More speed, hop up kits? Volvo 5.0 GXi

[capecoralbill]

I have a 2004 glastron 205 (29 ft) bowrider. I'm getting approx 55 mph with a 21 ss prop at 5100rpm. The engine is a 5.0 GXi SX. Does anyone have any hop up kits that will work with the fuel management system (bolt on) to give me more power and speed? Thanks

 

[bjcsc]

Re: More speed, hop up kits? Volvo 5.0 GXi

I think you may be at the limit of your hull and engine. Sounds like you're getting every ounce out of it to me. Depending on how much room you have, you could opt for a supercharger. There are several made for marine engines. 55mph on a 29' BR with a single Volvo 5.0 shows you both what these engines can do and that yours is running in peak condition...

Here's a <a href="http://www.procharger.com/marine/M_tech_specs.shtml"target="_blank">link</a> to one of the supercharger sites.

That said, if you want a go fast you might be better off trading in for a go fast instead of trying to make one out of a BR...

 

[Silvertip]

Re: More speed, hop up kits? Volvo 5.0 GXi

First, verify your tach. If its accurate, go up in prop pitch to get the RPM down. You are over reving. Adding a blower will stress the outdrive. Add a scatter shield around the bottom of the engine. When rods go through the pan they will likely continue on through the bottom of the boat. A 5.0 (even in a car) was never a high performance engine due to limited breathing ability from small valves. BJCSC has the right idea. Buy a faster boat.

 

[capecoralbill]

Re: More speed, hop up kits? Volvo 5.0 GXi

Sorry, I had a typo......it is a 20 ft bowrider, not a 29. sorry.

 

[rodbolt]

Re: More speed, hop up kits? Volvo 5.0 GXi

there are several companies that offer various kits for marine use, none are cheap and most will require a gear ratio change in the drive.
best thing is to keep your current set up well maintained or purchase a larger power plant.
the small block transom shield is good to about 350 HP then you will need the larger big block shield. the SX case is rated to about 450 HP and you can purchase a 425 Hp 8.1 from volvo.
most car mods dont work real well in the marine world as most car mods tend to shift the power curve to high.
big lumpy cams that can twist to 7K tend to not make enough power at low speeds to accelerate a boat. prop speeds,until you go surface piercing, dont like much more than 2500prop shaft RPM.
what kind of RPM is your setup currently running ?