Horsepower rating

[Mani]

Hey guys, I'm new to this forum, and to Supra boats. I bought one about a week and a half ago and I've been snooping around here ever since then.

This is a 1986 Sunsport with the 351W motor. It had a new interior job done recently and so far it has only needed a new raw water pump and some packing rope. The stringer seem to be in good shape as the floor is solid all around.

The point of this thread is that I'm thinking about adding a few things to the motor for HP gain. I can't read the manufacturer plate on the Hull or the Motor and can't tell what the horsepower rating for this boat is. I've tried to find it online with no luck. Could anyone help.

http://photos-c.ak.fbcdn.net/hphotos-ak-snc1/hs171.snc1/6440_241686455033_522820033_8320938_6313354_n.jpg
http://photos-b.ak.fbcdn.net/hphotos-ak-snc1/hs191.snc1/6440_241686445033_522820033_8320937_2276466_n.jpg
http://photos-a.ak.fbcdn.net/hphotos-ak-snc1/hs191.snc1/6440_241686440033_522820033_8320936_63335_n.jpg
http://photos-h.ak.fbcdn.net/hphotos-ak-snc1/hs191.snc1/6440_241686430033_522820033_8320935_995288_n.jpg

[michael hunter]

Welcome to the forum and to the Supra family. My 89 351w is 240hp.
That's a great looking boat you are going to love it.

[agetech]

Get rid of that heavy cast iron intake manifold and bolt up an aluminum intake for a few more horses. A cheap upgrade is to swap the heads with a set of GT40P heads from a late 90's Explorer, they will bolt right up with no manifold or clearance problems. (the head bolt holes will need to be drilled to 1/2" from 7/16" in the head) After that you could go with an aftermarket cam, the cam companies will be happy to recommend a cam for your boat. Also upgrade the distributer to electronic and get rid of the points. These mods should give you another 40 horses onto the 240 you have now.

[csuggs]

Great looking boat! Welcome to the family and the forum, too. I also have an 86 Sunsport Skier with 351W. The nameplate numbers on the PCM engine translate to 255hp, but the 1986 Supra owner's manual says that it's 240hp. So I'm not sure which is correct?
There's lots of good info on this forum for you to search. And again, welcome!
;)

[Mani]

Thanks a lot for the props guys. The title tells me it's 240 HP. I knew that. I guess I worded the question wrong.

I'm wondering what the maximum horsepower rating is for the Hull. I don't wan't too put too much horsepower in it and sink the boat.

[csuggs]

In 1986 you could buy that boat with a 351W or 454. The big block was rated at 330hp. Will it handle more? I dunno. Has someone out there pushed it with more than 33o ponies? I'm sure of it.

[mapleleaf]

With a gelcoat like that, who cares if the trailer wheels match... That boat Looks great!!!! Welcome to the forum, lets see her in action.......
.

[Mani]

Csuggs, Thanks for the info. I doubt I'll be pushing that 351W to over 330 HP. Probably closer to 280 or 290 and a four blade prop.

Mapleleaf, I'm the only one of my friends with a boat. I could get some action shots from the dock, or from inside the boat, but no good pics from another boat. :(

I've got a new raw water pump on the way along with some new water hoses, as the impeller pooped out on me last weekend. Upon further inspection I realized that the pump was just better off completely replaced.

Thanks again to all for being so welcoming.

[beast 496]

I have a 1985 Beast, which is basically the same hull. I removed the original 454 which was 330 hp and installed a new 496 HO which is 425hp. No problems at all. Once the hull reaches around 50 mph, you are basically overpowering the hull and plowing. Tops out at 52 mph with light load. Allan

[87SunSportMikeyD]

Mani you will find that these boats do not work well with a four-blade prop. This is what all the manufacturers have told me, and someone on these boards tried it anyways with poor results. The reason I believe it because newer boats use a larger diameter propellor. This allows for greater surface area and the fourth blade is much more effective. With smaller blades (over a half-inch smaller on each blade) the fourth blade just churns the water and causes lots of cavitation.

What you want is the ACME #913 which is a 13x10.5 LH 1"bore tapered. This gives you a TON more power, it rips out of the hole even fully weighted. Your new top end speed is about 36-38mph at about 4200rpms although I was told you can push it to 4600rpms without damage, however the boat does not have a rev-limiter like a car so be mindful.

Love the boat, there are one or two others with the blue allover paint and they are really cool. The interior looks like a really really good job of matching the original.

Are you planning on wakeboaridng/surfing behind her? Tower? Tell us more! :) Keep those pics coming, we love pics.