiser. The boat has sat in fresh water for 2 years with very little use.

Thanks in advance,
Baz.

 

[byron]

I cannot answer your question as my knowledge of such matters is limited. I can however tell you this. Any exhaust restriction whether intentional or not will restrict the power output of a unit.
Having said that, no doubt the manufacturers have the 'restriction' there for a purpose.

 

[bazza]

Oops - bellows, not baffles!

 

[enterprise]

I think you are refering to the exhaust shutters, these stop water entering the engine via the exhaust if the engine is not running.

They do fail, usualy the rubber encased metal shutters "chatter" within the cowhorn if the rubber has dissintigrated.

If pieces have started to drop down into the cowhorn then yes it would cause an obstruction & yes it would be noticable if it suddenly cleared but they do an important job & should only cause problem if damaged or broken, best check that it was the shutters & replace if found to be missing or damaged.

A note of caution:
After an overheat this hapened to us, the shuters droped into the cowhorn causing problems shifting gear, resulting in the shift interupter stalling the engine as we tried to berth, could have been a very expensive day without good neighbouring bertholders. /forums/images/graemlins/frown.gif

 

[syd]

Sounds like you definately need to have the leg exhaust channels cleaned. A restriction/blockage in the leg probably put more pressure on the bellows and helped it to pop. These engines generally need little back pressure and can be used with straight through exhausts.

Syd