mercruiser 5.7
New member
I have a 22ft Mariah fitted with a Mercruiser 5.7L v8 engine which breathes through a 2 barrel rochester carb. The top speed of the boat is around 40 mph on a good day. The boat is currently fitted with a 3 blade / 17 pitch prop. I have tried different prop pitches and this seems to be the best for the boat. Max revs are around 3800 to 4000rpm in water.
I am looking to increase the top speed by increasing the power of the engine.
1- Has anyone experience of fitting a K&N air filter or a perfomance carb spacer to this type of engine and what (if any) speed increse was achieved? ie is it worth speeding the approx £200 on these parts?![Confused :confused: :confused:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
2 - Is it better to replace the intake manifold so that it accept a 4 barrel carb? I have seen a 2 bbl to 4 bbl conversion kit from the US which promises better performance - as per link below. Has anyone bough/fitted one and did it provide any extra power / top speed?
How easy is the removal / relacement of the intake manifold / Is there anywher ein the uk which sells such an upgrade?
http://marine-performance-parts.com/2bbl4bblconversionkits.aspx
Any thought / experience gratefully received.
I am looking to increase the top speed by increasing the power of the engine.
1- Has anyone experience of fitting a K&N air filter or a perfomance carb spacer to this type of engine and what (if any) speed increse was achieved? ie is it worth speeding the approx £200 on these parts?
2 - Is it better to replace the intake manifold so that it accept a 4 barrel carb? I have seen a 2 bbl to 4 bbl conversion kit from the US which promises better performance - as per link below. Has anyone bough/fitted one and did it provide any extra power / top speed?
http://marine-performance-parts.com/2bbl4bblconversionkits.aspx
Any thought / experience gratefully received.