Want to repower my aq151c with a V8.

[Red28]

The boat has a AQ151C in it now. The outdrive is a SP-A volvo penta. Numbers on the drive that i found are
854019
SPA 215
3102054224
My motor is going bad and insted of rebuilding it, I would like to replace with a more powerfull setup. What motor would work for this. I know there is not a direct fit v8 for this but if the motor will work with my outdrive i can fab mounts ect...
Thanks

 

[HorizonblueDK]

Re: Want to repower my aq151c with a V8.

Your outdrive will not work with a V8, the gear ratio is way too low. You need a 1.61:1 ratio. You have 2.15:1 now. The ratio is found in the lower unit, so it is enough to change that, not the complete outdrive. But sometimes it is easier to change the complete outdrive.

A larger propeller only, will not do the job properly.

Replacing the lower unit on a 270/280/290/SP drive is not just a bolt on and go, one bearing must be shimmed correctly.

You need another bell housing and flywheel coupler, and a solution to the exhaust problem. Either an original Volvo Y-exhaust horn or directly through the transom.

 

[Red28]

Re: Want to repower my aq151c with a V8.

Thanks for your respose HorizonblueDK.
I picked up an old wellcraft with a 350 volvo penta set up and a 280 outdrive for 500 bucks! I think this should have all the pices i will need. Should be able to install the lower 280 on my SP upper with the proper shiming of bearings. That will give me the right ratio. I will have to glass in some suports for the motor mounts but that should not be that bad.
If there is anything that im not thinking of please let me know.

 

[HorizonblueDK]

Re: Want to repower my aq151c with a V8.

2 things:

You need a new driveshaft in the V8 bellhousing, since the older ones had coarse splines. Your SP drive has fine splines in the universal joint yoke. Depending on what type of universal joint you have(inner or outer circlip), you can replace the yoke only, instead. If you have inner circlip, you can find a yoke with coarse spline and replace that one.
I will not recommend it though, since you will get more noise in the boat, when turning. Coarse spline connection between driveshaft and universal joint is prone to make noise when turning.

The exhaust horn from the 280 drive does not fit the SP transom.