Supra Pirata repower

[Wulphie]

I bought a 1987 Pirata that someone pulled the engine and trans out of (It was on ebay, maybe you saw it) I have not picked up the boat yet but figured I would ask a couple questions before I finalize my plan.

I am not sure if the boat had a small block or big block. Would the boat have a different stringer spacing based on the engine it came with?

Would the boat have a different size dog house?

I have a line on a new Mercury 5.7 engine and trans at a very reasonable price if stringer spacing demands a small block, but I am thinking 260hp will not be enough for the boat and I will be pushing the engine hard all the time. Any thoughts?

There is a crusader xl 454 for sale near me that I could look at but not sure if it will fit under the dog house and not sure which PCM transmission I would need for this. Any thoughts?

It might sound crazy but I might just pull the 351 from the boat I have now and see if I can live with a small block in the Pirata and then make a decision on repower from there.

Thanks in advance for the help.

[92SupraComp]

An 80's will have a Chevy Big Block and a 90's will have a HO 351W. That 5.7, would leave you underpowered...

[haugy]

An 80's will have a Chevy Big Block and a 90's will have a HO 351W. That 5.7, would leave you underpowered...

That's not accurate. My 90's has a 454. There was no set specific for that boat.

To the OP, from what I've been told stringers will be different from Big Block to small block, but if you had the big block and want to go small block that's no problem. You can fabricate new motor mounts with wider arms. Easy. But if it did have a small black and you want to shove a big block in you might have problems. We are talking inches, but still.

Now I haven't seen and measured the width of a Saltare/Pirata with a 351w versus my 454, but I do know my 454 doghouse is huge compared to my old Mariah's 351 doghouse. And the motor mounts look exactly the same in style. Which would lead me to believe that the wider 454 block would need a wider stringer layout.

With that in mind. If I were you, I'd build a 351w stroked to 393 or even 409. A 393 stroker is very strong and reliable, and will put out around 400hp. Plenty for that boat. The 260hp from the engine you are considering and the 280 from the 351w would work, but you won't have the pop out of the hole. You would definitely want the 1.23:1 tranny.

You can build a 351w stroker for a budget price if you build smart and right the first time. If I picked up another big girl I'd go that route. Smaller, lighter engine with more power and about the same fuel consumption as a 454 stock (which sucks).

[cadunkle]

If it was me I'd see your situation as a golden opportunity to do a 460. Won't cost any more to build than a small block (and should be less than a stroked small block) but there will be more expense to marinize it. If you find a complete marine 460 you could minimize those costs. I'm a BBF guy, cheap easy power and a superior design than the 454. I'd do ported iron heads, more weight IMO is an advantage in a big boat like a Saltare or Pirata because you're not buying the biggest/widest/heaviest hull Supra made if your primary interest is slalom. Factory iron will support more HP than you'll make with a cam suitable for wet exhaust.

Not sure on stringer differences, maybe they were different as Haugy says but my guess would be any differences would be taken up with mounts or spacers. We have several of us here with Saltares and Piratas with 454 and I know at least one with a 351w, maybe we could get measurements on width between primary stringers and the height and dimensions of the mounting areas.

[Wulphie]

Thanks for the input guys.

I plan on picking up the Pirata this weekend so I can compare stringer measurements to the boat I have now.

I was originally hoping the boat was set up for a bigblock but Haugy has me thinking about the size of the doghouse and now I am hoping small block hahaha.

At this point I am thinking if the boat checks out sea worthy (gas tank good, stringers dry etc.) I will drop my 351 in and run the boat to see if the boat is a keeper. If its a boat I like and plan to keep for a couple of years I have no problem building a stroker motor.

By the way here is a link to pictures of the boat. . . http://www.boatangel.org/photos/JL23452-1987-Supra-Kevlar-23ft-wTrailer-photos-VirginiaBeach-VA/

[bens250ex]

I saw the boat on ebay, might want to check the stringers before slapping a engine on it. They kind of looked like they could need some attention.

[Wulphie]

Yes, plan on checking to be sure it is sea worthy before I run it this season. It would be great if I didn't need to rebuild the stringers but if I do its not the end of the world. I already have a boat that works fine so I could take my time and do the Pirata right.

Haugy has a point about the size of the engine box on the big block so right now I am hoping the boat was set up for a small block and I am fine with building a stroker motor over the winter if I decide its a boat I want to use for a couple seasons.

Thanks for the input guys. . .

[Wulphie]

Just a FYI, the Pirata I bought did come with a 454 and the stringer spacing is the same as my Brendella supercomp with a 351w. So it would seem a Pirata with a 351w would be the same as well. Only thing different is the distance from engine mount to trans mount is longer on the big block setup.

One question I still have for the guys with big blocks, what trans do you have? There is a engine and trans near me for sale, it has a Velvet drive model 10-18-002 trans 1 to 1 gear ratio. Is that the correct one?

Thanks.

[haugy]

Model I'll have to check. I do have a 1:1 transmission in mine.

[lively]

10-17-004 1:1 for the 351w sunsport


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[SquamInboards]

I don't think the transmission really matters, as long as you prop it correctly...

Also on the doghouse - you may just be able to build up the base to adjust for a different engine, assuming it's a two-piece with a plywood bottom part. I had to add about 3-4" to mine (I just rebuilt the whole bottom section) to accommodate the GT-40 with its big upper intake plenum, plus the MEFI box on the back. MUCH easier than a new doghouse!

[Century63]

Purchased a 1988 Pirata 4 years ago. Had 1000 hours on it and the 351 with velvet drive 71C 1:1. The boat would only go 3600 rpm. Took it to Donnie Bennett along with a 454 out of a 1987 Saltare that was being parted out. Bought the entire drive train engine thru prop. Took that to Donnie along with the boat. He had never seen so much water logged foam and rotten floor and stringers. He replaced the stringers and the floor and put the 454 drive train back into the boat. The prop on the 351 was a 13x13 and the 454 had a 14x13. Also the hp in the 351 was 240 and the 454 was 330. Donnie told me there was a difference in the stringers from one set up to the other and he made the adjustment when he replaced the stringers for the big block. I do not believe the doghouse needed any modification. He would be the one to talk to. Also, I still have the 351 drive train for sale.

[Wulphie]

Yeah, running the exhaust outside of the main stringers through the foam wasn't the greatest idea. The boat I bought was rack stored but the crappy supertrapp setup leaked and the foam soaked it up like a sponge and rotted the floor from underneath. Stringers are rotted a little where the cross supports are but ok otherwise. I already ripped out the foam and put a floor in. (if I decide to keep the boat I will do stringers over the winter) I picked up a engine package but realized today that mercruiser manifolds have longer runners than pcm so the complete engine is a couple inches wider and will not fit under the dog house. Bummer because it is such a clean package.

Btw, how does your boat drive? I love the idea of a dd cuddy. The more I work on the boat the more I become worried I will do a bunch of work and be disapointed in the performance.

[Century63]

The boat runs well. Runs around 4100 and would like it to run 4500. Have ordered an ACME 541 and will try it out in a couple of weeks. Have a 1963 Century that has a 425 Buick and it runs 5000 flat out. Need for more speed. 1474114741

[Wulphie]

I don't really care about the speed more about how the boat drives, bow lift getting on plane , cornering, holding speed etc etc. . .

If you want more speed you should look for a Allison with a 300 on it, cheapest way to break 100mph.