Mercruiser 3 Inch to 4 Inch Exhaust
Question: I Currently Have the Mercruiser Center Rise Style 3" Exhaust or the Old Log Style Exhaust System. Can I Convert to the Later, Better Performing 4" Center Rise Style Exhaust?
Yes it is very common to convert over to the later style 4" center rise style exhaust. The main reason being associated with the performance benefits the less restrictive 4" system offers. There are two main factors that need to be confirmed.
- If you currently have the log style system – do you have a power steering or alternator bracket that attaches to the front of the exhaust manifold? If you do there is no provision on the current center rise style exhaust for this. Therefore this will have to be addressed.
- If you have the old style Y-Pipe (bullhorn) shown in the image below you will be required to make modification on the connection to the Y-Pipe. The intermediate exhaust elbows are angled differently than what is required for the current 4" exhaust and there isn't a good, off-the-shelf match to fit the 4" exhaust to this Y-Pipe without some additional work.
